DE3520339A1 - Internal combustion engine with hydrostatic power transmission - Google Patents

Abstract

An internal combustion engine with hydrostatic power transmission, which has at least one combustion piston movable in a cylinder housing, is connected to a delivery piston (5) of a hydraulic pump. The hydraulic pump is provided with a device (7) for controlling the delivery flow of the hydraulic fluid.

Description

Combustion engine, or with hydrostatic power transmission

The invention relates to an internal combustion engine with hydrastatic Power transmission according to the preamble of claim 1.

The poor efficiency of internal combustion engines that use the energy the reciprocating combustion piston is transmitted via connecting rod and crankshaft, is known. The rotational energy thus generated is often then over again Hydraulic motors and hydraulic clutches into a hydrostatic power transmission converted.

It has therefore already been proposed that of a combustion piston to use generated energy directly for hydrostatic power transmission. Included is with the Combustion piston coaxially connected to a hydraulic piston, which acts on a second hydraulic piston via a column of liquid. Of the reciprocating second hydraulic piston sets the linear movement for power transmission into a rotational movement. Due to the coaxial connection of the hydraulic piston with the combustion piston, the latter is free from lateral forces. A scheme of Speed is not possible with this construction. Corresponding shift gears are available for this purpose required, because regulating the stroke of the internal combustion engine is problematic. Another disadvantage is that this type of power transmission is relative to the engine output is expensive; for example, there are two hydraulic pistons and a downstream crank drive necessary.

The present invention is therefore based on the object Internal combustion engine of the type mentioned to create its power output can be regulated while largely avoiding power-consuming parts.

According to the invention, this task is carried out by those in the characterizing part of claim 1 mentioned features solved.

The fact that the delivery flow of the hydraulic pump can be regulated can e.g. the combustion engine with a power consumption of zero, e.g. when starting, start up. Likewise, the power consumption or regulate its output. Because the combustion piston does not have any lateral forces is subject to high piston speeds with little wear achieved will.

As a hydraulic pump, known controllable piston pumps, E.g. eccentric radial piston or swash plate axial piston pumps can be used.

Advantageously, each delivery piston is coaxial with the Arrange the associated combustion pistons, e.g. several combustion pistons with be arranged axially parallel to their displacement directions about a central longitudinal axis can, or have piston axes pointing radially outward in a star shape.

To control the position of the individual combustion engines and those with you connected delivery piston can be a swash plate with an inclined axis on a control shaft be arranged, which lies in the central longitudinal axis, with the swash plate on the delivery piston or combustion piston acting control pins are pressed. This device works in the manner of a swash plate pump and the Combustion pistons can be position-controlled in the order in which they are fired will.

If the piston axles are arranged in a star shape, the swash plate is through replaced an eccentric.

The control pins can be the tappets with the delivery pistons or are connected to the combustion piston, or they are via a hydrostatic Coupling connected to these.

A very advantageous and inventive device for regulation of the flow is that in the cubic capacity the delivery piston arranged displacement bodies are provided which face away from the delivery piston Pressure surfaces with associated piston chambers are pressurized by a fluid via pressure channels are that arranged between the delivery piston and the displacement bodies springs are, and that the displacement body as a function of the operating pressure, a control pressure or a differential pressure in the system, the pressurization of the pressure surfaces of the Displacement body and the springs in the direction of reductions or enlargements the displacements are movable.

Due to the design of the piston pump with the displacement bodies the stroke volume can be adjusted in a simple manner and with only little adjustment of a delivery piston. Only very small moving masses are required for this. In addition, the adjustment times are very short and the flow rate is regulated continuously possible.

The flow rate can be regulated in many ways. For example, operating pressure can be applied to the pressure surfaces of the displacers will. In this case the force of the spring acts against the compressive force of the operating pressure, and as long as the compressive force of the spring is greater than that due to the operating pressure The force acting on the pressure surface of the associated displacement body remains this in its starting position. This means that the associated delivery piston is in Usually the maximum stroke volume is available for delivery. Exceeds However the compressive force resulting from the operating pressure is the force of the spring, then in correspondingly the displacement body in the direction of a reduction in displacement postponed. The shift takes place as a function of the operating pressure, and until there is a state of equilibrium with the associated spring forces adjusts. When the swash plate continues to rotate in the compression stroke, it compresses the respective piston adjusts the volume sucked in and thus also displaces the delivery piston trailing displacement body in turn up to equilibrium of forces. With this species is a regulation from a theoretical delivery volume of zero to a maximum Delivery rate possible.

Instead of a regulation via the operating pressure, the displacers can also be shifted by a separate control pressure. The control pressure can e.g. by the operator as required (e.g. cruise control) set. will.

Manual transmissions can be saved as a result of these configurations.

The same is also true of the combination of regulation by the operating pressure and an external control pressure possible.

In the case of regulation via the operating pressure, it is practically a load-dependent one Regulation achieved. For example, a higher flow rate can be achieved with a correspondingly lower flow rate Operating pressure and thus a high power transmission can be achieved, as well as a lower operating pressure at one high flow rate is possible, accordingly higher speeds are possible. The one from the piston pump The flow rate generated can, if necessary, be divided between several hydraulic circuits will. It is also possible with multi-cylinder engines with a corresponding Number of piston pumps to allow these to act on different hydraulic circuits.

Instead of regulating the displacement body via the operating pressure or A control pressure is also a regulation via a pressure difference in the operating pressure possible. Such a regulation is particularly suitable for use in working hydraulics Suitable in construction machines, forklifts and the like. To control the shifting movement For this purpose, the displacement piston can be a measuring orifice in the pressure line of the piston pump arranged in, behind which from the pressure outlet line to the pressure surfaces the displacement body leading control lines go off and in front of which connecting lines lead to the second pressure surfaces with associated piston chambers, which against the first pressure surfaces are directed and wherein the displacement body with in the pressure direction control springs acting on the first pressure surfaces are provided.

An increasing differential pressure shows an increasing demand on, with the displacement piston being pressurized accordingly remain in their rear end position, so that a high flow rate is guaranteed is. However, if a lower differential pressure occurs, the displacers can accordingly in the direction Displacement reduction are postponed. When the pressure rises The delivery volume can even be reduced to the zero stroke beyond a permissible level. All that is required is the characteristics of the springs involved, as well as the Coordinate printing areas. In this way there is a pressure and flow rate control possible with high precision with a short adjustment time.

So there is no significant energy needed to adjust the displacement body is destroyed, the necessary compensation chambers are advantageously used connect with each other. In this way there is no compression work to be done, rather, the hydraulic fluid is only used when the delivery piston is displaced pushed back and forth in the compensation chambers.

Advantageous refinements and developments of the invention result from the subclaims and from the following with reference to the drawing in principle described embodiments.

It shows: FIG. 1 a longitudinal section through the internal combustion engine according to the invention with control of the displacement body by operating pressure, Fig. 2 is a longitudinal section by the internal combustion engine according to the invention with control of the displacement body by external control pressure, Fig. 3 is a longitudinal section through the Internal combustion engine according to the invention with control of the displacement body by a Pressure difference, FIG. 4 shows an internal combustion engine corresponding to that according to FIG. 2 with a hydrostatic coupling to control the position of the combustion pistons.

Fig. 5 - 7 functional diagrams of a regulation of the displacement body by the operating pressure at different delivery rates.

Fig. 8-10 functional diagrams of a regulation of the displacement body with a differential pressure at different delivery rates.

The internal combustion engine according to the invention is shown in FIGS only shown in principle, two combustion pistons 1 being visible in each case. The longitudinal axes of the combustion piston 1 are axially parallel to a central one Longitudinal axis 2 in a housing 3. Several combustion pistons, e.g. three, four, six or more can be arranged in a circle around the longitudinal axis 2. Likewise is an in-line or boxer engine arrangement is also possible. The number of pistons does not have to be an even number be.

Each combustion piston 1 is provided with a hydraulic pump, which is connected to the internal combustion engine via a connecting rod 4 Delivery piston 5 has. In each case a plunger 6 is through the free interior space Displacer 7 and the delivery piston 5 out and at the front end with the Connecting rod 4 connected. The plunger 6 can also be attached separately to the delivery piston 5 or be attached to the combustion piston 1.

Springs 8 which are each arranged around the connecting rod 4 and are supported with one end on the housing 3, secure the installation of the plunger 6 on a swash plate 9 which is fastened on a control shaft 10. The swash plate 9 is used to control the position of the combustion piston 1 thus the correct one Firing order is maintained. With a radial arrangement of the delivery piston and combustion piston an eccentric will be used instead of a swash plate.

In addition to position control, this connection also enables the internal combustion engine started in a known manner via a starter 11 arranged on the control shaft 9 will. The starter usually consists of an electric motor with a freewheel. Likewise, via the control shaft 10 or a swash plate 9, the inlet and Exhaust valves of the combustion chambers of the internal combustion engine with the 4-stroke principle in known Way to be controlled.

Spaces 12 behind the combustion piston 1 are ventilated for the most part.

The function of the pump corresponds to that of a swash plate pump. That Oil is either via suction valves or, as shown in FIG. 1, via an annular chamber 13 sucked into piston chambers 14 and when driving over control edges 15 compressed by the piston 5. The compressed oil is released through check valves 16 and an annular space 17 are passed into a pressure channel 18 with an outlet opening 19. A suction opening 20 for the oil, from which it via the interior space to the annular chamber 13 is performed, can also be seen from FIG. 1.

The compressed oil can instead be discharged into a joint Pressure line also to separate pressure rooms, or pressure lines forwarded so that the effect of a multi-circuit pump can arise.

Displacement bodies 7 are responsible for regulating the flow rate of the pumps. which are slidably arranged in their bore. fever springs 21 are supported the displacement body on the delivery piston 5. The displacement bodies 7 each have a collar 22, which on its side facing away from the delivery piston 1 a Pressure surface 23 with an associated piston chamber 24 has. Via pressure channels 25 are the piston chambers 24 each with the pressure line under operating pressure 18 connected and ventilated. Rooms 27 are connected to each other.

In the figures 5 to 7 is the functional diagram for the flow control the hydraulic pumps more clearly visible.

As shown in FIG. 1, the oil is sucked in via an annular chamber 13 and control slots 15.

As long as the force of the springs 21 and the pressure force on the displacement body from the displacement 14 is greater than the pressure force of the operating pressure on the pressure surface 23, the displacement body 7 remains in its rear end position and the pump is the maximum stroke volume to disposal. However, if the Operating pressure accordingly until the pressure force on the pressure surface 23 predominates, so the displacement bodies 7 move accordingly to the left in the direction of a reduction in the respective cubic capacity 14. The shift takes place as long as until a state of equilibrium is reached again due to the compression of the springs 21 will. However, the displacement bodies also run at the same time during the work cycles according to the delivery piston.

In the figure 5 the functional diagram is shown in which the volume flow corresponds to the maximum volume flow.

In Fig. 6 the functional diagram is shown in which a reduction of the displacements 14 by a corresponding displacement of the displacers 7 and so that the volume flow was reduced.

7 shows the functional diagram for such a high operating pressure shown, in which the displacement body 7 completely to the left up to the plant were moved to the delivery piston 5, so that no more delivery occurs.

This means, for example, that when the consumer is switched off, no Funding is being done more. In practice, however, there will be a minimal gap between the delivery piston 5 and the displacement bodies 7 to maintain a Provide pilot current. Since compensation chambers 27 continue to have a corresponding Ring line 28 are connected to each other, must for the displacement of the displacement body 7 no compression work is performed, because the oil will only pushed back and forth between the individual rooms.

By appropriate design of the acted upon piston surfaces of the Delivery piston 5, the piston surface 23 of the displacement body 7 and the characteristic curve and Clamping the spring 21, the hydraulic pump can be controlled so that the product of delivery rate x pressure remains constant, i.e. the pump absorption torque stay constant. With the inventive regulation of the displacement body 7 over a load-dependent control is achieved for the operating pressure.

2 is a longitudinal section through the internal combustion engine according to the invention which is of essentially the same construction as that discussed in FIG.

For this reason, the same reference numerals are used for the same parts used. The only difference compared to the embodiment according to FIG. 1 is in that instead of regulating the displacement of the displacement body 7 on the Operating pressure the displacement of the displacement body by an external control pressure he follows. A control pressure connection 29 with one to all piston chambers is used for this purpose 24 of the displacement body 7 leading control pressure channel 30. This configuration the delivery rate can be selected as desired. However, it is also possible through appropriate Training and routing of the displacer in combination with the operating pressure to regulate.

The above regulation according to Figure 2 is required, for example, if the Internal combustion engine for a hydrostatic drive is used, which is to be approached from standstill, with a constant speed control Moment or variable, adjustable by changing the pump delivery volume Speed. This mode of operation is also advantageous when the internal combustion engine is coupled to a hydraulic motor through which torque is transmitted. In this way a starting clutch can be saved.

3 is a longitudinal section through a further embodiment of the internal combustion engine. This figure also corresponds essentially the embodiments shown in Figures 1 and 2, which is why here The same reference numerals have been used for the same parts. The only difference is that here the control of the displacement piston 7 takes place via a differential pressure. For this purpose, a measuring throttle 31 is arranged in the pressure line 18. In the direction of flow In front of this measuring throttle 31, a pressure line 32 leads to second piston chambers 33.

In addition to the collar 22 on each displacement piston is a distance to it further federal 34 provided. The arrangement of a second collar 34 with the one in between Space is used for pressure relief. Of course, however, the collar 22 formed on its side opposite the piston surface 23 as a pressure surface be. Behind the measuring throttle 31, in turn, pressure channels 25 lead into the piston chambers 24, where they act on the pressure surfaces 23. With this configuration, a printing and flow rate control with high precision possible with a short adjustment time. she is therefore particularly useful for regulating the internal combustion engine at a Suitable for construction machines, forklifts and the like. The measuring throttle arises a pressure difference, the different pressures for shifting the Displacement piston 7 can be used in cooperation with control springs 35. An increasing one Differential pressure creates an increasing demand. Here lie in the second 'Pressure chambers 33 before higher pressures than in the piston chambers 24 together with the springs 35. The displacement bodies therefore remain in their rear end position, so that a high volume flow is guaranteed. However, if a low differential pressure occurs, so the displacers are correspondingly in the direction of displacement reduction postponed. If the pressure rises above a permissible level, the delivery volume can be reduced to the zero stroke. All that is required is the characteristics to match the springs involved and the pressure surfaces accordingly.

The functional diagrams of the internal combustion engine are shown in FIGS. 8 to 10 shown in FIG. 3. The only differences from the functional schemes according to Figures 5 to 7 are merely that in the pressure outlet line 18, the measuring throttle 31 is arranged and the displacers 7 each at their rear, i.e. at the end facing away from the delivery piston 5, with the control spring 35 are provided.

For the sake of simplicity, only the collar 22 is shown in the schematic drawings, its two end faces as pressure surfaces for the pressures upstream and downstream of the measuring throttle 31 to serve.

FIG. 8 again shows, like FIG. 5, the functional diagram in which the pump's stroke spaces are fully available, because the Displacement bodies 7 remain in their rear starting position. Fig. 9 also shows like FIG. 6, an intermediate position with reduced displacements, while FIG. 10 as well as FIG. 7 shows the "zero stroke conveyance".

Fig. 4 shows a longitudinal section through an embodiment of the Internal combustion engine, which is essentially the embodiment shown in FIG with a control of the displacement body by an external control pressure. The only difference is that instead of a mechanical coupling for position control the combustion piston 1 has a hydrostatic coupling via a tappet 6 for this purpose was made. Like every hydraulic pump, the hydrostatic coupling has one Hydraulic ram 36 with a pressure chamber 37. From the pressure chamber 37 each leads a control pressure line 38 to the associated delivery piston 5. The control pressure line 38 opens into an annular space 39 behind an annular web 40 - based on the Combustion piston 1 - on the delivery piston 5.

The hydraulic tappets are attached to the swash plate at their free ends 9 pressed, which, as with the mechanical coupling, their oblique axis effect the attitude control.

The hydrostatic coupling shown in FIG. 4 be one Combustion engine controlling the displacement body with external control pressure can of course also be used in the other two cases according to the exemplary embodiments 1 and 3 use.

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Claims (17)

Claims: Combustion engine with hydrostatic power transmission, which has at least one combustion piston movable in a cylinder housing, which is connected to a delivery piston of a hydraulic pump, d u r c h g e it is not indicated that the hydraulic pump is equipped with a device (7) for regulation of the delivery flow of the hydraulic fluid is provided 2. Internal combustion engine according to claim 1 d a d u r c h e k e n n n z e i c h n e t that the hydraulic pump as a known piston pump with one or more return springs (21) Delivery pistons (5) in displacements (14) with suction lines (13) to the delivery pistons (5) and is formed with a pressure outlet line (18). 3. Internal combustion engine according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the delivery piston (5) is coaxial with the combustion piston (1). 4. Internal combustion engine according to claim 3, d a d u r c h g e k e n n z e i c h n e t that several combustion pistons (1) with their Verschieberichtunqen achsparaLlel are arranged around a central longitudinal axis (2). 5. Internal combustion engine according to claim 3, d a d u r c h g e k e n n z e i c h n e t that radial pistons arranged in a star shape are provided. 6. Internal combustion engine according to claim 4, d a d u r c h g e k e n n z e i c h n e t that for the position control of the individual combustion piston (1) and the connected to them delivery piston (5) a swash plate (9) with inclined Axis is arranged on a control shaft (10) which is in the central longitudinal axis lies on the swash plate (9) on the delivery piston (5) or combustion piston (1) acting control pins (6,36) are pressed on. 7. Internal combustion engine according to claim 4 or 5, d a d u r c h g e k e It is noted that the control pins (6) are plungers that are attached to the delivery piston (5) or combustion piston (1) are connected. ß. Internal combustion engine according to claim 4 or 5, d a d u r c h g e k e It is noted that the control pins (36) have a hydrostatic coupling are connected to the delivery piston (5) or combustion piston (1). 9. Internal combustion engine according to claim 6, d a d u r c h g e k e n n z e i c h n e t that the control shaft (10) with the output shaft of an electric motor (11) is connected as a starter. 10. Internal combustion engine according to claim 1 and 2, d a d u r c h g e k e n n z e i h n e t that the device for regulating the displacement of the delivery piston (5) arranged displacer (7), which on from the delivery piston (5) remote pressure surfaces (23) with associated piston chambers (24) via pressure channels (25) are pressurized by a fluid that between the delivery piston (5) and the displacement bodies (7) springs (21) are arranged, and that the displacement body (7) depending on the operating pressure, a control pressure or a differential pressure in the system, the pressurization of the pressure surfaces (22,34) of the displacement body (7) and the springs (21,35) in the direction of reductions or enlargements of the Displacements (14) are displaceable. 11. Internal combustion engine according to claim 10, d a d u r c h g e k e n n it is clear that the springs are also the return springs (21) for the delivery pistons (5) and the displacement bodies (7) are arranged coaxially to the delivery piston. 12. Internal combustion engine according to claim 7 and 11, d a d u r c h g e k It is noted that the pressure channels (25) with an operating pressure St (-henden Line are connected. 13. Internal combustion engine according to claim 7 and 11, d a d u r c h g e k It is noted that the tappets (6) are guided through the displacement body. 14. Internal combustion engine according to claim or 11, d a d u r c h g e k e n n z e i h n e t that in the pressure output line (18) or a subsequent one Pressure line a measuring throttle (31) is arranged, behind which: from the pressure output line the pressure channels (25) leading to the pressure surfaces (23) of the displacement bodies (7) depart and in front of soft pressure lines (32) to second pressure areas with associated Lead piston chambers (33) which are directed against the first pressure surfaces (23) and that the displacement bodies (7) act in the direction of pressure of the first pressure surfaces Control springs (35) are provided. 15. Internal combustion engine according to one of claims 10 to 14, d a d u r c h g e k e n n n z e i c h n e t that in each case the pressure surface is replaced by an annular surface formed by a collar (22, 34) projecting beyond the circumference of the displacement body (4) is. 16. Internal combustion engine according to claim 14 and 15, d a d u r c h g e k It is noted that the first ring surface is on a first collar (22) and the second ring surface lies on a second collar (34) at a distance from it. 17. Internal combustion engine according to one of claims 10 to 1 (d a d u r c h e k e n n n z e i c h n e t that the movement of the displacement body (7) necessary compensation chambers (27) are connected to one another.