JPS61274165A - Static hydraulic type continuously variable transmission - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency by installing the first valve board equipped with a discharge valve and a suction valve and the second valve board equipped with a distributing valve between a pump cylinder and a motor cylinder. CONSTITUTION:The first valve board 14 equipped with a discharge valve 42 and a suction valve 43 and the second valve board 15 equipped with a distributing valve 44 are installed in succession between the pump cylinder 7 of a hydraulic pump P and the motor cylinder 17 of a hydraulic motor M, and the pump cylinder 7, motor cylinder 17, the first valve board 14, and the second valve board 15 are connected to an output shaft 25 penetrating through the center part. Therefore, working oil can be received and delivered between the hydraulic pump P and the hydraulic motor M without relatively revolving the pump cylinder 7 and the motor cylinder 17, and the leak of working oil from the distributing valve 44 can be exceedingly reduced, and the power transmission efficiency can be improved.

Description

Detailed Description of the Invention A0 Objective of the Invention (1) Industrial Application Field The present invention forms a hydraulic closed circuit between a fixed displacement swash plate hydraulic pump and a variable displacement swash plate hydraulic motor. Concerning improvements to hydrostatic continuously variable transmissions.

(2) A hydrostatic continuously variable transmission using conventional technology is, for example, the
This is already known as described in Japanese Patent No. 467.

(3) Problems to be Solved by the Invention In conventional hydrostatic continuously variable transmissions, the pump cylinder of the hydraulic pump is rotatably and slidably pressed into contact with the distribution panel fixed to the motor cylinder of the hydraulic motor. Hydraulic oil for the hydraulic pump and the hydraulic motor is delivered and received through an oil passage penetrating the rotating sliding surface of the hydraulic pump and the hydraulic motor. For this reason, pressure oil tends to leak from between the opposing rotating sliding surfaces of the distribution panel and the pump cylinder, and such leakage causes a reduction in transmission efficiency.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydrostatic continuously variable transmission that can reliably transfer hydraulic fluid between a hydraulic pump and a hydraulic motor, has high transmission efficiency, and is easy to manufacture.

B1 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a hydraulic pump side pump between a pump cylinder of a hydraulic pump and a motor cylinder of a hydraulic motor which are arranged coaxially. interposing first and second valve discs in order from then on, connecting these two cylinders and the first and second valve discs to an output shaft passing through their centers, and positioning and fastening them to each other; The first valve board is provided with a plurality of suction valves and discharge valves corresponding to the plurality of cylinder holes of the pump cylinder, and the second valve board is provided with a plurality of suction valves and a plurality of discharge valves corresponding to the plurality of cylinder holes of the pump cylinder, and the second valve board is connected to the cylinder hole of the pump cylinder through the suction valve. A high pressure oil passage is formed which communicates with the cylinder hole of the pump cylinder via the low pressure oil passage and the discharge valve, and the low pressure and high pressure oil passages are alternately communicated with the plurality of cylinder holes of the motor cylinder as the motor cylinder rotates. It is characterized by the provision of a plurality of distribution valves that communicate with each other.

(2) Function High-pressure hydraulic oil is sent out from the cylinder hole in the discharge stroke of the hydraulic pump, opens the discharge valve, moves to the high-pressure oil passage, and then passes through the distribution valve to the cylinder hole in the expansion stroke of the hydraulic motor. will be sent to. On the other hand, the low-pressure hydraulic oil discharged from the cylinder hole during the contraction stroke of the hydraulic motor is transferred to the low-pressure oil path via another distribution valve, and then the suction valve is opened to release the hydraulic oil from the cylinder hole during the suction stroke of the hydraulic pump. is inhaled. In this way, the hydraulic fluid is repeatedly exchanged between the hydraulic pump and the hydraulic motor, thereby transmitting power from the hydraulic pump to the hydraulic motor.

a first valve board including a pump cylinder and a motor cylinder each having a plurality of cylinder holes, a suction valve and a discharge valve;
When individually machining the second valve plate equipped with high and low pressure oil passages and distribution valves, the cylinder holes and valve holes of each part can be machined through, thereby improving workability and machining accuracy.

(3) Embodiment Below, an embodiment of the present invention will be explained with reference to the drawings. In FIG. The signal is transmitted to the rear wheels (not shown) sequentially through the transmission T and the second chain reduction gear 3.

The continuously variable transmission T includes a constant displacement swash plate hydraulic pump P and a variable displacement swash plate hydraulic motor M, and has a crankcase 4 supporting a crankshaft 1 as a casing.
accommodated in it.

The hydraulic pump P is connected to the output sprocket of the primary reduction gear 2.
23, a pump cylinder 7 fitted to the inner circumferential wall of the input member 5 through a needle hair ring 6 so as to be relatively rotatable; Pump plungers 9, 9, . The pump swash plate 10, which is composed of a pump swash plate 10 abutting the end thereof, is rotatable via a thrust roller bearing 11 on the inner end wall of the input member 5 in a posture inclined at a certain angle with respect to the axis of the pump cylinder 7. The back is supported by
When the input member 5 rotates, the pump plungers 9, 9, . . . are given reciprocating motion to repeat the suction and discharge strokes.

Incidentally, in order to improve the followability of the pump plunger 9 with respect to the pump swash plate 10, a spring that biases the pump plunger 9 in the expansion direction may be compressed in the cylinder hole 8.

The input member 5 has a thrust roller bearing 1 on its back side.
It is supported by the support cylinder 13 via 2.

On the other hand, the hydraulic motor M includes a motor cylinder 17 disposed coaxially with the pump cylinder 7 and to the left thereof, and a plurality of odd number of cylinder holes arranged in an annular arrangement surrounding the rotation center of the motor cylinder 17. 18. Motor plungers 19, 19... are slid together with 18, 18..., respectively.
, a motor swash plate 20 that comes into contact with the outer ends of these motor plungers 19, 19..., a swash plate holder 22 that supports the back surface of this motor swash plate 20 via a thrust roller bearing 21, and further this swash plate. It is comprised of a cup-shaped swash plate anchor 23 that supports the holder 22.

The motor swash plate 20 can be tilted between an upright position perpendicular to the axis of the motor cylinder 17 and an inclined position inclined at an angle. Accompanying motor plunger 19.
19... can be given reciprocating motion to repeat the expansion and contraction strokes.

Incidentally, 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 compressed in the cylinder hole 18.

First and second valve discs 14.15 are interposed between the pump cylinder 7 and the motor cylinder 17 in order from the pump cylinder 7 side, and the output shaft 25 is located at the center of these four parts 7.14° 15.17. penetrate. By abutting the outer end of the motor cylinder 17 against a flange 25a integrally formed on the outer periphery of the output shaft 25, and tightening the outer end of the pump cylinder 7 with a nut 26 screwed onto the output shaft 25, the above four 7.degree. 14.15.17 are polymerized and bonded to each other and fixed to the output shaft 25.

At that time, as shown in Figure 1A, the above four parties 7°14.1
5.17 with the output shaft 25 and to define their mutual position, a key 16° 16 is fitted between each cylinder 7.17 and the output shaft 25, and the pump cylinder 7 Knock pins 24 and 24 are fitted between the first valve plate 14, the motor cylinder 17, and the second valve plate 15, respectively.

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

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

Further, the output shaft 25 is connected to the motor swash plate 20 and the swash plate holder 22.
and a thrust roller bearing 3 that passes through the center of the swash plate anchor 23, and a thrust roller bearing 3 that connects the back surface of the swash plate anchor 23 to the left end thereof.
A support cylinder 33 supported via 2 is spline fitted,
The output shaft 25 is fixed together with the input sprocket 3a of the secondary reduction gear 3 by a nut 34, and the left end portion of the output shaft 25 is rotatably supported by the crankcase 4 via the support cylinder 33 and roller bearing 35.

A hemispherical centering body 36 that engages with the inner circumferential surface of the pump swash plate 10 so as to be tiltable in all directions is slidably and spline fitted to the output shaft 25 . This centering body 36 presses the pump swash plate 10 against the thrust roller bearing 11 by the force of the plurality of disc springs 38, and thereby the pump swash plate 10 is pressed against the thrust roller bearing 11.
0 is always given an alignment effect.

Further, a hemispherical centering body 37 that engages with the inner circumferential surface of the motor swash plate 20 so as to be tiltable in all directions is slidably fitted onto the output shaft 25 by a spline. This centering body 37 presses the motor swash plate 20 against the thrust roller bearing 21 by the force of the plurality of disc springs 39, thereby constantly applying an alignment action to the motor swash plate 20.

The alignment action of each swash plate 10, 20 is strengthened, and the rotation direction between the pump swash plate 10 and the pump plungers 9, 9, . To prevent slippage, each swashplate 10.20 is provided with a spherical end 9a, 19a of the corresponding plunger 9.19.
Spherical recesses 10a and 20a are respectively formed to engage the spherical recesses 10a and 20a. At this time, the spherical recesses 10a, 20a are formed on the swash plate 10.
In any rotational position of 20, the spherical ends 9a, 1
The radius of curvature is set larger than that of the spherical ends 9a, 19a to ensure proper engagement with the spherical ends 9a.

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

The second valve plate 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.
Suction valves 43, 43... that allow hydraulic oil to flow in one direction from the pump cylinder 7 to the cylinder holes 8.8...
, and a discharge valve 42 that allows hydraulic oil to flow in one direction from the cylinders 8, 8, . . . of the pump cylinder 7 to the high-pressure oil passage 40 is provided on the first valve plate 14. Therefore, the number of suction valves 43 and discharge valves 42 is the same as that of pump plunger 9.
, 9, and so on.

In addition, the second valve board 15 includes high pressure and low pressure oil passages 40 and 41.
cylinder holes 18, 18 and 18 of the motor cylinder 17 alternately.
Distribution valves 44, 44, . . . are provided for communication control. Therefore, the number of distribution valves 44 is the same as the number of motor plungers 19, 19, . . . .

The distribution valves 44, 44... are spool type, and are radially bored in the second valve plate 15 between the cylinder holes 18, 18... of the motor cylinder 17 and the high and low pressure oil passages 40, 41. It slides into the provided valve holes 45, 45.... Further, the second valve plate 15 includes each valve hole 45 and high pressure and low pressure oil passages 40,
41 and the first and second bows) a, b
, as well as each valve hole 45 and the motor cylinder 1 adjacent thereto.
A third boat C communicating with the cylinder hole 18 of No. 7 is bored.

Thus, when the distribution valve 44 occupies a position radially outward of the valve hole 45, the corresponding third port c is communicated with the first port a and disconnected from the second port b, and the corresponding third port c is communicated with the first port b. The hole 19 is communicated with a high pressure oil passage 40. Furthermore, when the valve hole 45 occupies the radially inner position, the corresponding third port c is communicated with the second boat b and disconnected from the first boat a, and the corresponding cylinder hole 19 is connected to the low pressure oil passage 41. Communicate.

As shown in FIGS. 1 and 3, distribution valves 44, 44...
In order to control the operation to the outer position, the distribution valve 44.4
4... An eccentric ring 47 is disposed surrounding the group, and an inner end surface of each distribution valve 44 is provided 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 constantly applied during operation through a first oil supply hole 72, which will be described later.

The eccentric ring 47 is composed of the inner ring of a pole bearing 48 that is fitted into the crankcase 4, and as shown in FIG. It is installed at a position offset by a distance ε. Therefore, when the motor cylinder 17 rotates, each distribution valve 44 reciprocates between the outer position and the inner position within its valve hole 45 using the eccentricity ε of the eccentric ring 47 as a stroke.

A pair of trunnion shafts 80.80' aligned on the tilting axis ○ of the motor swash plate 20 are integrally bored at both ends of the swash plate holder 22, and these trunnion shafts 80.80' and is rotatably supported by the swash plate anchor 23. In other words, these trunnion shafts 80, 80' define the tilting axis 0.

An actuation lever 82 is fixed to the outer end of one trunnion shaft 80. When the trunnion shaft 80 is rotated using the operating lever 82, the swash plate holder 22 integrated therewith also rotates, and the swash plate holder 22 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 supported by a pair of positioning pins 49 so as not to rotate around the output shaft 25.
．． It is connected to the crankcase 4 via 49.

In the above configuration, when the input member 5 of the hydraulic pump P is rotated from the primary speed reduction 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 hydraulic oil from the low-pressure oil passage 41 when performing a suction stroke, and supplies high-pressure hydraulic oil to the high-pressure oil passage 40 when performing a discharge stroke.

The high-pressure hydraulic oil sent to the high-pressure oil passage 40 is fed to the cylinder hole 18 that accommodates the motor plunger 19 on the expansion stroke via the distribution valve 44 located on the outside, while the hydraulic oil is fed to the cylinder hole 18 that accommodates the motor plunger 19 on the contraction stroke. The hydraulic oil contained in the cylinder hole 18 is discharged to the low pressure oil passage 41 via the distribution valve 44 located inward.

During this period, the pump cylinder 7 receives reaction torque from the pump swash plate 10 via the pump plunger 9 in the discharge stroke, and the motor cylinder 17 receives reaction torque from the motor plunger 1 in the expansion stroke.
9 and the reaction torque received from the motor swash plate 20, the pump cylinder 7 and the motor cylinder 17
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, by changing the capacity of the hydraulic motor M to a value of zero, the gear ratio can be changed to a required value of one.

By the way, the capacity of the hydraulic motor M is the motor plunger 19.
Therefore, by tilting the motor swash plate 20 from an upright position to an inclined position, the gear ratio can be controlled steplessly up to a value of 1.

During such operation of the hydraulic pump P and the hydraulic motor M, the pump swash plate 10 moves from the pump plungers 9, 9...
Also, the motor swash plate 20 has motor plungers 19, 19...
・Each group receives a thrust load in the opposite direction,
The thrust load that the pump swash plate 10 receives is transferred to the output shaft 25 via the thrust roller bearing 11, the input member 5, the thrust roller bearing 12, the support tube 13, and the nuff 30.
The thrust load received by the motor swash plate 20 is also applied to the output shaft 25 via the thrust roller bearing 21, swash plate holder 22, swash plate anchor 23, thrust roller bearing 32, support cylinder 33, sprocket 3a, and napht 34. supported by. Therefore, the thrust load merely causes tensile stress on 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 plate 15 is further provided with one or more clutch valves 50 that can communicate between the high and low pressure oil passages 40 and 41 in a timely manner. This clutch valve 50 passes through the high pressure oil passage 40 from the low pressure oil passage 41 to the second valve plate 1.
The valve hole 51 in the radial direction opens on the outer periphery of the valve hole 5.

The clutch valve 50 has a vertical hole 52 that opens on its inner end surface, and a horizontal hole 53 that intersects with the vertical hole 52 and opens on the outer peripheral surface of the clutch valve 50. The horizontal hole 53 is closed by the inner wall of the valve hole 51 when the hole 81 is in the radially inner position (clutch-on position), and the horizontal hole 53 is closed by the inner wall of the valve hole 51 when the hole 81 is in the radially outer position (clutch-off position). It is designed to open at 40.

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

The clutch control ring 54 has a cylindrical inner circumferential surface 54a that defines a clutch-on position of the clutch valve 50, and a tapered surface 54b that extends to one end of the inner circumferential surface and defines a clutch-off position of the clutch valve 50. A spring 55 urges the clutch valve 50 to be held in the clutch-on position. This spring 55 is compressed between the clutch control ring 54 and a retainer 56 that is secured to the outer periphery of the pump cylinder 7 .

As shown in FIG. 2, the clutch control ring 54 is connected to a thalassoti lever (not shown) via a shift fork 57, an intermediate lever 58, and a talatch wire 59. The shift fork 57 has a base end supported by a shaft 60 on 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 wire 54, and the tip portion is connected to the intermediate lever 58 via the bush rod 61.

By pulling the clutch wire 59, if the clutch control wire 54 is moved to the right in FIG. 1 through the shift fork 57 against the force of the spring 55, the tapered surface 54b of the clutch control ring 54 Since the clutch valve 50 faces the clutch valve 50, the clutch valve 50 is moved to an outward position, that is, a clutch off position, by the pressure of the low pressure oil passage 40. As a result, the high pressure oil passage 40 is connected to the vertical hole 52 and the horizontal hole 5 of the clutch valve 50.
3, the high pressure oil path 40 is short-circuited to the low pressure oil path 41 via
The pressure decreases, making it impossible to supply pressure oil to the hydraulic motor M, and rendering the hydraulic motor M inoperative.

Furthermore, if the clutch control ring 54 is moved to the left by the elastic force of the spring 55 and the clutch valve 50 is operated to the clutch-on position, the horizontal hole 53 of the clutch valve 50 is closed by the inner wall of the valve hole 51, so that high pressure and the low pressure oil passages 40 and 41 are cut off,
The hydraulic oil is circulated as described above between the hydraulic pump P and the hydraulic motor M through these oil passages 40, 41, and the hydraulic motor M can be returned to the operating state. In this case, the actuation 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 generated force can be set relatively weak, and the operating force of the clutch control ring 54 can be reduced.

At an intermediate position between the rightward movement position and the leftward movement position of the clutch control ring 54, the opening degree of the horizontal hole 53 of the clutch valve 50 is moderately narrowed (see FIG. 1B), and the hydraulic pump P is adjusted according to the opening degree.
Since the hydraulic oil is circulated between the hydraulic motor M and the hydraulic motor M,
The hydraulic motor M can be in a half-clutched state. In this case, as the clutch valve 50 moves, the opening degree of the horizontal hole 53 gradually increases or decreases, so that a half-clutch state can be easily obtained and smooth overdrive can be performed.

Again, in FIGS. 1 and 2, the output shaft 25 is provided with an oil passage 63 with a dead end at its center,
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. The oil supply pipe 64 communicates with the inside of the 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 attached to the side wall, a replenishment pump 67, and a strainer 68. , the replenishment pump 69 is connected to the input member 5
is driven from through gears 70 and 71.

Therefore, 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 includes 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 the first oil supply hole 72 is connected to the valve holes 45 , 45 .・
- An annular groove 73 communicating with the group is provided, and when the distribution valve 44 is located outside the valve hole 45, the second port b connected to the low pressure oil passage 41 is connected to the first oil supply via the corresponding valve hole 45. Hole 72
It is designed to communicate with Therefore, if hydraulic oil leaks from the hydraulic closed circuit between the hydraulic pump P and the hydraulic motor M, the hydraulic oil flows from the first oil supply hole 72 to the low-pressure oil passage 41 when the distribution valve 44 is positioned outside the valve hole 45. will be replenished.

The output shaft 25 further includes a second oil supply hole 74 that extends in the radial direction from the oil passage 63 and opens into the inside of the cup-shaped input member 5, and a cup-shaped swash plate anchor that also extends in the radial direction from the oil passage 63. A third oil supply hole 75 that opens into the inside of the oil supply hole 74.75 is provided with an orifice 76.77.
are provided respectively. These orifices 76 and 77 maintain the discharge pressure of the supply pump 67 in the oil passage 63 and reliably replenish the hydraulic oil from the first oil supply hole 72 to the low pressure oil passage 41. and swash plate anchor 2
3. An appropriate amount of lubricating oil can be supplied inside.

The oil supplied inside the input member 5 lubricates the centering body 36, pump swash plate lO, pump plunger 9..., thrust roller bearing 11, needle bearing 6, etc.
In addition, the oil supplied inside the swash plate anchor 22 is
7. Lubricate the motor swash plate 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 within the input member 5. On the other hand, the swash plate anchor 23
Since the motor cylinder 17 is fitted into the open end of the swash plate anchor 23 via a needle bearing 78, a large amount of lubricating oil is also retained within the swash plate anchor 23.

In addition, 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 that communicates the inside and outside of the pump plunger 9 is bored. In order to further lubricate the inside of the plate anchor 23, a thin oil hole 113 is formed in the motor plunger 19 to communicate the inside and outside of the motor plunger 19.

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

The speed change control device 83 includes a cylinder 84 fixed to the crankcase 4 and a piston 85 slidably engaged with the cylinder 84. A window 86 is formed in the side wall of the cylinder 84, and a connection hole 87 is formed in the center of the piston 85, passing through it laterally and facing the window 86. is engaged with the connecting hole 87 through the window 86, so that the piston 85 can be slid in accordance with the rotation of the trunnion shaft 8o.

In FIG. 4, leftward movement of actuating lever 82 and thus piston 85 brings motor swash plate 20 into an upright position, and between piston 85 and the left end wall of cylinder 84 there is also a first oil chamber 88. Piston 85 and cylinder 84
A second oil chamber 89 is defined between the right end wall of the first oil chamber 88 and a return spring 90 that urges the piston 85 toward the second oil chamber 89.

The first and second oil chambers 88 and 89 are provided with a speed change control valve 91 in the middle.
They communicate with each other via a hydraulic conduit 92 interposed therebetween, and their interiors are filled with hydraulic oil.

The speed change control valve 91 has a valve face 93 installed at a suitable location in a vehicle's operating system and intervening in the middle of a hydraulic conduit 92, and a first and second valve face 93 interposed in series in an oil passage 94 within this valve face 93. It is composed of two 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 urged in the valve closing direction by valve springs 97 and 98, respectively.

The first and second check valves 95 and 96 are connected to first and second valve opening rods 100 and 101, respectively, which can be pushed in the valve opening direction. In addition, these first and second valve opening rods 100
, 101 are respectively connected to the lower surfaces of both left and right ends of a seesaw type shift lever 102 which is pivotably supported 103 on a valve surface 93.

The speed change lever 102 is operated by the driver to a horizontal hold position A, a deceleration position B that swings to the left, and a speed increase 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 valve opening rod 100 is pushed down to forcibly open the first check valve 95.
At the speed increase position C, the second valve opening rod 101 can be pushed down to forcibly open the second check valve 96.

By the way, since the number of motor plungers 19, 19... is odd, during the rotation of the motor cylinder 17,
Motor plunger 19.19... group is motor swash plate 20
The thrust load exerted on the tilting axis O of the motor swash plate 20 is
The strength changes alternately between one side and the other side, and a vibratory tilting torque acts on the motor swash plate 20. This vibratory tilting torque acts as a pressing force on the piston 85 alternately in the left and right directions via the actuating lever 82.

Therefore, if the shift lever 102 is shifted to the speed increase position C, the first check valve 95 is opened, and the second check valve 96 allows the flow from the first oil chamber 88 to the second oil chamber 89. The flow of oil is allowed, but the flow in the opposite direction is blocked,
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 the operating lever 82.

As a result, the piston 85 moves toward the first oil chamber 88 and rotates the operating lever 82 in the direction in which the motor swash plate 20 is raised.

Next, when the shift lever 102 is shifted to the deceleration position B, the second check valve 96 is opened, so the first check valve 95 moves the second oil chamber 89 to the first oil chamber 88. The flow of oil is allowed, but the flow in the opposite direction is blocked, and oil flows from the second oil chamber 89 to the first oil chamber 88 only when a rightward pressing force is applied to the piston 85 from the actuating lever 82. flows. As a result, the piston 85 moves toward the second oil chamber 89 and rotates the operating lever 82 in the direction of inclination of the motor swash plate 20.

When the shift lever 102 is returned to the hold position A, the check valves 95 and 96, which are closed, work together to completely block the flow of oil within the valve surface 93, making the piston 85 immobile. and hold the operating lever 82 in that position,
Motor swashplate 20 can be fixed in an upright or tilted position.

Furthermore, when the transmission T is in a stopped state, the gear shift lever 102
If the piston 85 is shifted to the deceleration position B and the first check valve 95 is opened, 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. Even if the motor swash plate 20 is moved to its rightward limit by the elastic force of the return spring 90, the operating 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 or near a right angle to the axis of the output shaft 25. As shown in FIG. In this way, when the actuating lever 82 presses the piston 85, the reaction force can be prevented 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 at the top of the cylinder 84, and a relief boat 110 and a supply boat 111 are bored in the earthen wall of the cylinder 84 to communicate the reserve tank 109 into the cylinder 84.

On the outer periphery of the left and right ends of the piston 85, there are first grooves having a one-way sealing function that closely contact the inner circumferential surface of the cylinder 84.
and second cup seals 105 and 106 are attached to the inner periphery of the cylinder 84, and an O-ring 10 that is in close contact with the outer circumferential surface of the intermediate portion of the piston 85 on both the left and right sides of the window 86.
7,108 is installed.

Thus, when the piston 85 is at the right limit of movement, the relief boat 110 opens into the first hydraulic chamber 88 immediately before the first cup seal 105, and the supply boat 111 always opens into the first hydraulic chamber 88 just before the first cup seal 105. It opens to the inner surface of the cylinder 84 between.

Therefore, when the piston 85 is located at the right movement limit, if a pressure increase occurs in the first oil chamber 88 due to an increase in oil temperature, etc.
The pressure is transferred from the relief boat 110 to the reserve tank 1.
Released to 09. Furthermore, when the piston 85 moves to the left, the first oil chamber 88 is pressurized by the piston 85 from the moment the first cup seal 105 passes through the opening of the relief boat 110, and the flow from the first oil chamber 88 to the second oil chamber 89 is increased. Allow oil to flow. At that time, if the pressure in the second hydraulic chamber 89 is reduced to a predetermined pressure or less, the inside of the reserve tank 109 and the second hydraulic chamber 89 are
Due to the pressure difference between
The liquid passes through the sliding gap and is supplied to the liquid chamber 89 while bending the second cam seal 106 toward the second oil chamber 89.

Note that if the reserve tank 109 is maintained at a high pressure state, the hydraulic conduit 92 is pretensioned by hydraulic pressure, so that the rigidity of the hydraulic conduit 92 against changes in hydraulic pressure accompanying the operation of the piston 25 is strengthened, and the piston 85 operation can be stabilized.

C0 Effects of the Invention As described above, according to the present invention, the first and second valve discs are interposed in order from the hydraulic pump side between the pump cylinder of the hydraulic pump and the motor cylinder of the hydraulic motor, which are arranged coaxially. , these two cylinders and the first and second valve discs are connected to an output shaft passing through their centers, and are positioned and fastened to each other, and the first valve disc includes a plurality of cylinders of the pump cylinder. A plurality of suction valves and a plurality of discharge valves are provided respectively corresponding to the holes, and the second valve board has a low pressure oil passage that communicates with the cylinder hole of the pump cylinder through the suction valve, and a low pressure oil passage that communicates with the cylinder hole of the pump cylinder through the discharge valve. In addition to forming a high-pressure oil passage communicating with the cylinder hole, a plurality of distribution valves were provided that alternately communicated the low-pressure and high-pressure oil passages with the plurality of cylinder holes of the motor cylinder as the motor cylinder rotated. Without relative rotation of the motor cylinder,
The hydraulic oil can be exchanged between the hydraulic pump and the hydraulic motor, and the reciprocating distribution valve has extremely little leakage of hydraulic oil, so the hydraulic oil can be reliably exchanged.
This can greatly contribute to improving transmission efficiency. Moreover, when individually machining the pump cylinder and motor cylinder each having a plurality of cylinder holes, the first valve plate having suction valves and discharge valves, and the second valve plate having high and low pressure oil passages and distribution valves, each part is The cylinder holes and valve holes can be machined through, improving workability and machining accuracy, and they can be easily assembled to the output shaft without changing their relative positions. Overall, it is extremely easy to manufacture.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a hydrostatic continuously variable transmission installed in a power transmission system of a motorcycle, and FIG. 1A is a diagram showing a pump cylinder in FIG. 1. , motor cylinder, first. A vertical sectional view of the assembly of the second valve plate and the output shaft,
FIG. 1B is an operational diagram of the clutch valve in FIG. 1, FIG. 2 is a partially longitudinal rear view of the continuously variable transmission, and FIG.
4 is a sectional view taken along the line IV--IV in FIG. 2, 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 oblique Plate, 14...first valve plate, 15...second valve plate, 16...
・Key, 17...Motor cylinder, 18...Cylinder hole, 19...Motor plunger, 20...Motor swash plate, 24...Knock pin, 40...High pressure oil path, 4
1...Low pressure oil path, 42...Discharge valve, 43...Suction valve, 44...Distribution valve, 47...Eccentric wheel patent applicant Honda Motor Co., Ltd. Figure 3 ¥5 Figure 4

Claims (1)

[Claims] In a hydrostatic continuously variable transmission in which a hydraulic closed circuit is formed between a constant displacement swash plate hydraulic pump and a variable displacement swash plate hydraulic motor, the pump cylinder and the hydraulic pump are coaxially arranged. First and second valve discs are interposed between the motor cylinders of the hydraulic motor in order from the hydraulic pump side, and an output shaft passes through the center of these two cylinders and the first and second valve discs. The first valve board is provided with a plurality of suction valves and discharge valves corresponding to the plurality of cylinder holes of the pump cylinder, and the second valve board is provided with a plurality of suction valves and a plurality of discharge valves, respectively, corresponding to the plurality of cylinder holes of the pump cylinder. A low pressure oil passage communicating with the cylinder hole of the pump cylinder via the discharge valve and a high pressure oil passage communicating with the cylinder hole of the pump cylinder via the discharge valve are formed, and the low pressure and high pressure oil passages are connected as the motor cylinder rotates. A hydrostatic continuously variable transmission characterized by providing a plurality of distribution valves that alternately communicate with a plurality of cylinder holes of a motor cylinder.