JPH0743019B2 - Hydrostatic continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention forms a closed hydraulic circuit between a constant displacement swash plate hydraulic pump and a variable displacement swash plate hydraulic motor. The present invention relates to improvement of a hydrostatic continuously variable transmission.

(2) Conventional Technology As a hydrostatic continuously variable transmission in which a swash plate type hydraulic pump and a hydraulic motor are combined, for example, as disclosed in British Patent No. 745543, a pump cylinder and a motor cylinder are coaxial. The two cylinders are arranged and connected integrally with each other, and between the two cylinders, an annular high-pressure oil passage connected to a large number of cylinder holes arranged in an annular shape of the pump cylinder and an annular arrangement of the motor cylinder are arranged. An annular low-pressure oil passage connected to a large number of cylinder holes is formed concentrically with each other and the low-pressure oil passage is surrounded by the high-pressure oil passage. A large number of distribution valves forming a hydraulic closed circuit between the hydraulic pump and the hydraulic motor between the cylinder hole of the motor cylinder and the cylinder hole of the motor cylinder are reciprocally movable between the outer position and the inner position in the radial direction. Conventionally known is a radial arrangement, in which an eccentric ring that reciprocates each distribution valve as the pump and the motor cylinder rotate is engaged with these distribution valve groups. Also, the hydraulic oil can be transferred between the hydraulic pump and the hydraulic motor without relatively rotating the motor cylinder, and the reciprocating distribution valve has an advantage that the hydraulic oil leaks little.

(3) Problems to be Solved by the Invention However, in the above-described conventionally known transmission, since the eccentric wheels (38, 45) that reciprocate the distribution valves are engaged with the inner ends of the distribution valves, the same distribution is achieved. When the delivery pressure of the replenishment pump is applied to the inner end of the valve, the delivery pressure causes the distribution valve to be separated from the engagement direction with the eccentric ring, that is, there is play between the distribution valve and the eccentric ring. Not only is there a problem that the operation noise is increased due to the rattling,
It becomes impossible to accurately reciprocate each distribution valve according to the outer peripheral cam surface of the eccentric wheel, and it becomes impossible to accurately transfer the hydraulic oil between the hydraulic pump and the hydraulic motor, which causes a reduction in transmission efficiency.

It is an object of the present invention to provide a hydrostatic continuously variable transmission that can solve the problems of the conventional ones.

B. Configuration of the Invention (1) Means for Solving the Problems To achieve the above object, according to the present invention, a pump cylinder of a constant displacement type swash plate hydraulic pump and a motor of a variable displacement type swash plate hydraulic motor. The cylinder and the cylinder are coaxially arranged, and the two cylinders are integrally connected to each other to be supported on the output shaft. Between the two cylinders, an annular high-pressure oil passage is connected to a large number of cylinder holes arranged in an annular shape in the pump cylinder. And an annular low pressure oil passage connected to a large number of cylinder holes arranged in an annular shape of the motor cylinder are formed concentrically with each other and the low pressure oil passage is surrounded by the high pressure oil passage. Is
A large number of distribution valves that form a hydraulic closed circuit between the hydraulic pump and the hydraulic motor between the cylinder hole of the pump cylinder and the cylinder hole of the motor cylinder through the oil passages are installed between the radially outer position and the inner position. Reciprocatingly and radially arranged, and an eccentric wheel that reciprocates each distribution valve as the pump and the motor cylinder rotate is engaged with these distribution valve groups. The eccentric wheel is disposed on the outer periphery of the distribution valve so that the inner peripheral surface of the eccentric wheel engages with the outer end of the distribution valve, and the distribution valve is engaged in the engagement direction with the eccentric wheel. The discharge side of a replenishment pump for replenishing the low-pressure oil passage with hydraulic oil is communicated with the inner end surface of each distribution valve in order to bias the hydraulic pressure to.

(2) Operation According to the above configuration, the supply pressure of the replenishment pump that acts on the inner end of each distribution valve effectively uses the discharge pressure to cause the multi-distribution valve to play back and forth between the eccentric wheels. Since it can always be engaged accurately, the operating noise of the transmission is reduced, and each distribution valve can be accurately reciprocated according to the inner cam surface of the eccentric wheel. Transfer of hydraulic oil between the motors is properly performed.

Also, since the delivery pressure of the replenishment pump that replenishes the low-pressure oil passage is relatively low, even if each delivery valve is specially biased in the direction of engagement with the eccentric wheel by that delivery pressure, The inward moving load with respect to is sufficient, and it is not necessary to additionally provide a return spring for urging each distribution valve toward the eccentric wheel.

(3) Example An example of the present invention will be described below with reference to the drawings. In FIG. 1, the power of the engine of the motorcycle is
It is transmitted from the crankshaft 1 to a rear wheel (not shown) through a chain type primary reduction gear 2, a hydrostatic continuously variable transmission T, and a chain type secondary reduction gear 3 in sequence.

The continuously variable transmission T is composed of a constant displacement type swash plate hydraulic pump P and a variable displacement type swash plate hydraulic motor M, and a crankcase 4 supporting the crankshaft 1 is used as a casing.
Accommodated in it.

The hydraulic pump P is an output sprocket 2a of the primary speed reducer 2.
A cup-shaped input member 5 integrally provided with a pump cylinder 7, a pump cylinder 7 that is rotatably fitted to an inner peripheral wall of the input member 5 via a needle bearing 6, and a center of rotation of the pump cylinder 7 is surrounded by the pump cylinder 7. , Which are slidably fitted in a plurality of odd-numbered cylinder holes 8, 8 ... of an annular array, respectively, and these pump plungers 9, 9
And a pump swash plate 10 that abuts the outer end of.

The pump swash plate 10 is rotatably supported at its back surface by an inner end wall of the input member 5 via a thrust roller bearing 11 in a posture inclined at an angle with respect to the axis of the pump cylinder 7, and when the input member 5 rotates, the pump swash plate 10 is rotated. The plunger 9 can be reciprocally moved to repeat the suction and discharge steps.

In order to improve the followability of the pump plunger 9 with respect to the pump swash plate 10, a spring for urging the pump plunger 9 in the extension direction may be contracted in the cylinder hole 8.

The back surface of the input member 5 is a thrust roller bearing 12
Is supported by the support cylinder 13 via.

On the other hand, the hydraulic motor M includes a motor cylinder 17 coaxially arranged to the left of the pump cylinder 7, and a plurality of odd-numbered cylinder holes arranged in an annular array in the motor cylinder 17 so as to surround the rotation center. The motor plungers 19, 19 that are slidably fitted to the 18, 18 ..., the motor swash plate 20 that contacts the outer ends of the motor plungers 19, 19 ..., and the back surface of the motor swash plate 20 through the thrust roller bearing 21. And a cup-shaped swash plate anchor 23 that supports the swash plate holder 22.

The motor swash plate 20 can tilt between an upright position that is perpendicular to the axis of the motor cylinder 17 and a tilted position that tilts at a certain angle. At that tilted position, the motor cylinder 17 rotates. Accordingly, the motor plungers 19, 19 ... Can be reciprocated to repeat the expansion and contraction strokes.

In order to improve the followability of the motor plunger 19 with respect to the motor swash plate 20, a spring that biases the motor plunger 19 in the extension direction may be contracted in the cylinder hole 18.

Between the pump cylinder 7 and the motor cylinder 17, first and second valve discs 14, 15 are interposed in order from the pump cylinder 7 side, and the output shaft 25 is provided at the center of these four discs 7, 14, 15, 17. Penetrate. A flange 25 integrally formed on the outer periphery of the output shaft 25
By hitting the outer end of the motor cylinder 17 against a and tightening the outer end of the pump cylinder 7 with the nut 26 that is screwed onto the output shaft 25, the four members 7, 14, 15, 17 are superposed and bonded to each other. And is fixed to the output shaft 25.

At that time, as shown in FIG. 1A, in order to ensure the connection of the four members 7, 14, 15, 17 with the output shaft 25, and to define their mutual position, the output power of each cylinder 7, 17 is increased. Key between axis 25
16 and 16 are installed, and pump cylinder 7 and first valve disc 1
4, knock pin 2 between the motor cylinder 17 and the second valve disc 15
4,24 are inserted.

Referring again to FIG. 1, the output shaft 25 also penetrates the input member 5 and rotatably supports the member 5 via a needle bearing 27.

The support cylinder 13 is fitted on the outer periphery of the right end portion of the output shaft 25 via a key 28, and is fixed by a nut 30. Above support tube
The right end of the output shaft is rotatably supported by the crankcase 4 via the roller bearing 13 and the roller bearing 31.

Further, the output shaft 25 penetrates through the central portions of the motor swash plate 20, the swash plate holder, and the swash plate anchor 23, and supports the back surface of the swash plate anchor 23 at its left end through a thrust roller bearing 32. The cylinder 33 is spline-fitted, and is fixed with the nut 34 together with the input sprocket 3a of the secondary speed reducer 3,
Output shaft 25 via the support cylinder 33 and roller bearing 35
The left end of the is rotatably supported by the crankcase 4.

A hemispherical centering body 36 that slidably engages with the inner peripheral surface of the pump swash plate 10 in all directions is slidably fitted to the output shaft 25. The aligning body 36 includes a plurality of disc springs 38.
Force presses the pump swash plate 10 against the thrust roller bearing 11, whereby the pump swash plate 10 is always aligned.

Further, a hemispherical centering body 37 that slidably engages with the inner peripheral surface of the motor swash plate 20 in all directions is slidably fitted to the output shaft 25. With this aligning body 37, the swash plate 20 of the motor is thrust by the force of a plurality of disc springs 39.
The swash plate 20 is constantly pressed against the swash plate 20.

The swash plates 10 and 20 are strengthened in alignment, and the pump swash plate 10
And the pump plungers 9,9 ... Group, the motor swash plate 20 and the motor plungers 19,19 .. Spherical recesses 10a, 20a for engaging the spherical end portions 9a, 19a of the respective are formed. At that time, the spherical concave portions 10a, 20a are swash plates 10, 20
The radius of curvature of the spherical end portions is ensured to ensure proper engagement with the spherical end portions 9a, 19a at any rotational position of.
It is set larger than that of 9a and 19a.

A hydraulic closed circuit is formed between the hydraulic pump P and the hydraulic motor 17 as follows.

The second valve disc 14 is provided with an annular low pressure oil passage 41 and an annular high pressure oil passage 40 surrounding the annular low pressure oil passage 41. From the low pressure oil passage 41 to the cylinder holes 8, 8 of the pump cylinder 7 in one direction. Intake valves 43, 43 ... Allowing the flow of hydraulic oil, and pump cylinder 7
A discharge valve 42 that allows the flow of hydraulic oil in one direction from the cylinders 8, 8, ... To the high-pressure oil passage 40 is provided in the first valve disk 14. Therefore, the numbers of the suction valves 43 and the discharge valves 42 are the same as the number of the pump plungers 9, 9 ,.

Further, the second valve board 15 is provided with distribution valves 44, 44 ... Which alternately control the high pressure and low pressure oil passages 40, 41 to communicate with the cylinder holes 18, 18 of the motor cylinder 17. Therefore, the distribution valve 44
Is the same as the number of motor plungers 19, 19.

Even if the distribution valves 44, 44 ... Are of the spool type, they are radially provided in the second valve disc 15 between the cylinder holes 18, 18 ... Group of the motor cylinder 17 and the high and low pressure oil passages 40, 41. The valve holes 15, 45 ... Further, in the second valve disc 15, first and second ports a and b communicating between the valve holes 45 and the high pressure and low pressure oil passages 40 and 41, and the valve holes 45 and the motor cylinders adjacent thereto. A third port c communicating with the cylinder hole 18 of 17 is provided. Thus, when the distribution valve 44 occupies the position radially outward of the valve hole 45, the corresponding third port c is connected to the first port a.
When it communicates with the second port b, the cylinder hole 19 is communicated with the high pressure oil passage 40. When the valve hole 45 is located radially inward, the corresponding third port c communicates with the second port b and the first port a does not communicate with each other, so that the corresponding cylinder hole 19 is connected to the low pressure oil passage 41. Communicate.

As shown in FIGS. 1 and 3, an eccentric wheel 47 is provided so as to surround the distribution valves 44, 44 ... Group so as to control the operation of the distribution valves 44, 44. , So that the outer end of each distribution valve 44 is engaged with the inner peripheral surface of the eccentric ring 47, the discharge pressure of the replenishment pump 67 is operating on the inner end surface of each distribution valve 44 through a first oil supply hole 72 described later. Always acted on.

The eccentric wheel 47 is composed of an inner ring of a ball bearing 48 fitted in the crankcase 4, and, as shown in FIG. 3, in the direction of the tilt axis O of the motor swash plate 20, the motor cylinder.
It is installed at a position eccentric from the center of 17 by a certain distance. Therefore, when the motor cylinder 17 rotates, each distribution valve 44
Reciprocates between the outer position and the inner position with the eccentric wheel ε of the eccentric wheel 47 as a stroke in the valve hole 45.

A pair of trunnion shafts 80, 80 'aligned on the tilt axis O of the motor swash plate 20 are integrally formed at both ends of the swash plate holder 22, and the trunnion shafts 80, 80' are provided with needle bearings 81 therebetween. Rotatably supported by the swash plate anchor 23. In other words, the tilt axis O is defined by the trunnion shafts 80 and 80 '.

An operating lever 82 is fixedly attached to the outer end of one trunnion shaft 80. Thus, when the trunnion shaft 80 is rotated by the operating lever 82, the tilt holder 22 integrated with it is also rotated, and this can be freely tilted even while the motor swash plate 20 is rotating.

The swash plate anchor 23 is supported on the outer periphery of the motor ring 17 via a needle bearing 78, and is connected to the crankcase 4 via a pair of positioning pins 49, 49 so as not to rotate around the output shaft 25. It

In the above configuration, when the input member 5 of the hydraulic pump P is rotated from the primary reduction gear device 2, the pump swash plate 10 alternately applies suction and discharge strokes to the pump plungers 9, 9. Then, each pump plunger 9 sucks the working oil from the low pressure oil passage 41 when performing the suction stroke, and feeds the high pressure working oil to the high pressure oil passage 40 when performing the discharge stroke.

The high-pressure hydraulic oil sent to the high-pressure oil passage 40 is fed to the cylinder hole 18 accommodating the motor plunger 19 in the expansion stroke via the distribution valve 44 at the outer position, while the motor plunger 19 in the contraction stroke is supplied. The hydraulic oil in the cylinder hole 18 to be stored is discharged to the low pressure oil passage 41 via the distribution valve 44 at the inner position.

During this time, the reaction torque that the pump cylinder 7 receives from the pump swash plate 10 via the pump plunger 9 in the discharge stroke,
The pump cylinder 7 and the motor cylinder 17 are rotated by the sum of the reaction torque that the motor cylinder 17 receives from the motor swash plate 20 via the motor plunger 19 in the expansion stroke, and the rotation torque is transmitted from the output shaft 25 to the secondary reduction gear. 3 is transmitted.

In this case, the gear ratio of the output shaft 25 to the input member 5 is given by the following equation.

Therefore, if the capacity of the hydraulic motor M is changed to a value of zero, the gear ratio can be changed to a required value of one.

By the way, 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 20 from the upright position to a certain tilt position. be able to.

During such operation of the hydraulic pump P and the hydraulic motor M, the pump swash plate 10 receives thrust loads from the pump plungers 9, 9 ... Group, and the motor swash plate 20 receives thrust loads in the opposite directions from the motor plungers 19, 19 ... Group. However, the thrust load received by the pump swash plate 10 is supported by the output shaft 25 via the thrust roller bearing 11, the input member 5, the thrust roller bearing 12, the support cylinder 13 and the nut 30, and the thrust load received by the motor swash plate 20. Is thrust roller bearing 21, swash plate holder 22, swash plate anchor 23, thrust roller bearing
It is also supported by the output shaft 25 via the support tube 33, the support tube 33, the sprocket 3a and the nut 34. Therefore, the thrust load causes only a tensile stress on the output shaft 25, and
It has no effect on the crankcase 4 supporting the 25.

Referring again to FIG. 1, the second valve plate 15 is further provided with one or a plurality of clutch valves 50 capable of communicating between the high and low pressure oil passages 40 and 41 in a timely manner. This clutch valve 50 is a low pressure oil passage.
From 41, it penetrates through the high-pressure oil passage 40 and is slidably fitted into a radial valve hole 51 opening to the outer periphery of the second valve disc 15. The clutch valve 50 has
A vertical hole 52 opening on the inner end surface thereof and a horizontal hole 53 crossing the vertical hole 52 and opening on the outer peripheral surface of the clutch valve 50 are provided, and the clutch valve 50 is located in the radial direction of the valve hole 81. The lateral hole 53 is closed by the inner wall of the valve hole 51 when the lateral position (clutch-on position) is occupied, and the lateral hole 53 is opened to the high pressure oil passage 40 when the lateral outward position (clutch-off position) is occupied. Has become.

The clutch valve 50 receives the hydraulic pressure of the low-pressure oil passage 40 at its inner end so as to be biased to the clutch-off position side, and has its outer end at the pump cylinder 7 and the first and second valve discs 14, 15. A clutch control ring 54 slidably fitted on the outer periphery is engaged.

The clutch control ring 54 has a cylindrical inner peripheral surface 54a that defines the clutch on position of the clutch valve 50, and a tapered surface 54b that is continuous with one end of the inner peripheral surface and defines the clutch off position of the clutch valve 50, and A spring 55 urges the clutch valve 50 to the side that holds the clutch on position. The spring 55 is contracted between the clutch control ring 54 and the retainer 56 locked to the outer circumference of the pump cylinder 7.

As shown in FIG. 2, the clutch control ring 54 is connected to a clutch lever (not shown) via a shift fork 57, an intermediate lever 58 and a clutch wire 59. Shift fork
57, the base end is pivotally supported 60 on the crankcase 4, the intermediate part is engaged with the side surface of the flange 54c of the clutch control wire 54, and the distal end is connected to the intermediate lever 58 via the push rod 61. To be done.

By pulling the clutch wire 59, the clutch control wire 54 is moved rightward in FIG. 1 through the shift fork 57 against the force of the spring 55. Is opposed to the clutch valve 50, the clutch valve 50 is moved to the outer position, that is, the clutch off position by the pressure of the low pressure oil passage 40. As a result, the high-pressure oil passage 40 is short-circuited to the low-pressure oil passage 41 via the vertical hole 52 and the horizontal hole 53 of the clutch valve 50, so that the pressure of the high-pressure oil passage 40 decreases and the supply of the pressure oil to the hydraulic motor M is reduced. The hydraulic motor M can be deactivated by disabling the feeding.

When the clutch control ring 54 is moved to the left by the strong force of the spring 55 to operate the clutch valve 50 to the clutch-on position, the lateral hole 53 of the clutch valve 50 is closed by the inner wall of the valve hole 51, so that the high pressure The low hydraulic pressures 40 and 41 are cut off, the hydraulic oil P is circulated between the hydraulic pump P and the hydraulic motor M through the paths 40 and 41, and the hydraulic motor M can be returned to the operating state. . In this case, since the operation of the clutch valve 50 to the clutch-on position is performed against the hydraulic pressure of the low pressure oil passage 41 acting on the inner end surface of the clutch valve 50, the disconnection of the spring 55 that moves the clutch control ring 54 to the left. The force generated can be set relatively weak, and the operation force of the clutch control ring 54 can be reduced.

At the intermediate position between the right-hand position and the left-position of the clutch control ring 54, the opening degree of the lateral hole 53 of the clutch valve 50 is appropriately reduced (the first position).
1B), the hydraulic oil is circulated between the hydraulic pump P and the hydraulic motor M according to the opening degree, so that the hydraulic motor M can be in a half-clutch state. In this case, since the opening degree of the lateral hole 53 gradually increases or decreases as the clutch valve 50 moves, a half-clutch state can be easily obtained, and smooth transient operation can be performed.

Referring again to FIGS. 1 and 2, the output shaft 25 is provided with an oil passage 63 having a deep stop at the center thereof, and an open end of the oil passage 63 is provided with an oil passage 63 of the crankcase 4. The oil supply pipe 64 supported by the side wall is inserted. The oil supply pipe 64 communicates with the inside of an oil pan 69 at the bottom of the crankcase 4 via an oil passage 45 formed in the side wall of the crankcase 4, a filter 66 mounted on the side wall, a replenishment pump 67 and a strainer 68. ,
The supply pump 69 is driven from the input member 5 via gears 70 and 71. Therefore, the oil in the oil pan 69 is constantly supplied to the oil passage 63 by the replenishment pump 67 while the input member 5 is rotating.

The output shaft 25 also has one or more first oil supply holes 72 extending radially from the oil passage 63 toward the valve hole 45 of the distribution valve 44.
And an annular groove 73 that communicates the first oil supply hole 72 with the valve holes 45, 45 ... Group, and when the distribution valve 44 comes to a position outside the valve hole 45, the second oil flow passage 41 connects with the low pressure oil passage 41. Valve hole corresponding to port b 45
It communicates with the first oil supply hole 72 via. Therefore, if the working shaft leaks from the closed hydraulic circuit between the hydraulic pump P and the hydraulic motor M, when the distribution valve 44 comes to the position outside the valve hole 45, the working oil flows from the first oil supply hole 72 to the low pressure oil passage 41. Is replenished.

The output shaft 25 is further provided with a second oil supply hole 74 that extends radially from the oil passage 63 and opens inside the cup-shaped input member 5, and a cup-shaped inclined anchor 23 that also extends radially from the oil passage 63.
And a third oil supply hole 75 that opens inside the oil supply hole, and orifices 76 and 77 are provided in these oil supply holes 74 and 75, respectively.
With these orifices 76 and 77, a replenishment pump 67
While reliably supplying the operating shaft from the first oil supply hole 72 to the low-pressure oil passage 41 while maintaining the discharge pressure thereof, and supplying an appropriate amount of lubricating oil from the oil passage 63 to the inside of the input member 5 and the swash plate anchor 23. be able to.

The oil supplied to the inside of the input member 5 lubricates the aligning body 36, the pump swash plate 10, the pump plunger 9, ..., The thrust roller bearing 11, the needle bearing 6 and the like, and is also supplied to the inside of the swash plate anchor 22. Oil is aligned body 37, motor swash plate
Lubricate 20, motor plunger 19, thrust bearing 21, etc. In this case, since the pump cylinder 7 is fitted to the open end of the cup-shaped input member 5 via the needle bearing 6, a large amount of lubricating oil is retained in the input member 5. On the other hand, since the motor cylinder 17 is fitted to the open end of the swash plate anchor 23 via the needle bearing 78, a large amount of lubricating oil is retained also in the swash plate anchor 23.

Further, for further lubrication of the sliding surface of the pump plunger 9 and the inside of the input member 5, a thin oil hole 112 communicating between the inside and outside of the pump plunger 9 is bored, and the sliding surface of the motor plunger 9 and the slanted surface Due to the different lubrication of the inside of the plate anchor 23, the motor plunger 19 is provided with a thin oil hole 113 communicating the inside and outside thereof.

In FIGS. 2, 4, and 5, the motor swash plate 20 is used.
For operating the tilting operation of the trunnion shaft 80.
A shift control device 83 is connected to 82.

The shift control device 83 includes a cylinder 84 fixed to the crankcase 4 and a piston 85 slidably fitted on the cylinder 84. There is a window 86 on the side wall of the cylinder 84 and a piston 85.
A connecting hole 8 is formed in the central portion of the trunnion so as to pass through it laterally and faces the window 86. The operating lever 82 of the trunnion shaft 80 is engaged with the connecting hole 87 through the window 86, The piston 85 can be slid according to the rotation of the trunnion shaft 80.

In FIG. 4, the actuating lever 82 and thus the piston 85
To the left of the piston 85 and the left end wall of the cylinder 84 causes the first swash plate 20 to stand upright.
An oil chamber 88 is defined, and a second oil chamber 89 is defined between the piston 85 and the right end wall of the cylinder 84. The first oil chamber 88 is returned to urge the piston 85 toward the second oil chamber 89. The spring 90 is retracted.

The first and second oil chambers 88 and 89 are communicated with each other via a hydraulic conduit 92 in which a shift control valve 91 is interposed, and the inside thereof is filled with hydraulic oil.

The shift control valve 91 is arranged in a proper position of the vehicle control device and intervenes in the middle of the hydraulic conduit 92, and the first and the first and second serially installed oil passages 94 in the valve box 93. 2 Check valves 95,96
Composed of and. These first and second check valves 95, 96
Are arranged such that their forward directions are opposite to each other, and are always urged in the valve closing direction by valve springs 97 and 98, respectively.

First and second check valves 95 and 96 are connected to first and second valve rods 100 and 101, respectively, which can push them in the valve opening direction. In addition, these first and second valve rods 500 and 101 are
A seesaw-type change lever 102 that is pivotally supported 103 by 3
Are connected to the lower surfaces of the left and right end portions of the left and right sides, respectively.

The gear shift lever 102 is operated by the operator to a horizontal hold position A, an acceleration position B swinging leftward, and an image immediate position C grounding rightward. At the hold position A, both reverses 9
Keep the valve closed at 6,96, and at the deceleration position B, the first valve opening 100
The first check valve 9 can be forcedly opened by depressing, and at the deceleration position C, the second start rod 101 can be pushed down to forcibly open the second check valve 96.

By the way, since the number of the motor plungers 19, 19 ... Is an odd number, the thrust load exerted on the motor swash plate 20 by the motor plungers 19, 19 ... Group during the rotation of the motor cylinder 17 is the tilt axis O of the motor swash plate 20. The strength changes alternately between the one side and the other side with the boundary as a boundary, and a vibrational tilting torque acts on the motor swash plate 20. Then, this oscillatory tilting torque acts on the piston 85 via the actuating lever 82 alternately as a pressing force in the left-right direction.

Therefore, if the shift lever 102 is shifted to the speed increasing position C,
Since the first check valve 95 is opened, the second check valve 96 allows the flow of oil from the first oil chamber 88 to the second oil chamber 89, but flows in the opposite direction. Is blocked and the operating lever
Oil flows from the first oil chamber 88 to the second oil chamber 89 only when a leftward pressing force acts on the piston 85 from 82. As a result, the piston 85 moves to the first oil chamber 88 side, and the operating lever 82
Is rotated in the standing direction of the motor swash plate 20.

Next, when the speed change lever 102 is shifted to the deceleration position B, the second check valve 96 is opened this time, so that the first check valve 95 is opened.
Allows the oil flow from the second oil chamber 89 to the first oil chamber 88, but blocks the flow in the opposite direction, and only when the rightward pressing force acts from the actuating lever 82 to the piston 85, Oil flows from the second oil chamber 89 to the first oil chamber 88. As a result, the piston 85 moves to the second oil chamber 89 side, and the operating lever 82
Will be rotated in the direction of inclination of the motor swash plate 20.

When the speed change lever 102 is returned to the hold position A, the two check valves 96, 96 which are in the open state cooperate with each other to completely prevent the oil flow in the valve box 93, so that the piston 85 cannot move. Become,
Hold the operating lever 82 at that position, and
Can be fixed in an upright or tilted position.

Further, if the transmission lever 102 is shifted to the deceleration position B and the first check valve 95 is opened in the stopped state of the transmission T, the oil flow from the second oil chamber 89 to the first oil chamber 88 will occur. Therefore, even if the piston 85 is in the left movement position, it can be moved to the right movement limit by the elastic force of the return spring 90, and the actuation lever 82 can be rotated to the maximum tilt position of the motor swash plate 20. .

As shown in FIG. 5, the cylinder 84 is arranged at a right angle to or near the axis of the output shaft 25. In this way, when the operating lever 82 pushes the piston 85,
It is possible to prevent the reaction force from acting on the swash plate anchor 23 in the axial direction of the output shaft 25 via the trunnion shaft 80.

In FIG. 4, a reserve tank 109 is installed above the cylinder 84, and the reserve tank 109 is installed in the cylinder 84.
Relief port 110 and supply boat 111 communicating inside
Are drilled in the upper wall of the cylinder 84.

Cylinder 84 is attached to the right end of piston 85 and the outer periphery of the right end.
The first and second cup seals 105, 106 having a one-way sealing function that are in close contact with the inner peripheral surface of the cylinder are mounted, and the cylinder 84
O-rings 107, 108 that are in close contact with the outer peripheral surface of the intermediate portion of the piston 85 are mounted on the inner periphery of the left and right sides of the window 86.

Thus, the relief port 110 opens to the first hydraulic chamber 88 immediately before the first cup seal 105 when the piston 85 is located in the right limit, and the supply port 111 always keeps the second cup seal 106 and the O-ring. It is adapted to open to the inner surface of the cylinder 84 with respect to 108.

Therefore, when the piston 85 is located in the right limit, when the pressure rises in the first oil chamber 88 due to the rise of the oil temperature or the like, the pressure is released from the relief port 110 to the reserve tank 109. Further, when the piston 85 moves to the left, the first oil chamber 88 is pressurized by the piston 85 from the time when the first cup seal 105 passes through the opening of the release port 110, and the first hydraulic chamber 88
To allow the oil to flow from the second oil chamber 89. At this time, if the second hydraulic chamber 89 is depressurized to a predetermined pressure or less, the oil in the reserve tank 109 will flow from the supply port 111 to the cylinder 84 and the piston 85 due to the pressure difference between the reserve tank 109 and the second oil chamber 89. The second cup seal 106 is supplied to the second oil chamber 89 while being deflected toward the second oil chamber 89 through the sliding gap.

If the inside of the reserve tank 109 is kept at a high pressure, the hydraulic conduit 92 is pretensioned by the hydraulic pressure.
The rigidity of 92 is enhanced, and the operation of the piston 85 can be stabilized.

C. Effects of the Invention As described above, according to the present invention, the eccentric ring that reciprocates the distribution valve is provided on the outer periphery of the distribution valve group so that the inner peripheral surface of the eccentric ring engages with the outer end of each distribution valve. The discharge side of the replenishment pump for replenishing hydraulic oil to the low pressure oil passage communicates with the inner end surface of each distribution valve so as to hydraulically bias each distribution valve in the engagement direction with the eccentric wheel. By effectively utilizing the discharge pressure of the replenishment pump acting on the inner end of the distribution valve, each distribution valve can be always and accurately engaged with the eccentric ring without causing rattling between them. Therefore, not only can it contribute to the low noise range of the transmission, but also each distribution valve can be accurately reciprocated according to the inner peripheral cam surface of the eccentric wheel, and the transfer of hydraulic oil between the hydraulic pump and hydraulic motor. Can always be done properly,
It can contribute to the improvement of transmission efficiency.

Also, since the delivery pressure of the replenishment pump that replenishes the low-pressure oil passage is relatively low, even if each delivery valve is specially biased in the direction of engagement with the eccentric wheel by that delivery pressure, Since the inward moving load on the valve can be small, the power loss can be suppressed to a small level, and there is no need to provide a special return spring for urging each distribution valve toward the eccentric ring. Can also contribute.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a hydrostatic continuously variable transmission interposed in a power transmission system of a motorcycle, and FIG. 1A is a pump cylinder in FIG. , Motor cylinder, first and second valve disk and output shaft assembly longitudinal sectional view, 1B
1 is an operational view of the clutch valve in FIG. 1, FIG. 2 is a partially longitudinal rear view of the continuously variable transmission, FIG. 3 is a sectional view taken along the line III-III of FIG. 1, and FIG. FIG. 5 is a sectional view taken along the line IV-IV of FIG. 5, and FIG. 5 is a plan view of the continuously variable transmission. T ... continuously variable transmission, P ... hydraulic pump, M ... hydraulic motor, 7 ... pump cylinder, 8 ... cylinder hole, 9 ...
Pump plunger, 10 ... Pump swash plate, 14 ... First valve disc, 15 ... Second valve disc, 16 ... Key, 17 ... Motor cylinder, 18 ... Cylinder hole, 19 ... Motor plunger, 20 …
… Motor swash plate, 24 …… knock pin, 40 …… high pressure oil passage, 41
...... Low pressure oil passage, 42 ...... Discharge valve, 43 …… Suction valve, 44 …… Distribution valve, 47 …… Eccentric wheel, 67 …… Supply pump

Claims (1)

[Claims] 1. A pump cylinder (7) of a constant displacement type swash plate hydraulic pump (P) and a motor cylinder (17) of a variable displacement type swash plate hydraulic motor (M) are coaxially arranged and both cylinders are arranged. (7, 17) are integrally connected and supported by the output shaft (25), and between the cylinders (7, 17), a large number of cylinder holes (annularly arranged in the pump cylinder (7) ( 8) an annular high-pressure oil passage (40) and a large number of cylinder holes (18) arranged in an annular shape in the motor cylinder (17).
And an annular low-pressure oil passage (41) continuous with each other are formed concentrically with each other and the low-pressure oil passage (41) is surrounded by the high-pressure oil passage (40). Is a hydraulic closing between the hydraulic pump (P) and the hydraulic motor (M) between the cylinder hole (8) of the pump cylinder (7) and the cylinder hole (18) of the motor cylinder (17) via these oil passages. A large number of distribution valves (44) forming a circuit are radially arranged so as to be reciprocable between an outer position and an inner position in the radial direction, and a pump and a motor cylinder (7) are arranged in the distribution valve (44) group. , 17) is a hydrostatic continuously variable transmission in which an eccentric wheel (47) for reciprocating each distribution valve (44) is engaged, wherein the eccentric wheel (47) is The inner peripheral surface of each of the distribution valves (44)
Is arranged on the outer periphery of the distribution valve (44) group so as to engage with the outer end of the distribution valve (44), and the low pressure is applied to bias the distribution valves (44) in the engagement direction with the eccentric ring (47). A hydrostatic continuously variable transmission characterized in that the discharge side of a replenishment pump (67) for replenishing hydraulic oil to the oil passage (41) is communicated with the inner end surface of each distribution valve (44).