JP2011033046A - Hydraulic actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic actuator capable of obtaining a large load in the first half of an operation stroke and obtaining greater speed in the second half of the operation stroke while supplying fixed hydraulic pressure. <P>SOLUTION: A small-diameter piston 20 is fitted slidably into a sub-cylinder 19a formed inside a large-diameter piston 19 that is fitted slidably into a cylinder 18a of a hydraulic actuator A. An oil chamber 22 is made to face the back surface of the large-diameter piston 19 and the oil chamber 22 is made to face the back surface of the small-diameter piston 20 via an oil hole 19b formed in the back surface of the large-diameter piston 19. Therefore, by only supplying the fixed hydraulic pressure to the oil chamber 22, the large load can be generated by moving the large-diameter piston 19 in the first half of the stroke of the hydraulic actuator A from Fig.2(A) to Fig.2(B) and the greater working speed can be obtained by moving the small-diameter piston 20 in the second half of the stroke of the hydraulic actuator A from Fig.2(B) to Fig.2(C). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydraulic actuator for driving a piston movably supported in a cylinder with hydraulic pressure acting on an oil chamber defined on the back surface of the piston.

  In a so-called twin-clutch type automatic transmission, the next shift stage is pre-shifted in advance during establishment of the predetermined shift stage, and the predetermined shift stage is released and the pre-shift is performed by switching a pair of clutches. If the pre-shift timing is delayed in order to establish the next shift stage, there is a problem that the shift time becomes longer than that of the conventional automatic transmission. Therefore, it is known from Patent Document 1 below that the next shift stage is predicted early based on the vehicle speed and the throttle opening, and the pre-shift is performed based on this prediction.

  Also, in an automatic transmission that shifts by operating the synchronizer with a hydraulic actuator, the synchronizer operates smoothly by changing the amount of hydraulic pressure supplied to the hydraulic actuator during the shift change process, reducing shift shock In addition, a technique that shortens the time required for gear shifting is known from Japanese Patent Application Laid-Open No. 2004-228561.

Japanese Patent Laid-Open No. 10-318361 JP 2008-175236 A

  By the way, the invention described in the above-mentioned patent document 1 can achieve a desired effect when the prediction of the next shift stage is correct, but if the prediction is not satisfied, the preshift is canceled and a new preshift is performed. Therefore, there is a possibility that the shift time will be significantly increased.

  Further, the invention described in Patent Document 2 requires that the hydraulic pressure supplied to the hydraulic actuator be changed during the shift change process, which complicates the structure and control of the hydraulic control circuit. There is a problem that it is difficult to supply a hydraulic pressure of a desired magnitude at this timing.

  The present invention has been made in view of the circumstances described above, and provides a hydraulic actuator capable of obtaining a large load in the first half of the operating stroke and a large speed in the second half of the operating stroke while supplying a constant hydraulic pressure. The purpose is to do.

  In order to achieve the above object, according to the first aspect of the present invention, a hydraulic actuator that drives a piston movably supported inside a cylinder with hydraulic pressure acting on an oil chamber defined on the back surface of the piston. The piston includes a large-diameter piston that is slidably fitted to the cylinder, and a small-diameter piston that is slidably fitted to a sub-cylinder formed inside the large-diameter piston and outputs a driving force. A hydraulic actuator is proposed in which the oil chamber faces the back surface of the large-diameter piston, and the oil chamber communicates with the back surface of the small-diameter piston through an oil hole formed in the large-diameter piston. The

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the cylinder includes a stopper that restricts a movement limit of the large-diameter piston, and when the large-diameter piston contacts the stopper. A hydraulic actuator is proposed in which the small diameter piston starts to move relative to the large diameter piston.

  According to a third aspect of the invention, in addition to the configuration of the second aspect, the hydraulic actuator drives a synchronization device of a transmission, and the large-diameter piston is moved when the synchronization of the synchronization device is completed. A hydraulic actuator is proposed which is in contact with the stopper.

  According to a fourth aspect of the invention, in addition to the configuration of the second aspect, the hydraulic actuator drives a synchronization device of a transmission, and the small-diameter piston moves after the synchronization of the synchronization device is completed. A hydraulic actuator is proposed which is characterized by starting

  According to the configuration of the first aspect, the small diameter piston is slidably fitted to the sub-cylinder formed inside the large diameter piston that is slidably fitted to the cylinder of the hydraulic actuator, and the oil is disposed on the back surface of the large diameter piston. Since the oil chamber is exposed to the back surface of the small-diameter piston through the oil hole formed on the back surface of the large-diameter piston, the first half of the stroke of the hydraulic actuator can be obtained simply by supplying a constant oil pressure to the oil chamber. The large-diameter piston can be moved to generate a large load, and the small-diameter piston can be moved in the second half of the stroke of the hydraulic actuator to obtain a large operating speed.

  According to the second aspect of the present invention, since the cylinder is provided with a stopper for restricting the movement limit of the large diameter piston, a large load is generated on the large diameter piston until the large diameter piston moves and contacts the stopper. After the large-diameter piston contacts the stopper, the small-diameter piston can be moved at a high speed.

  According to the third aspect of the present invention, the hydraulic actuator is used for driving the synchronization device of the transmission, and the large-diameter piston contacts the stopper when the synchronization of the synchronization device is completed. Can be obtained by operating a large-diameter piston.

  According to the fourth aspect of the present invention, the hydraulic actuator is used for driving the synchronization device of the transmission, and the small-diameter piston starts moving after the synchronization of the synchronization device is completed. A large operating speed can be obtained by operating the small diameter piston in the required region.

The figure which shows the structure of a hydraulic actuator and a synchronizer (1st Embodiment). Action | operation explanatory drawing of a hydraulic actuator (1st Embodiment). The figure which shows the relationship between the stroke amount of a synchronizer, and a required load (1st Embodiment). Operation | movement explanatory drawing of the synchronizing device of a transmission provided with a wet clutch (1st Embodiment). Operation | movement explanatory drawing of the synchronizer of a transmission provided with a dry clutch (2nd Embodiment). The figure which shows the structure of a hydraulic actuator (3rd Embodiment). The figure which shows the structure of a hydraulic actuator (4th Embodiment). The figure which shows the structure of a hydraulic actuator (5th Embodiment).

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the hydraulic actuators A and A of the present embodiment are used for the purpose of driving a transmission synchronization device S. Two hydraulic actuators A and A are provided across the synchronizer S, and when the left hydraulic actuator A in the figure is operated to move the shift fork 17 to the right, the first shift stage is established, and the right side in the figure is established. When the hydraulic actuator A is actuated to move the shift fork 17 to the left, the second shift stage is established. In FIG. 1, the part related to the establishment of the first shift stage and the part related to the establishment of the second shift stage have substantially the same structure and operation. The description will focus on the part related to the establishment of the first gear.

  The synchronizer S has a well-known structure, and includes a hub 11 coupled to a rotation shaft (not shown) of the transmission, and an annular sleeve 12 that is spline-fitted to the outer peripheral surface of the hub 11 so as to be axially slidable. , A gear 13 (a gear main body portion is not shown) supported on the rotating shaft so as to be relatively rotatable, an annular blocking ring 14 disposed so as to be relatively rotatable between the hub 11 and the gear 13, and the hub 11 and the blocking ring. 14 and an annular synchronizer spring 15 disposed between the two.

  Chamfers 12a that are spline-fitted to the outer peripheral surface of the hub 11 are formed on the inner peripheral surface of the sleeve 12, and chamfers 14a that are engageable with the chamfers 12a of the sleeve 12 are formed on the outer peripheral surface of the blocking ring 14. On the outer peripheral surface of the gear 13, dog teeth 13a that can be engaged with the chamfers 12a of the sleeve 12 are formed. A tapered cone surface 14 b is formed on the inner periphery of the blocking ring 14, and a tapered cone surface 13 b that contacts the tapered cone surface 14 b of the blocking ring 14 is formed on the outer periphery of the gear 13.

  A guide portion 17a of the shift fork 17 is slidably supported on a shift guide rod 16 disposed in the axial direction between the synchronization device S and the hydraulic actuator A. The shift fork 17 includes a driven portion 17b driven by a hydraulic actuator A on one end side across the guide portion 17a, and a fork-like drive that engages with an annular groove 12b formed on the outer periphery of the sleeve 12 on the other end side. A portion 17c is provided.

  The hydraulic actuator A includes a cup-shaped cylinder member 18, a cup-shaped large-diameter piston 19 that is slidably fitted to a cylinder 18 a constituted by the inner peripheral surface of the cylinder member 18, and an inner periphery of the large-diameter piston 19. A cup-shaped small-diameter piston 20 that is slidably fitted to a sub-cylinder 19a constituted by a surface, and a stopper 21 made of a clip that regulates the moving end of the large-diameter piston 19 are provided.

  The cylinder member 18 includes an oil chamber 22 between the back surface of the large-diameter piston 19, and the oil chamber 22 is connected to a hydraulic circuit (not shown) through an oil hole 18b. The large diameter piston 19 is sealed between the cylinder 18 a by the seal member 23, and the small diameter piston 20 is sealed between the sub cylinder 19 a by the seal member 24. A sub oil chamber 25 is defined between the large diameter piston 19 and the small diameter piston 20, and the oil chamber 22 and the sub oil chamber 25 communicate with each other through an oil hole 19 b formed in the large diameter piston 19. The front surface of the small-diameter piston 20 contacts the driven portion 17b of the shift fork 17.

  FIG. 2A shows a state in which the hydraulic actuator A is inoperative. The large-diameter piston 19 moves backward in the cylinder 18a to the left in the drawing and is separated from the stopper 21, and the small-diameter piston 20 has a large diameter. The inside of the sub-cylinder 19a of the piston 19 is retreated to the left in the figure and has a bottom. When hydraulic oil is supplied to the oil chamber 22 from this state, the hydraulic pressure is transmitted to the oil chamber 22 and the auxiliary oil chamber 25, but the pressure receiving area of the large diameter piston 19 is larger than the pressure receiving area of the small diameter piston 20, and the small diameter. Since the piston 20 receives a reaction force from the shift fork 17, the large-diameter piston 19 moves forward together with the small-diameter piston 20. The large-diameter piston 19 is prevented from moving forward at a position where it abuts against the stopper 21 (see FIG. 2B).

  When the large-diameter piston 19 moves forward with the small-diameter piston 20 from the state shown in FIG. 2A to the state shown in FIG. 2B, the thrust is generated by the large pressure-receiving surface of the large-diameter piston 19 facing the oil chamber 22. Therefore, the large-diameter piston 19 and the small-diameter piston 20 move forward at a low speed with a large thrust.

  When the large-diameter piston 19 comes into contact with the stopper 21 and stops, hydraulic oil flows from the oil chamber 22 into the auxiliary oil chamber 25 through the oil hole 19b of the large-diameter piston 19, and the small-diameter piston 19 has a smaller diameter than the stopped large-diameter piston 19. The piston 20 moves forward in the right direction in the figure (see FIG. 2C). Since the forward limit position of the small-diameter piston 20 is regulated by the synchronizing device S that is operated by the small-diameter piston 20 via the shift fork 17, no special stopper is required.

  When the small-diameter piston 20 moves forward with respect to the large-diameter piston 19 from the state shown in FIG. 2B to the state shown in FIG. 2C, the thrust is generated by the small pressure receiving surface of the small-diameter piston 20 facing the auxiliary oil chamber 25. Therefore, the small-diameter piston 20 moves forward at a high speed with a small thrust.

  As described above, even if the hydraulic pressure supplied from the hydraulic circuit is constant, the hydraulic actuator A of the present embodiment generates a large thrust in the first half of the operation (first operation region), but the operation speed is low. In the latter half of the operation (second operation region), only a small thrust is generated, but the operation speed is high.

  Next, the operation of the hydraulic actuator A and the synchronizer S when shifting the transmission will be described.

  The transmission according to the present embodiment is of a so-called twin clutch type, and the first input shaft to which the driving force of the engine is transmitted through the first clutch and the driving force of the engine are transmitted through the second clutch. A second input shaft, and an odd gear (first speed, third speed, fifth speed,...) Is established with a gear train disposed between the first input shaft and the output shaft. Even-numbered gear stages (second speed, fourth speed, sixth speed,...) Are established with a gear train arranged between the output shaft. For example, the first clutch is engaged and the second clutch is disengaged during traveling at the first gear, and the second gear is preshifted in advance during traveling at the first gear. . When shifting up from the first gear to the second gear, the pre-shifted second gear is established and driven without delay by simply disengaging the first clutch and engaging the second clutch. Force can be transmitted and driving force can be shifted up without interruption.

  In the present embodiment, wet clutches are employed for the first and second clutches. In the wet clutch, a drag force due to the viscosity of the hydraulic oil acts on the friction engagement element, so that a relatively large synchronous load is required when the synchronization device S provided on the first and second input shafts operates.

  FIG. 4 shows the operation of the hydraulic actuator A and the synchronizer S during the pre-shift of the transmission over time. When the hydraulic actuator A is driven from the state of FIG. 4 (A), it is pressed by the small diameter piston 20. The shift fork 17 advances, and the sleeve 12 that is spline-fitted to the hub 11 fixed to the rotating shaft advances. The load by which the sleeve 12 advances is transmitted to the blocking ring 14 via the synchronizer spring 15, and the blocking ring 14 is urged toward the gear 13 (see FIG. 4B).

  When the sleeve 12 further advances, the tooth tips of the chamfers 12a of the sleeve 12 abut the tooth tips of the chamfers 14a of the blocking ring 14, and the tapered cone surface 13b of the gear 13 and the tapered cone surface 14b of the blocking ring 14 Come into contact with each other and torque due to frictional force is generated (see FIG. 4C). When the sleeve 12 further advances, the rotation of the sleeve 12 (that is, the rotation of the rotating shaft) is synchronized with the rotation of the gear 13 by the torque, and the chamfers 12a of the sleeve 12 can scrape the chamfers 14a of the blocking ring 14. (See FIG. 4D).

  When the rotation of the sleeve 12 is synchronized with the rotation of the gear 13, the torque disappears. Therefore, when the sleeve 12 further moves forward, the chamfers 12a of the sleeve 12 scrape the chamfers 14a of the blocking ring 14 so that the sleeve 12 and the blocking ring 14 are separated. Further, the teeth of the chamfers 12a of the sleeve 12 are engaged with the teeth of the dog teeth 13a of the gear 13 (see FIG. 4E). When the sleeve 12 further advances, the chamfers 12a of the sleeve 12 scrape the dog teeth 13a of the gear 13 (see FIG. 4F), and finally the chamfers 12a of the sleeve 12 become the dog teeth 13a of the gear 13. Engage to complete the pre-shift (see FIG. 4G).

  FIG. 3 shows the magnitude of the load that should be generated by the hydraulic actuator A during the above-described pre-shift process. In the first operating region of the first half, when borking (see FIG. 4C), when blocking the ring ( 4D) and when the dog teeth are separated (see FIG. 4F), a large load is required. In the second operating region after the dog teeth are separated, only a relatively small load is required. Although not required, the hydraulic actuator A requires a high operating speed in order to perform a quick shift change.

  As described above, a transmission using a wet clutch requires a large synchronous load in a relatively long first operating region in the first half of the preshift, and quick operation in a relatively short second operating region in the second half of the preshift. The large-diameter piston 19 starts to move so that the large-diameter piston 19 of the hydraulic actuator A operates in the first operating region and the small-diameter piston 20 of the hydraulic actuator A operates in the second operating region. If the stroke from the contact to the stopper 21 is set, a constant hydraulic pressure is simply supplied to the hydraulic actuator A, and the sleeve 12 is driven slowly with a large load in the first operation region, and the sleeve 12 is supplied in the second operation region. Can be driven quickly with a small load, and a reliable and prompt shift change can be realized.

  In addition, since it is only necessary to supply a constant hydraulic pressure to the hydraulic actuator A, it is not necessary to complicate the hydraulic circuit, and this can be realized at low cost.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, wet clutches are used for the first and second clutches that transmit the driving force of the engine to the first and second input shafts (rotating shafts) of the transmission. The form adopts a dry clutch. Unlike the wet clutch, the dry clutch does not drag the hydraulic oil, so the first operating area where a large load is required for the synchronization of the synchronization device S is until the bake in FIG. This is the second operation region where the operation of is required.

  That is, in the first embodiment, the first operation region is lengthened and the second operation region is shortened, but in the second embodiment, the first operation region is shortened and the second operation region is lengthened.

  In order to give the above-mentioned operation characteristics to the hydraulic actuator A, the stroke from when the large-diameter piston 19 starts to move to contact with the stopper 21 may be set shorter than that in the first embodiment.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the volume of the auxiliary oil chamber 25 partitioned between the large-diameter piston 19 and the small-diameter piston 20 is set to be relatively large. However, in the third embodiment, the auxiliary oil chamber 25 is configured as described above. Is set to be relatively small.

  Thus, by setting the volume of the auxiliary oil chamber 25 small, the time lag until the small diameter piston 20 starts moving after the hydraulic oil flows into the auxiliary oil chamber 25 is minimized, and the operation of the small diameter piston 20 is performed. Responsiveness can be improved.

  Next, a fourth embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the stopper 21 is constituted by a clip which is a separate member from the cylinder member 18, but in the second embodiment, the stopper 21 is constituted integrally with the cylinder member 18. As a result, the number of parts can be reduced.

  Next, a fifth embodiment of the present invention will be described with reference to FIG.

  In each of the above-described embodiments, the shift fork 17 slidably supported on the shift guide rod 16 is driven by the small-diameter piston 20 of the hydraulic actuator A. In the fifth embodiment, the small-diameter of the hydraulic actuator A is driven. A shift fork 17 is fixed to a shift rod 26 formed integrally with the piston 20. In order to stabilize the support of the shift rod 26, it is desirable to connect both ends of the shift rod 26 to the two small diameter pistons 20, 20 of the pair of hydraulic actuators A, A.

  According to the fifth embodiment, the shift guide rod 16 can be eliminated and the shift fork 17 can be downsized, which can contribute to downsizing of the transmission.

  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, although the hydraulic actuator A is applied to the transmission synchronization device S in the embodiment, the hydraulic actuator A of the present invention can be applied to any application other than the synchronization device S.

18a Cylinder 19 Large diameter piston 19a Sub cylinder 19b Oil hole 20 Small diameter piston 21 Stopper 22 Oil chamber A Hydraulic actuator S Synchronizer

Claims (4)

In the hydraulic actuator for driving the piston (19, 20) movably supported inside the cylinder (18a) with oil pressure acting on the oil chamber (22) defined on the back surface of the piston (19, 20),
The piston (19, 20) slides on a large diameter piston (19) slidably fitted to the cylinder (18a) and a sub cylinder (19a) formed inside the large diameter piston (19). It consists of a small-diameter piston (20) that fits freely and outputs driving force,
The oil chamber (22) faces the back surface of the large-diameter piston (19), and the oil chamber (22) passes through the oil hole (19b) formed in the large-diameter piston (19). ) Is connected to the back surface of the hydraulic actuator.   The cylinder (18a) includes a stopper (21) for restricting the movement limit of the large-diameter piston (19). When the large-diameter piston (19) comes into contact with the stopper (21), the small-diameter piston (20) 2. Hydraulic actuator according to claim 1, characterized in that it starts to move with respect to the large-diameter piston (19). The hydraulic actuator (A) drives a transmission synchronizer (S),
The hydraulic actuator according to claim 2, wherein the large-diameter piston (19) abuts on the stopper (21) when the synchronization of the synchronization device (S) is completed. The hydraulic actuator (A) drives a transmission synchronizer (S),
The hydraulic actuator according to claim 2, characterized in that the small-diameter piston (20) starts to move after the synchronization of the synchronizer (S) is completed.

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