JP2920772B2 - Hydrostatic continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial application field The present invention integrally connects a pump cylinder of a swash plate type hydraulic pump and a motor cylinder of a swash plate type hydraulic motor on a transmission shaft. The cylinder block includes an inner oil passage surrounding the transmission shaft between the cylinder hole group of the pump cylinder and the cylinder hole group of the motor cylinder, and an outer oil passage surrounding the inner oil passage. And a number of first distribution valves for alternately connecting the pump ports connected to the respective cylinder holes of the pump cylinder to the inner and outer oil passages, and the inner and outer motor ports connected to the respective cylinder holes of the motor cylinder. A large number of second distribution valves alternately communicating with the oil passage are radially arranged, and these second distribution valves are radially arranged.
The present invention relates to a hydrostatic continuously variable transmission in which first and second valve actuating devices for operating a first and second distribution valves are arranged on an outer periphery of a cylinder block.

(2) Conventional technology This type of hydrostatic continuously variable transmission is disclosed in, for example, Japanese Patent Application Laid-Open No. 64-79.
It is already known as disclosed in the '469 publication.
In the structure disclosed in the above-mentioned publication, the cylinders of the pump cylinder and the motor cylinder are formed to have the same diameter, and the cylinder block is formed as small as possible by making the pitch circles of both cylinder hole groups the same diameter.

(3) Problems to be Solved by the Invention However, when trying to increase the capacity of the hydraulic motor by making the cylinder hole of the motor cylinder larger in diameter than that of the pump cylinder, the pitch circle of both cylinder hole groups must be increased as in the past. If the diameters are the same, the wall between the cylinder holes of the motor cylinder becomes too thin or the partition wall between the cylinder holes of the pump cylinder becomes too thick, which is disadvantageous in strength and compactness.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hydrostatic continuously variable transmission that can be configured to be compact without insufficient strength while increasing the capacity of a hydraulic motor. .

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a motor cylinder in which each cylinder hole is formed larger in diameter than each cylinder hole of a pump cylinder. In order to make the pitch circle of the cylinder hole group of the pump cylinder larger than the pitch circle of the cylinder hole group of the pump cylinder, and to make the pitch circles of the pump port group and the motor port group substantially equal to each other, each motor port is positioned at the center of the corresponding cylinder hole. It is characterized by being arranged eccentrically to the center side of the cylinder block.

(2) Operation According to the above configuration, although the cylinder hole of the motor cylinder is formed larger in diameter than the cylinder hole of the pump cylinder, the pitch circle of the former cylinder hole group is made larger than the pitch circle of the latter cylinder hole group. Thereby, an appropriate thickness can be given to the inter-wall between the cylinder holes.

In addition, since each motor port is decentered from the center of the corresponding cylinder hole toward the center of the cylinder block, and the pitch circle of the motor port group is made substantially the same diameter as the pitch circle of the pump port group, the inner and outer oil passages are formed. The diameter of the cylinder block and the first and second valve driving means can be minimized as much as possible.

(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. Being supported.

The continuously variable transmission T has an input cylinder shaft 5 rotatably supported on an intermediate wall of a casing 4 via a ball bearing 6 and an output shaft 31 as a transmission shaft surrounded by the input cylinder shaft 5. 1 and are arranged in parallel. The crankshaft 1 drives the input cylinder shaft 5 via a primary transmission R ₁ and a primary torque damper D ₁ , and the output shaft 31 via a secondary transmission R ₂ , a secondary torque damper D ₂ and a propeller shaft 3. The rear wheels (not shown) of the motorcycle are driven.

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

The hydraulic pump P is provided with a ball bearing 11 on the inner peripheral wall of a cylindrical first cylinder holder 16 connected to the left end of the input cylinder shaft 5.
Pump cylinder 7 which is rotatably supported via a cylinder
And a large number and an odd number of annular arrangements (9 in the illustrated example) provided around the rotation axis of the pump cylinder 7.
, And a pump swash plate 10 having a front surface in contact with the outer ends of the pump plungers 9, 9 ...
The pump swash plate 10 is provided with an angular contact bearing 12 and a radial contact bearing 12 so as to hold 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. It is rotatably supported on the input cylinder shaft 5 via the ball bearing 13. The angular contact bearing 12 is configured to provide a centering action to the pump swash plate 10.

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

On the other hand, the hydraulic motor M has a motor cylinder 17 disposed coaxially to the left of the pump cylinder 7 and the cylinder holes 8, which are provided in an annular arrangement around the rotation axis of the motor cylinder 17. 8 and the same number of cylinder holes 18, 18
A large number of motor plungers 19, 19, each sliding on
, A motor swash plate 20 having a front surface in contact with outer ends of the motor plungers 19, 19, and a motor swash plate holder 22 for supporting the motor swash plate 20 via an angular contact bearing 14 and a radial ball bearing 15. And a motor swash plate anchor 23 that supports the rear surface of the motor swash plate holder 22.

In this hydraulic motor M, the cylinder hole 18 and the motor plunger 19 are formed with a larger diameter than that of the hydraulic pump P so that the maximum capacity is larger than that of the hydraulic pump P.

Opposing surfaces of the motor swash plate holder 22 and the motor swash plate anchor 23
f ₁ and f ₂ are the axis of the motor cylinder 17 and the trunnion axis O ₂
Are formed on a spherical surface centered at the intersection with.

The motor swash plate holder 22 is integrally provided with a pair of trunnion shaft 22a disposed on the trunnion axis O ₂ perpendicular to the rotational axis of the motor cylinder 17, and 22a at both ends, which are rotated in the motor swash plate anchor 23 Supported as possible.

The angular contact bearing 14 is configured to cooperate with the motor swash plate holder 22 to impart a centering action to the motor swash plate 20.

The motor swash plate anchor 23 is bolted to the left side wall of the casing 4.
It is fixed at 21 (FIG. 1). At the right end of the motor swash plate anchor 23, a cylindrical second cylinder holder 24 is fixed with bolts 32. The second cylinder holder 24 can rotate the outer peripheral surface of the motor cylinder 17 via a ball bearing 26. To support.

The motor swash plate 20 is configured to move by the rotation of the motor swash plate holder 22 between an upright position that is perpendicular to the axis of the motor cylinder 17 and a maximum tilt position that tilts at a certain angle, In the inclined state, the motor plungers 19 are reciprocated with the rotation of the motor cylinder 17 so that the expansion and contraction strokes can be repeated.

On one side of the motor swash plate holder 22, and actuating arm 25 extending in a direction perpendicular to the trunnion axis O ₂ is fixed, the shift control device 27 the actuating arm 25 for controlling the tilt angle of the motor swash plate 20 Linked to

The pump cylinder 7 and the motor cylinder 17 are integrally connected to each other to form a cylinder block B, and an output shaft 31 passes through the center of the cylinder block B. The outer end of the motor cylinder 17 abuts on a flange 31a formed on the outer periphery of the output shaft 31 via an annular oil passage forming body 35, and the pump cylinder is engaged with a stopper ring 28 locked on the same outer periphery. 7 and the cylinder block B
(The pump cylinder 7 in the illustrated example) is spline-fitted to the output shaft 31 so that the cylinder block B
To be fixed.

The right end of the output shaft 31 extends through the pump swash plate 10 to the outside of the input cylinder shaft 5, and is rotatably supported outside the pump swash plate 10 on the input cylinder shaft 5 via the angular contact bearing 29. Is done.

The left end of the output shaft 31 is the motor swash plate 20, the motor swash plate holder
It extends through the motor swash plate anchor 22 and the motor swash plate anchor 23, and is rotatably supported by the motor swash plate anchor 23 via an angular contact bearing 30.

In this way, in the continuously variable transmission T, the components from the input cylinder shaft 5 to the output shaft 31 are assembled into one assembly, and the input cylinder shaft 5 and the output shaft 31 are connected to each right end as shown in FIG. in part, it is respectively spline-coupled to the output member and the input member of the second torque damper D ₂ of the primary torque damper D _1.

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.

In FIG. 3, a cylinder block B has a ring-shaped inner oil passage 52 and a ring-shaped inner oil passage 52 concentrically arranged around the output shaft 31 between a group of cylinder holes 8 of the pump cylinder 7 and a group of cylinder holes 18 of the motor cylinder 17. Outer oil passage 53 and both oil passages 52 and 53
The same number of cylinder holes 8, 8,... And 18, 18,... Penetrating radially through the annular partition wall and the outer peripheral wall of the outer oil passage 53.
Valve holes 54, 54 ... and second valve holes 55, 55 ... and adjacent cylinder holes
, And the first valve holes 54, 54, and the pump ports a, a, which communicate with each other, the adjacent cylinder holes 18, 18,.
Are provided with a large number of motor ports b, b,.

In the above, the group of cylinder holes 8 of the hydraulic pump P and the group of cylinder holes 18 of the hydraulic motor M are arranged such that the latter pitch circle has a larger diameter than the former pitch circle (that is, d _1).
<D ₃ ), and the pump port a group and the motor port b group are arranged such that their pitch circles have substantially the same diameter (that is, d ₂ ≒ d ₄ , and in the illustrated example, d ₄ is slightly smaller than d _2). Large diameter). In order to obtain such an arrangement of the port groups, the corresponding cylinder holes 8 and the pump ports a are arranged coaxially on the hydraulic pump P side, while the corresponding motors corresponding to the respective cylinder holes 18 are arranged on the hydraulic motor M side. The port b is eccentrically arranged toward the center of the cylinder block B.

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 31.

The first valve holes 54, 54 ... have spool-type first distribution valves 61,
61 and the second valve holes 55 are slidably fitted with the spool type second distribution valves 62, 62, respectively. Are provided at the outer ends of the first distribution valves 61, 61,... As a first valve operating device surrounding the first distribution valves 61, 61,.
Are provided at the outer ends thereof as second valve actuators surrounding them.
The eccentric 64 is engaged via ball bearings 65 and 66, respectively, and the first distribution valve 6
The outer end of 1,61 ... is the first forcing wheel concentric with the first eccentric wheel 63
Are connected to each other by a second forcing wheel 68 which is concentric with the second eccentric wheel 64.

First eccentric ring 63 is integrally connected to the inner end of the first cylinder holder 16, from the center of the output shaft 31 along the imaginary trunnion axis O ₁ as shown in FIG. 3 by a predetermined distance epsilon _first eccentric Placed in the position.

Thus, when relative rotation occurs between the input cylinder shaft 5 and the pump cylinder 7, each of the first distribution valves 61 causes the first eccentric wheel 63 to move a distance twice the eccentric amount ε ₁ in the first valve hole 54. As a stroke, the pump cylinder 7 is reciprocated between an inner position and an outer position in the radial direction. Then, as shown in FIG. 3, in the discharge region D of the hydraulic pump P, the first distribution valve 61 moves toward the inner position, and connects the corresponding pump port a to the outer oil passage.
53 and is in communication with the inner oil passage 52. The pump plunger 9 during the discharge stroke moves the outer oil passage
In the suction area S, the first distribution valve 61 moves to the outer position side to connect the corresponding pump port a to the inner oil passage 52 and not to communicate with the outer oil passage 53. And the inner oil passage 52 is operated by the pump plunger 9 during the suction stroke.
Hydraulic oil is sucked into the cylinder hole 8 from.

It said second eccentric wheel 64, the second is connected to the inner end of the cylinder holder 24, as shown in FIG. 4, the trunnion axis O ₂
It is arranged at a predetermined distance epsilon ₂ eccentric position from the center of the output shaft 31 along.

And Thus, when the motor cylinder 17 is rotated, the second distributing valves 62, the motor cylinder as stroke twice the eccentric distance epsilon ₂ in the second eccentric ring 64 by the second valve hole 55 17
Is reciprocated between the radially inner position and the outer position. Then, in the expansion region Ex of the hydraulic motor M, the second distribution valve 62 moves on the inward position side to connect the corresponding motor port b to the outer oil passage 53 and to disconnect the inner oil passage 52, and High-pressure hydraulic oil is supplied from the oil passage 53 to the cylinder hole 18 of the motor plunger 19 during the expansion stroke, and in the contraction region Sh, the second distribution valve 62 moves to the outer position side to move the corresponding motor. The port b is communicated with the inner oil passage 52 and is not connected with the outer oil passage 53, and hydraulic oil is discharged from the cylinder hole 18 of the motor plunger 19 to the inner oil passage 52 during the contraction stroke.

In FIG. 2 again, an oil chamber 43 is defined at the left end of the output shaft 31 by the pair of first and second valve cylinders 40 and 41 fitted to the output shaft 31 and the end plate 42. The oil chamber 43 is provided on one side with a supply pump 44 driven by the engine E (see FIG. 1).
The other side communicates with the inner oil passage 52 via the first valve cylinder 40 and the low-pressure oil passage 45 in the output shaft 31 on the other side.
In addition, it communicates with the outer oil passage 53 via a second valve cylinder 41 and a high-pressure oil passage 46 in the output shaft 31.

First and second check valves 47 and 48 are housed in the first and second valve cylinders 40 and 41, respectively, and both check valves are connected to the corresponding oil passages 45 and 46 from the oil chamber 43. It allows the flow of oil and blocks the opposite flow.

Next, the operation of this embodiment will be described. Engine E
When the input cylinder shaft 5 of the hydraulic pump P is driven to rotate, the discharge and suction strokes are alternately given to the pump plungers 9, 9,.

The pump plunger 9 pumps hydraulic oil from the cylinder hole 8 to the outer oil passage 53 while passing through the discharge region D, and pumps hydraulic oil from the inner oil passage 52 to the cylinder hole 8 while passing through the suction region S. Inhale.

The high-pressure hydraulic oil sent to the outer oil passage 53 is supplied to the hydraulic motor M
Cylinder hole of motor plunger 19 in the expansion region Ex
On the other hand, the hydraulic oil is discharged from the cylinder hole 18 to the inner oil passage 52 by the motor plunger 19 located in the contraction region Sh.

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 via the motor and the rotation torque is transmitted from the output shaft 31 to the secondary reduction gear 3.

In this case, the speed ratio of the output shaft 31 to the input cylinder shaft 5 is given by the following equation.

Therefore, if the capacity of the hydraulic motor M is changed from the maximum value to zero, the gear ratio can be changed from the maximum value (low state) to 1 (top state). In addition, since the capacity of the hydraulic motor M is determined by the stroke of the motor plunger 19, the gear ratio can be steplessly controlled from the maximum value to 1 by tilting the motor swash plate 20 from the inclined position to the upright position. it can.

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 load received by the pump swash plate 10 is supported by the output shaft 31 via the angular contact bearing 12, the input cylinder shaft 5 and the angular contact bearing 29, The thrust load applied to the plate 20 is supported on the output shaft 31 via the angular contact bearing 14, the motor swash plate holder 22, the motor swash plate anchor 23, and the angular contact bearing 30. Therefore, the thrust load only generates a tensile stress on the output shaft 31 and does not act on the casing 4 supporting the shaft 31 at all.

In this case, the motor swash plate holder 22 and the motor swash plate anchor
23 faces 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 , so that the interaction of these spherical surfaces causes the motor swash plate holder 22 to exhibit a centering function. I do. As a result, the motor swash plate holder 22 is smoothly rotated in the trunnion axis O ₂ around obtained, the motor swash plate 20
Can be easily controlled.

Further, in the hydraulic pump P and the hydraulic motor M, each swash plate 10, 20 is provided with a spherical end 9a, 19a of the corresponding plunger 9, 19.
And the angular contact bearings 12 and 14 receive the centering action from the front and rear, and the outer circumference is supported by the radial ball bearings 13 and 15, so that it can maintain a fixed position in any inclined state and accurately rotate synchronously with the cylinder block B. can do.

In an operation state such as the continuously variable transmission T, the first and second check valves 47 and 48 are closed by the pressures of the inner and outer oil passages 52 and 53, that is, the pressures of the low and high pressure oil passages 45 and 46. Low and high pressure oil passages 45,
Prevents the backflow of hydraulic oil from 46 to the supply pump 44 side,
During normal load operation, if the pressure in the low-pressure oil passage 45 becomes lower than the discharge pressure of the supply pump 44 due to oil leakage from the hydraulic closed circuit between the hydraulic pump P and the hydraulic motor M, the first check valve 40 Is opened, the oil discharged from the supply pump 44 is supplied to the inner oil passage 52 via the low-pressure oil passage 45. Also, during reverse load operation, if the pressure in the high-pressure oil passage 46 becomes lower than the discharge pressure of the replenishment pump 44 due to oil leakage from the hydraulic closed circuit, the second check valve 48 is opened. Oil flows through the high pressure oil passage 46 to the outside oil passage
Resupplied to 53.

In such a continuously variable transmission T, the motor cylinder 17
Is formed to have a larger diameter than the cylinder hole 8 of the pump cylinder 7 and the maximum capacity of the hydraulic motor M is made larger than that of the hydraulic pump P. Obtainable.

At this time, 7,17 both both because larger than the pitch circle diameter d ₁ of the pitch circle diameter d ₃ of the cylinder bore 8 group of the pump cylinder 7 of the cylinder hole 18 group of the motor cylinder 17, the cylinder bore 8
Each partition between the cylinder holes 18 and between the cylinder holes 18 can be given an appropriate thickness.

Moreover, by displacing toward the center of the cylinder block B from the center of the cylinder bore 18 corresponding to each motor port b, substantially the same pitch circle diameter d ₄ of the motor ports b group and a pitch circle diameter d ₂ of the pump ports a group Inner and outer oil passages
52 and 53 can be brought as close as possible to the center side of the cylinder block B. As a result, it is possible to minimize an increase in the diameter of the cylinder block B and the first and second eccentric rings 63 and 64 surrounding the cylinder block B.

In the illustrated example, the amount of eccentricity of the second eccentric wheel 64 is fixed. It may be.

C. Effects of the Invention As described above, according to the present invention, although the cylinder hole of the motor cylinder is formed to have a larger diameter than the cylinder hole of the pump cylinder, the pitch circle of the former cylinder hole group is changed to the pitch of the latter cylinder hole group. Since the diameter is made larger than the circle, the partition wall between the two cylinder holes can be given an appropriate thickness, and the durability of the cylinder block can be ensured while reducing the weight.

In addition, since each motor port is decentered from the center of the corresponding cylinder hole toward the center of the cylinder block, and the pitch circle of the motor port group is made substantially the same diameter as the pitch circle of the pump port group, the inner and outer oil passages are formed. The cylinder block and the first and second valve actuating means can be made more compact in the radial direction as close as possible to the center side of the cylinder block.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a plan view of a power unit for a motorcycle provided with a hydrostatic continuously variable transmission of the present invention, and FIG. 2 is a longitudinal section of the continuously variable transmission. FIG. 3, FIG. 3 and FIG. 4 are sectional views taken along lines III-III and IV-IV of FIG. B: Cylinder block, M: Hydraulic motor, P: Hydraulic pump, T: Continuously variable transmission, a: Pump port, b
…… Motor port, d ₁ … Diameter of pitch circle of pump cylinder cylinder hole group, d ₂ …… Diameter of pitch circle of motor port group, d ₃ …… Diameter of pitch circle of cylinder group of motor cylinder, d ₄ … Motor port group pitch circle diameter 7: Pump cylinder, 8: Cylinder hole, 9: Pump plunger, 17: Motor cylinder, 18: Cylinder hole, 19: Motor plunger, 31: As transmission shaft Output shaft, 52 ... Inside oil passage, 53 ... Outside oil passage, 61 ... First distribution valve, 62 ... Second distribution valve, 63 ... First eccentric ring as first valve operating device, 64 ... ... Second eccentric wheel as second valve operating device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-79469 (JP, A) JP-A-63-203960 (JP, A) JP-A-1-171636 (JP, A) 68856 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 39/00-39/14

Claims (1)

(57) [Claims] A cylinder block is formed by integrally connecting a pump cylinder of a swash plate type hydraulic pump and a motor cylinder of a swash plate type hydraulic motor on a transmission shaft. The cylinder block has a cylinder bore of a pump cylinder. An inner oil passage surrounding the transmission shaft between the group and the cylinder hole group of the motor cylinder and an outer oil passage surrounding the inner oil passage are formed, and a pump port connected to each cylinder hole of the pump cylinder is formed inside. A number of first distribution valves alternately communicating with the outer and outer oil passages and a number of second distribution valves alternately communicating motor ports connected to the respective cylinder holes of the motor cylinder with the inner and outer oil passages, respectively. These
In a hydrostatic continuously variable transmission in which first and second valve actuating devices for operating the first and second distribution valves are arranged on the outer periphery of a cylinder block, each cylinder hole of a motor cylinder is replaced with each cylinder hole of a pump cylinder. While having a larger diameter, the pitch circle of the cylinder hole group of the motor cylinder is made larger than the pitch circle of the cylinder hole group of the pump cylinder, while the pitch circles of the pump port group and the motor port group are made substantially equal to each other. The motor port is eccentrically arranged from the center of the corresponding cylinder hole toward the center of the cylinder block,
Hydrostatic continuously variable transmission.