JPH0721314B2 - Hydraulic transmission for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objectives of the Invention (1) Field of Industrial Application The present invention provides a distribution board in a motor cylinder of a swash plate type hydraulic motor surrounding a swash plate type hydraulic pump, and the distribution board is provided in the distribution board. A fixed shaft having a basically cylindrical support shaft fixed to define the oil chamber and having a distribution ring at the tip which is in sliding contact with the distribution plate and defines the high pressure oil chamber and the low pressure oil chamber in the oil chamber is provided. Inserted in the support shaft, the distribution board is configured to transfer hydraulic oil between the hydraulic pump and hydraulic motor, and the high pressure oil chamber and low pressure oil chamber, forming a closed hydraulic circuit between the hydraulic pump and hydraulic motor. The present invention relates to a hydraulic transmission for a vehicle of a type in which the hydraulic pressure of the low-pressure oil chamber during vehicle deceleration is higher than that during normal traveling.

(2) Related Art Conventionally, in such a hydraulic transmission, the seal of the low-pressure oil chamber has a contact-type seal member, such as a seal ring, interposed between a fixed shaft and a support shaft that rotates together with the motor cylinder of the hydraulic motor. It is carried out by wearing
55-152622).

(3) Problems to be Solved by the Invention By the way, in such a hydraulic transmission, when the vehicle is decelerated, the hydraulic motor causes a pump action, and the discharge thereof causes the hydraulic pump to rotate as a motor, so that the engine brake is obtained. However, if such a decelerating action occurs during high-speed running, high rotational friction and high pressure act on the seal member, which is not preferable in terms of durability performance of the seal member.

Therefore, it is conceivable to interpose a non-contact type seal member having a predetermined gap between at least one of the support shaft and the fixed shaft.

However, when the oil temperature rises, the viscosity of the hydraulic oil decreases, so the amount of oil leaking from the gap increases, and in some cases, leakage exceeds the discharge capacity of the replenishment pump that compensates for this amount of leaked oil. As a result, there is a problem in that the hydraulic motor that is acting as a pump becomes short of suction and noise is generated.

The present invention has been made in view of the above circumstances, and is a hydraulic shift for a vehicle in which noise due to a rise in oil temperature is reduced and durability is ensured to seal between the support shaft and the fixed shaft. The purpose is to provide a machine.

B. Structure of the Invention (1) Means for Solving the Problems According to the present invention, between the fixed shaft and the support shaft, a ring-shaped microscopic that allows the hydraulic oil to leak from the low-pressure oil chamber to the oil tank side. A gap is formed, and an oil passage connecting the minute gap and the high-pressure oil chamber is provided with a check valve that allows only oil to flow from the minute gap to the high-pressure oil chamber.

(2) Operation According to the above configuration, when the oil temperature is relatively low, the sealability between the support shaft and the fixed shaft can be sufficiently secured by the minute gap, and the problem of durability can be avoided.
If the oil temperature rises and the viscosity of the hydraulic oil decreases while the hydraulic motor is operating as a pump, even if an oil amount exceeding the discharge capacity of the replenishment pump tries to flow out from the minute gap, Can be guided to the high pressure oil chamber, so that noise due to insufficient suction of the hydraulic motor can be reduced.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, a hydraulic continuously variable transmission CVT for a vehicle is shown.
Is a constant discharge hydraulic pump P connected to an input shaft 2 driven by an engine (not shown), and a variable displacement hydraulic motor M arranged on the same axis as the hydraulic pump P.
The hydraulic motors M are connected to each other to form a hydraulic closed circuit C, and a hydraulic motor M is connected to wheels W via an output shaft 11, a forward / reverse gear device G, a counter shaft 18, and a differential device D. Such a continuously variable transmission CVT is housed in a mission case 1 formed by connecting two case halves 1a and 1b.

The hydraulic pump P includes a pump cylinder 4 connected to the input shaft 2 by a spline 3 and a large number of cylinder holes arranged in an annular array in the pump cylinder 4 so as to surround the input shaft 2.
A large number of plungers 6, 6, which are respectively slidably attached to 5, 5 ,. Power from the engine is transmitted to the input shaft 2 via the flywheel 7.

On the other hand, the hydraulic motor M is provided with a motor cylinder 8 concentrically surrounding the pump cylinder 4 of the hydraulic pump P so as to be able to rotate relative thereto, and the motor cylinder 8
, A large number of motor plungers 10, which are slidably fitted into a large number of cylinder holes 9, 9 ...
10 and are provided.

An output shaft 11 is coaxially projected on one end of the motor cylinder 8 in the axial direction, and a support shaft 12 is coaxially projected on the other end. Output shaft 11
Is supported on the end wall of one case half body 1a via a needle bearing 13, and the support shaft 12 is supported on the end wall of the other case half body 1b via a ball bearing 14.

The input shaft 2 penetrates the end wall of one case half 1a in an oil-tight manner and is arranged concentrically within the output shaft 11. Moreover, a plurality of needle bearings 15 are provided between the inner surface of the output shaft 11 and the outer surface of the input shaft 2, so that the input shaft 2 and the pump cylinder 4 are relatively opposed to the output shaft 11 and the motor cylinder 8. It is rotatable.

Between the output shaft 11 and a sub shaft 18 which is rotatably supported on both end walls of the transmission case 1 in parallel with the output shaft 11 via roller bearings 16 and ball bearings 17,
Forward and reverse gear units G are provided.

The forward and reverse gear device G includes a pair of drive gears 19 and 20 fixed to the output shaft 11 and one drive gear 19 to mesh with the auxiliary shaft 1
A driven gear 21 rotatably supported by 8 and a driven gear 21 rotatably supported by a counter shaft 18 corresponding to the other drive gear 20.
22 and an intermediate gear meshing with the driving gear 20 and the driven gear 22.
23, a driven clutch toothed wheel 24 fixed to the counter shaft 18 between drive clutch geared wheels 21a, 22a integrally provided at opposed portions of both driven gear wheels 21, 22, a driven clutch toothed wheel 24 and both driving clutches. A clutch member 25 for selectively connecting the toothed wheels 21a, 22a is provided, and a shift fork 26 is engaged with the clutch member 25 to selectively operate the clutch member 25.

A gear 28 meshed with the input gear 27 of the differential device D is attached to the counter shaft 18.
Are integrally provided, and the differential device D is switched and driven in the forward direction and the reverse direction of the vehicle in accordance with the operation of the clutch member 25.

The motor cylinder 8 and the pump cylinder 4 of the hydraulic pump P
An oil-tight chamber 31 is defined between and, and a swash plate 32 facing the end surface of the pump cylinder 4 is supported inside the motor cylinder 8 in the oil-tight chamber 31. The swash plate 32 is in sliding contact with an annular shoe 33.

Each of the plungers 6, 6 ... And the shoe 33 are swingably connected via a connecting rod 44, and the circumferential step of the shoe 33 is supported by the motor cylinder 8 via a roller bearing 42. The retainer ring 34 is in contact with the retainer ring 34, and the retainer ring 34 is in contact with the spring holder 35 connected to the input shaft 2 via the spline 36 in order to allow axial movement and prevent relative rotation. Further, a coil spring 37 surrounding the input shaft 2 is interposed between the spring holder 35 and the pump cylinder 4, and the spring force of the coil spring 37 causes the spring holder.
The shoe 35 elastically presses the shoe 33 toward the swash plate 32 via the holding ring 34. Moreover, the spring holder 35 and the pressing ring 34 are in spherical contact with each other, and the spring holder 35 evenly contacts the pressing ring 34 to transmit the elastic force of the coil spring 37 to the pressing ring 34.

The oil-tight chamber 31 includes the shoe 33, the pressing ring 34, and the spring holder.
By 35, the first chamber 31a on the swash plate 32 side and the pump cylinder 4
It is partitioned into the second chamber 31b on the side.

The inner peripheral side of the sliding surface between the swash plate 32 and the shoe 33 faces the first chamber 31a, and the lubricating oil leaked from the sliding surface is in contact with the first chamber 31a.
flow to a. By the way, in order to achieve lubrication between the swash plate 32 and the shoe 33, an annular hydraulic pocket 38 is provided on the front surface of the shoe 33.
33, the connecting rod 44 and the oil holes 39, 4 bored in the plunger 6
Via 0, 41, it communicates with the pump chamber 45 defined between each plunger 6 and the pump cylinder 4. Therefore, the pressure oil in the pump chamber 45 is supplied to the hydraulic pocket 38 through the oil holes 41, 40, 39. As a result, the sliding surfaces of the shoe 33 and the swash plate 32 are lubricated. At the same time, the hydraulic pressure in the hydraulic pocket 38 exerts a pressure on the shoe 33 so as to receive the projecting thrust of the plunger 6, so that the contact pressure between the shoe 33 and the swash plate 32 is reduced.

On the other hand, the motor-side cylinder 8, the swash plate 32, the shoe 33 and the roller bearing 42 form an annular lubrication chamber 43 surrounding the sliding surface so as to face the outer peripheral side of the sliding surface between the swash plate 32 and the shoe 33. The lubricating chamber 43 is defined as the second chamber 31.
Form part of b.

In the lubrication chamber 43, the pressure oil in the hydraulic pocket 38 constantly leaks through the sliding surface between the shoe 33 and the swash plate 32, and after the leakage oil fills the lubrication chamber 43, the second oil passes through the roller bearing 42. It flows to the side of chamber 31b. Therefore, new lubrication oil is always held in the lubrication chamber 43, and the shoe 33
Also, the sliding surface of the swash plate 32 can be surely lubricated from the outside of the shoe 33.

In addition to the oil from the lubricating chamber 43, leaked oil from the sliding surfaces of the plunger 6 and the cylinder hole 5 and the sliding surfaces of the pump cylinder 4 and the distribution board 46 flows into the second chamber 31b.

A communication passage 47 that communicates between the first chamber 31a and the second chamber 31b is bored in the spring holder 35. Further, between the output shaft 11 and the input shaft 2 of the motor cylinder 8, the first chamber 31a communicating with the first chamber 31a is connected.
A discharge path 48 is formed, and the first discharge path 48 is a second discharge path.
It is connected to an oil tank (not shown) provided at the bottom of the mission case 1 via 49, the pressure control valve 50 and the third discharge passage 51.

The pressure control valve 50 opens when the oil pressure in the oil tight chamber 31 exceeds a set value, and adjusts the oil pressure in the oil tight chamber 31 to a predetermined value.

Bevel gears 61, 62 meshing with each other are fixedly provided at opposing ends of the pump cylinder 4 and the shoe 33. These bevel gears 6
1, 62 are formed as synchronous gears with the same number of teeth, and when the pump cylinder 4 rotates together with the input shaft 2, the shoe
33 is rotationally driven synchronously via bevel gears 61 and 62. As a result, the plunger 6 running on the upside of the inclined surface of the swash plate 32
Is given a discharge stroke from the swash plate 32 through the connecting rod 44, and the plunger 6 running on the downward side of the inclined surface is given a suction stroke.

In the hydraulic motor M, an annular motor swash plate 63 that faces the motor cylinder 8 is fitted to an annular swash plate holder 64. The swash plate holder 64 integrally includes a pair of trunnion shafts 65 projecting to both outer sides thereof, and the trunnion shafts 65 are pivotally supported by the mission case 1. Therefore, the motor swash plate 63 can be tilted around the axis of the trunnion shaft 65 together with the swash plate holder 64.

The tip of each motor plunger 10 is swingably connected to a plurality of motor shoes 66 that are in sliding contact with the motor swash plate 63. Moreover, in order to maintain the sliding contact state of each motor shoe 66 with the motor swash plate 63, a holding plate that presses the back surface of each motor shoe 66.
67 is rotatably supported by a ring 69 fixed to the swash plate holder 64 with bolts 68. The connecting portion between each motor shoe 66 and each motor plunger 10 has a holding plate at a plurality of circumferential positions.
It penetrates through 67, so that the holding plate 67 rotates together with the motor shoe 66.

Each motor shoe 66 is provided with a hydraulic pocket 70 on the front surface that is in sliding contact with the motor swash plate 63. On the other hand, each cylinder hole 9
A hydraulic chamber 71 defined between the closed end of the motor plunger 10 and each motor plunger 10 is communicated with the hydraulic pocket 70 through a series of oil holes 72, 73 formed in the motor plunger 10 and the motor shoe 66. . Therefore, the pressure oil in the hydraulic chamber 71 is
It is supplied to the hydraulic pocket 70 through 3 and exerts pressure on the motor shoe 66 so as to receive the protruding thrust of the motor plunger 10. As a result, the motor shoe 66 and the motor swash plate 63 are
The contact pressure therebetween is reduced, and the sliding surfaces of the motor shoe 66 and the motor swash plate 63 are lubricated.

On the inner peripheral surface of the swash plate holder 64, a cylindrical partition wall body 74 that is opposed to the inner peripheral surface of the pressing plate 67 with a small gap is fitted, and the partition wall body 74, the swash plate holder 64, and the pressing plate. Lubrication chamber 75 surrounding the sliding surface of motor shoe 66 and motor swash plate 63 by 67
Is defined.

Thus, the pressure oil in each hydraulic pocket 70 is stored in the motor shoe 66.
Also, the oil constantly leaks through the sliding surface of the motor swash plate 63, and the leaked oil fills the lubricating chamber 75 as lubricating oil and then leaks from the gaps around the holding plate 67. Therefore, new lubricating oil is always held in the lubricating chamber 75, and the sliding surface of the motor shoe 66 and the motor swash plate 63 can be reliably lubricated from the outside of the motor shoe 66 by the oil.

In this case, when the pressure in the lubrication chamber 75 approaches the pressure in the hydraulic pocket 70, the fluid bearing function of the hydraulic pocket 70 with respect to the motor shoe 66 is impaired, so the lubrication chamber 75 retains oil while maintaining a pressure state close to atmospheric pressure. Hydraulic pocket 70 to
The clearances around the pressing plate 67 are appropriately selected according to the amount of oil leaked from the.

The mission case 1 is provided with a servomotor 81 for tiltably driving the swash plate holder 64, that is, the motor swash plate 63. The servo motor 81 includes a servo cylinder 82 fixed to the mission case 1 and a servo cylinder 82 for dividing the servo cylinder 82 into a left oil chamber 83 and a right oil chamber 84.
Servo piston 85 sliding on 82 and servo piston 85
Piston rod 86 that is integrally provided in the oil cylinder and pierces the end wall of the servo cylinder 82 on the left oil chamber 83 side in an oil-tight and movable manner.
And the tip portion is slid into a valve hole 87 formed in the servo piston 85 and the piston rod 86, and the servo cylinder
And a pilot valve 88 penetrating an end wall of the right side oil chamber 84 side of 82 in an oiltight and movable manner.

The piston rod 86 is connected to the swash plate holder 64 via a pin 89. An oil passage 90 provided in the servo cylinder 82 is always in communication with the left oil chamber 83, and the hydraulic pressure supplied from the oil passage 90 acts on the servo piston 85. In the servo piston 85 and the piston rod 86, a passage 91 for communicating the right side oil chamber 84 with the valve hole 87 according to the right movement of the pilot valve 88, and the right side oil chamber 84 for the left side oil chamber with the left movement of the pilot valve 88. A passage 92 communicating with 83 is provided. Further, the valve hole 87 communicates with the oil tank at the bottom of the mission case 1 via the return path 93.

The servo piston 85 performs an amplification operation by the hydraulic pressure supplied from the oil passage 90 so as to follow the leftward and rightward movements of the pilot valve 88, whereby the swash plate holder 64, that is, the motor swash plate 63, is at the maximum tilt position shown And a right-angled position that is perpendicular to each motor plunger 10. At this time, the motor swash plate 63 reciprocates each motor plunger 10 as the motor cylinder 8 rotates to repeat expansion and contraction. The stroke of the motor plunger 10 depends on the inclination of the motor swash plate 63. Is adjusted steplessly.

A hydraulic closed circuit C is formed between the hydraulic pump P and the hydraulic motor M via a distribution board 46 and a distribution ring 97. Thus, when the pump cylinder 4 is rotated by the input shaft 2, the pump chamber 45 of the cylinder hole 5 accommodating the plunger 6 in the discharge stroke.
The high-pressure hydraulic oil discharged from the cylinder is fed to the hydraulic chamber 71 of the cylinder hole 9 accommodating the motor plunger 10 in the expansion stroke. On the other hand, the hydraulic oil discharged from the hydraulic chamber 71 of the cylinder hole 9 accommodating the motor plunger 10 in the contraction stroke returns to the pump chamber 45 of the cylinder hole 5 accommodating the plunger 6 in the suction stroke. During this time, the reaction torque applied to the motor cylinder 8 by the plunger 10 in the discharge stroke via the swash plate 63,
The motor cylinder 8 or the output shaft 11 is rotationally driven by the sum of the reaction torque received by the motor plunger 10 in the expansion stroke from the motor swash plate 63.

In this case, the motor cylinder 8 with respect to the pump cylinder 4
The gear ratio of is given by the following equation.

As is clear from this equation, if the displacement of the hydraulic motor M determined by the stroke of the motor plunger 10 is changed from zero to a certain value, the gear ratio can be changed from 1 to a certain required value.

The motor cylinder 8 is composed of first to fourth portions 8a to 8d divided in the axial direction. The output shaft 11 is integrally provided in the first portion 8a, and the swash plate 32 is provided in the first portion 8a. A cylinder hole 9 is provided in each of the second, third and fourth portions 8b-8d. The third portion 8c constitutes the distribution board 46, and the support shaft 12 is integrally provided on the fourth portion 8d.

The first and second parts 8a and 8b are connected by a plurality of bolts 98, and the second, third and fourth parts 8b to 8d are provided with a plurality of knock pins 99 and 100 at their joints and are positioned in relation to each other. Bolts 101 are integrally connected.

The inner end of the input shaft 2 is supported at the center of the distribution board 46 via a needle bearing 105, and the pump cylinder 4 is elastically brought into sliding contact with the distribution board 46 by a spring 37.

Referring also to FIG. 2, a supporting plate 107 is fixed to the outer surface side of the end wall of the case half 1b with a bolt 106, and the supporting shaft 107 of the motor cylinder 8 is fixed to the supporting plate 107.
A cylindrical fixed shaft 108 projecting inside is fixedly connected. A distribution ring 97, which is in sliding contact with the distribution plate 46, is eccentrically supported at the inner end of the fixed shaft 108, and the distribution ring 97 allows the oil chamber 109 provided in the fourth portion 8d of the motor cylinder 8 to be provided.
Are partitioned into an inner chamber 110 as a high pressure oil chamber and an outer chamber 111 as a low pressure oil chamber. On the other hand, the distribution board 46 is provided with discharge and suction ports 112 and 113.
The pump chamber 45 of the plunger 6 in the discharge stroke communicates with the inner chamber 110 by 12 and the pump chamber 45 of the plunger 6 in the suction stroke communicates with the outer chamber 111 by the suction port 113. A large number of communication ports 114, 114 ... Are bored in the distribution board 46, and each hydraulic chamber 71 of the motor cylinder 8 is communicated with the inner chamber 110 or the outer chamber 111 by these communication ports 114, 114.

Therefore, when the pump cylinder 4 rotates, the high-pressure hydraulic oil generated by the discharge stroke of the plunger 6 flows into the inner chamber 110 from the discharge port 112, and further, through the communication port 114 communicating with the inner chamber 110, the expansion stroke. Of the motor plunger 10 into the hydraulic chamber 71
Give thrust to 10. On the other hand, the motor plunger on the contraction stroke
The hydraulic oil discharged by 10 is returned to the pump chamber 45 of the plunger 6 in the suction stroke via the communication port 114 and the suction port 113 communicating with the outer chamber 111, and the above-described circulation of the hydraulic oil causes the hydraulic oil to be discharged as described above. Transmission from the hydraulic pump P to the hydraulic motor M is performed.

The side wall of the fixed shaft 108 is provided with, for example, two short-circuit ports 115 capable of communicating between the inner chamber 110 and the outer chamber 111,
Cylindrical clutch valve that opens and closes those short-circuit ports 115 1
16 is rotatably fitted in the fixed shaft 108. The clutch valve 116 is provided with a valve hole 117 corresponding to the short-circuit port 115 on a side wall near the tip thereof, and an operation connecting portion 119 to which an operation shaft 118 connected to a clutch control device (not shown) is connected to a base end portion thereof. To be

Rotate the clutch valve 116 to open the valve hole 117 to the short circuit port 11
When the valve is fully opened, the clutch is off and the valve hole 117
The clutch-on state is obtained when the valve is shifted from the short-circuit port 115 and fully closed, and the half-clutch state is obtained when the valve hole 117 and the short-circuit port 115 are slightly shifted to the half-open state. That is, in the clutch off state, the discharge port 11
The hydraulic oil discharged from 2 to the inner chamber 110 is immediately short-circuited to the outer chamber 11 and the suction port 113 through the short-circuit port 115, and the hydraulic motor M becomes inoperable. Is prevented, a circulating action of hydraulic oil from the hydraulic pump P to the hydraulic motor M occurs, and normal transmission is performed.

The clutch valve 116 has a built-in hydraulic servomotor 121 operated by the pilot valve 120.
A valve rod 123 having a diameter smaller than the inner diameter of the clutch valve 116 is provided at the tip portion of 22. The valve rod 123 projects into the inner chamber 110, and has a closing valve 124 for the discharge port 112 at its tip.
Is attached so that it can swing freely. Then, the servo piston 12
The discharge port 112 can be closed by bringing the closing valve 124 into close contact with the distribution board 46 by the left movement of 2. This closing is performed when the motor swash plate 73 is placed in the upright state and the gear ratio is set to 1, whereby the plunger 6 is hydraulically locked and the pump cylinder 4 passes through each plunger 6 and the swash plate 32. The motor cylinder 8 can be mechanically driven,
As a result, the thrust of the motor plunger 10 on the motor swash plate 63 disappears, and the load on each bearing due to the thrust is removed.

An oil passage 139 communicating with the inner chamber 110 and an oil passage 140 communicating with the outer chamber 111 are bored in the fixed shaft 108 and the support plate 107. The support plate 107 has an oil passage 9 connected to the servo motor 81.
An oil passage 141 communicating with 0 is bored and the oil passage 141
And a switching valve 142 for selectively switching the communication state between the oil passages 139 and 140. This switching valve 142 is provided on both oil passages 139,
It operates so as to communicate with the oil passage 141 having the higher hydraulic pressure of 140. Therefore, the servo motor 81 for tilting the motor swash plate 63 of the hydraulic motor M includes the inner chamber 110 and the outer chamber 1.
The hydraulic pressure will be supplied from the one with higher hydraulic pressure.

One ends of links 127, 128 are connected to the pilot valves 88, 120 of both servo motors 81, 121, and the other ends of the links 127 are interlocked and connected with a rotating shaft 129 rotated by an operating means (not shown). Further, a cam 130 is provided on the rotating shaft 129, and a cam follower 131, which is in sliding contact with the cam 130, is provided at the other end of the link 128. As a result, when the servo motor 81 is operated to put the motor swash plate 63 in the upright state, the servo motor 121 operates so that the discharge port 112 is blocked by the blocking valve 124.

A supply pump F is provided outside the end wall of the case half 1a. The replenishment pump F is driven by the input shaft 2, pumps oil from the oil tank at the bottom of the transmission case 1, and through the replenishment oil passage 137 and the check valve 138 provided in the input shaft 2. Supply hydraulic fluid to the hydraulic closed circuit C.

On the outer periphery of the fixed shaft 108, a basically cylindrical seal member 171 that forms an annular minute gap 170 with the inner surface of the support shaft 12 is inserted, and the seal member 171 includes the fixed shaft 108 and the support shaft 12. In order to float the seal member 171 and keep the minute gap 170 in an annular shape irrespective of a slight positional deviation therebetween, it is connected to the outer surface of the fixed shaft 108 by a spline 172 having radial play of the fixed shaft 108. Further, in order to restrict the axial movement of the seal member 171, a restriction flange 173 facing one end of the seal member 171 is provided so as to project over the entire outer surface of the fixed shaft 108, and the other end of the seal member 171 is supported by the support plate 107. Can be received.

A fitting groove 174 is provided over the entire circumference on the outer surface of the fixed shaft 108 near the restriction flange 173 between the restricting collar 173 and the spline 172. 175 and the backup ring 176 are fitted. A fitting groove 177 is provided on the outer surface of the fixed shaft 108 near the spline 172 over the entire circumference, and the fitting groove 177 has an O-ring 17 slidingly contacting the inner surface of the seal member 171.
8 and the backup ring 179 are fitted.

The seal member 171 and the fixed shaft 10 are provided between the fitting grooves 174 and 177.
An annular chamber 180 is formed between 8 and a plurality of communication holes 181 for communicating the annular chamber 180 with the gap 170 are formed in the seal member 171.

In the clutch valve 116, a large-diameter hole 182 on the inner chamber 110 side and a small-diameter hole 183 on the outer side are coaxially connected to each other via a taper seal surface 184 having a large diameter toward the large-diameter hole 182 side to form an axis line. The large-diameter holes 182 are formed in parallel, and the ends of the large-diameter holes 182 on the inner chamber 110 side are closed by a closing member 186 having a guide hole 185. A valve chamber 187 is defined between the closing member 186 and the taper seal surface 184.
187 has a spherical valve body 188 that can be seated on the tapered sealing surface 184.
The valve chamber 187, the taper seal surface 184 and the valve body 188 cooperate with each other to form the check valve V of the present invention. The outer end of the small diameter hole 183 is closed by a cap 189, and the small diameter hole 183 communicates with the annular chamber 180 via an oil hole 190 bored in the clutch valve 116.

Therefore, the small gap 170 between the fixed shaft 108 and the support shaft 12 is
Communication hole 181, annular chamber 180, oil hole 190, small diameter hole 183, valve chamber 187
Also, the fluid is communicated with the inner chamber 110 via the guide hole 185, and only the working oil is allowed to flow from the minute gap 170 to the inner chamber 110 by the action of the valve element 188 in the valve chamber 187.

Next, the operation of this embodiment will be described. When the vehicle is decelerated, the hydraulic motor M acts as a pump to discharge the high pressure oil to the outer chamber 111. However, when the oil temperature is relatively low, the spindle 12 and the stationary shaft 12 are fixed. The minute gap 170 between the shafts 108 ensures sufficient sealing performance, and solves the problem of durability when a contact-type sealing member is provided.

By the way, when the oil temperature rises, the viscosity of the hydraulic oil decreases, so that the high-pressure oil in the outer chamber 111 tries to leak from the minute gap 170 to the outside. However, in the valve chamber 187, the valve body 188 separates from the taper seal surface 184 in response to the low hydraulic pressure in the inner chamber 110, and the high-pressure oil flowing into the gap 170 has the communication hole 181 and the annular shape. Chamber 180, oil hole 190, small diameter hole 183, valve chamber 187
And is guided to the inner chamber 110 via the guide hole 185. Therefore, even if the amount of oil flowing into the gap 170 exceeds the amount of oil discharged from the replenishment pump F, most of that oil, for example, 50%.
Is introduced into the inner chamber 110, and there is no shortage of suction of the hydraulic motor M, and noise generation can be suppressed.

Further, when the vehicle is accelerated, the hydraulic pump P discharges high-pressure oil into the inner chamber 110. At this time, the valve body 188 is tapered by the high pressure oil introduced into the valve chamber 187 through the guide hole 185.
It is seated at 84, blocking the gap between the inner chamber 110 and the gap 170. Therefore, during acceleration, the high-pressure oil does not leak to the outside through the gap 170 and is not short-circuited to the outer chamber 111.

C. Effects of the Invention As described above, according to the present invention, between the fixed shaft and the support shaft, an annular minute gap that allows the hydraulic oil to leak from the low pressure oil chamber to the oil tank side is formed. A check valve that allows only oil to flow from the minute gap to the high pressure oil chamber is provided in the oil passage that connects the gap and the high pressure oil chamber. When the oil temperature is relatively low during deceleration of the vehicle when the oil pressure is high, the necessary sealability can be secured by the minute gap, and the problem of durability can be avoided. Even if the flow rate of hydraulic oil from the low pressure oil chamber to the minute gap increases as the viscosity of hydraulic oil decreases due to the increase in oil temperature, most of the hydraulic oil can be returned to the high pressure oil chamber through the check valve. Since the amount of hydraulic oil that is about to leak from the low pressure oil chamber to the oil tank side through the minute gap is suppressed as much as possible, it is possible to avoid insufficient suction of the hydraulic motor due to excessive leakage of the hydraulic oil. It is possible to effectively suppress the generation of noise due to insufficient intake.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is an overall vertical sectional side view, and FIG. 2 is an enlarged view of a main part of FIG. 12 …… spindle, 46 …… distribution panel, 97 …… distribution ring, 108 …… fixed shaft, 109 …… oil chamber, 110 …… inner chamber as high-pressure oil chamber,
111 ... Outer chamber as low-pressure oil chamber, 170 ... Minute gap, C ... Hydraulic closed circuit, M ... Hydraulic motor, P ... Hydraulic pump, V ... Check valve

Claims (1)

[Claims] 1. A distribution plate (4) is attached to a motor cylinder (8) of a swash plate hydraulic motor (M) surrounding a swash plate hydraulic pump (P).
6) is provided, and an oil chamber (109) is defined in the distribution board (46), and a basically cylindrical support shaft (12) is fixedly mounted on the distribution board (46) in sliding contact therewith. High pressure oil chamber (110) inside the oil chamber (109)
And a low pressure oil chamber (111), a fixed shaft (108) having a distribution ring (97) at its tip end is inserted into the support shaft (12), and the distribution plate (46) includes a hydraulic pump (P) and a hydraulic pressure. The motor (M) and the high pressure oil chamber (110) and the low pressure oil chamber (11
1) is configured to transfer hydraulic oil between them, and a hydraulic closed circuit (C) is connected between the hydraulic pump (P) and the hydraulic motor (M), and the low pressure oil chamber (111) is used when the vehicle is decelerated. ), The hydraulic pressure of which is higher than that during normal traveling. In the hydraulic transmission for a vehicle, between the fixed shaft (108) and the support shaft (12), the low pressure oil chamber (111) to the oil tank side. An annular minute gap (170) is formed to allow hydraulic oil to leak to the minute gap (1
70) and the oil passage connecting the high pressure oil chamber (110),
A hydraulic transmission for a vehicle, comprising a check valve (V) which allows only oil to flow from the minute gap (170) toward the high-pressure oil chamber (110).