JP4052813B2 - Hydrostatic continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrostatic continuously variable transmission that prevents an excessive increase in hydraulic pressure during deceleration.
[0002]
[Prior art]
A hydrostatic type is known as a continuously variable transmission for a motorcycle or an automobile. Such a hydrostatic continuously variable transmission is disclosed in, for example, Japanese Patent Publication No. 7-56340 and Japanese Patent Laid-Open No. 4-203553. The schematic configuration is shown in FIG.
[0003]
As shown in FIG. 6, the hydrostatic continuously variable transmission includes a constant displacement swash plate type hydraulic pump P connected to the crankshaft side of the engine and a variable displacement swash plate type connected to the drive wheel side. And a hydraulic motor M. The hydraulic pump P and the hydraulic motor M are low-pressure passages during normal load operation, but the inner oil passage (low-pressure oil passage) 52 that becomes a high-pressure passage during deceleration, that is, during reverse load operation, and normal load operation. Although it is a high-pressure passage, it is connected to form a hydraulic closed circuit via an outer oil passage (high-pressure oil passage) 53 that becomes a low-pressure passage during reverse load operation. A replenishment oil passage 47 connected to a replenishment pump 88 that sucks up oil from the oil reservoir 87 is connected to the inner oil passage 52 via a first check valve 95 and to the outer oil passage 53 via a second check valve 96. It is connected to the.
[0004]
Further, a clutch valve 69 that operates according to a driver's clutch operation is interposed between the inner oil passage 52 and the outer oil passage 53. These clutch valves 69 are opened to the outside with the clutch-on position that shuts off between the two oil passages 52 and 53, the clutch-off position that communicates between the two oil passages 52 and 53, and the both oil passages 52 and 53 in communication. It is possible to switch between three communication / release positions.
[0005]
A pressure regulating valve 97 is provided between the outer oil passage 53 and the inner oil passage 52. With this pressure regulating valve 97, during normal load operation, that is, during acceleration, when the oil passage of the outer oil passage 53 on the high pressure side becomes a certain value or more, a part of the hydraulic oil in the outer oil passage 53 is removed from the inner oil passage. The oil pressure in the outer oil passage 53 is prevented from becoming excessive.
[0006]
[Problems to be solved by the invention]
In the hydrostatic continuously variable transmission configured as described above, during reverse load operation, that is, during engine braking, driving is performed from the wheel side so that the hydraulic motor M performs pumping and the hydraulic pump P performs motoring. Thus, the outer oil passage 53 becomes a low pressure passage, and the inner oil passage 52 becomes a high pressure passage. In particular, in a vehicle such as a motorcycle, when landing after a small jump, the hydraulic pressure in the inner oil passage 52 increases greatly. Thus, if the oil pressure on the inner oil passage 52 side becomes excessive, the transmission main body must be enlarged in order to increase pressure resistance.
[0007]
In the hydrostatic continuously variable transmission, the hydraulic oil can be prevented from excessively rising during deceleration even though the hydraulic fluid is prevented from excessively rising during normal load operation as described above. It was made in view of what was not planned.
[0008]
[Means for Solving the Problems]
The configuration of the present invention that solves the above problems includes a high-pressure oil passage that sends hydraulic oil from the hydraulic pump side to the hydraulic motor side between the hydraulic pump and the hydraulic motor, and hydraulic oil from the hydraulic motor side to the hydraulic pump side. In a hydrostatic continuously variable transmission comprising a hydraulic closed circuit composed of a low-pressure oil passage that feeds the hydraulic pump, the hydraulic pump is integrally fitted to the outer peripheral surface of the output shaft of the hydrostatic continuously variable transmission Pump cylinder, ring body fitted integrally with the outer peripheral surface of the pump cylinder, a plurality of cylinder holes provided in an annular arrangement with respect to the rotation axis of the pump cylinder, and sliding in each of the cylinder holes A pump plunger which is freely fitted, and an annular inner oil passage is constituted by the outer peripheral surface of the output shaft and the inner peripheral surface of the pump cylinder, and the outer peripheral surface of the pump cylinder and the inner peripheral surface of the ring body And ring The Configure outer oil passage, a first pressure regulating valve for releasing the hydraulic pressure of the inner oil passage to the outer oil passage when the pressure of the inner oil passage becomes equal to or larger than the prescribed value, the pressure of the outer oil passage A second pressure regulating valve that opens the oil pressure of the outer oil passage to the inner oil passage when a predetermined value or more is reached , wherein one of the inner oil passage or the outer oil passage is the high pressure oil passage, and the other is the A low-pressure oil passage, wherein the first pressure regulating valve is arranged between two adjacent cylinder holes, and the second pressure regulating valve is arranged next to the cylinder hole facing the first pressure regulating valve. And
[0009]
According to the hydrostatic continuously variable transmission configured as described above, even when the hydraulic pressure of the inner oil passage that was on the low pressure side during normal traveling becomes high due to the hydraulic motor functioning as a hydraulic pump during deceleration, the hydraulic pressure When the pressure exceeds a predetermined value, the first pressure regulating valve is opened and the oil is led to the outer oil passage which is on the high pressure side during normal running but is on the low pressure side when decelerating. Therefore, the oil pressure in the inner oil passage is excessive. Is prevented.
Furthermore, the second pressure regulating valve that opens the hydraulic pressure in the outer oil passage to the inner oil passage when the pressure in the outer oil passage becomes a predetermined value or more is made to substantially face the first pressure regulating valve with respect to the rotation axis of the pump cylinder. Therefore, the hydraulic pressure discharged from the high pressure oil passage can be relaxed using the entire annular oil passage, and the first pressure regulating valve can be used while maximizing the effect of the pressure regulating valve without increasing the volume of the oil passage. And the influence which the 2nd pressure regulation valve has on the rotation balance of a pump cylinder can be suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic configuration of a hydrostatic continuously variable transmission according to the present invention, and FIG. 2 shows a longitudinal section of a hydrostatic continuously variable transmission according to an embodiment applied to a power unit of a vehicle. 3 shows a longitudinal section of the check valve portion in the embodiment shown in FIG. 2, FIG. 4 shows a longitudinal section of the pressure regulating valve portion, and FIG. 5 shows a schematic side view showing the arrangement of the valves.
[0011]
As shown in FIG. 1, the basic structure of this hydrostatic continuously variable transmission is the same as the conventional one. That is, it has a constant displacement swash plate hydraulic pump P connected to the crankshaft side of the engine and a variable displacement swash plate hydraulic motor M connected to the reducer side. The motor M is a low-pressure path during normal load operation, but an inner oil path (low-pressure oil path) 52 that becomes a high-pressure path during deceleration, that is, during reverse load operation, and a high-pressure path during normal load operation. However, during reverse load operation, a hydraulic closed circuit is connected via an outer oil passage (high pressure oil passage) 53 that becomes a low pressure passage. A replenishment oil passage 47 connected to a replenishment pump 88 that sucks up oil from the oil reservoir 87 is connected to the inner oil passage 52 via a first check valve 95 and to the outer oil passage 53 via a second check valve 96. Connected to.
[0012]
In addition, a plurality of clutch valves 69 are provided between the inner oil passage 52 and the outer oil passage 53 to operate in accordance with the driver's clutch operation. These clutch valves 69 are opened to the outside with the clutch-on position that shuts off between the two oil passages 52 and 53, the clutch-off position that communicates between the two oil passages 52 and 53, and the both oil passages 52 and 53 in communication. It is possible to switch between three communication / release positions.
[0013]
A pressure regulating valve 97 is provided between the outer oil passage 53 and the inner oil passage 52. When the oil passage of the outer oil passage 53 on the high pressure side becomes a certain value or more during normal load operation, that is, during acceleration, the pressure regulating valve 97 causes a part of the hydraulic oil in the outer oil passage 53 to become the inner oil passage. Thus, the hydraulic pressure is prevented from becoming excessive.
[0014]
In the present invention, in addition to the above configuration, an engine brake pressure regulating valve 130 is further provided between the outer oil passage 53 and the inner oil passage 52. Due to the engine brake pressure regulating valve 130, during reverse load operation, that is, during deceleration, when the oil passage in the inner oil passage 52 on the low pressure side during normal operation becomes a certain value or more, a part of the hydraulic oil in the inner oil passage 52 Is guided to the outer oil passage 53 to prevent the hydraulic pressure from becoming excessive.
[0015]
Next, the configuration of the hydrostatic continuously variable transmission according to an embodiment will be described in detail. In FIG. 2, a swash plate hydraulic pump P is a pump that is supported by an input cylinder shaft 5 having an output gear 2 a of a primary reduction gear, and an inner peripheral wall of the input cylinder shaft 5 via a ball bearing 6 so as to be relatively rotatable. A cylinder 7, a plurality of cylinder holes 8 provided in an annular arrangement so as to surround the rotation axis of the pump cylinder 7, and a plurality of pump plungers 9 slidably fitted in the cylinder holes 8, respectively. A plate 10 that engages and abuts the front surface with the outer end of each pump plunger 9, and this plate 10 is centered on a virtual trunnion axis center O 1 that is orthogonal to the axis of the pump cylinder 7, with respect to the axis of the pump cylinder 7 A pump swash plate 12 that supports the plate 10 via an angular contact bearing 13 and a radial bearing 14 so as to be held at a certain angle. It consists of. The pump swash plate 12 is formed integrally with the input cylinder shaft 5.
[0016]
The pump swash plate 12 causes the pump plunger 9 to reciprocate through the plate 10 and the bearings 13 and 14 when the input cylinder shaft 5 rotates to repeat the suction and discharge strokes.
[0017]
The hydraulic motor M is integrated with the pump cylinder 7 and is provided coaxially with the pump cylinder 7 and positioned on the right side in FIG. 2 so as to surround the rotation axis of the motor cylinder 17. Cylinder holes 18, a plurality of motor plungers 19 slidably fitted in the cylinder holes 18, a plate 20 for engaging and abutting the front surface with the outer ends of the motor plungers 19, and angular contacts A motor swash plate 22 that supports the plate 20 via a bearing 27 and a radial bearing 28, and a motor swash plate anchor 23 that supports the back surface of the motor swash plate 22.
[0018]
Opposing contact surfaces 22a and 23a of the motor swash plate 22 and the motor swash plate anchor 23 that are in contact with each other are formed in a spherical shape centered on the intersection of the axis of the motor cylinder 17 and the trunnion shaft center O2. Moreover, the motor swash plate 22 is supported by the motor swash plate anchor 23 so as to be capable of relative rotation around the trunnion shaft center O2.
[0019]
A cylindrical cylinder holder 24 is connected to the end of the motor swash plate anchor 23 on the motor cylinder 17 side, and a ball bearing 25 is interposed between the cylinder holder 24 and the outer periphery of the motor cylinder 17.
[0020]
The plate 20 has an upright position perpendicular to the axis of the motor cylinder 17 and a certain angle when the motor swash plate 22 is rotated around the trunnion shaft center O2 by a ball screw mechanism 79 connected to the motor 80. In the inclined state, the motor plunger 19 can be reciprocated with the rotation of the motor cylinder 17 to repeat the expansion and contraction strokes.
[0021]
The pump cylinder 7 and the motor cylinder 17 are integrally connected to each other to constitute a cylinder block B. The cylinder block B and the output shaft 31 are integrated.
[0022]
One side of the output shaft 31 with the cylinder block B as a boundary passes through the plate 10 and the pump swash plate 12, and supports the end of the pump swash plate 12 via the angular contact ball bearing 33. A ball bearing 35 is interposed between the pump swash plate 12 and the casing 4.
[0023]
The other side of the output shaft 31 with the cylinder block B as a boundary extends through the plate 20, the motor swash plate 22, and the motor swash plate anchor 23. A motor swash plate anchor 23 is supported via an angular contact bearing 41 on the end side (the right end side in FIG. 2) of the output shaft 31. The motor swash plate anchor 23 is integrated with the casing 4. An input gear 3 a of the secondary reduction gear is attached to the outer periphery of the output shaft 31 on the outer side in the axial direction of the output shaft 31.
[0024]
The interior of the hollow output shaft 31 that is integral with the cylinder block B is a supply oil passage 47. The supply oil passage 47 is connected to an oil reservoir 87 via an oil filter 89 and a supply pump 88 at one end of the output shaft 31 (left end in FIG. 2). The replenishment oil passage 47 is closed with a plug 48 at the other end of the output shaft 31, or is opened with a throttle.
[0025]
An annular groove is formed on the outer peripheral surface of the output shaft 31 between the cylinder hole 8 group of the pump cylinder 7 and the cylinder hole 18 group of the motor cylinder 17, and the cylinder block is integrally fitted to the output shaft 31. An annular inner oil passage 52 is formed with the inner peripheral surface of B. An annular groove is formed in the outer peripheral surface of the cylinder block B, and an annular outer oil passage 53 is formed with the inner peripheral surface of the ring body 56 that is integrally fitted with the outer peripheral surface of the cylinder block B. Yes.
[0026]
An annular partition wall between the inner oil passage 52 and the outer oil passage 53 of the cylinder block B between the cylinder hole group 8 of the pump cylinder 7 and the cylinder hole group 18 of the motor cylinder 17, and the outer peripheral wall of the outer oil passage 53, The same number of first valve holes 57 as the cylinder holes 8 are provided on the cylinder hole 8 group side so as to penetrate the ring body 56 radially, and the same number of second valve holes 58 as the cylinder holes 18 are provided in the cylinder holes. Each is provided on the 18th group side. Each cylinder hole 8 and each first valve hole 57 are communicated by a pump port 59, and each cylinder hole 18 and each second valve hole 58 are communicated by a motor port 60.
[0027]
A spool-type first distribution valve 61 is slidably fitted in the first valve hole 57, and a spool-type second distribution valve 62 is slidably fitted in the second valve hole 58, respectively. A first eccentric ring (eccentric cam) 63 surrounding the first distribution valve 61 is surrounded at the outer end of the first distribution valve 61, and the second distribution valve 62 is surrounded at the outer end of the second distribution valve 62. Second eccentric rings (eccentric cams) 64 are engaged via slip rings (or ball bearings) 65 and 66, respectively.
[0028]
The outer end portion of the first distribution valve 61 is connected to each other by a first expanding ring 67 that is concentric with the first eccentric ring 63, and the outer end portion of the second distribution valve 62 is concentric with the second eccentric ring 64. They are connected to each other by some second expanding ring 68.
[0029]
The first eccentric ring 63 is provided integrally with the input cylinder shaft 5, and is eccentrically located by a predetermined distance from the center of the cylinder block B along the tilting center (virtual trunnion shaft center O1) of the pump swash plate 12. Is done. The second eccentric ring 64 is connected to the cylinder holder 24 and is eccentric by a predetermined distance from the center of the cylinder block B along the tilt center (virtual trunnion shaft center O2) of the motor swash plate 20. Be positioned.
[0030]
Here, the operation of the first distribution valve 61 will be described. When relative rotation occurs between the input cylinder shaft 5 and the pump cylinder 7, that is, the cylinder block B, each first distribution valve 61 is moved by the first eccentric ring 63. The first valve hole 57 is reciprocated between the radially inner position and the outer position of the pump cylinder 7 with a stroke twice as long as the eccentric distance. Then, in the discharge region of the hydraulic pump P, the first distribution valve 61 moves in the inward position side to connect the corresponding pump port 59 to the outer oil passage 53 and to disconnect the inner oil passage 52. As a result, the hydraulic oil is pumped from the cylinder hole 8 to the outer oil passage 53 by the pump plunger 9 during the discharge stroke.
[0031]
Further, in the suction region of the hydraulic pump P, the first distribution valve 61 moves on the outer position side to connect the corresponding pump port 59 to the inner oil passage 52 and disconnect the outer oil passage 53. Thus, the hydraulic oil is drawn into the cylinder hole 8 from the inner oil passage 52 by the pump plunger 9 during the suction stroke.
[0032]
The operation of the second distribution valve 62 will be described. When the motor cylinder 17, that is, the cylinder block B rotates, each second distribution valve 62 is separated by a second eccentric ring 64 in the second valve hole 58 twice the eccentric distance. Is reciprocated between the radially inner position and the outer position of the cylinder block B. In the expansion region of the hydraulic motor M, the second distribution valve 62 moves in the inward position, communicates the corresponding motor port 60 to the outer oil passage 53 and disconnects the motor port 60 and the inner oil passage 52 from each other. As a result, high-pressure hydraulic oil is supplied from the outer oil passage 53 to the cylinder hole 18 of the motor plunger 19 during the expansion stroke.
[0033]
Further, in the contraction region of the hydraulic motor M, the second distribution valve 62 moves on the outer position side, and the corresponding motor port 60 communicates with the inner oil passage 52 and does not communicate between the motor port 60 and the outer oil passage 53. As a result, the hydraulic oil is discharged from the cylinder hole 18 of the motor plunger 19 during the contraction stroke to the inner oil passage 52.
[0034]
Thus, the cylinder block B has a reaction torque that the pump cylinder 7 receives from the pump swash plate 12 through the pump plunger 9 in the discharge stroke, and a reaction torque that the motor cylinder 17 receives from the motor swash plate 22 through the motor plunger 19 in the expansion stroke. And the rotational torque is transmitted from the output shaft 31 to the secondary reduction device. In this case, the gear ratio of the output shaft 31 to the input cylinder shaft 5 is given by the following equation.
[0035]
Gear ratio = 1 + (capacity of hydraulic motor M / capacity of hydraulic pump P)
[0036]
Therefore, if the capacity of the hydraulic motor M is changed from zero to a certain value, the gear ratio can be changed from 1 to a necessary value. Moreover, since the capacity of the hydraulic motor M is determined by the stroke of the motor plunger 19, the gear ratio is continuously controlled from 1 to a certain value by tilting the motor swash plate 22 from the upright position to a certain tilt position. can do.
[0037]
Although not shown in FIG. 2, the clutch valve shown in FIG. 1 is provided on the outer periphery of the cylinder block B at equal intervals of 120 degrees and between the first valve holes 57 and the second valve holes 58 adjacent to each other. It has been. The clutch valve is moved from the clutch-on position where the gap between the inner oil passage 52 and the outer oil passage 53 is cut off by the operation of the clutch lever, and the inner oil passage 52 and the outer oil passage 53 are moved. A clutch-off position that communicates with each other, and a communication that further moves from the clutch-off position to communicate between the inner oil passage 52 and the outer oil passage 53 and to open the inner oil passage 52 and the outer oil passage 53 to the outside.・ Switching between discharge positions is possible.
[0038]
Next, the check valves 95 and 96 provided in the cylinder block B will be described with reference to FIGS. The cylinder block B is provided with a communication hole 90 that communicates with the inner oil passage 52 and a communication hole 91 that communicates with the replenishment oil passage 47, and between these communication holes 90, 91, supply oil is supplied from the inner oil passage 52. A first check valve 95 for preventing backflow of hydraulic oil to the passage 47 is provided. The first check valve 95 includes a valve body 103 having an oil passage 101 that connects the communication holes 90 and 91, a spherical valve body 104 that abuts a valve seat 103 a provided in the valve body 103, and the valve body 104. It consists of a valve spring 105 that urges the valve body 104 to apply a spring force to be pressed against the valve seat 103a.
[0039]
The cylinder block B is provided with a communication hole 113 communicating with the replenishment oil passage 47, and the backflow of hydraulic oil from the outer oil passage 53 to the replenishment oil passage 47 is prevented between the communication hole 113 and the outer oil passage 53. A second check valve 96 is provided. The second check valve 96 includes a valve main body 109 having an oil passage 112 that connects the communication hole 113 and the outer oil passage 53, a spherical valve body 110 that contacts a valve seat 109 a provided in the valve main body 109, It comprises a valve spring 111 that urges the valve body 110 to apply a spring force so as to press the body 110 against the valve seat 109a. In addition, the opening part opened from the outer peripheral direction of the pump cylinder 7 in order to process the communication holes 91 and 113 is sealed by the inner peripheral surface of the inner race of the bearing 102, and a special part for sealing the opening part is necessary. Since it is eliminated, the number of parts is small and it can be manufactured at low cost.
[0040]
The cylinder block B is provided with a communication hole 121 communicating with the inner oil passage 52, and a pressure regulating valve 97 for preventing an excessive increase in the oil pressure of the outer oil passage 53 is provided between the communication hole 121 and the outer oil passage 53. Is provided. The pressure regulating valve 97 has a valve chamber 122 inside, a valve body 115 having a communication hole 124 that connects the valve chamber 122 and the communication hole 121, and a passage 125 that connects the valve chamber 122 and the outer passage 53. , A movable body 127 that holds a spherical valve body 126 that contacts the valve seat 115a formed on the valve body 115, a fixing member 129 provided on the valve body 115, and the valve body 126 that contacts the valve seat 115a. The valve spring 128 is provided between the fixed member 129 and the movable body 127 in order to achieve this.
[0041]
In the pressure regulating valve 97, the oil pressure of the outer oil passage 53 acts on the valve body 126 and the valve opening force is given to the valve body 126, but in a normal operation state where the oil pressure of the outer oil passage 53 is below a specified value. Since the force of the valve spring 128 that urges the valve body 126 in the valve closing direction is larger than the valve opening force, the valve body 126 is closed, that is, communicates with the outer oil passage 53 as shown in FIG. The passage 125 and the communication hole 124 communicating with the inner oil passage 52 are held in a blocked state. When the oil pressure in the outer oil passage 53 exceeds the specified value, the valve opening force becomes larger than the force of the valve spring 128, so that the valve body 126 and the movable body 127 are valve spring 128 as shown in FIG. The valve body 126 is moved away from the valve seat 115a by compressing the valve seat 115a, the passage 125 leading to the outer oil passage 53 and the communication hole 124 leading to the inner oil passage 52 are communicated, and the excessive oil passage of the outer oil passage 53 is connected. The oil is discharged to the inner oil passage 52 through the communication hole 125, the valve chamber 122, and the communication holes 124 and 121.
[0042]
When the oil pressure in the outer oil passage 53 is restored, the valve body 126 is returned to the closed state shown in FIG. Therefore, an excessive increase in the hydraulic pressure in the outer oil passage 53 can be suppressed even when the vehicle is suddenly started or accelerated.
[0043]
In the cylinder block B, as described above, during reverse load operation, that is, during deceleration, if the oil pressure in the inner oil passage 52, which is the low pressure side during normal operation, exceeds a specified value, the problem is that the oil pressure becomes excessive. In order to prevent this, an engine brake pressure regulating valve (relief valve) 130 that guides part of the hydraulic oil in the inner oil passage 52 to the outer oil passage 53 is provided. A valve hole 131 is formed in the cylinder block B in parallel with the output shaft 31, and a valve main body 132 of the engine brake pressure regulating valve 130 is fitted in the valve hole 131. An annular oil passage 133 is formed between the outer peripheral surface of the valve main body 132 fitted in the valve hole 131 and the inner peripheral surface of the valve hole 131. A communication hole 134 that connects the annular oil passage 133 and the inner oil passage 52 is formed in the cylinder block B.
[0044]
A valve chamber 136 is formed in the valve main body 132 of the engine brake pressure regulating valve 130, and a communication hole 137 that connects the valve chamber 136 and the annular oil passage 133 is formed. A movable body 139 that holds a spherical valve body 138 that contacts a valve seat 132 a formed on the valve chamber 136 side of the valve body 132 is accommodated in the valve chamber 136, and a fixed member 140 provided in the valve body 132. A valve spring 141 is provided between the movable body 139 and the movable body 139 for biasing the valve body 138 with a spring force so that the valve body 138 contacts the valve seat 132a. An oil passage 142 is formed between the movable body 139 and the valve main body 132, and an oil passage 143 is also formed between the fixed member 140 and the valve main body 132, and the oil passage 143 serves as the outer oil passage 53. Connected. That is, when the valve body 138 is separated from the valve seat 132 a, the inner oil passage 52 becomes the outer passage 53 via the communication hole 134, the annular oil passage 133, the communication hole 137 of the valve body 132, and the oil passages 142 and 143. It comes to be connected.
[0045]
In the engine brake pressure regulating valve 130, the valve body 138 is subjected to a valve opening force by the oil pressure of the inner oil passage 52. However, in a normal operation state where the oil pressure of the inner oil passage 52 is below a specified value, the valve body 138 is opened. Since the force of the valve spring 141 urging in the valve closing direction is larger than the valve opening force, the valve body 138 is closed, that is, the communication hole 137 leading to the inner oil passage 52 and the outer side as shown in FIG. The oil passage 142 leading to the oil passage 53 is kept in a blocked state.
[0046]
During reverse load operation, that is, during engine braking, if the oil pressure in the inner oil passage 52 exceeds a specified value, the valve opening force becomes greater than the force of the valve spring 141. Therefore, as shown in FIG. 138 and the movable body 139 move while compressing the valve spring 141 so that the valve body 138 is separated from the valve seat 132a, and the passage 137 leading to the inner oil passage 52 and the oil passages 142, 143 leading to the outer oil passage 53 communicate with each other. The excessive hydraulic oil in the inner oil passage 52 is discharged to the outer passage 53 through the communication hole 134, the annular oil passage 133, the communication hole 137 of the valve body 132, and the oil passages 142 and 143, and the inner oil passage. The pressure rise in 52 is suppressed.
[0047]
When the oil pressure in the inner oil passage 52 is restored, the valve body 138 is returned to the closed state shown in FIG. 4A by the spring force of the valve spring 141.
[0048]
In the above embodiment, the engine brake pressure regulating valve 130 is incorporated in the cylinder block B. However, the engine brake pressure regulating valve 130 is not limited to this location, and for example, a valve cylinder is provided in the output shaft. Can also be incorporated.
[0049]
【The invention's effect】
According to the hydrostatic continuously variable transmission according to the present invention, between the hydraulic pump and the hydraulic motor, a high-pressure oil passage that sends hydraulic oil from the hydraulic pump side to the hydraulic motor side and the hydraulic pump from the hydraulic motor side In a hydrostatic continuously variable transmission comprising a hydraulic closed circuit comprising a low pressure oil passage for sending hydraulic oil to the side, when the pressure in the low pressure oil passage exceeds a predetermined value, the hydraulic pressure in the low pressure oil passage is increased to the high pressure Since the pressure regulating valve that opens to the oil passage is provided, even if the hydraulic pressure in the hydraulic circuit, which was on the low pressure side during normal driving, becomes high pressure due to the hydraulic motor functioning as a hydraulic pump during deceleration, the hydraulic pressure remains at the specified value. In such a case, the relief valve is opened and the oil is led to the high pressure oil passage that is on the high pressure side during normal driving but on the low pressure side during deceleration, so the oil pressure in the low pressure oil passage becomes excessive. Is prevented. In particular, in a vehicle such as a motorcycle, it is possible to prevent an excessive increase in the hydraulic pressure in the continuously variable transmission at the time of landing after a small jump, and there is no possibility of causing a problem in the continuously variable transmission.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a hydrostatic continuously variable transmission according to the present invention.
FIG. 2 is a longitudinal sectional view of a hydrostatic continuously variable transmission according to an embodiment applied to a power unit of a vehicle.
3 is a longitudinal section of a check valve portion of the embodiment shown in FIG. 2. FIG.
4 is a longitudinal section of the pressure regulating valve portion of the embodiment shown in FIG.
FIG. 5 is a schematic side view showing the arrangement of the valve of the embodiment shown in FIG. 2;
FIG. 6 is a schematic configuration diagram of a conventional hydrostatic continuously variable transmission.
[Explanation of symbols]
4 casing, 5 input cylinder shaft,
8 Cylinder hole, 7 Pump cylinder,
10 plate (pump), 12 pump swash plate,
17 motor cylinder, 18 cylinder hole,
20 plate (motor), 22 motor swash plate,
31 Output shaft, 47 Supply oil passage,
52 inner oil passage, 53 outer oil passage,
56 ring body, 57 first valve hole,
58 second valve hole, 59 pump port,
60 motor port, 61 first distribution valve,
62 second distribution valve, 63 first eccentric ring,
64 second eccentric ring, 67 first expanding ring,
68 second expanding ring, 88 refill pump,
95 first check valve, 96 second check valve,
97 pressure regulating valve, 130 engine brake pressure regulating valve,
B cylinder block, M swash plate hydraulic motor,
P swash plate type hydraulic pump,

Claims (1)

A hydraulic closed circuit comprising a high-pressure oil passage that sends hydraulic oil from the hydraulic pump side to the hydraulic motor side and a low-pressure oil passage that sends hydraulic oil from the hydraulic motor side to the hydraulic pump side between the hydraulic pump and the hydraulic motor In the hydrostatic continuously variable transmission comprising:
The hydraulic pump includes a pump cylinder that is integrally fitted to the outer peripheral surface of the output shaft of the hydrostatic continuously variable transmission, a ring body that is integrally fitted to the outer peripheral surface of the pump cylinder, and the pump cylinder A plurality of cylinder holes provided in an annular arrangement with respect to the rotation axis, and a pump plunger that is slidably fitted in each of the cylinder holes,
An annular inner oil passage is configured from the outer peripheral surface of the output shaft and the inner peripheral surface of the pump cylinder,
An annular outer oil passage is constructed from the outer peripheral surface of the pump cylinder and the inner peripheral surface of the ring body,
A first pressure regulating valve for releasing the hydraulic pressure of the inner oil passage to the outer oil passage when the pressure of the inner oil passage becomes equal to or larger than the specified value, when the pressure of the outer oil passage becomes equal to or larger than a specified value A second pressure regulating valve that opens the oil pressure of the outer oil passage to the inner oil passage ;
One of the inner oil passage or the outer oil passage is the high-pressure oil passage, the other is the low-pressure oil passage,
The first pressure regulating valve is arranged between two adjacent cylinder holes, and the second pressure regulating valve is arranged next to the cylinder hole facing the first pressure regulating valve. Step transmission.

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