JP2709933B2 - Hydrostatic continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial Application Field The present invention relates to a pump cylinder of a swash plate type hydraulic pump and a motor cylinder of a swash plate type hydraulic motor which are integrally and coaxially connected to each other. Between the pump cylinder and the motor cylinder, an annular high-pressure oil passage communicating with a motor port located in an expansion stroke region of the hydraulic motor and an annular low-pressure oil passage communicating with a motor port located in a contraction stroke region of the hydraulic motor are concentric. A large number of distribution valves are formed radially and can reciprocate between radially outer and inner positions to alternately connect a number of pump ports of the hydraulic pump to a high-pressure oil passage and a low-pressure oil passage. An eccentric wheel circumscribing these distribution valves is connected to an input member of a hydraulic pump so that the eccentric wheel can move between a clutch-off position and a clutch-on position. In order to connect the pump port in the discharge stroke area of the hydraulic pump to the high-pressure oil path and the pump port in the suction stroke area to the low-pressure oil path, and to disengage the hydraulic pump in the clutch off position, the distribution valve The present invention relates to a hydrostatic continuously variable transmission for controlling the transmission.

(2) Prior Art The present applicant has already proposed such a hydrostatic continuously variable transmission as disclosed in JP-A-62-224769.

(3) Problems to be Solved by the Invention In the hydrostatic continuously variable transmission that has already been proposed, an external operating member is connected to the eccentric wheel via a cam mechanism, and this operating member is manually operated, whereby the eccentric wheel is operated. Since the position control is performed, the structure is complicated and the operation is troublesome.

The present invention has been made in view of such circumstances, and has as its object to provide a hydrostatic continuously variable transmission having a simple structure capable of automatically controlling the position of an eccentric wheel according to the rotation speed of an input cylinder shaft. I do.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention relates to connecting an eccentric wheel to a clutch spring which biases the eccentric wheel toward a clutch off position, and A weight capable of exerting a centrifugal force for moving the eccentric wheel toward the clutch-on position against the spring force of the clutch spring is provided.

(2) Action When the input member is rotated, the eccentric rotates with it,
A centrifugal force is generated in the weight of the eccentric ring in a direction opposite to the direction of the spring force applied to the eccentric ring by the clutch spring.

Thus, when the rotation speed of the input member is relatively low,
Since the centrifugal force cannot overcome the spring force of the clutch spring, the eccentric wheel is held in the clutch off position by the clutch spring, thereby controlling the distribution valve to short-circuit the hydraulic pump.

When the rotation speed of the input member rises above a predetermined value, the centrifugal force overcomes the spring force of the clutch spring and shifts the eccentric wheel to the clutch-on position, thereby starting hydraulic transmission from the hydraulic pump to the hydraulic motor. Control the distribution valve to achieve this.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings. First, in FIG. 1, a power unit U for a motorcycle includes an engine E and a hydrostatic continuously variable transmission T. The crankshaft 1 and the continuously variable transmission T of the engine E are housed in a common casing 4. Supported. The continuously variable transmission T has an input cylinder shaft 5 and an output shaft 15 arranged in parallel with the crankshaft 1. The crankshaft 1 drives the input cylinder shaft 5 via the primary reduction gear 2, and the output shaft 15 A rear wheel (not shown) of the motorcycle is driven via the next reduction device 3.

In FIGS. 1 and 2, the continuously variable transmission T includes a constant displacement swash plate type hydraulic pump P and a variable displacement type swash plate type hydraulic motor M.

The hydraulic pump P has an input cylinder shaft 5 as an input member, a pump cylinder 7 rotatably fitted to the inner peripheral wall of the input cylinder shaft 5 via a ball bearing 6, and an axis line of the pump cylinder 7. Pump plungers 9, 9 ... sliding in a large number and odd number of cylinder holes 8, 8 ... in an annular arrangement provided so as to surround the pump plungers 9, 9 ... A swash plate 10 and a rear surface of the swash plate 10 for holding the pump swash plate 10 at a fixed angle with respect to the axis of the pump cylinder 7 about a virtual trunnion axis O ₁ orthogonal to the axis of the pump cylinder 7. And a pump swash plate holder 12 that supports the pump swash plate via an angular contact bearing 11.
Reference numeral 12 is fitted on the inner wall of the input cylinder shaft 5. A driven gear 2b of the primary reduction gear 2 is attached to an outer end of the input cylinder shaft 5 via a torque damper.

Thus, when the input cylinder shaft 5 rotates, the pump swash plate 10 can sequentially reciprocate the pump plungers 9, 9,... To repeat the suction and discharge strokes.

On the other hand, the hydraulic motor M is provided with a motor cylinder 17 disposed coaxially to the left of the pump cylinder 7 and the cylinder holes 8, 8 arranged in an annular arrangement provided around the axis of the motor cylinder 17. Motor plungers 19, 19 sliding in the same number of cylinders 18, 18, and motor swash plate 2 having a front surface in contact with the outer ends of these motor plungers 19, 19 ...
0, a motor swash plate holder 22 for supporting the rear surface of the motor swash plate 20 via a tapered roller bearing 21, and a motor swash plate anchor for supporting the rear surface of the motor swash plate holder 22.
The motor swash plate anchor 23 is fixed to the casing 4 with bolts 27.

Each cylinder hole 18 is formed to have a larger diameter than the cylinder hole 8 so that the maximum capacity of the hydraulic motor M is increased by the hydraulic pump P
Is set to be sufficiently larger than the above capacity, and a large reduction ratio can be obtained.

The motor swash plate holder 22 is integrally provided with a pair of semi-cylindrical trunnion shaft 22a disposed on the trunnion axis O ₂ perpendicular to the axis of the motor cylinder 17, and 22b at both ends, both trunnion shaft 22a, 22b is a motor The bearing hole 23a and the bearing recess 23b formed in the swash plate anchor 23 are rotatably fitted respectively. Also, the motor swash plate holder 22 and the motor swash plate anchor 23
The opposing surfaces f ₁ and f ₂ that abut against each other are formed in a spherical surface centered on the intersection of the axis of the motor cylinder 17 and the trunnion axis O ₂ . Therefore, the motor swash plate holder 22, while receiving the motor swash plate red 23 color-centering action can be rotated in the trunnion axis O ₂ around.

The motor swash plate anchor 23 is integrally provided with a cylindrical cylinder holder 24 extending rightward from the motor swash plate anchor 23. The cylinder holder 24 rotatably supports the outer peripheral surface of the motor cylinder 17 via a ball bearing 25. Is done.

As shown in FIGS. 8 to 10, an operating lever 26 is fixed to one trunnion shaft 22a.
Motor that can rotate forward and reverse through a ball nut mechanism 28
29 is concatenated. The ball nut mechanism 28 includes a screw shaft 30 and a nut 32 screwed to the screw shaft 30 via a circulation ball 31. The output shaft of the electric motor 29 is connected to the screw shaft 30, A pair of forks projecting from the side
The distal end of the operating lever 26 is connected to 33, 33 via a pin 34.

The electric motor 29 is supported by a bracket 35 protruding from the outer surface of the cylinder holder 24, and the screw shaft 30 is supported by a pair of brackets 36, 37 protruding from the outer surface of the motor swash plate anchor 23 and the cylinder holder 24. It is rotatably supported via ball bearings 38,39.

And Thus, if normal rotation the screw shaft 30 by the electric motor 29, the nut 32 is moved to the left in Figure 8, rotates the motor swash plate holder 22 to the trunnion axis O ₂ around via the actuating lever 26 ,
The motor swash plate 20 can be raised, and if the screw shaft 30 is reversed, the nut 32 moves to the right and the motor swash plate 20
20 can be tilted. Then, the motor swash plate 20
When the motor cylinder 17 rotates in the inclined state,
A reciprocating motion is sequentially applied to the motor plungers 19, 19,... So that the expansion stroke and the contraction stroke can be repeated.

Referring again to FIGS. 1 and 2, the pump cylinder 7 and the motor cylinder 17 are integrally connected to each other to form a cylinder block B. The cylinder block B and the output shaft 15 penetrating the center thereof are splined. Combined 40.

The drive gear 3a of the secondary reduction gear 3 is formed integrally with the output shaft 15 adjacent to the driven gear 2b of the primary reduction gear 2. The meshing portion between the driving gear 2a and the driven gear 2b in the primary reduction gear 2 and the driving gear 3a in the secondary reduction gear 3
The meshing portion of the driven gear 3b is disposed on the opposite side with respect to the axis of the output shaft 15.

The left end of the output shaft 15 is supported by the motor swash plate anchor 23 via a tapered roller bearing 41, and this bearing
A bearing holder 42 supporting the inner race 41 is fixed to the output shaft 15 by a cotter 43.

The right end of the output shaft 15 is supported by the casing 4 via a ball bearing 44 and a tapered roller bearing 45 which are arranged with the drive gear 3a interposed therebetween, and also supports the input cylinder shaft 5.

In order to rotate the pump swash plate 10 synchronously with the pump cylinder 7, the pump swash plate 10 is formed with a spherical recess 10a with which the spherical end 9a of the corresponding pump plunger 9 engages.

Further, in order to rotate the motor swash plate 20 synchronously with the motor cylinder 17, the motor swash plate 20 is formed with a spherical concave portion 20a with which the corresponding spherical end portion 19a of the motor plunger 19 engages.

Each of the spherical concave portions 10a, 20a is formed with a radius larger than the radius of the corresponding spherical end portions 9a, 19a, and the engagement state with the spherical end portions 9a, 19a is ensured at any position. It has become.

As shown in FIG. 11, the outer peripheral surfaces of the pump cylinder 7 and the motor cylinder 17 have respective cylinder holes.
8,8…; 18,18… Multiple grooves 4 to reduce weight
6,47 are formed.

1, 2 and 5, the cylinder block B has an output shaft 15 between a group of cylinder holes 8, 8... Of the pump cylinder 7 and a group of cylinder holes 18, 18. Annular oil passages 52 concentrically arranged around the center
The cylinder holes 8, 8,... Radially penetrating the outer oil passage 53, the annular partition wall between the oil passages 52, 53 and the outer peripheral wall of the outer oil passage 53.
And the same number of first valve holes 54, 54 ... and second
The valve holes 55, 55, the adjacent cylinder holes 8, 8 and the first valve hole 5
, And a plurality of motor ports b, b, which mutually communicate the adjacent cylinder holes 18, 18,... And the second valve holes 55, 55, respectively. Provided. Inner oil passage 5
The second and outer oil passages 53 correspond to the low-pressure oil passage and the high-pressure oil passage of the present invention, respectively.

The inner oil passage 52 is formed as an annular groove in the inner peripheral surface of the cylinder block B, and its open surface is closed by the outer peripheral surface of the output shaft 15.

The first valve holes 54, 54,...
And the second valve holes 55 are slidably engaged with the second distribution holes 57, 57, respectively. A first eccentric ring 58 surrounding the first distribution valves 56, 56... And a second eccentric ring 59 surrounding them are disposed at the outer ends of the second distribution valves 57, 57. The outer ends of the first distribution valves 56, 56... Are concentric with the first eccentric 58 to engage them via the bearings 60, 61 and to force their engagement.
They are connected to each other by a forcing wheel 62, and the second distribution valves 57, 57
Are connected to each other by a second forcing wheel 63 concentric with the second eccentric wheel 59.

As shown in FIG. 3, the first eccentric wheel 58 swings between a clutch-on position n and a clutch-off position f.
It is connected to the inner end of the input cylinder shaft 5 via a pivot 64 parallel to the output shaft 15. Then, the first eccentric ring 58, the clutch-on position n, occupies a predetermined distance epsilon ₁ eccentric position from the center of the output shaft 15 along the trunnion axis O _2, also the center of the clutch-off position f in the output shaft 15 Occupies a position eccentric by a distance ε ₂ greater than the eccentric wheel ε ₁ , and the clutch off position f is set such that the inner peripheral edge of the first eccentric wheel 58 is
When the clutch-on position n is in contact with the first stopper 65 projecting from the inner end face of the input cylinder shaft 5, the inward projection 67 of the first eccentric wheel 58 is opposite to the first stopper 65 on the inner end face of the input cylinder shaft 5. Each of them is regulated by contacting the second stopper 66 projecting from the side.

Further, on the first eccentric wheel 58 and the input cylinder shaft 5, spring receiving pieces 68, 69 which oppose each other in the circumferential direction on the side opposite to the pivot 64 are protruded, and a clutch spring 70 is contracted between them. The first eccentric wheel 58 is urged in the direction of the clutch off position f by the spring force.

Further, the first eccentric wheel 58 is integrally formed with a weight 71 that exerts a centrifugal force in the direction of the clutch-on position n when rotating.

Further, the first eccentric wheel 58 is provided with an eave 72 covering the spring 70 to prevent the clutch spring 70 from coming off.
Is formed continuously.

Furthermore, the first eccentric wheel 58 and the input cylinder shaft 5 have the first
A guide groove 73 and a guide projection 74 are provided on the opposite side to the pivot 64 so as to swingably engage with each other in order to regulate the swing path of the eccentric wheel 58 around the pivot 64 (see FIGS. 3 and 4). .

Thus, as shown in FIG. 5, when the first eccentric wheel 58 occupies the clutch-on position n and the relative rotation occurs between the input cylinder shaft 5 and the pump cylinder 7, each of the first distribution valves 56 First
It is reciprocated between the radially inner position and outer position of the pump cylinder 7 to twice the eccentric distance epsilon ₁ as a stroke in eccentric 58 by the first valve hole 54. Then, in the discharge region D of the hydraulic pump P, the first distribution valve 56 moves on the inward position side to connect the corresponding pump port a to the outer oil passage 53 and not to the inner oil passage 52. Further, in the suction area S, the first distribution valve 56 moves on the outer position side, and connects the corresponding pump port a to the inner oil passage 52 and disconnects the corresponding pump port a from the outer oil passage 53.

When the first eccentric wheel 58 occupies the clutch off position f (see FIG. 6), when the relative rotation occurs between the input cylinder shaft 5 and the pump cylinder 7, each of the first distribution valves 56 is turned on by the first eccentric wheel. 58
By being reciprocated between the radially inner position and outer position of the pump cylinder 7 to twice the eccentric distance epsilon ₂ as stroke in the first valve hole 54, the first distribution in the inner and outer positions Valve 56 provides direct communication between the inner and outer oil passages 52,53.

On the other hand, as shown in FIG. 7, the second eccentric wheel 59 is integrally connected to the cylinder holder 24 so as to occupy a position eccentric by a predetermined distance ε ₃ from the center of the output shaft 15 along the trunnion axis O _2. You.

And Thus, when the motor cylinder 17 is rotated, the second distributing valves 57, the second eccentric ring 59, the motor cylinder and twice the eccentric distance epsilon ₃ as a stroke in the second valve hole 55
It is reciprocated between the 17 radially inner and outer positions.
In the expansion region Ex of the hydraulic motor M, the second distribution valve 57
Moves on the inward position to connect the corresponding motor port b to the outer oil passage 53 and to the inner oil passage 52. Further, in the contraction region Sh, the second distribution valve 57 moves the outer position skin to connect the corresponding motor port b to the inner oil passage.
It communicates with the outside oil passage 53 while communicating with the outside oil passage 53.

In the above configuration, when the input cylinder shaft 5 of the hydraulic pump P is driven from the engine E via the primary reduction gear 2, and the pump swash plate 10 alternately gives the pump plungers 9, 9,. Each pump plunger 9 pumps hydraulic oil from the cylinder hole 8 to the outside oil passage 53 while passing through the discharge region D, and inside the oil passage while passing through the suction region S.
Hydraulic oil is sucked into the cylinder hole 8 from 52.

By the way, in the idling state of the engine E, the rotation speed of the input cylinder shaft 5 is low, and the centrifugal force exerted by the weight 71 of the first eccentric wheel 58 rotating with the input cylinder shaft 5 is weak.
The first eccentric wheel 58 is held at the clutch off position f by the clutch spring 70. Therefore, as described above, the first distribution valve
Since 56 communicates directly between the inner and outer oil passages 52 and 53, the cylinder hole 8 for accommodating the pump plunger 9 in the suction stroke is provided.
And the cylinder hole 8 accommodating the pump plunger 9 in the discharge stroke is short-circuited through the inner and outer oil passages 52 and 53, and hydraulic transmission to the hydraulic motor M is not performed.

The centrifugal force of the weight 71 increases with the rotation of the engine E and hence the rotation of the input cylinder shaft 5, and when the centrifugal force exceeds the set load of the clutch spring 70, the first eccentric wheel 58 moves to the clutch-on position n. Toward the axis 64.

When the first eccentric wheel 58 reaches the clutch-on position n, as described above, the first distribution valve 56 sets the pump port a in the suction area S.
Is connected to the inner oil passage 52 and is not connected to the outer oil passage 53, and in the discharge area D, the pump port a is connected to the outer oil passage 53 and is not connected to the inner oil passage 52. The hydraulic oil pressure-fed to the outer oil passage 53 is supplied to the cylinder hole 18 of the motor plunger 19 located in the expansion region Ex of the hydraulic motor M, while it is supplied from the cylinder hole 18 by the motor plunger 19 located in the contraction region Sh. Hydraulic oil is discharged to 52.

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 motor plunger 19 in the expansion stroke
The cylinder block B is rotated by the sum of the reaction torque received from the motor swash plate 20 through the motor and the rotation torque is transmitted from the output shaft 15 to the secondary reduction gear 3.

While the first eccentric wheel 58 passes between the clutch off position f and the clutch on position n, part of the hydraulic oil discharged from the hydraulic pump P short-circuits to the suction side, and the remainder is supplied to the hydraulic motor M. The hydraulic pump M is
The clutch is in a half-clutch state where transmission of hydraulic pressure to the motor is moderately suppressed. Thus, the transmission of hydraulic pressure from the hydraulic pump P to the hydraulic motor M is automatically started in response to the increase in the rotation of the engine E, and the vehicle starts smoothly.

The gear ratio of the output shaft 31 to the input cylinder shaft 5 can be obtained 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 one to a certain required value. In addition, since the capacity of the hydraulic motor M is determined by the stroke of the motor plunger 19, the speed ratio is steplessly controlled from 1 to a certain value by tilting the motor swash plate 20 from the upright position to a certain tilt position. can do.

During the operation of the transmission T, the pump swash plate 10 holds the pump plunger.
9,9 ... from the group, the motor swash plate 20 is the motor plunger 19,
The thrust loads received by the pump swash plate 10 in the opposite directions from the group 19 are received through the angular contact bearing 11, the pump swash plate holder 12, the input cylinder shaft 5, the tapered roller bearing 45, and the drive gear 3a. The thrust load supported by the output shaft 15 and received by the motor swash plate 20 is tapered roller bearing 21, motor swash plate holder
22, motor swash plate anchor 23, tapered roller bearing 41,
It is supported on the output shaft 15 via the bearing holder 42 and the cotter 43. Therefore, the above thrust load is
However, it does not affect the casing 4 supporting the shaft 15 at all.

In this case, the motor swash plate holder 22
20 is supported via a tapered roller bearing 21 and the rear surface is supported by a motor swash plate anchor 23, so that even if a thrust load is received from a group of motor plungers 19, 19. Nothing. Moreover,
The motor swash plate holder 22 and the motor swash plate anchor 23 face the spherical surfaces f ₁ and f ₂ centered on the intersection of the axis of the motor cylinder 17 and the trunnion axis O _2. The swash plate holder 22 exhibits a centering function. As a result, the motor swash plate holder 22 is
It is possible to smoothly rotate around O _2, and the inclination angle of the motor swash plate 20 can be easily controlled. At this time, the trunnion shafts 22a and 22b of the motor swash plate holder 22 and the motor swash plate anchor 23
By the engagement between the bearing hole 23a and the bearing recess 23b, the rotation around the trunnion axis O ₂ than the axis of the motor swash plate holder 22 is prevented.

Motor swash plate anchor 23 with a concave spherical surface f ₂ also becomes thicker toward the periphery from the center, has a high rigidity,
It can sufficiently withstand a large load from the motor swash plate holder 22 and the tapered roller bearing 21.

Further, the driven gear 2b and the driving gear 3a respectively provided on the concentrically arranged input cylinder shaft 5 and the output shaft 15 are arranged adjacent to each other in the axial direction, and furthermore, the driving gear 2a meshed with the driven gear 2b.
And the driven gear 3b meshing with the driving gear 3a are arranged on opposite sides of the axis of the output shaft 15, so that during transmission, the driven gear 3b increases from the mating gears 2a, 3b to the driven gear 2b and the driving gear 3a, respectively. Even if a radial load is applied, the directions of the two loads are opposite to each other, and since the interval between the points of action of the two loads is extremely small, the bending moment and the oscillating moment applied to the output shaft 15 due to both the loads are extremely small. . As a result, it is possible to reduce the load on the bearings 41 and 44 that support both ends of the output shaft 15 and extend the life of the bearings.

1, 2, and 5, a center oil passage 80 having one end closed is formed in the center of the output shaft 15. Hydraulic oil is supplied through oil filters 82 and 83. The supply pump 81 is driven from the crankshaft 1 via a transmission (not shown), and sucks oil in an oil reservoir 84 provided at the bottom of the casing 4. The primary oil filter 82 is mounted on the right side wall of the casing 4 so as to face the inlet of the central oil passage 80, and the secondary oil filter 83 is mounted on the central oil passage 80 from the inlet to the center.

A valve cylinder 85 adjacent to the inner end of the secondary oil filter 83 is fitted to the center of the output shaft 15 so as to cross the center oil passage 80 so that both ends face the inner oil passage 52. This valve cylinder 85 is the fifth
As clearly shown in the figure, a cross-shaped horizontal hole 86 opened to the central oil passage 80, and a pair of valve chambers 87, which face each other across the horizontal hole 86 and communicate the horizontal hole 86 to the inner oil passage 52, 87 and each valve chamber 8
A first check valve 88 for preventing a reverse flow of oil from the inner oil passage 52 to the center oil passage 80 is accommodated in 7.

The inner peripheral surface of the cylinder block B is opposed to both end surfaces of the valve cylinder 85 with a small gap therebetween (see FIG. 1), thereby preventing the valve cylinder 85 from being pulled out from the output shaft 15.

The output shaft 15 and the cylinder block B are provided with a valve cylinder 85.
A series of replenishment oil passages 90 connecting the central oil passage 80 on the more upstream side and the outer oil passage 53 is provided, and in the middle of the replenishment oil passage 90,
The second to prevent the backflow of oil from the outer oil passage 53 to the center oil passage 80
A check valve 91 is interposed.

Thus, during a normal load operation in which the hydraulic pump M hydraulically drives the hydraulic motor M, the pressure of the low-pressure side inner oil passage 52 is reduced by the pressure of the central oil passage 80 due to oil leakage from the hydraulic closed circuit therebetween. The first check valves 88, 88 open and the central oil passage 8
Hydraulic oil is supplied to the inner oil passage 52 from zero. On the other hand, at this time, the hydraulic oil in the outer oil passage 53 on the high pressure side is prevented from flowing out to the center oil passage 80 by the second check valve 91.

During reverse load operation, that is, during engine braking,
The hydraulic motor M performs the pumping operation, and the hydraulic pump P performs the motoring operation. Therefore, the outer oil passage 53 changes to a low pressure, and the inner oil passage 52 changes to a high pressure. If the pressure drops due to the pressure in the central oil passage 80, the second
The check valve 91 is opened to supply hydraulic oil from the center oil passage 80 to the outer oil passage 53, and outflow of hydraulic oil from the inner oil passage 52 to the center oil passage 80 is prevented by the first check valves 88,88. You.

C. Effects of the Invention As described above, according to the present invention, the eccentric wheel is connected to the clutch spring that biases the eccentric wheel toward the clutch-off position, and the eccentric wheel is opposed to the spring force of the clutch spring. A weight that can exert a centrifugal force to move toward the clutch-on position is attached, so that the position control of the eccentric wheel can be automatically performed according to the rotation speed of the input member by centrifugal action of the weight, The shut-off state and the hydraulic transmission state between the pump and the hydraulic motor can be accurately obtained regardless of the skill of the operator. In addition, since the weight is attached to the eccentric wheel, a special interlocking mechanism for transmitting the centrifugal force of the weight to the eccentric wheel is unnecessary, and the structure is extremely simple.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a longitudinal plan view of a power unit for a motorcycle provided with a hydrostatic continuously variable transmission of the present invention interposed in a power transmission system of the motorcycle. FIGS. 3 and 3 are sectional views taken along lines II-II and III-III of FIG. 1, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, and FIG. 5 is a sectional view taken along line VV of FIG. 6 (shown at the clutch-on position of the eccentric wheel), FIG. 6 is a sectional view similar to FIG. 5 showing the eccentric wheel at the clutch-off position, FIG. 7 is a sectional view taken along the line VII-VII of FIG.
8 is a view taken in the direction of arrow VIII in FIG. 2, and FIG. 9 is a view taken along IX-IX in FIG.
FIG. 10 is an exploded perspective view of the periphery of a motor swash plate holder, and FIG. 11 is a perspective view of a cylinder block. a pump port, b motor port, f clutch off position, n clutch on position, M hydraulic motor, P hydraulic pump, T continuously variable transmission, 5 input Input cylinder shaft as a member 7 Pump cylinder 8 Cylinder hole 9 Pump plunger 10
… Pump swash plate, 15 …… Output shaft, 17 …… Motor cylinder,
18 ... Cylinder bore, 19 ... Motor plunger, 20 motor swash plate, 52 ... Inner oil passage as low pressure oil passage, 53 ... Outer oil passage as high pressure oil passage, 56 ... Distribution valve, 58 ... Eccentric, 70
…… Clutch spring, 71 …… Weight

Continuing from the front page (72) Inventor Kazuhiko Nakamura 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda Technical Research Institute Co., Ltd. (56) References JP-A-62-177353 (JP, A) JP-A-61-274167 (JP, A)

Claims (1)

(57) [Claims] A swash plate type hydraulic pump pump cylinder and a swash plate type hydraulic motor motor cylinder are coaxially and integrally connected to each other, and a motor port located between the pump cylinder and the motor cylinder in an expansion stroke region of the hydraulic motor. And an annular low-pressure oil passage communicating with the motor port in the contraction stroke region of the hydraulic motor, and concentrically reciprocate between an outer position and an inner position in the radial direction. A large number of distribution valves capable of alternately connecting a large number of pump ports of a hydraulic pump to a high-pressure oil passage and a low-pressure oil passage are arranged radially, and an eccentric ring circumscribing these distribution valves is used as a clutch off position and a clutch. The eccentric wheel is connected to the input member of the hydraulic pump so that it can move between the ON positions. A hydrostatic continuously variable transmission that controls a distribution valve so that a pump port existing in a suction stroke region communicates with a low-pressure oil passage in a pressure oil passage and a hydraulic pump is short-circuited at a clutch-off position. In the above, a clutch spring for urging the eccentric wheel toward the clutch-off position is connected to the eccentric wheel, and a centrifugal force for moving the eccentric wheel toward the clutch-on position against the spring force of the clutch spring is exerted. A hydrostatic continuously variable transmission, characterized in that a weight is obtained.