JP2009024562A - Variable capacity type hydraulic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of the deterioration of turning performance caused by a large size and the heavy weight of an entire axle driving device caused by the inevitable installation of an inclined rolling cylinder and the like, in a conventional variable capacity type hydraulic motor comprising a swash plate control mechanism for controlling an inclined rolling angle of a movable swash plate. <P>SOLUTION: A swash plate control mechanism 20 is driven by a turning force transmitted from a steering wheel or a turning operation tool via a link mechanism 110. The swash plate control mechanism 20 is configured for generating the moment around the inclined rolling center 23a exerted to a movable swash plate M1a on the inclined rolling angle increase side at the time of turning by providing the inclined rolling center 23a of the movable swash plate M1a eccentrically from the motor shaft center 6b. Furthermore, a line of the action 87a of a piston synthesized force 87 of a pressing force component 85 applied on the movable swash plate M1a from a sliding piston 81 passes the inclined rolling center 23a of the movable swash plate M1a in a maximum inclined rolling position of the movable swash plate M1a. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  In the present invention, a motor shaft is rotatably provided in an axle driving device, and a cylinder block into which a plurality of pistons are slidably fitted is connected to the motor shaft, and the piston is opposed to the cylinder block. The present invention relates to a variable displacement hydraulic motor in which a movable swash plate that is slidably contacted is provided, and the number of rotations of a motor shaft can be changed by a tilt angle of the movable swash plate.

Conventionally, in the control mechanism of the tilt angle of the movable swash plate, considering that it is used for a hydraulic pump, the tilt of the movable swash plate is normally tilted so that the tilt angle is tilted to a lower side when the load is high. The center is provided on the axis of the motor shaft. For this reason, when the same control mechanism is applied to the hydraulic motor, the movable swash plate tilts toward the tilt angle decreasing side at high loads, and the capacity of the hydraulic motor decreases. The capacity of the motor is further reduced. In addition, the movable swash plate is returned for a moment due to the peak pressure at the start of the vehicle, and when the load is reduced, the movable swash plate is greatly tilted to the maximum tilt position, and the stopper and the lever provided at the maximum tilt position collide violently, A loud sound or vibration may occur.
Therefore, a pair of tilting cylinders for tilting the movable swash plate to the tilt angle increasing side and tilting angle decreasing side, a tilting regulator for driving the tilting cylinder, and the like are provided, and the tilting regulator is externally provided. A swash plate control mechanism that drives the tilt cylinder by sending a signal from it to accurately control the tilt angle regardless of the position of the tilt center of the movable swash plate, and further, the tilt center of the movable swash plate By decentering the shaft from the axis of the motor shaft, the moment force that urges the movable swash plate to the tilt angle increasing side is constantly applied to the movable swash plate to tilt the tilt angle to the increasing angle side. A technique related to a swash plate control mechanism that omits the tilting cylinder is known (for example, see Patent Document 1).
Japanese Patent No. 2843789

However, the swash plate control mechanism includes at least a tilting cylinder for tilting the movable swash plate toward the tilt angle reducing side, a tilting regulator for driving the tilting cylinder, and the like separately from the hydraulic motor. It was necessary to provide in.
Therefore, when the hydraulic motor for driving the steered wheels is installed in the axle drive device and the vehicle is turning to reduce the output by suppressing the output from the hydraulic motor to improve the turning performance, the technology related to the swash plate control mechanism described above is used. When applied, it is necessary to install the tilting cylinder, the tilting regulator, etc., and the entire axle drive device becomes larger and heavier and the turning performance is reduced, or there is a space for arranging various link structures for steering. There is a problem that the interference between the members is increased by being limited to a small size, and the link structure is complicated in order to avoid the interference, resulting in an increase in manufacturing cost and a decrease in maintainability.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
That is, in claim 1, a motor shaft is rotatably provided in the axle driving device, and a cylinder block into which a plurality of pistons are slidably fitted is connected to the motor shaft, and is opposed to the cylinder block. In a variable displacement hydraulic motor that has a movable swash plate with which the piston is slidably contacted and is capable of changing an output from the motor shaft according to a tilt angle of the movable swash plate, a steered wheel driven by the axle drive device A swash plate control mechanism that tilts the movable swash plate in accordance with a turning angle of the swash plate, and the swash plate control mechanism is driven by a turning force transmitted from the steering wheel or a turning operation tool via a link structure. In the swash plate control mechanism, the tilt center of the movable swash plate is decentered from the axis of the motor shaft, and a moment about the tilt center acting on the movable swash plate is generated on the tilt angle increasing side during turning. Like One in which the.
According to a second aspect of the present invention, in the variable displacement hydraulic motor, at the maximum tilt position of the movable swash plate at the time of turning of the steering wheel, the piston combined force obtained by synthesizing each pressing force acting on the movable swash plate from the sliding sliding piston. The tilt center is decentered from the axis of the motor shaft so that the action line passes over the tilt center of the movable swash plate.
According to a third aspect of the present invention, the movable swash plate is slidably held by a swash plate guide, and the swash plate guide has a position adjusting structure capable of moving in a tilting direction of the swash plate and fixing at a predetermined position. It is.
According to a fourth aspect of the present invention, the position adjustment structure is configured such that a gap adjustment member is detachably interposed between a housing that houses the variable displacement hydraulic motor and the swash plate guide, and the thickness of the gap adjustment member By changing the above, the tilt center position of the movable swash plate can be adjusted.
According to a fifth aspect of the present invention, the swash plate guide is provided separately from the bearing portion of the motor shaft.

Since this invention was comprised as mentioned above, there exists an effect shown below.
That is, in claim 1, a motor shaft is rotatably provided in the axle driving device, and a cylinder block into which a plurality of pistons are slidably fitted is connected to the motor shaft, and is opposed to the cylinder block. In a variable displacement hydraulic motor that has a movable swash plate with which the piston is slidably contacted and is capable of changing an output from the motor shaft according to a tilt angle of the movable swash plate, a steered wheel driven by the axle drive device A swash plate control mechanism that tilts the movable swash plate in accordance with a turning angle of the swash plate, and the swash plate control mechanism is driven by a turning force transmitted from the steering wheel or a turning operation tool via a link structure. In the swash plate control mechanism, the tilt center of the movable swash plate is decentered from the axis of the motor shaft, and a moment about the tilt center acting on the movable swash plate is generated on the tilt angle increasing side during turning. Like Therefore, by using the turning force from the steering wheel or turning operation tool, it is possible to eliminate the need for any tilting cylinders, tilting regulators, etc. As well as ensuring a wide space in the axle drive device, it is possible to prevent interference between members and prevent complication of various link structures, reducing the manufacturing cost and improving maintainability by reducing the number of parts. Can be planned. Moreover, by adjusting the moment acting on the movable swash plate, the operating force of the movable swash plate can be greatly reduced, and even if the turning force is small, it will not be attenuated during transmission, The movable swash plate can be tilted quickly and accurately using only the turning force without using a tilting regulator, etc., and the deterioration of the turning performance caused by driving the movable swash plate with the turning force is surely prevented. can do.
According to a second aspect of the present invention, in the variable displacement hydraulic motor, at the maximum tilt position of the movable swash plate at the time of turning of the steering wheel, the piston combined force obtained by synthesizing each pressing force acting on the movable swash plate from the sliding sliding piston. The tilt center is decentered from the axis of the motor shaft so that the line of action passes over the tilt center of the movable swash plate. The applied pressing force can be made almost uniform to distribute the load on the movable swash plate and improve the durability of the hydraulic motor. The replacement frequency can be increased to improve the operating rate and reduce maintenance costs. Can do. In particular, when a sliding part such as thrust bearing is provided on the movable swash plate and the piston top is slidably contacted with the sliding part, the sliding part can be adjusted by adjusting the position and structure of the sliding part. It is possible to apply a pressing force to the center of a receiving member such as a ball or a roller constituting the roller, improve sliding performance in addition to durability, increase output efficiency of the hydraulic motor, and reduce fuel consumption. .
According to a third aspect of the present invention, the movable swash plate is slidably held by a swash plate guide, and the swash plate guide has a position adjustment structure that can move in the tilting direction of the swash plate and can be fixed at a predetermined position. Without changing the entire hydraulic motor, it is possible to easily change the eccentric amount of the tilting center of the movable swash plate simply by adjusting the position of the swash plate guide. The high turning performance can always be secured. Furthermore, even if the required turning conditions are different and the moment acting on the movable swash plate is different, it is only necessary to move the position of the swash plate guide, and the same swash plate guide or movable swash plate should be used. Therefore, a hydraulic motor excellent in versatility can be configured.
According to a fourth aspect of the present invention, the position adjustment structure is configured such that a gap adjustment member is detachably interposed between a housing that houses the variable displacement hydraulic motor and the swash plate guide, and the thickness of the gap adjustment member The tilt center position of the movable swash plate can be adjusted by changing the position of the movable swash plate, so the eccentric amount of the tilt center of the movable swash plate can be changed by simply changing the number and thickness of the gap adjustment members. It is possible to reduce the cost for installing the position adjustment structure and the installation space, and to reduce the manufacturing cost of the hydraulic motor and make it compact.
According to a fifth aspect of the present invention, since the swash plate guide is provided separately from the bearing portion of the motor shaft, the swash plate guide can be moved independently of the bearing portion, and the movable swash plate can be tilted. It is easy to change the amount of eccentricity of the center, and in addition, it becomes easy to incorporate a receiving member such as a ball or a roller into the bearing portion, and the assemblability of the hydraulic motor can be improved.

Next, embodiments of the invention will be described.
FIG. 1 is a partial plan view of a plane showing the overall configuration of an axle drive device incorporating a variable displacement hydraulic motor according to the present invention, FIG. 2 is a partial cross-sectional view of the rear surface, and FIG. 3 is an axle drive device showing a link structure. 4 is a rear view of the main part of the axle drive device when the rear cover is removed, FIG. 5 is a sectional view taken along the line AA in FIG. 3, and FIG. 6 is a tilt center of the movable swash plate. 7 is a partial cross-sectional view of the back surface of the hydraulic motor eccentric to the tilt angle increasing side, FIG. 7 is a partial cross-sectional view of the back surface of the hydraulic motor in which no moment is generated around the tilt center at the maximum tilt position of the movable swash plate, and FIG. 9 is a partial cross-sectional view of the back of a hydraulic motor having a swash plate position adjustment structure. FIG. 9 shows a position adjustment structure of the swash plate guide, and a moment is generated around the tilt center at the maximum tilt position of the movable swash plate. 10 is a partial cross-sectional view of the rear surface of the hydraulic motor. FIG. FIG. 11 is a bottom sectional view of a swash plate guide having a position adjusting structure, and FIG. 12 is an axle drive device incorporating a hydraulic motor according to the present invention. FIG. 2 is a hydraulic circuit diagram of a four-wheel drive type vehicle that employs for driving front wheels. In the following embodiments, the direction of arrow F in FIG.

First, the overall configuration of the axle drive device 1 incorporating the variable displacement hydraulic motors M1 and M2 according to the present invention will be described with reference to FIGS.
The axle drive device 1 has a main case 2, and a center pin hole 2a having a front and rear horizontal penetrating shape is formed at the upper end of the left and right central portion of the main case 2, and the center pin is inserted through the center pin through the center pin hole 2a. The axle drive device 1 is pivotally supported with respect to a vehicle frame (not shown) so that left and right ends thereof can swing up and down.

  In the main case 2, a PTO shaft 36 is pivotally supported in the front-rear horizontal direction on the left and right sides of the center pin hole 2 a, and the front and rear ends of the PTO shaft 36 protrude forward and backward of the main case 2. In the main case 2 on the left and right other side of the center pin hole 2a, a variable capacity type first hydraulic motor M1 and a second hydraulic motor M2 according to the present invention, which will be described in detail later, are arranged side by side. Yes.

  The first hydraulic motor M1 and the second hydraulic motor M2 are respectively provided with a motor shaft 6 in the horizontal direction, and the outer end of the motor shaft 6 of the first hydraulic motor M1 is connected via a coupling. The second hydraulic motor M2 is connected to the extension shaft 34 on the same axis via the coupling and the extension shaft 35 on the same axis. It is connected so that it can rotate together.

  By providing the extension shaft 35, an arrangement space is secured in the main case 2 between the left second hydraulic motor M 2 and the left extension shaft 34, and of the arrangement space, the extension shaft 35 is directly above the extension shaft 35. The PTO shaft 36 is pivotally supported in a portion inside the main case 2.

  Steering cases 7 are attached to the left and right ends of the main case 2, and the steering case 7 includes a kingpin case portion 7a having upper portions fixed to the left and right ends of the main case 2, and the kingpin case. A rotating case portion 7b is rotatably fitted to a lower portion of the portion 7a via a bearing, and an axle support case portion 7c is fixedly provided at an outer end of the rotating case portion 7b.

  A transmission shaft 8 acting as a king pin is rotatably supported in the kingpin case portion 7a. A bevel gear 8a is fixed to the upper end of the transmission shaft 8, and the bevel gear 8a is connected to the extension shaft 34. It is meshed with a bevel gear 34a fixed to the outer end. The lower end of the transmission shaft 8 protrudes downward from the lower end of the kingpin case portion 7a and is supported at the bottom of the rotating case portion 7b. A bevel gear 8b is fixed to the lower end portion of the transmission shaft 8. Yes.

  On the other hand, in the substantially horizontal axle 9, the inner end portion of the axle 9 is pivotally supported by the rotating case portion 7b and the middle portion in the axial center direction is pivotally supported by the axle support case portion 7c. A large-diameter bevel gear 9b is fixed to the axle 9 between a shaft support portion to the moving case portion 7b and a shaft support portion to the axle support case portion 7c, and the bevel gear 9b is provided at the lower end of the transmission shaft 8. It is meshed with the bevel gear 8b.

  A flange 9a is formed on the outer end of the axle 9 outside the axle support case portion 7c so as to be fixed to the rim portion of the wheel, and the wheel fixed to the flange 9a is connected to the axle drive device 1. Further, the wheel is supported so as to be steerable and drivable by the hydraulic motors M1 and M2, so that the wheel rotates the rotating case portion 7b and the axle support case portion 7c around the kingpin case portion 7a. It is a steerable wheel that can turn left and right.

  In addition, a link structure 110 described later is interposed between the first hydraulic motor M1 and the second hydraulic motor M2 and the rotation case portion 7b. The force generated when turning by the steered wheels (hereinafter referred to as “turning force”) is transmitted to the swash plate control mechanism 20 according to the present invention, and the outputs from the first hydraulic motor M1 and the second hydraulic motor M2 are changed. I can do it.

  A tie rod stay 11 is formed at the rear end portion of the turning case portion 7b of the steering case 7 so as to extend rearward. In the tie rod stay 11, a tie rod pivot support portion is provided at the rear portion, that is, away from the steering case 7. A tie rod pivotal support portion 11b is formed on the front portion, that is, closer to the steering case 7 than 11a. The tie rod stays 11 and 11 are extended so that the distance between the tie rod stays 11 and 11 decreases toward the rear, and the distance between the tie rod pivots 11b and 11b is longer than the distance between the tie rod pivots 11a and 11a. .

  In FIG. 1, for convenience, both a short rear tie rod 37 interposed between the tie rod pivots 11a and 11a of both tie rod stays 11 and 11 and a long front tie rod 38 interposed between the tie rod pivots 11b and 11b. However, in actuality, the tie rod 37 is interposed between the tie rod pivots 11a and 11a or the tie rod 38 is interposed between the tie rod pivots 11b and 11b. is there. That is, when it is desired to increase the turning angle of the wheel attached to the axles 9 and 9 with respect to the operation of the steering wheel, the rear tie rod 37 is selected, and when it is desired to keep the turning angle of the wheel small, the front tie rod is selected. 38 can be selected.

  With the configuration described above, the wheels are supported by the axle drive device 1 in a steerable manner, and the outputs from the first hydraulic motor M1 and the second hydraulic motor M2 can be changed in conjunction with the turning angle of the wheels. ing.

Next, the basic configuration of the hydraulic motor and its swash plate control mechanism and the link structure to the swash plate control mechanism will be described with reference to FIGS.
First, the hydraulic motors M1 and M2 will be described with reference to FIGS.
An oil passage plate 4 is fixed in the main case 2, the first hydraulic motor M 1 is attached to the right surface of the oil passage plate 4, and the second hydraulic motor M 2 is attached to the left surface. A pair of kidney ports 4c and 4d are formed so as to penetrate between the left and right surfaces to which the hydraulic motors M1 and M2 are attached, respectively.

  Further, in the oil passage plate 4, the kidney ports 4 c and 4 d are connected to a hydraulic source disposed outside the axle drive device 1 such as a hydraulic pump P described later, and therefore the oil passage 4 a is connected to the kidney port 4 c. However, an oil passage 4 b is extended from the kidney port 4 d and is opened outward on the rear surface of the oil passage plate 4.

  As a result, the hydraulic oil supplied from one of the oil passages 4a and 4b is distributed to both hydraulic motors M1 and M2 through the kidney port 4c or 4d connected thereto, and then discharged from both hydraulic motors M1 and M2. The hydraulic oil can be collected in the other oil passage 4b or 4a through the other kidney port 4d or 4c and then returned to the hydraulic source, and the hydraulic motors M1 and M2 can be fluidly connected in parallel to the hydraulic source.

  A pair of left and right swash plate guides 5 are fixed in the main case 2 with the hydraulic motors M1 and M2 and the oil passage plate 4 interposed therebetween. Of these, the right swash plate guide 5 has a movable swash plate M1a of the first hydraulic motor M1, and the left swash plate guide 5 has a movable swash plate M2a of a second hydraulic motor M2. It is supported freely.

  The motor shafts 6 and 6 of the hydraulic motors M1 and M2 are horizontally arranged on the same axis, and the inner ends of the motor shafts 6 and 6 are rotated in the oil passage plate 4. It is supported freely. Each motor shaft 6 passes through the hydraulic motors M1 and M2 and further freely passes through the movable swash plates M1a and M2a. It is pivotally supported by.

  In addition, the rear end of the main case 2 where both the hydraulic motors M1 and M2, the oil passage plate 4 and the two swash plate guides 5 are opened is opened, and the rear cover 3 is detachably fixed to the opening. The rear cover 3 is removed from the main case 2 so that both the hydraulic motors M1 and M2, the oil passage plate 4 and the like can be easily accessed.

  The rear cover 3 is provided with oil passages 3a and 3b communicating with the upper and lower oil passages 4a and 4b formed in the oil passage plate 4 in the front-rear and horizontal directions, respectively. The communicating oil passage 3a is bent upward, and a port member 32 is fitted into the upper end opening thereof. An outer opening port 32a is formed in the port member 32, and the port 32a is It communicates with the oil passage 3a.

  The oil passage 3b communicating with the lower oil passage 4b is also bent upward, opened at the rear lower side of the port member 32, and the port member 33 is fitted into the opening. Is formed with an outer opening-shaped port 33a, and the port 33a communicates with the oil passage 3b. A hydraulic pipe is connected to the port members 32 and 33 so as to communicate with the respective ports 32a and 33a, and hydraulic oil is allowed to flow between the hydraulic sources.

  A swash plate control mechanism for synchronously tilting the movable swash plates M1a and M2a of the hydraulic motors M1 and M2 in accordance with the turning of the left and right steering wheels supported by the axle drive device 1 on the rear cover 3 having such a configuration. 20 is supported.

The basic configuration of the swash plate control mechanism 20 will be described with reference to FIGS.
Three front and rear horizontal rotation axes of a pivot 21 constituting a link structure 110 described later, a first motor control shaft 23 for controlling the movable swash plate M1a, and a second motor control shaft 26 for controlling the movable swash plate M2a are the rear cover. The second motor control shaft 26 is disposed on the left side of the first motor control shaft 23 and the pivot shaft 21 is disposed on the right side of the first motor control shaft 23 in the left-right direction. 26 is disposed at the same height, and the pivot 21 is disposed at substantially the same height as the shafts 23 and 26.

  In the main case 2, arms 28 are fixed to the inner ends of the motor control shafts 23 and 26, and the arms 28 are engaged with the movable swash plates M1a and M2a, respectively. By the rotation of the motor control shafts 23 and 26, the movable swash plates M1a and M2a with which the arms 28 engage can be tilted. Specifically, each arm 28 is formed with a projection 28a, and the projection 28a is inserted into a groove (not shown) formed at the side end of each movable swash plate M1a / M2a, thereby allowing each arm 28 to move. The movable swash plates M1a and M2a are engaged with each other. As a result, the motor control shafts 23 and 26 are rotated by the turning force transmitted through the link structure 110, and the movable swash plates M 1 a and M 2 a can be tilted through the arms 28.

  In addition, a spring 29 for returning to the initial position is wound around a boss portion of each arm 28 that is externally fitted on each motor control shaft 23, 26, and one end portion of each end portion of each spring 29 is The other end is pressed against a pair of left and right locking pins 30 planted on the rear cover 3, and is restored by each spring 29. By force, one end of each spring 29 is pushed by the pusher 28 b so as to be farther from the other end locked by the locking pin 30. When each spring 29 is in the initial state, that is, the position where the pushing portion 28b is no longer pushed by one end of the spring 29 is the initial position of the arm 28 and its motor control shaft 23 or 26. Position.

  Further, an initial position adjusting pin 31 is implanted in the rear cover 3, and the initial position adjusting pin 31 is formed on an arm 28 fixed to the first motor control shaft 23 for the first hydraulic motor M1. It is in contact with the initial position adjusting arm portion 28c. As a result, the arm 28 fixed to the first motor control shaft 23 is moved to the limit position where the pushing portion 28b is pushed by one end of the spring 29, that is, the spring 29 is still pushed to the pushing portion 28b. It is possible to lock at a position having a force to push the first position, and this locking position can be finely adjusted as an initial position of the first motor control shaft 23 and the arm 28 fixed thereto. Yes. On the other hand, the arm 28 fixed to the second motor control shaft 26 for the second hydraulic motor M2 is not provided with such an initial position adjustment pin 31, and is originally a pushing portion by one end portion of the spring 29. The pushing limit position 28b is the initial position of the second motor control shaft 26 and the arm 28.

  A shaft support portion 31a extends outwardly from the initial position adjustment pin 31. The shaft support portion 31a is rotatably supported by the rear cover 3, and the initial position adjustment pin 31 is an eccentric pin. The line is shifted from the center line of the shaft support 31a. Normally, an initial position adjustment pin 31 is fixed by screwing a nut to the outer end of the shaft support portion 31a protruding rearward and rearward of the rear cover 3, and fastening the shaft support portion 31a to the rear cover 3 with the nut. However, when it is necessary to adjust the initial position of the movable swash plate M1a to adjust the initial total capacity of the hydraulic motors M1 and M2, the nut is loosened and the initial position adjustment pin 31 is moved to the center of the shaft support 31a. By rotating so as to revolve around the line, the initial position of the arm 28 fixed to the motor control shaft 23, which is defined by the position of the initial position adjusting pin 31, is adjusted.

The link structure 110 from one steering case 7 to the motor control shafts 23 and 26 of the swash plate control mechanism 20 will be described with reference to FIGS.
In the link structure 110, a link stay 12 is fixed to a turning case 7b of the right steering case 7 closer to the first hydraulic motor M1, and one end of a link rod 13 is fixed to the link stay 12. Is pivotally supported. On the other hand, the pivot 21 is rotatably supported on the rear cover 3 on the right side of the first motor control shaft 23, and a first arm 22 is fixed to the pivot 21. The other end of the link rod 13 is pivotally supported at the tip of 22.

  During straight travel, the first arm 22 is disposed at the straight travel position shown in FIG. When turning left, the turning case portion 7b of the right steering case 7 rotates so that the rear end thereof swings to the right. Therefore, the link rod 13 is pulled to the right, and when turning right, the turning case portion 7b of the right steering case 7 Since the rear end swings to the left, the link rod 13 is pushed to the left. A pair of horizontal left and right push-up pins 22a and 22b are projected rearward of the first arm 22 directly above the pivot shaft 21, and the left and right push-up pins 22a and 22b are the same when traveling straight. The left push-up pin 22b is higher than the right push-up pin 22a when turning left, and the right push-up pin 22a is higher than the left push-up pin 22b when turning right.

  Further, an arm member 24 is fixed to the first motor control shaft 23 engaged with the movable swash plate M1a of the first hydraulic motor M1 behind the rear cover 3, and the arm member 24 includes The second arm 24a extending to the right side and the third arm 24b extending to the left side are integrally formed. A pressing arm 25 is fastened to the second arm 24a by a bolt.

  In the configuration as described above, when the vehicle travels straight, the pressing arm 25 is placed on the push-up pins 22a and 22b at the same height as described above. When turning left, the left push-up pin 22b rises to push up the pressing arm 25, rotate the second arm 24a to the left, and the third arm 24b that rotates integrally with the second arm 24a moves downward. And move. When turning right, the right push-up pin 22a is raised to push up the push arm 25, the second arm 24a is turned to the left, and the third arm 24b that is turned integrally with the second arm 24a is Move down. Therefore, whether the turning case portion 7b of the steering case 7 is turned left or right, the arm member 24 and the first motor control shaft 23 are counterclockwise according to the turning angle from the straight position. It is rotated around the same amount.

  On the other hand, on the second motor control shaft 26 engaged with the movable swash plate M2a of the second hydraulic motor M2 behind the rear cover 3, a fourth arm 27 extending to the right is fixed. The fourth arm 27 is provided with a pressing pin 27a that projects horizontally, and the third arm 24b of the arm member 24 is placed on the pressing pin 27a. Since the fourth arm 27 is biased upward by the spring 29, the pressing pin 27a is held so as to always contact the third arm 24b. Accordingly, the third arm 24b of the arm member 24 is rotated downward depending on the turning angle of the steering wheel, whether the left turn or the right turn. Therefore, the fourth arm 27 is moved downward via the pressing pin 27a. The second motor control shaft 26 is rotated clockwise together with the fourth arm 27.

  That is, it is possible to form the link structure 110 that can rotate the first motor control shaft 23 counterclockwise and the second motor control shaft 26 clockwise when the steering wheel turns left or right. Through the link structure 110, the rotational force of the steered wheels (hereinafter referred to as “turning force”) is directly transmitted to the motor control shafts 23 and 26 of the swash plate control mechanism 20. The turning force may be an operating force of a turning operation tool such as a handle by the driver, and is not particularly limited unless a large driving device such as a tilting regulator is used.

  In order to improve the turning performance by decelerating the steering wheel during turning, the tilt angle of the movable swash plates M1a and M2a at the initial position is minimized, that is, the capacity of the hydraulic motors M1 and M2 when traveling straight is minimized. As the steering wheel turns, the tilt angle of the movable swash plates M1a and M2a is increased, that is, the capacity of the hydraulic motors M1 and M2 is increased.

  Next, the control structure of the moment acting on the movable swash plate in the swash plate control mechanism 20 will be described with reference to FIGS. As described above, the first hydraulic motor M1 and the second hydraulic motor M2 are arranged in the left-right symmetrical positions with the common oil passage plate 4 sandwiched between them with the same configuration as described above. The swash plate control mechanism 20 on the hydraulic motor M1 side will be described as an example, and the second hydraulic motor M2 will be omitted.

  As shown in FIG. 6, in the first hydraulic motor M1, a cylinder block 80 is rotatably attached to the right surface of the oil passage plate 4, and the motor shaft is attached to the oil passage plate 4 as described above. 6 is rotatably supported, and a spline portion 6a is formed in the middle portion of the motor shaft 6, and the center hole of the cylinder block 80 is engaged with the spline portion 6a. The block 80 is integrally rotatable.

  A plurality of cylinder holes 80a are formed in the cylinder block 80 at equal intervals on the circumference around the axis of the cylinder block 80, and a biasing spring 82 is provided in the cylinder hole 80a. The piston 81 is fitted through the biasing spring 82 so as to be slidable back and forth within the cylinder hole 80a.

  Each piston 81 is urged in the protruding direction by the urging spring 82, and the spherical protruding end 81a of each piston 81 is slidably contacted with a thrust bearing 84 constituting the inclined surface of the movable swash plate M1a. ing. The thrust bearing 84 is fitted and fixed in the inner recess 83a of the swash plate main body 83 constituting the main part of the movable swash plate M1a, while the outer surface 83b of the swash plate main body 83 is recessed in the swash plate guide 5. It is fitted to a spherical sliding surface 5a so as to be freely slidable. Further, as described above, the groove portion for fitting the projection 28a of the arm 28 at the inner end of the motor control shaft 23 is formed at the side end of the swash plate body 83, and the rotation of the motor control shaft 23 is performed. Thus, the thrust bearing 84 can be tilted via the swash plate body 83.

  Here, the thrust bearing 84 is arranged with a ring-shaped fixed plate 84a fitted and installed on the inner concave portion 83a side of the swash plate body 83, and the fixed plate 84a with its axis line aligned with the protruding end of the piston 81. A ring-shaped rotating plate 84c that functions as a thrust plate of 81a, and a ball 84b that functions as a rolling element interposed between the rotating plate 84c and the fixed plate 84a. The plate 84c can be smoothly rotated by rolling the ball 84b in a state where the outer surface of the plate 84c is formed in a flat shape and is in contact with the protruding end 81a of the piston 81.

  In such a configuration, as described above, the hydraulic oil supplied from the ports 32a and 33a passes through the oil passages 3a and 3b, the oil passages 4a and 4b, and the kidney ports 4c and 4d, respectively. When pumped inward, the piston 81 in the cylinder hole 80a protrudes due to the hydraulic pressure, the protruding end 81a presses the thrust bearing 84, and the pressing force 85 at that time is the side on which the piston 81 slides down the thrust bearing 84, That is, in FIG. 6, it is converted into a downward force in the drawing, and as a result, the cylinder block 80 incorporating the piston 81 rotates and the motor shaft 6 is engaged with the spline portion 6 a in the center hole of the cylinder block 80. Are also rotated together.

  At this time, when the first motor control shaft 23 which functions as an input shaft to the swash plate control mechanism 20 is rotated, the rotational power is moved through the arm 28, the groove portion of the swash plate body 83, and the like. The movable swash plate M1a is transmitted to M1a and tilts about the tilt center 23a of the first motor control shaft 23, and smoothly moves along the sliding surface 5a of the swash plate guide 5. After tilting, it is set and held at a predetermined tilt angle.

The moment of force acting on the thrust bearing 84 when the movable swash plate is tilted will be described.
As shown in FIG. 11, the hydraulic motor m1 in which the tilt center 23a of the movable swash plate m1a is on the motor shaft 6b of the motor shaft 6 will be described. Also in the hydraulic motor m1, as described above, the first motor control shaft 23 is rotated counterclockwise as shown by the arrow 88 by the turning force transmitted from the link structure 110, and the movable swash plate m1a is moved to the motor. From the neutral position orthogonal to the shaft 6, the piston 81 is tilted toward the tilting angle increasing side so as to go to the maximum tilting position where the piston 81 enters the cylinder hole 80 a as much as possible. As a result, the capacity of the hydraulic motor m 1 is increased. The steering wheel is decelerated and decelerated.

  Here, a plurality of balls 84b are arranged between the fixed plate 84a and the rotating plate 84c so that the ball center 84d is on the same circumference centered on the common axis of the fixed plate 84a and the rotating plate 84c. The common axis passes through the tilt center 23a. When the tilt center 23a is on the motor shaft 6b, the action line 85a of the pressing force 85 is set so as to pass through the ball center 84d in the neutral position. However, in such a case, the action line 85a of the pressing force 85 moves to the tilt angle increasing side from the ball center 84d as the tilt angle increases. Therefore, the action line 87a of the piston resultant force 87 obtained by combining these pressing forces 85. As a result, at the maximum tilt position shown in FIG. 11, the action line 87a of the piston resultant force 87 is tilted by the distance 89 from the tilt center 23a on the motor shaft 6b. It will pass through the angle increase side. Therefore, a clockwise moment indicated by an arrow 90 is generated around the tilting center 23a on the movable swash plate m1a based on the piston resultant force 87.

  That is, when the tilt center 23a is on the motor shaft center 6b of the motor shaft 6, the movable swash plate m1a is tilted by the turning force transmitted from the link structure 110 so as to decelerate the steering wheel during turning. Even if the inclination is to be increased, the reverse moment based on the pressing force 85 received from the piston 81 acts on the movable swash plate m1a, and stable turning performance cannot be obtained.

  On the other hand, in the first hydraulic motor M1 shown in FIG. 6 described above, the tilt center 23a of the movable swash plate M1a is decentered toward the tilt angle increasing side by an eccentric amount 91a from the motor shaft center 6b of the motor shaft 6. Are arranged. Therefore, from the neutral position, the action line 85a of the pressing force 85 passes through the tilt angle decreasing side from the ball center 84d, and the action line 87a of the piston resultant force 87 obtained by synthesizing these pressing forces 85 is also included. In this case, the tilt angle decreases from the tilt center 23a.

  Further, as the tilt angle increases, the distance between the action line 85a of the pressing force 85 and the ball center 84d decreases, but the relative positional relationship does not change, and the movable swash plate M1a is When the maximum tilt position is reached, the action line 87a of the piston resultant force 87 passes through the tilt angle decreasing side by the distance 92 from the tilt center 23a. Therefore, a counterclockwise moment indicated by an arrow 93 is generated around the tilt center 23a on the movable swash plate M1a based on the piston resultant force 87.

  That is, when the tilt center 23a is eccentric to the tilt angle increasing side with respect to the motor shaft center 6b of the motor shaft 6, the turning force transmitted from the link structure 110 to decelerate the steering wheel during turning. When the movable swash plate M1a is tilted in the direction indicated by the arrow 88 on the tilt angle increasing side, the moment in the same direction as the arrow 88 is also applied to the movable swash plate M1a by the pressing force 85 received from the piston 81. Accordingly, the operating force required for tilting the movable swash plate M1a can be greatly reduced.

  That is, a motor shaft 6 is rotatably provided in the axle drive device 1, and a cylinder block 80 into which a plurality of pistons 81 are slidably fitted is connected to the motor shaft 6, and is opposed to the cylinder block 80. In the first hydraulic motor M1, which is a variable displacement hydraulic motor that is provided with a movable swash plate M1a that is in sliding contact with the piston 81 and that can change the output from the motor shaft 6 according to the tilt angle of the movable swash plate M1a. The swash plate control mechanism 20 tilts the movable swash plate M1a according to the turning angle of the steered wheels driven by the axle drive device 1, and the swash plate control mechanism 20 includes the steered wheels or the turning operation tool. The swash plate control mechanism 20 drives the tilt center 23a of the movable swash plate M1a from the motor shaft 6 which is the shaft center of the motor shaft 6. Since a moment around the tilt center 23a acting on the movable swash plate M1a is generated on the tilt angle increasing side during turning, the turning force from the steering wheel or the turning operation tool is used. This eliminates the need for any tilting cylinder, tilting regulator, etc., reduces the size and weight of the axle drive device 1 and improves the turning performance, and secures a large space in the axle drive device 1. Thus, interference between members can be prevented, various link structures can be prevented from becoming complicated, and the manufacturing cost can be reduced and the maintainability can be improved by reducing the number of parts. Moreover, by adjusting the moment acting on the movable swash plate M1a, the operating force of the movable swash plate M1a can be greatly reduced, and even if the turning force is small, it is not attenuated during transmission, and is used for tilting. The movable swash plate M1a can be tilted quickly and accurately with only the turning force without using a cylinder, a tilting regulator, etc., and the turning performance is reduced due to the driving of the movable swash plate with the turning force. It can be surely prevented.

  Further, as shown in FIG. 7, the eccentric amount of the tilt center 23a of the movable swash plate M1a from the motor shaft center 6b of the motor shaft 6 is set to an eccentric amount 91b smaller than the eccentric amount 91a, and the maximum tilt is set. At the rolling position, the action line 85a of each pressing force 85 may pass through the ball center 84d of each ball 84b, and the action line 87a of the piston resultant force 87 may pass through the tilting center 23a.

  In this case, in the state where the movable swash plate M1a is tilted to the maximum tilt position frequently used when turning the steering wheel, a moment around the tilt center 23a due to the pressing force 85 received from the piston 81 is not generated. Further, since each pressing force 85 acts toward the ball center 84d of each ball 84b, the ball 84b can roll with the least resistance, and the load applied to the thrust bearing 84 is not only uniform. In addition, the rolling performance of the ball 84b is increased, and the sliding resistance by the thrust bearing 84 is reduced.

  That is, in the first hydraulic motor M1, which is the variable displacement hydraulic motor, at the maximum tilt position of the movable swash plate M1a when turning the steering wheel, each pressing force acting on the movable swash plate M1a from the piston 81 in sliding contact The tilting center 23a is decentered from the motor axis 6b, which is the axis of the motor shaft 6, so that the action line 87a of the piston resultant force 87 obtained by combining 85 passes over the tilting center 23a of the movable swash plate M1a. The generation of a moment around the tilt center 23a during turning is suppressed, the pressing force 85 acting on the movable swash plate M1a is made substantially uniform, the load on the movable swash plate M1a is distributed, and the durability of the first hydraulic motor M1 It is possible to improve the performance, and to increase the operating rate and reduce the maintenance cost by extending the replacement frequency. In particular, when the movable swash plate M1a is provided with a sliding portion such as a thrust bearing 84 and the protruding end 81a which is the top of the piston 81 is slidably contacted with the sliding portion, the position and structure of the sliding portion. By adjusting the pressure, the pressing force 85 can be applied to the center of the receiving member such as the ball 84b and the roller constituting the sliding portion, and the sliding performance is improved in addition to the durability, and the first hydraulic motor M1. The output efficiency can be improved and fuel consumption can be reduced.

  Further, like the hydraulic motor M4 shown in FIGS. 8 to 10, the first hydraulic motor M1 is provided with a position adjusting structure 102 that can freely adjust the position of the tilt center 23a with respect to the motor axis 6b. It may be.

  In the position adjusting structure 102, a motor mounting base 2b is suspended from the upper part of the main case 2, and the oil path plate 4 is fixed to the lower surface of the motor mounting base 2b. The inner end portion of the motor 6 is rotatably supported, and the outer end portion of the motor shaft 6 is rotatable by a bearing portion 2c by a receiving member such as a ball or a roller provided on the side wall of the motor mounting base 2b. It is supported.

  Between the bearing portion 2c and the oil passage plate 4, there is a cylinder block 80 in which the piston 81 is housed, a movable swash plate M4a, and a swash plate guide 103 that supports the movable swash plate M4a so as to slide and rotate. Are arranged in order from the inside. After the swash plate guide 103 is stacked on the lower surface of the motor mounting base 2b with a gap adjusting member 104a or 104b such as a metal plate interposed therebetween, fastening members such as front and rear bolts so as to avoid the through hole 103a of the motor shaft 6 The swash plate guide 103 is detachably fixed to the motor mounting base 2b by penetrating 105 and 105 from below and screwed into the motor mounting base 2b.

  For example, in FIG. 8, by using the gap adjusting member 104a, the movable swash plate M4a is moved up and down together with the swash plate guide 103 supporting the movable swash plate M4a, and the movable swash plate M4a is tilted. The center 23 a is adjusted so as to be on the motor shaft center 6 b of the motor shaft 6.

  Thus, at the maximum tilt position, as in FIG. 11, the action line 87a of the piston resultant force 87 passes the tilt angle increasing side by the distance 89 from the tilt center 23a on the motor shaft 6b. Thus, a clockwise moment indicated by an arrow 90 is generated in the movable swash plate M4a around the tilt center 23a based on the piston resultant force 87.

  Therefore, as shown in FIG. 9, by using the gap adjusting member 104b thinner than the gap adjusting member 104a, the movable swash plate M4a is raised together with the swash plate guide 103 supporting the movable swash plate M4a. That is, it is moved to the tilt angle increasing side, and the tilt center 23a of the movable swash plate M4a is decentered from the motor shaft center 6b of the motor shaft 6 to the tilt angle increasing side by an eccentric amount 91b.

  Then, in the maximum tilt position, as in the case of FIG. 7, the action line 85a of each pressing force 85 passes through the ball center 84d of each ball 84b, and the action line 87a of the piston resultant force 87 also passes the tilt center 23a. As a result, the moment around the tilting center 23a caused by the pressing force 85 received from the piston 81 hardly occurs. As the gap adjusting members 104a and 104b, in addition to using a single member having a different thickness, a plurality of thin plates having the same thickness may be stacked to adjust the overall thickness. There is no particular limitation as long as the amount of eccentricity can be secured.

  That is, in the position adjusting structure 102, the gap adjusting members 104a and 104b are detachably provided by the fastening member 105, whereby the swash plate guide 103 is moved to the tilt angle increasing side and supported by the swash plate guide 103. The tilt center 23a of the movable swash plate M4a is also moved to the tilt angle increasing side together.

  Note that the fastening direction of the fastening member 105 is configured to be the same as the tilting direction of the movable swash plate M4a. Thus, the interposing gap adjusting member is provided without providing a complicated structure. The amount of eccentricity of the movable swash plate M4a in the tilting direction can be freely adjusted by a simple operation such as changing the thickness of the plate and fastening it.

  That is, the movable swash plate M4a is slidably held by a swash plate guide 103, and the swash plate guide 103 includes a position adjusting structure 102 that can be moved in the swash plate tilting direction and fixed at a predetermined position. The eccentric amount of the tilting center 23a of the movable swash plate M4a can be changed simply by adjusting the position of the swash plate guide 103 without disassembling the entire hydraulic motor M4, and the eccentric amount suitable for the turning condition. Can be adjusted quickly to ensure high turning performance at all times. Furthermore, even when the required turning conditions are different and the moments acting on the movable swash plate M4a are different, it is only necessary to move the position of the swash plate guide 103, the same swash plate guide 103, the movable swash plate M4a, etc. The hydraulic motor M4 having excellent versatility can be configured.

  Further, the position adjusting structure 102 is configured such that gap adjusting members 104a and 104b are detachably interposed between the housing 2 housing the variable displacement hydraulic motor M4 and the swash plate guide 103. Since the position of the tilt center 23a of the movable swash plate M4a can be adjusted by changing the thickness of the members 104a and 104b, the movable swash plate can be adjusted by simply changing the number and thickness of the gap adjusting members. The amount of eccentricity of the tilt center 23a of M4a can be changed, the cost required for the installation of the position adjustment structure 102 and the installation space can be reduced, the manufacturing cost of the hydraulic motor M4 can be reduced, and the size can be reduced. Can do.

  In addition, since the swash plate guide 103 is provided separately from the bearing portion 2c of the motor shaft 6, the swash plate guide 103 can be moved independently of the bearing portion 2c, and the movable swash plate M4a The eccentric amount of the tilt center 23a can be easily changed, and in addition, the receiving member such as a ball or a roller can be easily incorporated into the bearing portion 2c, and the assemblability of the hydraulic motor can be improved.

Next, a four-wheel drive vehicle 100 to which the axle drive device 1 incorporating the hydraulic motors M1 and M2 according to the present invention as described above is applied for front wheel drive will be described with reference to FIG.
The vehicle 100 is provided with an axle drive device 101 for driving the rear wheels 49 and an axle drive device 1 for driving the front wheels 10. As described above, the front wheel 10 is fixed to the outer end of the axle 9 that is supported by the steering case 7 attached to the left and right ends of the axle drive device 1 to form a steering wheel.

  A hydraulic pump P is accommodated in the axle drive device 101, and a charge pump 44 and a hydraulic motor M3 are attached to the axle drive device 101. The pump shaft of the pump P also serves as a drive shaft of the charge pump 44, protrudes forward, and is linked to the output shaft of the engine 40 through a transmission shaft, a universal joint, and the like (not shown).

  The hydraulic motor M3 is supplied with hydraulic oil from a hydraulic pump P. The motor shaft has a differential mechanism 47 that differentially connects the left and right rear axles 48 and 48 via a reduction gear train (not shown). The rear axles 48 protrude from the left and right side ends of the axle drive device 101, and rear wheels 49 are attached to the outer ends thereof.

  Further, in the axle drive device 101, a pump shaft of the hydraulic pump P is extended and connected to a PTO shaft 36 supported by the axle drive device 1 via a PTO clutch, a reduction gear train, etc. (not shown). The PTO shaft 36 is driven by the engine 40.

  The hydraulic pump P and the hydraulic motor M3 in the axle drive device 101 are each provided with a movable swash plate Pa / M3a. Among these, the movable swash plate Pa of the hydraulic pump P is provided with a pedal, The discharge direction and the discharge amount of the hydraulic pump P are determined by determining the tilt direction and tilt angle of the movable swash plate Pa by being linked to the main transmission operating tool such as a lever, and thereby the hydraulic motor M3. The rotational direction and rotational speed of the hydraulic motors M1 and M2 in the axle drive device 1 are determined.

  On the other hand, the movable swash plate M3a of the hydraulic motor M3 is linked to a sub-transmission operation tool such as a pedal or a lever provided in the vehicle 100, and its tilt angle is switched in two stages. Thereby, the high and low two speed stages can be revealed with respect to the rotational speed of the motor shaft of the hydraulic motor M3.

  As described above, the movable swash plates M1a and M2a of the hydraulic motors M1 and M2 in the axle driving device 1 are moved from the initial position by the swash plate control mechanism 20 in accordance with the left and right turning of the front wheels 10 as steering wheels. It tilts steplessly to the tilt position according to the turning angle, thereby shifting the front wheels 10 and 10 according to the turning radius, and when turning either the front wheels 10 or 10 or the rear wheels 49 or 49 To avoid dragging.

The axle drive device 101 has a drive setting switching valve 70 built therein.
An oil path 58 is provided between the drive setting switching valve 70 and one supply / discharge port of the hydraulic pump P, and an oil path is provided between the drive setting switching valve 70 and one supply / discharge port of the hydraulic motor M3. 59, an oil passage 60 is interposed between the other supply / discharge port of the hydraulic pump P and the other supply / discharge port of the hydraulic motor M3.

  Further, oil passages 71 and 72 are provided between the front and rear axle drive devices 1 and 101 by piping or the like, and the oil passages 71 and 72 are connected to the drive setting switching valve 70 in the axle drive device 101. On the other hand, it is connected to the port members 32 and 33 of the axle drive device 1 respectively, and the kidney port 4c, which is one of the supply / discharge ports of the hydraulic motors M1 and M2, is connected to the oil passage 71, and both hydraulic motors M1 and M2 are connected. The other supply / discharge port, the kidney port 4d, is connected to the oil passage 72 to form a parallel circuit of the hydraulic motors M2 and M3.

  In such a configuration, the drive setting switching valve 70 can be switched between the four-wheel drive position and the two-wheel drive position. FIG. 12 shows the drive setting switching valve 70 at the four-wheel drive position. At this time, the oil passage 59 and the oil passage 72 are connected, the oil passage 58 and the oil passage 71 are connected, and the hydraulic motor M3. And an HST closed circuit in which a pair of hydraulic motors M1 and M2 are connected in series to the hydraulic pump P. In this state, if the movable swash plate Pa of the hydraulic pump P is arranged in the forward tilt direction, the oil discharged from the hydraulic pump P is the oil passage 60, the hydraulic motor M3, the oil passage 59, the drive setting switching valve 70, the oil The flow passes through the path 72, both hydraulic motors M1 and M2, the oil path 71, the drive setting switching valve 70, and the oil path 58 to return to the hydraulic pump P, and all the hydraulic motors M1, M2, and M3 are driven and the vehicle 100 It becomes a wheel drive car.

  When the drive setting changeover valve 70 is set to the two-wheel drive position, the oil passage 58 and the oil passage 59 are connected via the drive setting changeover valve 70, and an HST closed circuit is configured between the hydraulic pump P and the hydraulic motor M3. Only the hydraulic motor M3 is driven, and the vehicle 100 becomes a two-wheel drive vehicle. Note that the oil passage 71 and the oil passage 72 are disconnected from the oil passages 58 and 59 through the drive setting switching valve 70, and the discharge oil from the hydraulic pump P is not supplied to the hydraulic motors M1 and M2. The hydraulic motors M1 and M2 can be freely rotated by the rotation of the front wheels 10 and 10 following the rear wheels 49 and 49 driven by the hydraulic motor M3. From the hydraulic motors M1 and M2 to the front wheels 10 and 10 To avoid the dynamic brake.

  The charge pump 44 sucks oil from the oil reservoir in the case of the axle drive device 101 through the filter 74 and from the external reservoir tank 73, and the pressure reducing valve 56, the pressure adjusting valve 57, and Via either a resistance check valve 61, a charge check valve 62 connected to an oil passage 60 that is high in forward travel, or a charge check valve 63 connected to an oil passage 59 that is high in reverse travel, Supply hydraulic fluid to HST closed circuit. An orifice 64 that bypasses the charge check valve 63 is provided to extend the neutral range of the hydraulic pump P.

  Furthermore, as a check valve that can supply hydraulic oil from the oil reservoir in the case of the axle drive device 101 for supplying hydraulic oil when hydraulic oil leaks from the HST closed circuit when stopping on a slope, etc. A check valve 66 is connected to the oil passage 60, and a check valve 65 is connected to the oil passage 59.

  The relief oil of the pressure reducing valve 56 is taken out of the axle drive device 101 and connected to one steering case 7 of the axle drive device 1 via the power steering valve 16 in the power steering hydraulic unit 15. 18 is supplied. The power steering valve 16 is linked to a handle 17 provided on the vehicle 100. The power steering valve 16 is switched by the movement of the steering wheel 17, and the power steering hydraulic cylinder 18 is operated to support the front wheels 10 and 10. 7 is turned left and right. The return oil from the power steering valve 16 is returned to the oil reservoir in the axle drive device 101 via the line filter 75.

  In the axle drive device 101, the relief oil from the resistance valve 61 is supplied to a PTO clutch switching valve 68 that is an electromagnetically controlled hydraulic valve after the pressure is adjusted by a pressure adjusting valve 67. The PTO clutch switching valve 68 is switched between a clutch disengagement position and a clutch engagement position. FIG. 12 shows a PTO clutch switching valve 68 that is in a clutch disengagement position when not energized. At this time, oil is drained from the PTO clutch 50 and the PTO brake 51, whereby the PTO clutch At the same time, the PTO brake 51 brakes the lower transmission side portion of the PTO clutch 50, thereby preventing the inertial rotation of the PTO shaft 36.

  When the PTO clutch switching valve 68 is energized to the clutch engaged position, hydraulic oil from the resistance valve 61 is supplied to the clutch operating hydraulic chamber of the PTO clutch 50, and the PTO clutch 50 is engaged and the PTO shafts 53 and 36 are connected to the engine. Power is transmitted, and at the same time, hydraulic oil is supplied to the PTO brake 51, whereby the PTO brake 51 is pulled away from the lower transmission side of the PTO clutch 50, and the braking force to the PTO shafts 53 and 36 can be released. .

  In the present invention, a motor shaft is rotatably provided in an axle driving device, and a cylinder block into which a plurality of pistons are slidably fitted is connected to the motor shaft, and the piston is opposed to the cylinder block. The present invention can be applied to all variable displacement hydraulic motors that are provided with a movable swash plate that is in sliding contact and in which the output from the motor shaft can be changed by the tilt angle of the movable swash plate.

It is a plane partial sectional view showing the whole axle drive device incorporating a variable capacity type hydraulic motor concerning the present invention. It is a back surface partial sectional view. It is a rear view of the principal part of the axle drive device which shows a link structure. It is a rear view of the principal part of an axle drive device when a rear cover is removed. It is AA arrow sectional drawing in FIG. FIG. 5 is a partial cross-sectional view of the back surface of the hydraulic motor in which the tilt center of the movable swash plate is eccentric to the tilt angle increasing side. FIG. 6 is a partial cross-sectional view of the rear surface of the hydraulic motor in which no moment is generated around the tilt center at the maximum tilt position of the movable swash plate. It is a back surface partial cross section figure of the hydraulic motor which has the position adjustment structure of a swash plate guide. FIG. 4 is a partial cross-sectional view of the back surface of a hydraulic motor having a swash plate guide position adjustment structure and generating no moment around the tilt center at the maximum tilt position of the movable swash plate. It is a back surface partial cross section figure of the hydraulic motor in which the inclination center of a movable swash plate exists on the motor shaft center of a motor shaft. It is a bottom view of the swash plate guide which has a position adjustment structure. 1 is a hydraulic circuit diagram of a four-wheel drive vehicle in which an axle drive device incorporating a hydraulic motor according to the present invention is used for front wheel drive.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axle drive device 2 Housing 2c Bearing part 6 Motor shaft 6b Shaft center 10 Steering wheel 20 Swash plate control mechanism 23a Tilt center 80 Cylinder block 81 Piston 85 Pushing force 87 Piston resultant force 87a Action line 102 Position adjustment structure 103 Swash plate guide 104a 104b Clearance adjusting member 110 Link structure M1, M2, M4 Variable displacement hydraulic motor M1a, M2a, M4a Movable swash plate

Claims (5)

  A motor shaft is rotatably provided in the axle driving device, and a cylinder block into which a plurality of pistons are slidably fitted is connected to the motor shaft, and a movable slant that is opposed to the cylinder block and is in sliding contact with the piston. In a variable displacement hydraulic motor, in which a plate is disposed and the output from the motor shaft can be changed by the tilt angle of the movable swash plate, the movable wheel is movable according to the turning angle of the steering wheel driven by the axle drive device. A swash plate control mechanism for tilting the swash plate, and the swash plate control mechanism is driven by a turning force transmitted through the link structure from the steering wheel or the turning operation tool. The tilt center of the movable swash plate is decentered from the axis of the motor shaft so that the moment around the tilt center acting on the movable swash plate is generated on the side of the tilt angle increase during turning. Variable capacity Hydraulic motor.   In the variable displacement hydraulic motor, at the maximum tilt position of the movable swash plate at the time of turning of the steering wheel, the action line of the piston combined force obtained by combining the pressing forces acting on the movable swash plate from the piston in sliding contact is the movable swash plate. 2. The variable displacement hydraulic motor according to claim 1, wherein the tilt center is decentered from the axis of the motor shaft so as to pass over the tilt center of the motor.   The movable swash plate is slidably held by a swash plate guide, and the swash plate guide includes a position adjustment structure that can move in a tilting direction of the swash plate and can be fixed at a predetermined position. The variable displacement hydraulic motor according to claim 1 or 2.   The position adjustment structure is configured such that a gap adjustment member is detachably interposed between a housing housing the variable displacement hydraulic motor and the swash plate guide, and by changing the thickness of the gap adjustment member, 4. The variable displacement hydraulic motor according to claim 3, wherein the tilt center position of the movable swash plate is adjustable. 5. The variable capacity hydraulic motor according to claim 3, wherein the swash plate guide is provided separately from a bearing portion of the motor shaft.

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