JP2011179561A - Automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage to an automatic transmission with a simple structure when a driving force is reversely transmitted from the wheel side to the automatic transmission when the automobile is towed.
A brake B1 capable of restraining one element of a planetary gear unit is provided with a main piston 16 and a sub piston 24 that are actuated by oil pressure from an oil pump 29. A predetermined shift speed can be established in the automatic transmission by moving forward by hydraulic pressure and engaging the brake B1. At this time, the sub piston 24 moves backward by the hydraulic pressure from the oil pump 29, so that the operation of the main piston 16 is performed. There is no interference with. When the engine is stopped and the hydraulic pressure from the oil pump 29 disappears, the sub piston 24 moves forward by the resilient force of the engagement spring 27 and the brake B1 is engaged. It can be over-rotated.
[Selection] Figure 2

Description

  The present invention includes at least one planetary gear unit to which driving force from a driving source for traveling is input, and an output element of a plurality of elements of the planetary gear unit is always connected to a wheel, The invention relates to an automatic transmission in which at least one element can be restrained by a frictional engagement device.

  When pulling and moving a faulty automobile, the driving force input from the rotating wheels driven by the road surface is transmitted back to the automatic transmission, but the oil pump is stopped during towing and the automatic transmission Since oil cannot be supplied to the part to be lubricated, the part to be lubricated may overheat and cause abnormal wear or seizure.

  Therefore, a clutch is provided on the output shaft of the automatic transmission, and the clutch is engaged to transmit the driving force of the engine to the wheel during normal traveling, and the clutch is disengaged when towed to release the clutch from the wheel. Patent Document 1 below discloses that the driving force is prevented from being transmitted in reverse.

Japanese Patent Laid-Open No. 4-63724

  However, in the above conventional one, since the clutch provided on the output shaft requires a capacity capable of transmitting the driving force of the engine, it is necessary to use a large-capacity and large-sized clutch. There was an increasing problem.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent damage to an automatic transmission with a simple structure when the driving force is transmitted from the wheel side to the automatic transmission when the automobile is towed. And

  In order to achieve the above object, according to the first aspect of the present invention, at least one planetary gear unit to which a driving force from a traveling drive source is input is provided, and a plurality of elements of the planetary gear unit are included. In an automatic transmission in which an output element is always connected to a wheel and at least one of the plurality of elements can be restrained by a friction engagement device, the friction engagement device is a hydraulic pressure driven by the travel drive source A main piston and a sub piston that are operated by hydraulic pressure from a supply source; the main piston is advanced by hydraulic pressure from the hydraulic supply source to engage the friction engagement device; and the sub piston is an elastic spring of an engagement spring. The friction engagement device is engaged by advancing by the generated force, and is disengaged by retreating by the hydraulic pressure from the hydraulic pressure supply source. Automatic transmission is proposed, wherein the door.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the friction engagement device is a brake that couples the at least one element to a non-rotating portion. A transmission is proposed.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect, the friction engagement device is a clutch that couples the at least one element to a transmission input shaft. An automatic transmission is proposed.

  The first brake B1, the second brake B2 and the first clutch C1 of the embodiment correspond to the friction engagement device of the present invention, and the large sun gear Ss1, the planetary carrier Cs and the small sun gear Ss2 of the embodiment are in accordance with the present invention. The automatic transmission housing H of the embodiment corresponds to the non-rotating portion of the present invention, and the input shaft IS of the embodiment corresponds to the transmission input shaft of the present invention. The planetary gear unit PUs for shifting in the form corresponds to the planetary gear unit of the present invention, the ring gear Rs in the embodiment corresponds to the output element of the present invention, and the oil pump 29 in the embodiment corresponds to the hydraulic supply source of the present invention. To do.

  According to the configuration of the first aspect, when the vehicle is towed, the driving source for driving stops and the automatic transmission cannot be lubricated, the driving force is transmitted back from the wheels to the automatic transmission, and the output element of the planetary gear unit is driven. Therefore, a specific member of the automatic transmission may be in an overspeed state. However, the friction engagement device capable of restraining at least one of the plurality of elements of the planetary gear unit is provided with a main piston and a sub piston that are operated by hydraulic pressure from a hydraulic supply source driven by a traveling drive source, During normal driving, the main piston moves forward with the hydraulic pressure from the hydraulic pressure supply source and the friction engagement device engages to establish a predetermined gear stage in the automatic transmission. At this time, the sub piston is supplied with hydraulic pressure. Since it moves backward by hydraulic pressure from the source, it does not interfere with the operation of the main piston. In addition, when the towed drive source stops and the hydraulic pressure from the hydraulic supply source disappears, the sub-piston moves forward with the spring force of the engagement spring and engages the friction engagement device. Even if the output element of the planetary gear unit is driven by the driving force transmitted back to the machine, at least one element of the plurality of elements of the planetary gear unit is constrained by the friction engagement device, so that the specific transmission of the automatic transmission The member can be prevented from being over-rotated, and abnormal wear and seizure of the specific member can be prevented. Since the sub piston only needs to generate a load that overcomes the friction of the planetary gear unit, its size, weight, and cost can be reduced.

  According to the second aspect of the present invention, at least one element of the planetary gear unit is coupled to the non-rotating portion by a brake when towed, so that the automatic transmission is driven by the driving force that is reversely transmitted from the wheel to the output element of the planetary gear unit. It is possible to prevent the specific member from over-rotating and to prevent abnormal wear and seizure.

  According to the third aspect of the present invention, at least one element of the planetary gear unit is coupled to the transmission input shaft by a clutch when towed, so that the automatic transmission is performed with the driving force that is reversely transmitted from the wheels to the output element of the planetary gear unit. It is possible to prevent a specific member of the machine from over-rotating and to prevent occurrence of abnormal wear and seizure.

Skeleton diagram of automatic transmission. 2 is a detailed view of part 2 of FIG. The speed diagram of the planetary gear unit for speed change. The operation | movement table | surface of the friction engagement apparatus of an automatic transmission. The speed diagram explaining the effect | action of a subpiston.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, an automatic transmission T for 6 forward speeds and 1 reverse speed for an automobile is constituted by a reduction planetary gear unit PUr constituted by a single pinion type planetary gear unit and a Ravigneaux type planetary gear unit. A planetary gear unit PUs for speed change, first to third clutches C1, C2, and C3 made of a wet multi-plate hydraulic clutch, first and second brakes B1 and B2 made of a wet multi-plate hydraulic brake, and a one-way clutch F1 With. The automatic transmission T has an axially symmetric structure with respect to the input shaft IS to which the engine driving force is input, but only one side portion of the input shaft IS is shown in FIG.

  The reduction planetary gear unit PUr includes a sun gear Sr, a ring gear Rr, a planetary carrier Cr, and a plurality of pinions Pr that are rotatably supported by the planetary carrier Cr and simultaneously mesh with the sun gear Sr and the ring gear Rr. The sun gear Sr is fixed to the housing H of the automatic transmission T, the planetary carrier Cr is connected to the input shaft IS, and the ring gear Rr is connected to the third clutch C3.

  When the gear ratio of the speed reduction planetary gear unit PUr (the number of teeth of the ring gear Rr / the number of teeth of the sun gear Sr) is i, the rotational speed of the planetary carrier Cr as the input element is “1”, which is the same as the rotational speed of the input shaft IS. Yes, since the rotational speed of the sun gear Sr as the fixed element is “0”, the rotational speed N1 of the ring gear Rr as the output element is N1 = (i + 1) / i, and the rotational speed of the input shaft IS is “1”. The speed is increased.

  The planetary gear unit PUs for speed change is rotatable to a large sun gear Ss1, a small sun gear Ss2, a ring gear Rs, a planetary carrier Cs, a plurality of large pinions Ps1 rotatably supported by the planetary carrier Cs, and the planetary carrier Cs. A plurality of supported small pinions Ps2. Large pinion Ps1 meshes with ring gear Rs, large sun gear Ss1 and small pinion Ps2 simultaneously, and small pinion Ps2 meshes with small sun gear Ss2.

  The planetary carrier Cs can be coupled to the ring gear Rr of the speed reduction planetary gear unit PUr via the third clutch C3, and can be coupled to the housing H via the second brake B2 or the one-way clutch F1. The small sun gear Ss2 can be coupled to the input shaft IS via the first clutch C1. The large sun gear Ss1 can be coupled to the housing H via the first brake B1, and can be coupled to the input shaft IS via the second clutch C2. The ring gear Rr is connected to the wheel via the output shaft OS.

  When the first speed is established with the D range selected, the second brake B2, which is a hydraulic brake, is not engaged, and the one-way clutch F1 is engaged instead to reduce the load on the oil pump. Is planned. However, when the first gear is established by engagement of the one-way clutch F1, the one-way clutch F1 slips and the engine brake cannot be used when the vehicle decelerates, so the L range where the driver requests engine braking is selected. In this state, the second brake B2 is engaged and the first gear is established to enable use of the engine brake.

  Next, a specific structure of the first brake B1 will be described based on FIG.

  The first brake B1 includes a clutch outer 11 connected to the housing H of the automatic transmission T, a clutch inner 12 connected to the large sun gear Ss1 of the transmission planetary gear unit PUs, and a non-rotatable and axially slidable clutch. A plurality of friction engagement elements 13 that are movably fitted, a plurality of friction engagement elements 14 that are non-rotatable and slidable in the axial direction, and the friction engagement elements 13. ... Are kept on the clutch outer 11 so as not to fall off, a main piston 16 that presses the friction engagement elements 13... A piston guide 17 for slidably guiding the main piston 16, a main oil chamber 18 for driving the main piston 16 in the engaging direction by hydraulic pressure, It includes a plurality of return springs 19 ... for biasing the Npisuton 16 in engagement releasing direction, and a spring retainer 20 for supporting the return spring 19 ... end of.

  The piston guide 17 is an annular member, and the piston main body 16a of the main piston 16 is slidable on the first cylinder surface 17a and the second cylinder surface 17b via two seal members 21 and 22. These seal members 21 and 22 define a liquid-tight main oil chamber 18 between the main piston 16 and the piston guide 17.

  The main piston 16 includes a pressing portion 16b extending radially outward from the piston main body portion 16a and facing the friction engagement element 13 at the right end in the figure, and a cylindrical portion 16c extending from the piston main body portion 16a in the axial direction. An annular spring retainer 20 fitted between the piston guide 17 and the cylindrical portion 16 c of the piston 16 is locked to the piston guide 17 by a circlip 23. The axial ends of the plurality of return springs 19 in a compressed state are locked to the spring seats 16d provided in the piston main body 16a and the spring seats 20a provided in the spring retainer 20.

  An annular cylinder 17c is formed on the outer periphery of the piston guide 17, and an annular sub-piston 24 is slidably fitted therein. The sub-piston 24 is urged leftward in the figure by a plurality of engagement springs 27, and the pressing portion 24a abuts against the frictional engagement element 13 at the right end in the figure and presses it in the engagement direction. When hydraulic pressure is supplied to the sub oil chamber 28 sealed through the members 25 and 26, the sub piston 24 moves backward in the disengagement direction against the elastic force of the engagement springs 27.

  The hydraulic control device 31 to which the oil pumped by the oil pump 29 driven by the engine is supplied from the oil tank 30 applies the clutch pressure to the main oil chamber 18 of the first brake B1 when the first gear and the reverse gear are established. The line pressure is always supplied to the sub oil chamber 28 of the first brake B1 during the operation of the engine.

  FIG. 3 is a velocity diagram of the speed-change planetary gear unit PUs. The four vertical lines are a first rotation element (large sun gear Ss1), a second rotation element (planetary carrier Cs), from the left side to the right side in the figure. This corresponds to the third rotating element (ring gear Rs) and the fourth rotating element (small sun gear Ss2). The gear ratio between the ring gear Rs and the small sun gear Ss2 (the number of teeth of the ring gear Rs / the number of teeth of the small sun gear Ss2) is j, and the gear ratio between the ring gear Rs and the large sun gear Ss1 (the number of teeth of the ring gear Rs / the teeth of the large sun gear Ss1). When the number is k, the interval between the first to fourth elements is k: 1: j-1.

  As is apparent from the operation table of FIG. 4, the small sun gear Ss2 is connected to the input shaft IS by the engagement of the first clutch C1 to become the rotational speed “1”, and the second brake B2 (or the one-way clutch F1). The planetary carrier Cs is constrained by the housing H and becomes the rotational speed “0” due to the engagement, so that the ring gear Rs, which is the output element, rotates at the rotational speed “1st”, and the first gear is established.

  The engagement of the first clutch C1 causes the small sun gear Ss2 to be connected to the input shaft IS so that the rotational speed becomes “1”, and the engagement of the first brake B1 causes the large sun gear Ss1 to be constrained by the housing H to cause the rotational speed “0”. As a result, the ring gear Rs, which is the output element, rotates at the rotation speed “2nd”, and the second gear is established.

  The engagement of the first clutch C1 causes the small sun gear Ss2 to be connected to the input shaft IS so that the rotational speed becomes “1”, and the engagement of the second clutch C2 causes the large sun gear Ss1 to be connected to the input shaft IS and causes the rotational speed “1”. As a result, each element of the planetary gear unit PUs for shifting is in a locked state where relative rotation is not possible, and the ring gear Rs as the output element rotates at the same rotational speed “1” as the input shaft IS, so that the third speed gear stage is set. Establish.

  The engagement of the first clutch C1 causes the small sun gear Ss2 to be connected to the input shaft IS to become "1", and the engagement of the third clutch C3 changes the rotation speed of the planetary carrier Cs to the output rotation of the planetary gear unit for reduction PUr. By reaching the number “N1”, the ring gear Rs, which is the output element, rotates at the rotational speed “4th” to establish the fourth speed gear.

  The engagement of the second clutch C2 causes the large sun gear Ss1 to be connected to the input shaft IS so that the rotational speed becomes “1”. By reaching the number “N1”, the ring gear Rs, which is the output element, rotates at the rotational speed “5th”, and the fifth gear is established.

  The rotation speed of the planetary carrier Cs becomes the output rotation speed “N1” of the speed reduction planetary gear unit PUr by the engagement of the third clutch C3, and the large sun gear Ss1 is restrained by the housing H by the engagement of the first brake B1. By becoming “0”, the ring gear Rs, which is the output element, rotates at the rotational speed “6th”, and the sixth speed gear stage is established.

  The engagement of the second clutch C2 causes the large sun gear Ss1 to be connected to the input shaft IS so that the rotational speed becomes “1”, and the engagement of the second brake B2 restrains the planetary carrier Cs to the housing H and causes the rotational speed “0”. As a result, the ring gear Rs, which is the output element, rotates in the reverse direction at the rotation speed “Rev” to establish the reverse gear.

  In FIG. 2, the hydraulic pressure generated by the oil pump 29 driven by the engine is supplied to the hydraulic control device 31 during operation of the engine, and the line pressure that is always output by the hydraulic control device 31 is transmitted to the sub oil chamber 28. Thus, the sub-piston 24 retracts against the elastic force of the engagement springs 27, and the pressing portion 24a of the sub-piston 24 is separated from the friction engagement elements 13 at the right end in the figure.

  When establishing the second gear and the sixth gear, the clutch pressure from the hydraulic control device 31 is supplied to the main oil chamber 18, and the main piston 16 moves forward against the resilient force of the return springs 19 ... Then, the pressing portion 16a presses the friction engagement elements 13, ..., and engages the first brake B1. At this time, as described above, since the sub-piston 24 is retracted by the line pressure, it does not interfere with the operation of the main piston 16.

  Now, when the automobile breaks down and cannot run, and when the rear part of the vehicle body is lifted by the tow truck and pulled backward, the rotation of the grounded front wheel is transmitted to the ring gear Rs of the planetary gear unit PUs for shifting through the output shaft OS. Since the engine stops and the oil pump 29 stops when the vehicle is towed, the lubricating oil is not supplied to each lubricated portion of the automatic transmission T, and the line pressure disappears. The springs 27 are moved forward by the elastic force of the springs 27, and the pressing portion 24a presses the friction engagement elements 13 to 14 to engage the first brake B1.

  FIG. 5A shows a speed diagram of the planetary gear unit PUs for shifting when the conventional automatic transmission without the sub-piston 24 is towed. Since the oil pump 29 has stopped, The clutches C1 to C3 and the first and second brakes B1 and B2 are all disengaged, and the one-way clutch F1 is also disengaged because the front wheels are driven in the reverse direction by the road surface. As a result, the speed diagram line changes in a hatched range according to the magnitude relationship of the friction of the first to third clutches C1 to C3, the first and second brakes B1 and B2, and the one-way clutch F1. Therefore, for example, the rotational speed of the planetary carrier Cs fluctuates in the range of a, and when the rotational speed reaches the maximum b, the one-way clutch F1 connected to the planetary carrier Cs over-rotates and supplies lubricating oil. May cause abnormal wear and seizure.

  However, according to the present embodiment, the first brake B1 is automatically engaged when the oil pump 29 is stopped when towed, so that the planetary gear for speed change is shown in FIG. 5 (A) by a thick solid line. The speed diagram of the unit PUs is established, and the rotation speed of the planetary carrier Cs, that is, the rotation speed of the one-way clutch F1, is suppressed to c, so that the above-described abnormal wear and seizure are eliminated.

  In addition, the sub-piston 24 only needs to generate a load that can overcome the friction of the planetary gear unit PUs for shifting, and it is not necessary to generate a large load for transmitting the output of the automatic transmission T. Therefore, the sub-piston 24 is added. As a result, the increase in size, weight and cost is minimized.

  In the embodiment described above, the sub piston 24 is provided in the first brake B1, but the sub piston 24 can be provided in the second brake B2 and the first clutch C1.

  FIG. 5B is a velocity diagram when the sub-piston 24 is provided in the second brake B2 and the second brake B2 is engaged when towed. As shown by a thick solid line in the drawing, since the planetary carrier Cs is restrained by the housing H when the second brake B2 is engaged, it is possible to prevent the planetary carrier Cs from over-rotating. However, in this case, the rotational speeds of the large sun gear Ss1 and the small sun gear Ss2 are increased.

  FIG. 5C is a speed diagram when the first piston C1 is provided with the sub-piston 24 and the first clutch C1 is engaged when towed. As shown by the thick solid line in the figure, since the small sun gear Ss2 is connected to the input shaft IS when the first clutch C1 is engaged, the rotation of the small sun gear Ss2 is stopped by the stopped engine friction to prevent over-rotation. can do. However, in this case, the rotational speed of the large sun gear Ss1 becomes high.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the automatic transmission T according to the embodiment includes one shift planetary gear unit PUs, but may include a plurality of shift planetary gear units PUs. Further, the structure of the planetary gear unit PUs for transmission is not necessarily a Ravigneaux type, and may be a single pinion type or a double pinion type.

B1 First brake (friction engagement device)
B2 Second brake (friction engagement device)
C1 first clutch (friction engagement device)
Cs planetary carrier (at least one element)
H Housing (non-rotating part)
IS input shaft (transmission input shaft)
PUs Speed change planetary gear unit (planetary gear unit)
Rs ring gear (output element)
Ss1 Large sun gear (at least one element)
Ss2 Small sun gear (at least one element)
16 Main piston 24 Sub piston 27 Engaging spring 29 Oil pump (hydraulic supply source)

Claims (3)

At least one planetary gear unit (PUs) to which driving force from a driving source for traveling is input, and an output element (Rs) of a plurality of elements of the planetary gear unit (PUs) is always connected to a wheel, In an automatic transmission in which at least one of the elements (Ss1, Cs, Ss2) can be restrained by the friction engagement device (B1, B2, C1),
The friction engagement device (B1, B2, C1) includes a main piston (16) and a sub-piston (24) that are operated by hydraulic pressure from a hydraulic pressure supply source (29) driven by the travel drive source. The piston (16) is advanced by hydraulic pressure from the hydraulic pressure supply source (29) to engage the friction engagement devices (B1, B2, C1), and the sub-piston (34) is connected to the engagement spring (27). The friction engagement device (B1, B2, C1) is engaged by advancing by an elastic force, and the friction engagement device (B1, B2, C1) is retracted by an oil pressure from the oil pressure supply source (29). ) Is disengaged.   The automatic transmission according to claim 1, wherein the friction engagement device (B1, B2) is a brake that couples the at least one element (Ss1, Cs) to a non-rotating portion (H). .   The automatic transmission according to claim 1, wherein the friction engagement device (C1) is a clutch that couples the at least one element (Ss2) to a transmission input shaft (IS).

Images