JPH063269B2 - Switching valve device - Google Patents

Description

Detailed Description of the Invention A. OBJECT OF THE INVENTION (1) Industrial field of application The present invention relates to a switching valve device in which at least three states are selectively obtained.

(2) Prior Art The applicant of the present invention provides, as such a switching valve device, one check valve in a rotary valve body fitted in a valve box so as to traverse the oil passage. Selective to 3 positions: a position where a check valve is placed in a position that shuts off the passage in only one direction, a position where a check valve is placed in a position that shuts off the oil passage only in the other direction, and a position where the oil passage is shut off completely I have previously proposed the one that can be rotated (Japanese Patent Application No. 59-277816).

(3) Problems to be Solved by the Invention In the above-mentioned proposed switching valve device, there is a slight gap between the valve box and the rotary valve that allows the valve to rotate, so that the closed state can be reliably obtained. It is difficult, and particularly when controlling the hydraulic pressure, the pressure tends to leak from the high pressure side to the low pressure side through the gap.

The present invention has been made in view of such circumstances, and the above 3
An object of the present invention is to provide the switching valve device that can surely obtain the valve closed state in one of the two states.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides first and second check valves in an oil passage provided in a valve box, in which the forward directions are opposite to each other. Firstly, the first check valve is forcibly opened and the second check valve is free in the valve box. Switching position, a second switching position where the second check valve is forcibly opened and the first check valve is free, and a neutral switching position where both of the check valves are free. It is characterized in that an opening / closing means that can be selectively switched is provided.

(2) Operation According to the above configuration, the first check valve is forcibly opened and the second check valve is freely operated to effectively function by switching the valve opening means to the first switching position. With this configuration, the oil passage in the valve box or the second check valve blocks only one direction. Further, by switching the valve opening means to the second switching position, the second check valve is forcibly opened and the first check valve is freed to function effectively. The oil passage is shut off only in the other direction by the first check valve.

Further, by switching the valve opening means to the neutral switching position so that both check valves are free to function effectively, the two check valves cooperate to shut off the oil passage in both directions. To be done.

(3) Embodiment Hereinafter, one embodiment of the present invention will be described 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 comprises a swash plate hydraulic pump P having a constant capacity, a swash plate hydraulic motor M having a variable capacity, and a crankshaft 1
The crankcase 4 supporting the above is used as a casing and accommodated therein.

The hydraulic pump P is the output sprocket 2 of the primary speed reducer 2.
The cup-shaped input member 5 integrally provided with a, the pump cylinder 7 that is relatively rotatably fitted to the inner peripheral wall of the input member 5 via the needle bearing 6, and the rotation center of the pump cylinder 7 A plurality of ring-shaped and odd-numbered cylinder holes 8 arranged so as to surround the pump plungers 9, 9 ... Sliding with each other, and a pump swash plate 10 abutting the outer ends of the pump plungers 9, 9 ,. Composed of.

The back face of the pump swash plate 10 is rotatably supported by the inner end wall of the input member 5 via a thrust roller bearing 11 in a posture inclined at a constant angle with respect to the axis of the pump cylinder 7.
When the input member 5 is rotated, the pump plungers 9, 9 ... Can be reciprocated to repeat the suction and discharge strokes.

In order to improve the followability of the pump plunger 9 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 the thrust roller bearing 1
It is supported by the support cylinder 13 via 2.

On the other hand, the hydraulic motor M includes a motor cylinder 17 coaxially arranged on the left side of the pump cylinder 7, and a plurality of odd-numbered cylinder holes arranged in the motor cylinder 17 so as to surround its rotation center. The motor plungers 19 and 19 slidably engaged with the motors 18 and 18, the motor swash plate 20 that abuts the outer ends of the motor plungers 19 and 19, and the rear and outer peripheral surfaces of the motor swash plate 20 are thrust roller bearings. It comprises a swash plate holder 22 supported via 21 and a cup-shaped swash plate anchor 23 which further supports the swash plate holder 22.

The motor swash plate 20 can be tilted 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. Motor plunger 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 for urging 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. The outer end of the motor cylinder 17 is abutted against the flange 25a integrally formed on the outer periphery of the output shaft 25, and the outer end of the pump cylinder 7 is tightened with a nut 26 that is screwed to the output shaft support 25. The members 7, 14, 15, 17 are superposed on each other and fixed to the output shaft support 25.

At that time, as shown in FIG.
Keys 16 and 16 are mounted between each cylinder 7 and 17 and the output shaft 25 in order to ensure the connection of the output shafts 25 and 5 and to define their mutual position, and also to the pump cylinder 7 The knock pins 24, 24 are fitted between the first valve disc 14, the motor cylinder 17, and the second valve disc 15, respectively.

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

The output shaft 25 includes a motor swash plate 20 and a swash plate holder 22.
Also, a support cylinder 33 that penetrates the center of the swash plate anchor 23 and supports the back surface of the swash plate anchor 23 via a thrust roller bearing 32 is spline-fitted to the left end of the swash plate anchor 23. The input sprocket 3a is fixed with a nut 34, and the left end of the output shaft 25 is rotatably supported by the crankcase 4 via the support cylinder 33 and the roller bearing 35.

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 presses the pump swash plate 10 against the thrust roller bearing 11 by the force of the plurality of disc springs 38, whereby the piston swash plate 1 is pressed.
It always gives 0 a centering effect.

Further, a hemispherical centering body 37 that slidably engages with the inner peripheral surface of the motor swash plate 20 in all directions relative to the output shaft 25 is slidably spline-fitted. The aligning body 37 presses the motor swash plate 20 against the thrust roller bearing 21 by the force of a plurality of disc springs 39, thereby always providing the motor swash plate 20 with an aligning action.

The centering action of each swash plate 10, 20 is strengthened, and furthermore, slippage in the rotational direction between the pump swash plate 10, the pump plungers 9, 9, ... Group, the motor swash plate 20, and the motor plungers 19, 19, ... Group is prevented. For this purpose, the swash plates 10 and 20 are respectively formed with spherical recesses 10a and 20a for engaging the spherical ends 9a and 19a of the corresponding plungers 9 and 19, respectively. At this time, the spherical concave portions 10a, 20a have a radius of curvature such that the spherical end portions 9a, 19a are secured in proper engagement with the spherical end portions 9a, 19a at any rotational position of the swash plates 10, 20. It is set larger than that of 19a.

A hydraulic closed circuit is formed between the hydraulic pump P and the hydraulic motor M 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.
To the cylinder holes 8, 8 of the pump cylinder 7 to allow the flow of hydraulic oil in the negative direction, and from the cylinders 8, 8 of the pump cylinder 7 to the high-pressure oil passage 40 in the negative direction. A discharge valve 42 that allows the flow of hydraulic oil is provided in the first valve disc 14. Therefore, the numbers of the suction valves 43 and the discharge valves 42 are the same as the numbers of the pump plungers 9, 9 ,.

In addition, the second valve board 15 includes high pressure and low pressure oil passages 40, 41.
Are alternately provided to the cylinders 18, 18 of the motor cylinder 17 for distribution control. Therefore, the number of distribution valves 44 is equal to that of the motor plungers 19,1.
It is the same as the number of 9, ...

The distribution valves 44, 44 ... Are of a spool type, and have a group of cylinder holes 18, 18 ...
0, 41 are slidably fitted into valve holes 45, 45 ... Radially drilled in the second valve disc 15. And further the second valve board 15
The 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 4.
5 and the cylinder hole 1 of the motor cylinder 17 adjacent thereto
A third port c communicating with 8 is bored. When the distribution valve 44 occupies the position radially outward of the valve hole 45, the corresponding third port c communicates with the first port a and the corresponding second port b does not communicate with each other, so that the corresponding cylinder hole is formed. 19 is communicated with the high pressure oil passage 40. When the valve hole 45 is located radially inward, the corresponding third port c is moved to the second position.
It communicates with port b and disconnects with the first port a,
The corresponding cylinder hole 19 communicates with the low pressure oil passage 41.

As shown in FIGS. 1 and 3, in order to control the operation of the distribution valves 44, 44 ... To the outer position, the distribution valves 44, 44.
... The eccentric wheels 47 are arranged so as to surround the group, and the outer end of each distribution valve 44 is engaged with the inner peripheral surface of the eccentric wheel 47.
The discharge pressure of the replenishment pump 67 is constantly applied to the inner end surface of each distribution valve 44 through a first oil supply hole 72 described later during operation.

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, is a constant distance from the center of the motor cylinder 17 in the direction of the tilt axis O of the motor swash plate 20. ε Installed at an eccentric position. Therefore, when the motor cylinder 17 rotates,
Each distribution valve 44 reciprocates between the outer position and the inner position with a stroke that is twice the eccentric amount ε of the eccentric ring 47 in the valve hole 45.

At both ends of the swash plate holder 22, a pair of trunnion shaft supports 80, 80 'aligned on the tilt axis O of the motor swash plate 20 are bored at one end, and these trunnion shafts 80, 80' have a needle bearing 81. It is rotatably supported by the swash plate anchor 23 through the above. 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. When the trunnion shaft 80 is rotated by the operating lever 82, the swash plate holder 22 integrated with the trunnion shaft 80 is also rotated, and the swash plate holder 20 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 cylinder 17 via a needle bearing 78, and is prevented from rotating around the output shaft 25 by a pair of positioning pins 4.
It is connected to the crankcase 4 via 9, 49.

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 the suction stroke and the discharge stroke 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 supplied 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 and the reaction torque that the motor cylinder 17 receives from the motor swash plate 20 via the motor plunger 19 in the expansion stroke. Depending on the sum, the pump cylinder 7 and the motor cylinder 1
7 is rotated, and its rotational torque is transmitted from the output shaft 25 to the secondary reduction gear 3.

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 from zero to a certain value, the gear ratio can be changed from 1 to a certain required value.

By the way, the capacity of the hydraulic motor M depends on the motor plunger 19
Since it is determined by the stroke, the gear ratio can be continuously controlled from 1 to a certain value by tilting the motor swash plate 20 from the upright position to a certain tilt position.

During such operation of the hydraulic pump P and the hydraulic motor M, the pump swash plate 10 applies thrust loads in the opposite directions from the pump plan snake 9, 9, ... 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 received by the motor swash plate 20. The load is the same as the output shaft 25 via the thrust roller bearing 21, the swash plate holder 22, the swash plate anchor 23, the thrust roller bearing 32, the support cylinder 33, the sprout 3 a and the nut 34.
Supported by. Therefore, the thrust load only causes tensile stress in the output shaft 25, and does not act on the crankcase 4 supporting the shaft 25 at all.

Referring again to FIG. 1, the second valve disc 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
The low-pressure oil passage 41 penetrates through the high-pressure oil passage 40, and the second valve disc 15
Is slidably fitted in a radial valve hole 51 opening to the outer periphery of the. The clutch valve 50 has a vertical hole 52 that opens to the inner end surface thereof,
A lateral hole 53 is formed so as to intersect with the vertical hole 52 and open to the outer peripheral surface of the clutch valve 50. When the clutch valve 50 occupies a radially inner position (clutch-on position) of the valve hole 81, a lateral hole 53 is formed. The hole 53 is closed by the inner wall of the valve hole 51, and the lateral hole 53 is opened to the high pressure oil passage 40 when occupying the radially outer position (clutch off position).

The clutch valve 50 receives the oil pressure of the low-pressure oil passage 40 at its inner end so as to be biased toward 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 that defines clutch-off of the clutch valve 50. A spring 55 biases the 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. The shift fork 57 has a base end portion which is axially supported by the crankcase 4.
At the same time, the intermediate portion is engaged with the side surface of the flange portion 54c of the clutch control ring 54, and the tip portion is connected to the intermediate lever 58 via the bush rod 61.

By pulling the clutch wire 59, the clutch control ring 54 is moved to the spring 5 via the shift fork 57.
If the taper surface 54b of the clutch control ring 54 is opposed to the clutch valve 50 if the clutch control ring 54 is moved to the right in FIG. It is moved to the clutch-off position. As a result, the high-pressure 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 in the high-pressure oil passage 40 decreases and the pressure oil is fed to the hydraulic motor M. Can be disabled, and the hydraulic motor M can be deactivated.

Further, when the clutch control ring 54 is moved to the left by the elastic 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. The low pressure oil passages 40 and 41 are cut off, and the hydraulic oil P is circulated between the hydraulic pump P and the hydraulic motor M through the oil passages 40 and 41.
The hydraulic motor M can be returned to the operating state. In this case, 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, so that the spring 55 that moves the clutch control ring 54 to the left is elastic. 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 and left moving positions of the clutch control ring 54, the opening of the lateral hole 53 of the clutch valve 50 is appropriately reduced (see FIG. 1B), and the hydraulic pump P is opened in accordance with the opening.
Since hydraulic oil is circulated between the hydraulic motor M and
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.

Again in FIGS. 1 and 2, the output shaft 25 is provided with an oil passage 63 having a deep stop at the center thereof.
An oil supply pipe 64 supported by the side wall of the crankcase 4 is inserted into the open end of the oil passage 63. This refueling pipe 64
Is an oil passage 63 formed in the side wall of the crankcase 4,
It communicates with the inside of the oil pan 69 at the bottom of the crankcase 4 via a filter 66, a replenishment pump 67 and a strainer 68 mounted on the same side wall, and the replenishment pump 67 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.

In the output shaft 25, one or a plurality of first oil supply holes 72 extending in the radial direction from the oil passage 63 toward the valve hole 45 of the distribution valve 44, and the first oil supply holes 72 are provided in the valve holes 45, 45 ... An annular groove 73 communicating with the group is provided, and the distribution valve 44 has a valve hole 4
At the outer position of 5, the second pump b connected to the low-pressure oil passage 41 communicates with the first oil supply hole 72 via the corresponding valve hole 45. Therefore, if hydraulic oil leaks from the hydraulic closed circuit between the hydraulic pump P and the hydraulic motor M,
When the distribution valve 44 reaches the position outside the valve hole 45, hydraulic oil is replenished from the first oil supply hole 72 to the low pressure oil passage 45.

The output shaft 25 further has a second oil supply hole 74 that extends in the radial direction from the oil passage 63 and opens inside the cup-shaped input member 5.
And a third oil supply hole 75 that also extends in the radial direction from the oil passage 63 and opens inside the cup-shaped swash plate anchor 23. The oil supply holes 74 and 75 have orifices 76 and 7 respectively.
7 are provided respectively. These orifices 76, 77
Thus, the discharge pressure of the replenishment pump 67 is held in the oil passage 63 to surely replenish the working oil from the first oil supply hole 72 to the low pressure oil passage 41, while the input member 5 and the swash plate anchor 23 are fed from the oil passage 63. An appropriate amount of lubricating oil can be supplied inside.

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. The oil is aligned body 37,
The motor swash plate 20, the motor plunger 19, ..., The thrust bearing 21 and the like are lubricated. 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, the motor cylinder 1 is connected to the open end of the swash plate anchor 23 through the needle bearing 78.
Since 7 is fitted, a large amount of lubricating oil is retained also in the swash plate anchor 23.

Further, in order to further lubricate 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 are inclined. In order to further lubricate the inside of the plate anchor 23, the motor plunger 19 is provided with a thin oil hole 113 that communicates the inside and outside thereof.

2, FIG. 4 and FIG. 5, the motor swash plate 2 is shown.
A shift control device 83 is connected to the operating lever 82 of the trunnion shaft 80 for the tilting operation of 0.

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

In FIG. 4, the left movement of the actuating lever 82, and thus the piston 85, causes the motor swash plate 20 to stand upright, and the first oil chamber 88 is formed between the piston 85 and the left end wall of the cylinder 84. Piston 85 and cylinder 84
A second oil chamber 89 is defined between the second oil chamber 89 and the right end wall of the first oil chamber, and a return spring 90 that biases the piston 85 toward the second oil chamber 89 is contracted in the first oil chamber 88.

The first and second oil chambers 88 and 89 are provided with a switching valve device 91 on the way.
Are communicated with each other through a hydraulic conduit 92, and the inside thereof is filled with hydraulic oil.

The switching valve device 91 is installed at a proper position of a vehicle control device and intervenes in the middle of the hydraulic conduit 92, and the first and the first serially installed oil passages 94 in the valve box 93. 2 check valves 95 and 96. These first and second
The check valves 95 and 96 are arranged so that their forward directions are opposite to each other, and are always biased 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. Also, these first and first valve opening rods 100,
101 is connected to the lower surface of the left and right ends of a seesaw-type speed change lever 102, which is pivotally supported by a valve box 93. In the above, the first and second valve opening rods 100, 1
01 and the shift lever 102 constitute the valve opening means of the present invention.

The gear shift lever 102 is operated by the operator into a horizontal hold position A, a deceleration position B that swings to the left, and an acceleration position C that swings to the right. At the hold position A, both check valves 95 and 96 are kept closed, and at the deceleration position B, the first check valve 95 is pushed down to forcibly open the first check valve 95, and at the speed increasing position C. The second check valve 9 is pushed by pushing down the second valve opening rod 101.
6 can be forcibly opened.

Thus, the hold position A is the neutral switching position of the present invention,
The deceleration position B corresponds to the first switching position of the present invention, and the shift position C corresponds to the second switching position of the present invention.

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 on the one side and on the other side at the boundary, and a vibrational tilting torque acts on the motor swash plate 20. Then, this oscillating tilting torque acts on the piston 85 via the actuating lever 82 alternately in the left-right direction as a pressing force.

Therefore, when the speed change lever 102 is shifted to the speed increasing position C, the second check valve 96 is opened, so that the first check valve 95 moves from the first oil chamber 88 to the second oil chamber 89. Oil flow is allowed, but flow in the opposite direction is blocked, and oil is transferred from the first oil chamber 88 to the second oil chamber 89 only when a leftward pressing force acts on the piston 85 from the operating lever 82. Flowing. 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 first check valve 95 is opened this time, so that the second check valve 96 causes the second oil chamber 89 to the first oil chamber 88. The oil flow to the first oil chamber 88 is allowed to flow from the second oil chamber 89 to the first oil chamber 88 only when the rightward pressing force of the piston 85 is applied from the operating lever 82 while the flow in the opposite direction is blocked. Flows. As a result, the piston 85 moves to the second oil chamber 89 side, and the actuating lever 82 is rotated in the inclination direction of the motor swash plate 20.

When the speed change lever 102 is returned to the hold position A, the check valves 95 and 96 which are closed are cooperated to completely prevent the oil flow in the valve box 93, so that the piston 85 cannot move. Then, hold the operating lever 82 at that position,
The motor swash plate 20 can be fixed in an upright position or an inclined position.

In addition, when the transmission T is stopped, the shift lever 102
Is shifted to the deceleration position B and the first check valve 95 is opened, the oil can flow from the second oil chamber 89 to the first oil chamber 88, so that the piston 85 is in the left movement position. But. The elastic force of the return spring 90 moves to the right limit, and the operating lever 82 can be rotated to the maximum tilt position of the motor swash plate 20.

In this case, the pivot 103 of the speed change lever 102 is configured to be movable up and down, and the speed change lever 102 causes the double check valves 95,
If 96 is forcibly opened at the same time, the resistance of the oil passage 94 can be minimized, and the rightward movement of the piston 85 by the return spring 90 can be performed more smoothly.

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 presses the piston 85, it is possible to prevent the reaction force thereof from acting on the swash plate anchor 23 via the trunnion shaft 80 in the axial direction of the output shaft 25.

In FIG. 4, a reserve tank 109 is installed above the cylinder 84, and a relief port 110 and a supply port 111 that connect the reserve tank 109 to the inside of the cylinder 84 are formed in the upper wall of the cylinder 84.

The outer periphery of the left end portion and the right end portion of the piston 85 has a first one-way sealing function that is in close contact with the inner peripheral surface of the cylinder 84.
Also, the second cup seals 105 and 106 are mounted, and the O-ring 10 that is in contact with the outer peripheral surface of the intermediate portion of the piston 85 on the left and right sides of the window 86 is attached to the inner periphery of the cylinder 84.
7, 108 are attached.

Thus, the relief port 110 is opened 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 is always connected to the second cup seal 106 and the O-ring. It is adapted to open to the inner surface of the cylinder 84 between the first and second cylinders 108.

Therefore, when the piston 85 is located in the right limit, if the pressure rises in the first oil chamber 88 due to the rise of the oil temperature or the like,
The pressure is from the relief port 110 to the reserve tank 1
It is released to 09. Further, when the piston 85 operates, the first oil chamber 88 is pressurized by the piston 85 from when the first cup seal 105 passes through the opening of the relief port 110, and the first oil chamber 88 moves to the second oil chamber 89. Allows oil flow. At this time, if the second hydraulic chamber 89 is depressurized to a predetermined pressure or less, the inside of the reserve tank 109 and the second oil chamber 89
Due to the pressure difference between the two, the oil in the reserve tank 109 passes through the sliding gap between the cylinder 84 and the piston 85 from the supply port 111, and the second cup seal 106 is moved to the second oil chamber 8.
It is supplied to the chamber 89 while being bent to the 9 side.

If the inside of the reserve tank 109 is kept at a high pressure, the hydraulic conduit 92 is pretensioned by the hydraulic pressure, so that the rigidity of the hydraulic conduit 92 against the change in the hydraulic pressure due to the operation of the piston 85 is strengthened, and the piston 85 The operation of can be stabilized.

C. EFFECTS OF THE INVENTION As described above, according to the present invention, the first check valve is forcibly opened and the second check valve is free and effective in the state where the valve opening means is switched to the first switching position. Since the second check valve can shut off the oil passage in the valve box in only one direction, the second reverse valve can be operated in a state where the valve opening means is switched to the second switching position. The stop valve is forcibly opened and the first
Since the check valve can be freely functioned effectively, the oil passage in the valve box can be blocked only in the other direction by the first check valve, and the valve opening means is switched to the neutral switching position. In this state, both check valves can be freely set to function effectively, so that the oil passages in the valve box can be blocked in both directions by the cooperation of the two check valves. By simply switching the valve opening means to the above three positions, it is possible to easily select three types of shutoff modes for the oil passage, one direction, the other direction, and both directions, thereby expanding the range of use as a switching valve. In addition, since a valve mechanism other than the check valve having an excellent closing function is not provided, a reliable closed state can be obtained in any of the three types of shutoff modes described above. Moreover, the valve opening means forcibly opens the individual check valves themselves and does not directly act on the valve springs of the check valves, so that the respective check valves are forcibly opened. It is possible to clearly switch between the state and the state in which the valve is opened and held in the closed state, and the three types of shutoff modes described above can be reliably obtained.

[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 mounted in a power transmission system of a motorcycle, and FIG. 1A is a pump cylinder in FIG. , A longitudinal sectional view of the assembly of the motor cylinder, the first and second valve discs and the output shaft,
FIG. 1B is an operation diagram of the clutch valve in FIG. 1, FIG. 2 is a partially longitudinal rear view of the continuously variable transmission, and FIG. 3 is III of FIG.
-III line sectional view, FIG. 4 is a IV-IV line sectional view of FIG. 2, and FIG. 5 is a plan view of a continuously variable transmission. 91 ... Switching valve device, 93 ..., Oil valve box, 94 ... Oil passage, 95
... first check valve, 96 ... second check valve, 97 ... valve spring, 98
... Valve springs, 100, 101 and 102 ... First and second valve rods and shift levers that constitute valve opening means

Claims (1)

[Claims] 1. A first and a second check valve (95, 96) are installed in series in an oil passage (94) provided in a valve box (93) with their forward directions being opposite to each other, and these check valves are provided. The valves (95, 96) are biased in the closing direction by springs (97, 98), and the first check valve (95) is forcibly opened and the second check valve is opened in the valve box (93). First switching position (B) for freeing (96)
Which of the two check valves (95, 96) and the second switching position (C) forcibly opening the second check valve (96) and freeing the first check valve (95). Valve opening means (10) that can be selectively switched between the neutral switching position (A) and the neutral switching position (A).
0-102) are provided, The switching valve apparatus characterized by the above-mentioned.