JP3104529B2 - Variable valve timing device and hydraulic control valve thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing device used to change the operation timing of intake and exhaust valves of an engine.

[0002]

2. Description of the Related Art Conventionally, as this kind of technology, there is a technology previously proposed by the present applicant in Japanese Patent Application No. 5-256132. This prior art shows an example of a variable valve timing device provided in an engine.

[0003] As shown in FIG. 8, this device includes a variable valve timing mechanism (VVT) 63 including a timing pulley 62 provided on a camshaft 61. The VVT 63 has a ring gear 64 interposed between the pulley 62 and the camshaft 61 inside the timing pulley 62. The ring gear 64 has helical teeth on the inner and outer circumferences, and the cam shaft 61 and the timing pulley 62 are connected via the helical teeth and the like. The camshaft 61 operates an intake / exhaust valve (not shown) based on the rotation. The timing pulley 62 is drivingly connected to a crankshaft (not shown) via a timing belt 65. When the ring gear 64 moves while rotating along the axial direction of the camshaft 61, the rotation phase between the shaft 61 and the timing pulley 62 is changed, and the operation timing of the intake / exhaust valve is changed.

Here, in order to move the ring gear 64, the gear 64 is moved inside the timing pulley 62.
The first and second hydraulic chambers 66 and 67 are provided on both sides of the first hydraulic chamber, respectively. Lubricating oil stored in an oil pan 68 can be supplied to the two hydraulic chambers 66 and 67 through two oil paths 70 and 71 based on the operation of an oil pump 69.

In order to control the supply of hydraulic pressure to the hydraulic chambers 66 and 67, a hydraulic control valve (OCV) 72 is provided midway between the hydraulic passages 70 and 71. This OCV72
Has a sleeve 73, a spool 74, and a solenoid 75. The sleeve 73 has an introduction port 76 for introducing the hydraulic pressure discharged from the oil pump 69, and first and second discharge ports 77 and 78 for supplying the hydraulic pressure to the first and second hydraulic chambers 66 and 67, respectively. , Each hydraulic chamber 6
First and second drain ports 79 and 80 are provided for draining the oil returning from the oil pans 6 and 67 to the oil pan 68. Then, by moving the spool 74 by the solenoid 75, the supply of the hydraulic pressure to each of the hydraulic chambers 66 and 67 and the drain of the oil are switched.

[0008] Here, the state of the spool 74 shown in FIG. 8 is set to the neutral position, and the spool 74 is moved from the position to the left in FIG.
And the second discharge port 78 communicates with the second drain port 80. As a result, the hydraulic pressure from the oil pump 69 is supplied to the first hydraulic chamber 66, and the ring gear 64 is moved rightward in FIG.
The oil in the second hydraulic chamber 67 is drained to the oil pan 68. The movement of the ring gear 64 causes the camshaft 6
One rotation phase is advanced. The movement direction of the ring gear 64 for cam advance is called an advance direction.

On the other hand, by moving the spool 74 to the right in FIG. 8, the introduction port 76 communicates with the second discharge port 78 and the first discharge port 77
To the drain port 79. As a result, the hydraulic pressure from the oil pump 69 is supplied to the second hydraulic chamber 67, and the ring gear 64 is moved leftward in FIG.
The oil of No. 6 is drained to the oil pan 68. Due to the movement of the ring gear 64, the rotation phase of the camshaft 61 is retarded. Thus, ring gear 6 for cam retardation
4 is called a retard direction.

Further, as shown in FIG. 8, by holding the spool 74 at its neutral position, the ring gear 64 can be held at an intermediate position between the advance and the retard. Here, since the camshaft 61 receives a driving reaction when the intake / exhaust valve is operated, a rotational force due to the driving reaction acts on the ring gear 64. In the prior art, the ring gear 64 receives a reaction force that moves in the retard direction due to the relationship between the rotational force and the direction of the helical teeth. Therefore, in the prior art, in order to hold the ring gear 64 at the intermediate position, a neutral pressure is applied to the first hydraulic chamber 66 in consideration of the reaction force received by the gear 64 in consideration of the reaction force. The relationship between the spool 74 and the sleeve 73 at the position has been set. That is, as shown in FIG. 9, when the spool 74 is held at the neutral position, the space between the introduction port 76 and the first discharge port 77 is slightly opened, and the second discharge port 78 and the second drain The relationship between the spool 74 and the sleeve 73 is set such that the space between the spool 80 and the port 80 is substantially closed.

[0009]

Therefore, in the prior art, when the spool 74 is held at the neutral position, the space between the ports 78 and 80 is substantially closed, so that the connection between the spool 74 and the sleeve 73 is prevented. Although there is a small gap between them that allows the movement of the spool 74, very little oil can pass between the spool 74 and the sleeve 73 at both ports 78 and 80. Furthermore, foreign matter such as minute metal powder may be mixed in the oil. Therefore, if the holding state as described above continues for a while, the flow of oil stagnates near the second discharge port 78, and foreign matter in the oil accumulates at that portion, and the foreign matter is There is a risk of being caught between the sleeve 73 and the sleeve 73. Further, in order to always adjust the intermediate position of the ring gear 64 optimally, it is conceivable to slightly vibrate the spool 74 in the axial direction. Tends to be problematic.

The present invention has been made in view of the above-described circumstances, and has as its object to provide a device driven by switching a hydraulic path by a hydraulic control valve. An object of the present invention is to provide a variable valve timing device that can prevent a foreign object from being caught.

[0011]

According to a first aspect of the present invention, there is provided a camshaft of an engine and a timepiece provided on the camshaft.
A ring gear is interposed between the pulley and the ring pulley.
The supply of hydraulic pressure to the first and second hydraulic chambers provided at both ends in the axial direction of the gear is controlled by a hydraulic control valve, thereby rotating the ring gear while moving it in the axial direction.
To twist the camshaft,
A variable valve timing device configured to make the operation timing of the valve variable, wherein the hydraulic control valve includes a sleeve that movably accommodates a spool, and an introduction port for introducing a predetermined hydraulic pressure to the sleeve, First and second discharge ports for supplying hydraulic pressure introduced from the introduction port to the first and second hydraulic chambers, respectively, and a drain port for draining oil returned from each hydraulic chamber are formed. By moving the spool and selectively switching the communication of each discharge port to the introduction port and the drain port, the supply of hydraulic pressure to each hydraulic chamber is switched to move the ring gear , and the spool is held at the neutral position. By supplying a slight hydraulic pressure to the first hydraulic chamber, the ring gear is driven against the reaction force of the camshaft.
In the variable valve timing device which is held at an intermediate position in the moving direction , a spool is arranged at a neutral position to supply a hydraulic pressure introduced from an introduction port through a first discharge port to a first hydraulic chamber. When suppressing oil leaking from the second hydraulic chamber to the drain port through the second discharge port, a first valve formed between the spool and the sleeve between the second discharge port and the drain port. When the closing margin is supplied to the second hydraulic chamber with the hydraulic pressure introduced from the introduction port through the second discharge port, and the oil leaking from the first hydraulic chamber to the drain port through the first discharge port is suppressed. In addition, it is intended to be set smaller than a second closing margin formed between the spool and the sleeve between the first discharge port and the drain port.

According to a second aspect of the present invention, there is provided a camshaft for an engine.
And the timing pulley provided on the shaft
A ring gear is interposed between the two ends of the ring gear in the axial direction.
By controlling the hydraulic pressure control valve supplies the hydraulic to the first and second hydraulic chambers provided corresponding to, phosphorus
Gear shaft while moving it in the axial direction
Torsion, and the operation timing of the intake and exhaust valves
A variable valve timing device in the ring so as to vary the hydraulic control valve includes a sleeve movably accommodating the spool, and the introduction port for introducing a predetermined oil pressure in the sleeve, the inlet port First and second discharge ports for supplying the hydraulic pressure introduced from the first and second hydraulic chambers, respectively, and a drain port for draining the oil returned from each hydraulic chamber, are formed. To shift the ring gear by selectively switching the communication of each discharge port to the introduction port and drain port.
It causes the movement, by supplying a slight pressure to the first hydraulic chamber to hold the spool in the neutral position, the ring gear
In the middle of its movement direction against the driving reaction force of the camshaft
In the variable valve timing device, the spool is disposed at the neutral position, and the hydraulic pressure introduced from the introduction port through the first discharge port is supplied to the first hydraulic chamber, and the second hydraulic pressure is supplied to the first hydraulic chamber. When suppressing oil leaking from the chamber to the drain port through the second discharge port,
A first closing gap formed between the spool and the sleeve between the second discharge port and the drain port is introduced into the second hydraulic chamber from the introduction port through the second discharge port. When supplying oil pressure and suppressing oil leaking from the first oil pressure chamber to the drain port through the first discharge port, the oil pressure is formed between the spool and the sleeve between the first discharge port and the drain port. The first closing margin is formed to be larger than the gap of the second closing margin to make the oil passing resistance of the first closing margin almost equal to the oil passing resistance of the second closing margin. It is intended to be set to be larger than the closing margin. Achieve the above purpose
According to the third aspect of the present invention,
Is driven by switching the hydraulic path
Yes to change the Barubutai timing of the intake and exhaust valves of Jin
Used for variable valve timing device and spool
Equipped with a sleeve that movably accommodates
Is an introduction port for introducing a predetermined hydraulic pressure and its introduction
Hydraulic pressure introduced from an inlet port is supplied to first and second hydraulic passages.
And second discharge ports for supplying respectively to the
Drain the oil returned from the first and second hydraulic passages.
To form a drain port for moving the spool
Each outlet port to the inlet port and drain port.
Switch the communication of the spool and neutralize the spool.
Position and supply some hydraulic pressure to the first hydraulic passage
To the hydraulic control valve of the variable valve timing system
And the first hydraulic passage pair
And introduced from the introduction port through the first discharge port.
The hydraulic pressure is supplied to the second discharge port from the second hydraulic passage.
When controlling oil leaking to the drain port through
Spoon between the second discharge port and the drain port
The first closing margin formed between the
To the second hydraulic passage through the second discharge port.
Supply the hydraulic pressure introduced from the
Leaks oil to the drain port through the first discharge port
When suppressing, the first discharge port and the drain port
A second formed between the spool and the sleeve in between
The purpose is to set it smaller than the closing margin of
You. In order to achieve the above object, the fourth aspect of the present invention is described in claim 4.
In the invention of the fourth aspect, by switching the hydraulic path,
Driven by the valve timing of the intake and exhaust valves of the engine
Variable valve timing device
Also equipped with a sleeve that accommodates the spool movably
The sleeve has a guide for introducing a predetermined hydraulic pressure.
The inlet port and the hydraulic pressure introduced from the
And a first and a second for supplying respectively to the second hydraulic passage.
A second discharge port and return from the first and second hydraulic passages;
And a drain port for draining oil
And move the spool to the introduction port and drain port.
Selectively switching the communication of each discharge port to
Then, hold the spool in the neutral position and place it in the first hydraulic passage.
Variable valve timing system to supply dry hydraulic pressure
Position the spool in the neutral position.
To the first hydraulic chamber through the first discharge port.
And a second hydraulic passage for supplying hydraulic pressure introduced from the port.
Leaking from the oil to the drain port through the second discharge port
When the second discharge port and the drain port
Between the spool and the sleeve between
1 with respect to the second hydraulic passage,
Supply hydraulic pressure introduced from the introduction port through the discharge port.
Supply and from the first hydraulic passage through the first discharge port
When suppressing oil leaking to the drain port
Spool and slot between outlet port and drain port
Larger than the gap of the second closing margin formed between
The first closing margin and the second closing
In order to make the oil flow resistance approximately equal to the
That the filter is set to be larger than the second closing margin.
are doing.

[0013]

According to the first aspect of the invention, the spool is held at the neutral position and a slight oil pressure is supplied from the first discharge port to the first hydraulic chamber, so that the ring gear is driven.
Position in the moving direction against the reaction force of the drive shaft
It is held in. At this time, the amount of oil returning from the second hydraulic chamber to the second drain port is extremely small. However, in the present invention, since the first closing margin between the second discharge port and the drain port is relatively small, the oil flow resistance at the closing margin is relatively small.

Accordingly, the amount of oil leaking from the second discharge port to the drain port increases as the oil flow resistance decreases, and the leakage flow increases, so that foreign matter in the oil near the second discharge port easily flows.

According to the second aspect of the present invention, the spool is held at the neutral position and a slight oil pressure is supplied from the first discharge port to the first hydraulic chamber, whereby the ring gear is rotated.
Is in the middle of its movement direction against the driving reaction force of the camshaft.
Held in position . At this time, the amount of oil returned from the second hydraulic chamber to the second discharge port is extremely small. However, in the present invention, since the gap of the first closing margin between the second discharge port and the drain port is formed large,
The larger the gap, the more easily the foreign matter in the oil passes through the first closing margin. Further, according to the configuration of the third invention,
If the first closed port between the second discharge port and the drain port
Because the margin is relatively small,
The oil flow resistance is relatively small. Therefore, the leakage current is large.
Foreign matter in the oil near the second discharge port
Easy to flow. According to the fourth aspect, the second aspect is provided.
The first clearance between the discharge port and drain port of
Because the gap is large, the gap is large
Foreign matter in oil can easily pass through the first closing margin
You.

[0016]

【Example】

(First Embodiment) A first embodiment in which the variable valve timing device according to the first invention is embodied in an automobile engine will be described below in detail with reference to FIGS.

FIGS. 1 to 3 are sectional views showing the structure and operation of the variable valve timing device in this embodiment. This device is configured to be driven using lubricating oil of the engine in order to vary the operation timing of an intake valve (not shown) of the engine.

This device has a variable valve timing mechanism (VVT) 3 including a timing pulley 2 provided at one end of a camshaft 1 for operating an intake valve, and a hydraulic pressure for controlling the supply of hydraulic pressure to the VVT 3. A control valve (OCV) 4. The journal 5 of the camshaft 1 is rotatably supported by a bearing 7 of a cylinder head 6 and a bearing cap 8. The journal 5 is formed with two journal grooves 9 and 10 extending along the outer periphery. First and second head oil passages 11 and 12 for supplying lubricating oil to the grooves 9 and 10 and the journal 5 are formed in the cylinder head 6. In this embodiment, an oil pan 13, an oil strainer 14, an oil pump 15, an oil filter 16
Thus, an engine lubrication device is configured. When the oil pump 15 is driven in conjunction with the engine, the oil pan 13
The lubricating oil is sucked up and discharged from the oil pump 15. After the discharged lubricating oil passes through the oil filter 16, it is pressure-fed to the lubrication system of each part of the engine and is also pressure-fed to each head oil passage 11, 12 via the OCV 4. In this embodiment, an OCV filter 16A different from the oil filter 16 is provided to purify the lubricating oil introduced into the OCV 4.

The timing pulley 2 has a pulley body 17 and
A cover 18 is provided so as to cover one side surface of the main body 17 and the tip of the camshaft 1. The pulley main body 17 has a substantially disk shape, a plurality of external teeth 17a are formed on the outer periphery, and a boss 17b is formed in the center. The pulley body 17 is mounted on the boss 17b so as to be relatively rotatable with respect to the camshaft 1. Pulley body 1
7 is a timing belt 19 attached to the external teeth 17a.
And is drivingly connected to a not-shown crankshaft. The cover 18 has a bottomed cylindrical shape, a flange 18a is formed on the outer periphery, and a communication hole 18b is formed in the center of the bottom. A plurality of internal teeth 1
8c is formed. The cover 18 has its flange 18
At a, it is fixed to the side surface of the pulley body 17 by a plurality of bolts 20 and pins 21. The communication hole 18b has a cover 2
2 is detachably mounted.

In a housing space 23 surrounded by the pulley body 17 and the cover 18, a bottomed cylindrical inner cap 24 is fixed to the tip of the camshaft 1 by a hollow bolt 25 and is prevented from rotating by a pin 26. ing. The peripheral wall 24a of the inner cap 24 is the boss 1 of the pulley body 17.
7b is included so that both 24 and 17 are relatively rotatable. Peripheral wall 24 of inner cap 24
A plurality of external teeth 24b are formed on the outer periphery of a.

A ring gear 27 is interposed between the timing pulley 2 and the camshaft 1, and the two gears 2 and 1 are connected by the gear 27. The ring gear 27 has an annular shape and is accommodated in the accommodation space 23 so as to be able to reciprocate along the axial direction of the camshaft 1. The ring gear 27 has a plurality of teeth 27a and 27b provided on the inner and outer circumferences thereof, both of which are helical teeth, and is rotatable relative to the camshaft 1 by moving in the axial direction. The inner teeth 27 a of the ring gear 27 mesh with the outer teeth 24 b of the inner cap 24, and the outer teeth 27 b of the ring gear 27 mesh with the inner teeth 18 c of the cover 18. Accordingly, when the timing pulley 2 is rotated, the pulley body 17 and the inner cap 24 connected by the ring gear 27 are integrally rotated, and the camshaft 1 is integrally rotated with the timing pulley 2.

In the housing space 23, a first hydraulic chamber 28 is formed between one axial end of the ring gear 27 and the bottom wall of the cover 18. Similarly, a second hydraulic chamber 29 is formed in the accommodation space 23 between the other axial end of the ring gear 27 and the pulley body 17.

Here, a first shaft oil passage 30 extending along the center of the camshaft 1 is formed in the camshaft 1 in order to supply oil pressure by lubricating oil to the first oil pressure chamber 28. The front end side of the oil passage 30 is located at the center hole 2 of the hollow bolt 25.
It communicates with the first hydraulic chamber 28 through 5a. The base end side of the oil passage 30 communicates with the journal groove 9 through an oil hole 31 extending in the radial direction of the camshaft 1.

On the other hand, a second shaft oil passage 32 extending parallel to the first shaft oil passage 30 is formed in the camshaft 1 in order to supply oil pressure by lubricating oil to the second oil pressure chamber 29. . One circumferential groove 33 extending along the outer periphery is formed at a position near the tip of the camshaft 1. A part of the circumferential groove 33 communicates with the oil passage 32. An oil hole 34 is formed in a part of the boss 17b of the pulley body 17 so as to communicate the peripheral groove 33 and the second hydraulic chamber 29. The proximal end side of the second shaft oil passage 32 communicates with the other journal groove 12. Second hydraulic chamber 29
In between the ring gear 27 and the pulley body 17,
A spring 35 for returning the ring gear 27 to the initial position shown in FIG. 3 is interposed.

In the above configuration, the first head oil passage 1
1, oil hole 31, first shaft oil passage 30, and center hole 25
The hydraulic passage for supplying the hydraulic pressure to the first hydraulic chamber 28 is constituted by a and the like. The second head oil passage 12, the second shaft oil passage 32, the oil hole 34 and the like constitute a hydraulic passage for supplying oil pressure to the second hydraulic chamber 29. Here, the above-described OCV 4 is provided in the middle of the hydraulic passage on the upstream side of the head oil passages 11 and 12 in order to control the supply of the hydraulic pressure to the hydraulic chambers 28 and 29.

The OCV 4 has a sleeve 36, a spool 3
7 and a linear solenoid 38. Sleeve 3
Reference numeral 6 denotes a cylindrical shape, and an introduction port 39 for introducing hydraulic pressure from the oil pump 15 and first and second hydraulic chambers 2.
First and second discharge ports 40 and 41 for supplying oil pressure to the oil pans 8 and 29, and first and second drains for draining oil returning from the hydraulic chambers 28 and 29 to the oil pan 13. Ports 42 and 43 are provided. The first discharge port 40 communicates with the first head oil passage 11 and
Is connected to the second head oil passage 12. The first and second drain ports 42 and 43 communicate with the oil pan 13, and the introduction port 39 communicates with the discharge port of the oil pump 15 via the oil filter 16.

The spool 37 has four cylindrical valve elements 37.
a, 37b, 37c, 37d, and are provided so as to be reciprocable in the axial direction along the inner periphery of the sleeve 36. The linear solenoid 38 is operated by energization, and moves the spool 37 to move the spool 37.
Attached to one end. A spring 44 for biasing the spool 37 toward the linear solenoid 38 is attached to the other end of the sleeve 36. Then, by operating the linear solenoid 38, the spool 37 can be moved between a first operating position shown in FIG. 3 and a second operating position shown in FIG.

Then, as shown in FIG.
Is moved to the second operating position, hydraulic pressure is supplied to the first head oil passage 11 through the introduction port 39 and the first discharge port 40, and the second head oil passage 1
2 is a second discharge port 41 and a second drain port 43
Through the oil pan 13. By this switching, hydraulic pressure is supplied to the first hydraulic chamber 28, and the ring gear 27 is rotated while being moved in the axial direction against the urging force of the spring 35 and the lubricating oil remaining in the second hydraulic chamber 29,
Torsion is imparted to the camshaft 1. As a result, the relative position of the camshaft 1 and the timing pulley 2 in the rotation direction changes, and the operation timing of the intake valve is advanced. By supplying the hydraulic pressure to the first hydraulic chamber 28 in this way, the ring gear 27 is moved to a position close to the pulley main body 17 as shown in FIG. The moving end is the maximum advance position for maximizing the valve timing.

On the other hand, as shown in FIG. 3, when the spool 37 is moved to the first operating position,
9 and the second discharge port 41, hydraulic pressure is supplied to the second head oil passage 12 and the first head oil passage 11
Is opened to the oil pan 13 through the first discharge port 40 and the first drain port 42. By this switching, hydraulic pressure is supplied to the second hydraulic chamber 29, and the ring gear 27 is rotated while being moved in the axial direction against the lubricating oil remaining in the first hydraulic chamber 28, so that Opposite torsion is provided. As a result, the camshaft 1
The operation timing of the intake valve is retarded when the relative position in the rotation direction between the motor and the timing pulley 2 changes. By applying the hydraulic pressure to the second hydraulic chamber 29 in this manner, the ring gear 27 is moved to a position close to the cover 18 as shown in FIG. The moving end is a maximum retard position for maximally retarding the valve timing.

On the other hand, as shown in FIG. 1, when the spool 37 is held at the neutral position, only the space between the introduction port 39 and the first discharge port 40 is slightly opened, and both ports 39 are opened. , 40, a slight oil pressure is supplied to the first head oil passage 11. With this arrangement, a slight hydraulic pressure is supplied only to the first hydraulic chamber 28, and the ring gear 27 is held at an intermediate position in the moving direction.

Here, the reason why a slight hydraulic pressure is supplied to the first hydraulic chamber 28 in order to hold the ring gear 27 at the intermediate position is in consideration of the driving reaction force received by the camshaft 1. That is, since the camshaft 1 receives a driving reaction when the intake valve is operated, the ring gear 27
Is given a rotational force based on the reaction force. And
From the relationship between the rotational force and the direction of the helical teeth of the ring gear 27, a moving force toward the maximum retard position is applied to the ring gear 27. In order to secure a sufficient hydraulic pressure against this moving force, a slight hydraulic pressure is supplied to the first hydraulic chamber 28. Therefore, the relationship between the spool 37 and the sleeve 36 at the neutral position is set.

Here, the spool 37 in the neutral position
The relationship between the sleeve 36 and the sleeve 36 is set as shown in FIGS. As shown in FIG. 4, when the spool 37 is held at its neutral position, only the portion between the introduction port 39 and the first discharge port 40 is slightly opened by the valve body 37b, and the introduction port 39 and the second discharge port are opened. The space between the port 41 and the port 41 is closed by the valve body 37c. Further, the space between the first discharge port 40 and the first drain port 42 is closed by the valve body 37b, and the second discharge port 41 and the second drain port 43 are closed.
Is substantially closed by the valve body 37c.

In the above state, the hydraulic pressure introduced from the introduction port 39 through the first discharge port 40 is supplied to the first hydraulic chamber 28, and the second hydraulic port 29 is supplied through the second discharge port 41. Oil leaking to the second drain port 43 is suppressed. At this time, as shown in FIG.
A first closing margin S1 is formed between the spool 37 (valve element 37c) and the sleeve 36 between the second discharge port 41 and the second drain port 43. On the other hand, although not actually performed in this embodiment, the arrangement of the spool 37 may be considered assuming the opposite case. That is, as shown in FIG. 5, the second discharge port 4
When the oil pressure introduced from the introduction port 39 is supplied through the first discharge port 40 and the oil leaking from the first hydraulic chamber 28 to the first drain port 42 through the first discharge port 40 is suppressed, the first discharge port 40 And the first drain port 42
A second closing margin S2 is formed between the spool 37 (valve element 37b) and the sleeve 36 between them. This embodiment is characterized in that the first closing margin S1 is set smaller than the second closing margin S2.

In this embodiment, the opening width (opening diameter) of the second discharge port 41 is made larger than the other, or the axial width of the valve body 37c corresponding to the discharge port 41 is made smaller than the other. As a result, the above settings are made.

With this setting, the spool 37 is held at the neutral position, and a slight oil pressure is supplied from the first discharge port 40 to the first hydraulic chamber 28. Is held at an intermediate position in the moving direction against the driving reaction force. At this time, the amount of oil returning from the second hydraulic chamber 29 to the second discharge port 41 is extremely small. However, according to the above configuration, since the first closing margin S1 between the second discharge port 41 and the second drain port 43 is relatively small, the closing margin S1 is small.
The oil flow resistance in No. 1 is also relatively small.

Therefore, the second oil flow resistance is reduced by the small amount.
The amount of oil leaking from the discharge port 41 to the second drain port 43 increases, and the oil leakage flow increases by that much. That is, in a state where the spool 37 is held at the neutral position,
In order to hold the ring gear 27 at the intermediate position, the flow of oil from the second discharge port 41 to the second drain port 43 is suppressed as much as possible. It becomes bigger. Therefore, even if foreign matter such as fine metal powder in oil flows into the vicinity of the second discharge port 41, the foreign matter easily flows to the second drain port 43 due to the oil leakage flow.
As a result, it is possible to prevent the OCV 4 from being caught by a foreign substance between the spool 37 (valve element 37c) and the sleeve 36 near the second discharge port 41. Furthermore, since it is possible to prevent foreign matter from being caught, the OC
Good operation responsiveness can be ensured for V4.

In addition, in this embodiment, the OCV 4 does not require a large machining for the conventional OCV 72,
It is possible to easily achieve the countermeasure against the foreign matter biting of V4. (Second Embodiment) Next, a first embodiment in which the variable valve timing apparatus according to the second invention is embodied in an automobile engine will be described with reference to FIGS. In this embodiment, the basic configuration such as VVT3 and OCV4 is the same as that of the first embodiment.
4 is only the shape of the spool 37. Therefore, in this embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different points will be mainly described.

FIG. 6 is a sectional view showing a main part of the OCV 4 in this embodiment, and FIG. 7 is an enlarged view of a portion surrounded by a broken-line circle in FIG. This embodiment is characterized by the shape of the valve body 37c corresponding to the second discharge port 41 in the spool 37. That is, this valve element 3
A step 45 having a smaller diameter than other parts is formed at the right end of the drawing of 7c. Here, as shown in FIG.
The height H and the axial length L are determined by the maximum particle size of the foreign matter passing through the OCV filter 16A and the second hydraulic chamber 29 to the second discharge port 41 when the spool 37 is held at the neutral position. It is determined by the amount of oil returned. The length L of the step 45 is set so as to be relatively larger than the amplitude when the spool 37 is vibrated little by little in the axial direction. Further, in FIG. 7, the seal width W between the valve body 37 c and the sleeve 36 corresponding to the second discharge port 41 in the axial direction changes with the movement of the spool 37.
Until 9 communicates with the first discharge port 40, it is set to “0” or a small positive value.

In this embodiment, the relationship between the spool 37 and the sleeve 36 at the neutral position is set as shown in FIGS. That is, when the spool 37 is held at the neutral position, the valve 37b slightly opens the space between the introduction port 39 and the first discharge port 40, and the space between the introduction port 39 and the second discharge port 41. It is closed by the valve 37c. Further, the space between the first discharge port 40 and the first drain port 42 is closed by the valve body 37b, and the second discharge port 41 and the second drain port 43 are closed.
Is substantially closed by the valve body 37c.

According to the above state, the hydraulic pressure introduced from the introduction port 39 through the first discharge port 40 is supplied to the first hydraulic chamber 28, and the second hydraulic port 29 is supplied through the second discharge port 41. Oil leaking to the second drain port 43 is suppressed. At this time, as shown in FIG.
A first closing margin S1 is formed between the spool 37 (valve element 37c) and the sleeve 36 between the second discharge port 41 and the second drain port 43. The gap between the closing margins S1 is formed larger than the gap between the second closing margins S2 in FIG. 5 described above. Also, the first closing margin S1 is set to be larger than the second closing margin S2 so that the oil passing resistance of the first closing margin S1 is substantially the same as the oil passing resistance of the second closing margin S2. I have.

Therefore, according to this embodiment, the spool 3
7 is held at the neutral position and a slight oil pressure is supplied from the first discharge port 40 to the first hydraulic chamber 28,
The ring gear 27 is held at an intermediate position in the moving direction against the driving reaction force of the camshaft 1. At this time, the amount of oil returned from the second hydraulic chamber 29 to the second discharge port 41 is extremely small. However, in this embodiment, the gap between the first closing margin S1 between the second discharge port 41 and the second drain port 43 is relatively large due to the step 45, so that the gap is large. Foreign matters in the oil are more likely to pass through the first closing margin S1 by a larger amount. That is, while the spool 37 is held at the neutral position, the flow of oil from the second discharge port 41 to the second drain port 43 can be suppressed as much as possible. This makes it easier for foreign matter to pass through the closing margin S1. For this reason, even if foreign matter such as fine metal powder flows into the vicinity of the second discharge port 41, the foreign matter will
The gap 5 facilitates passage to the second drain port 43. As a result, it is possible to prevent the OCV 4 from being caught by a foreign substance between the spool 37 and the sleeve 36 near the second discharge port 41.

In particular, in this embodiment, the height H of the step 45 is set to such an extent that the passage of foreign matter is allowed. Therefore, in order to optimally adjust the ring gear 27 to the intermediate position, even if the spool 37 is slightly vibrated in the axial direction by the linear solenoid 38 at the neutral position, foreign matter between the spool 37 and the sleeve 36 is not removed. No biting occurs.

As described above, it is possible to prevent the foreign matter from being caught, so that it is possible to ensure a good operation response of the OCV 4. Further, in this embodiment, since the length L of the step 45 is ensured to some extent, even if the spool 37 in the neutral position is vibrated little by little, the oil passage resistance in the first closing margin S1 suddenly changes. There is no.
As a result, adjustment for holding the ring gear 27 at the intermediate position can be stably performed.

In addition, in this embodiment, the OCV4
Therefore, it is only necessary to change the shape of the valve element 37c of the spool 37, and there is no need to perform a large process for the conventional OCV 72, and it is possible to easily achieve a countermeasure against the OCV 4 getting caught by a foreign substance.

The present invention can be embodied in another embodiment as follows. In another example below,
The same operation and effect as the above embodiment can be obtained. (1) In each of the above embodiments, only the operation timing of the intake valve is changed by the VVT 3 provided on the camshaft 1 on the intake side. On the other hand, a VVT may be provided on the exhaust-side camshaft, and only the operation timing of the exhaust valve may be changed by the VVT. Alternatively, VVTs may be provided on both the intake and exhaust camshafts, and the operation timings of the intake valve and the exhaust valve may be respectively changed by the respective VVTs.

(2) In each of the above embodiments, the camshaft 1
Due to the relationship between the driving reaction force of the ring gear 27 and the direction of the helical teeth of the ring gear 27, a slight hydraulic pressure is supplied to the first hydraulic chamber 28 to hold the ring gear 27 at the intermediate position against the driving reaction force. did.

On the other hand, when the relationship between the driving reaction force of the camshaft 1 and the direction of the helical teeth of the ring gear 27 is opposite to the above, the ring gear 27 is held at the intermediate position against the driving reaction force. For this purpose, the second hydraulic chamber 29 may be configured to supply a slight hydraulic pressure.

The embodiments of the present invention have been described above. However, it should be noted that each of the embodiments includes the following various embodiments according to the technical idea described in the claims. They are described together with their effects.

(A) In the first aspect of the invention, the opening width of the second discharge port is made larger than that of the other, or a valve body corresponding to the second discharge port is provided on the spool, and the valve body is provided. A variable valve timing apparatus in which the first closing margin is set by making the axial width of the first valve smaller than the others.

According to this configuration, there is no need to perform a large process for the hydraulic control valve, and a countermeasure against the foreign matter being caught by the hydraulic control valve can be easily achieved. (B) In the first aspect of the present invention, the second spool is attached to the spool.
A variable valve timing apparatus in which a first closing margin is set by providing a valve body corresponding to the discharge port of (1) and forming a step smaller in diameter at the end of the valve body than at other parts.

According to this configuration, there is no need to perform a large machining for the hydraulic control valve, and a countermeasure against the foreign material being caught by the hydraulic control valve can be easily achieved. In this specification, means and members according to the configuration of the present invention are defined as follows.

(A) The timing pulley is a gear for rotating the camshaft so that the operation timing of the intake / exhaust valve is in a correct relationship with the rotation of the crankshaft, in other words, the movement of the piston. Examples of the driving method include gear driving, chain driving, toothed belt driving (timing belt), and the like.

[0053]

As described above in detail, according to the first aspect of the present invention, when the spool is disposed at the neutral position, the first port is formed corresponding to the second discharge port. To supply the hydraulic pressure introduced from the introduction port to the second hydraulic chamber through the second discharge port, and suppress the oil leaking from the first hydraulic chamber to the drain port through the first discharge port. Sometimes, it is set smaller than the second closing margin formed corresponding to the first discharge port.

Therefore, the flow of oil leaking from the second discharge port to the drain port is increased by the smaller the oil flow resistance at the first closing margin, and foreign matter in the oil near the second discharge port easily flows. . As a result, it is assumed that the device is driven by switching the hydraulic pressure path by the hydraulic control valve, and the hydraulic control valve exerts an effect of preventing foreign substances in oil from being caught by the hydraulic control valve. According to the second aspect of the present invention, when the spool is disposed at the neutral position, the first closing gap formed corresponding to the second discharge port is formed in the second hydraulic chamber. To supply the hydraulic pressure introduced from the introduction port to the drain port through the second discharge port, and to suppress the oil leaking from the first hydraulic chamber to the drain port through the first discharge port.
Is formed to be larger than the gap of the second closing margin formed in correspondence with the discharge port of (i). In addition, the first closing margin is set to be larger than the second closing margin so that the oil passing resistance of the first closing margin and the oil passing resistance of the second closing margin are substantially the same.

Accordingly, since the gap between the first closing margins is formed to be large, foreign matters in the oil easily pass through the first closing margin by an amount corresponding to the large gap. As a result, it is assumed that the device is driven by switching the hydraulic pressure path by the hydraulic control valve, and the hydraulic control valve exerts an effect of preventing foreign substances in oil from being caught by the hydraulic control valve. According to the third aspect of the present invention, the spoo
When placing the tool in the neutral position,
Drain from the second discharge port as much as the passage resistance
The flow of oil leaking to the port increases and the second discharge port
Foreign matter in the vicinity flows easily. As a result, the hydraulic control valve
Can prevent foreign substances in the oil from being caught
Exerts its effect. According to the fourth aspect of the present invention,
If the spool is in the neutral position,
Because the gap is large,
Foreign matter in oil easily passes through the first closing margin
It becomes. As a result, at the hydraulic control valve, foreign matter in oil
This has the effect of preventing penetration.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a variable valve timing device according to a first embodiment of the invention.

FIG. 2 is a sectional view showing a variable valve timing device according to the first embodiment.

FIG. 3 is a sectional view showing a variable valve timing device according to the first embodiment.

FIG. 4 is a sectional view showing a main part of a hydraulic control valve (OCV) in the first embodiment.

FIG. 5 is a sectional view showing a main part of the hydraulic control valve in the first embodiment.

FIG. 6 is a sectional view showing a main part of a hydraulic control valve according to a second embodiment of the present invention;

FIG. 7 is a cross-sectional view showing an enlarged part of FIG. 6 in the second embodiment.

FIG. 8 is a cross-sectional view showing a variable valve timing device according to the related art.

FIG. 9 is a cross-sectional view showing a main part of a hydraulic control valve according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cam shaft, 2 ... Timing pulley, 3 ... Variable valve timing mechanism (VVT), 4 ... Hydraulic control valve (OC)
V), 27 ... ring gear, 28 ... first hydraulic chamber, 29 ...
Second hydraulic chamber, 36 ... sleeve, 37 ... spool, 39
... Introduction port, 40 ... First discharge port, 41 ... Second discharge port, 42 ... First drain port, 43 ... Second drain port, 45 ... Step, S1 ... First closing margin, S
2. The second closing margin.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01L 1/34 F16K 3/24 F16K 11/07

Claims (4)

(57) [Claims] An engine camshaft and its shaft
Ring gear between the timing pulley provided above
Interposed and provided at both axial ends of the ring gear
By controlling the supply of hydraulic pressure to the first and second hydraulic chambers by a hydraulic control valve, the ring gear is
To the camshaft.
A variable valve timing device that imparts kinking and thereby makes the operation timing of the intake and exhaust valves variable, wherein the hydraulic control valve includes a sleeve that movably accommodates a spool, and the sleeve has a predetermined sleeve. An introduction port for introducing hydraulic pressure, first and second discharge ports for supplying hydraulic pressure introduced from the introduction port to the first and second hydraulic chambers, respectively, and a return port from each of the hydraulic chambers. And a drain port for draining oil to be supplied, and by selectively switching communication between the introduction port and the discharge port to the drain port by moving the spool, supply of hydraulic pressure to the hydraulic chambers. To move the ring gear and to hold the spool at the neutral position to supply a slight hydraulic pressure to the first hydraulic chamber. As a result, the ring gear is
A variable valve timing device which is held at an intermediate position in a moving direction thereof against a driving reaction force of the shaft , wherein the spool is disposed at the neutral position and the first hydraulic chamber is positioned with respect to the first hydraulic chamber. When supplying oil pressure introduced from the introduction port through the first discharge port and suppressing oil leaking from the second hydraulic chamber to the drain port through the second discharge port, the second A first closing gap formed between the spool and the sleeve between a discharge port and the drain port is introduced from the introduction port to the second hydraulic chamber through the second discharge port. The first discharge port and the drain port when supplying oil to the drain port from the first hydraulic chamber through the first discharge port to the drain port. Variable valve timing system, wherein a second closed Shi Royori formed also set smaller between the spool and the sleeve between the. 2. An engine camshaft and its shaft.
Ring gear between the timing pulley provided above
Is interposed, provided corresponds to the axial ends of the ring gear
By controlling the supply of hydraulic pressure to the first and second hydraulic chambers by a hydraulic control valve, the ring gear is
To the camshaft.
A variable valve timing device that imparts kinking and thereby makes the operation timing of the intake and exhaust valves variable, wherein the hydraulic control valve includes a sleeve that movably accommodates a spool, and the sleeve has a predetermined sleeve. An introduction port for introducing hydraulic pressure, first and second discharge ports for supplying hydraulic pressure introduced from the introduction port to the first and second hydraulic chambers, respectively, and a return port from each of the hydraulic chambers. And a drain port for draining oil to be supplied, and by selectively switching communication between the introduction port and the discharge port to the drain port by moving the spool, supply of hydraulic pressure to the hydraulic chambers. To move the ring gear and to hold the spool at the neutral position to supply a slight hydraulic pressure to the first hydraulic chamber. As a result, the ring gear is
A variable valve timing device which is held at an intermediate position in a moving direction thereof against a driving reaction force of the shaft , wherein the spool is disposed at the neutral position and the first hydraulic chamber is positioned with respect to the first hydraulic chamber. When supplying oil pressure introduced from the introduction port through the first discharge port and suppressing oil leaking from the second hydraulic chamber to the drain port through the second discharge port, the second A first closing gap formed between the spool and the sleeve between a discharge port and the drain port is provided between the introduction port and the second hydraulic chamber through the second discharge port. Supply the hydraulic pressure introduced from the
When suppressing oil that leaks from the hydraulic chamber to the drain port through the first discharge port, a second valve formed between the spool and the sleeve between the first discharge port and the drain port. The first closing margin is formed so as to be larger than the clearance of the second closing margin, and to make the oil passing resistance of the first closing margin substantially equal to the oil passing resistance of the second closing margin. A variable valve timing device, wherein the variable valve timing device is set to be larger than the second closing margin. 3. Drive by switching hydraulic paths
Allowed valve timing of intake and exhaust valves of the engine
Used in variable valve timing systems
Equipped with a sleeve that movably accommodates the spool,
In the sleeve , An introduction port for introducing a predetermined hydraulic pressure
And the hydraulic pressure introduced from its introduction port
And second for supplying to the second hydraulic passage, respectively.
Return from the discharge port and the first and second hydraulic passages.
And a drain port for draining oil
Move the spool to move the introduction port and the drain
Communication with each of the discharge ports
While holding the spool in the neutral position.
It is possible to supply a small amount of hydraulic pressure to the first hydraulic passage.
In the hydraulic control valve of the variable valve timing device, Disposing the spool in a neutral position and the first hydraulic passage
On the other hand, from the introduction port through the first discharge port
Supply hydraulic pressure to be introduced, and from the second hydraulic passage
Leakage into the drain port through the second discharge port
When suppressing the oil that flows, the second discharge port and the
The spool and the sleeve between a lenport
Between the first hydraulic pressure and the second hydraulic pressure
The introduction port through the second discharge port to the passage;
Supply the hydraulic pressure introduced from the
The drain port from the channel through the first discharge port
When suppressing oil leaking to the first discharge port,
The spool and the spool between the drain port
Smaller than the second margin formed between
Of the variable valve timing device
Hydraulic control valve. 4. Drive by switching hydraulic paths
Allowed valve timing of intake and exhaust valves of the engine
Used in variable valve timing systems
Equipped with a sleeve that movably accommodates the spool,
The sleeve has an introduction port for introducing a predetermined oil pressure.
And the hydraulic pressure introduced from its introduction port
And second for supplying to the second hydraulic passage, respectively.
Return from the discharge port and the first and second hydraulic passages.
And a drain port for draining oil
Move the spool to move the introduction port and the drain
Communication with each of the discharge ports
While holding the spool in the neutral position.
It is possible to supply a small amount of hydraulic pressure to the first hydraulic passage.
In the hydraulic control valve of the variable valve timing device, Disposing the spool in the neutral position and setting the first hydraulic pressure
The inlet port through the first discharge port to the chamber
Supply the hydraulic pressure introduced from the Hydraulic passage
To the drain port through the second discharge port
When suppressing the leaking oil, the second discharge port and the front
The spool and the slot between the drain port
The first closing gap formed between the
Through the second discharge port to a second hydraulic passage
Supplying hydraulic pressure introduced from the introduction port, and
From the first hydraulic passage through the first discharge port
When suppressing oil leaking to the drain port, the first
The spout between the discharge port and the drain port
Second closure formed between the sleeve and the sleeve
And the oil is passed through the first closing margin.
Resistance and the oil flow resistance of the second closing margin are made substantially the same.
To close the first closing margin to the second closing margin.
Variable valve timing, which is set larger
Hydraulic control valve for operating device.