JPH0718479B2 - Hydrostatic continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to a pump plunger group of a hydraulic pump, which is formed by connecting a swash plate hydraulic pump and a hydraulic motor to each other via a hydraulic closed circuit. Also, the present invention relates to an improvement of a hydrostatic continuously variable transmission in which a motor plunger group of a hydraulic motor is annularly arranged in a common cylinder block whose center is coupled to a transmission shaft.

(2) Conventional Technology This type of continuously variable transmission is disclosed in Japanese Patent Laid-Open No. 61-153057.

(3) Problems to be Solved by the Invention In the conventional continuously variable transmission of this type, the pump plunger group and the motor plunger group are arranged in series in the axial direction of the cylinder block. Has to be long in the axial direction, which makes it difficult to make the entire transmission compact.

The present invention has been made in view of such circumstances, and provides a compact hydrostatic continuously variable transmission in which a pump plunger group and a motor plunger group can be housed in a cylinder having a short axial dimension. To aim.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a pump plunger group and a motor plunger group such that one plunger group surrounds the other plunger group. The arrangement is concentric, and the positions of both plunger groups are shifted in the circumferential direction of the cylinder block so that the inscribed circle of one plunger group passes through the other plunger group.

Either the pump plunger group or the motor plunger group may be arranged outside or inside.

(2) Action Since the pump plunger group and the motor plunger group are arranged concentrically, the axial dimension of the cylinder block that accommodates them can be significantly reduced.

Moreover, since the positions of the two plunger groups are displaced in the circumferential direction of the cylinder block so that the inscribed circle of the outer plunger group passes through the inner plunger group, the thickness of the cylinder block between the inner and outer plungers is increased. It is possible to dispose both plunger groups close to each other while sufficiently ensuring the above, and it is possible to suppress the increase in diameter of the cylinder block due to the concentric arrangement of both plunger groups as much as possible.

(3) Embodiment One embodiment of the present invention will be described below with reference to the drawings.
First, in FIG. 1, U is an automobile power unit,
The engine E, the hydrostatic continuously variable transmission T of the present invention, and the differential device Df are housed and supported in a casing C as a stationary frame.

The crankshaft 1 of the engine E and the input shaft 2 as a transmission shaft of the continuously variable transmission T arranged on the right end side thereof are arranged coaxially and are connected to each other via a torque damper Td.
Further, the output gear 3 of the continuously variable transmission T is arranged as close to the engine E as possible, and meshes with the ring gear 4 of the differential device Df. The left and right output shafts 5, 5'of the differential device Df are crankshafts 1
It is arranged parallel to the input shaft 2 and drives left and right axles (not shown).

The right end of the input shaft 2 is projected outside the casing C,
A pulley 6 for driving auxiliary equipment such as a power steering hydraulic pump and an air conditioning compressor is fixed to the projecting end thereof.

2 and 3, the continuously variable transmission T includes a variable displacement swash plate hydraulic pump P and a constant displacement swash plate hydraulic motor M. In this embodiment, the hydraulic oil of the hydraulic motor M is used. The present invention is applied to a distribution device.

The hydraulic pump P includes a large number and odd number of cylinder holes 8, 8 ... Which are arranged in a cylindrical cylinder block 7 so as to surround the center of rotation and open the right end, and these cylinder holes.
A large number of pump plungers 9,9 that are respectively slid onto 8,8 ...
, And a pump swash plate 10 that abuts the outer end, that is, the right end of these pump plungers 9, 9 ... 12 and also this trunnion shaft 12
And a swash plate anchor 13 that rotatably supports the cylindrical surface of the.

The swash plate anchor 13 is fixed to the casing C with bolts 15.

In order to prevent the trunnion shaft 12 from rotating in a predetermined angle while allowing the trunnion shaft 12 to rotate, a swash plate anchor 23 is formed.
A bolt 23 is fixed to one end surface of the trunnion shaft 12 through an arcuate elongated hole 22 centered on the axis O ₁ of the trunnion shaft 12 (see FIGS. 3 and 11).

The pump swash plate 10 is tilted by the rotation of the trunnion shaft 12 between an upright position that is perpendicular to the axis of the cylinder block 7 and two maximum tilt positions that are tilted at a certain angle to the left and right sides thereof. In that tilted state, the pump plunger is rotated as the cylinder block 7 rotates.
It is possible to repeat the suction and discharge strokes by giving a reciprocating motion to 9,9 ....

On the other hand, the hydraulic motor M is arranged on a pitch circle concentric with the pitch circle of the cylinder holes 8, 8 ... The same number of cylinder holes 18, 18 as the number of 8, 8, ..., the motor plungers 19, 19 ... which are respectively slid into these cylinder holes 18, 18 ..., and the motors which abut on the outer ends of these motor plungers 19, 19 Swash plate 20 and this motor swash plate 20
And a motor swash plate holder 27 that supports the back surface of the motor through a thrust roller bearing 26, and the output gear 3 is integrally formed on the outer periphery of the motor swash plate holder 27.

In the above description, the inner cylinder holes 8, 8 ... Group and the outer cylinder hole 18, 18, ... Group are displaced from each other by ½ pitch of each cylinder hole in the circumferential direction of the cylinder block 7, and The inscribed circles of the group of cylinder holes 18, 18 ... Are arranged so as to pass through the inner group of cylinder holes 8, 8.

Further, the motor swash plate 20 is moved by the motor swash plate holder 27 so that the virtual trunnion axis O ₂ orthogonal to the axis of the cylinder block 7 is generated.
Is held at a certain angle with respect to the axis of the cylinder block 7 about its center, and when the cylinder block 7 and the motor swash plate holder 27 rotate relative to each other, the motor plungers 19, 19 ... Reciprocate to expand and contract. The process can be repeated.

The input shaft 2 penetrating the central portion of the cylinder block 7 is coupled via a spline 32. The right end portion of the input shaft 2 extends so as to penetrate the pump swash plate 10, the trunnion shaft 12, and the swash plate anchor 13, and the first thrust bearing plate 35 and the swash plate anchor 13 locked to the right end portion. A thrust roller bearing 37 is interposed between them. The right end of the input shaft 2 is connected to the swash plate anchor via a needle bearing 38.
Further, it is rotatably supported by the casing C via a bush 39.

The first thrust support plate 35 is connected to the input shaft 2 via the key 43.

The left end portion of the input shaft 2 extends so as to penetrate the motor swash plate 20 and the motor swash plate holder 27, and the second thrust bearing plate 36 and the motor swash plate holder 27 locked to the outer periphery of the left end portion.
A thrust roller bearing 40 is provided between the input shaft 2 and the thrust roller bearing 40, and a needle bearing 41 is provided between the motor swash plate holder 27 and the input shaft 2. The left end of this input shaft 2 is the second
It is rotatably supported by the casing C together with the thrust bearing plate 36 via the roller bearing 42.

In order to rotate each swash plate 10, 20 in synchronization with the cylinder block 7, each swash plate 10, 20 has a corresponding plunger 9, 19
Spherical recesses 10a, 20a for engaging the spherical end portions 9a, 19a of the respective are formed.

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

The cylinder block 7 has an annular inner oil chamber on its inner peripheral side.
45 is also provided on the outer peripheral side, which is also annular and has a first, second, and third outer oil chambers 46, 47, 48 that are sequentially arranged in the axial direction from the right side, and between the inner oil chamber 45 and the third outer oil chamber 58. Communication is established via a plurality of radially extending oil passages 49 (see FIG. 8).

The cylinder block 7 also has first valve holes 51, 51 ... (See FIG. 4), which are the same number as the cylinder holes 8, 8 ... The number of cylinder holes 18, 18 ... Of the hydraulic motor M is the same as that of the second valve holes 52, 52.

The first valve holes 51, 51 ... Reach from the outer peripheral surface of the cylinder block 7 to the inner oil chamber 45, and in the middle of each valve hole 51, the pump port a penetrating the dead end of the cylinder hole 8 adjacent thereto. (See FIG. 3) and a first outer oil chamber 56 located radially outward of the pump port a (see FIGS. 3 and 6).
And an oil passage 53 leading to.

These first valve holes 51, 51 ... Have a spool-type first distribution valve 55,
55 ... are slidably engaged with each other, and an eccentric ring 57 surrounding them is engaged with the outer ends of the distribution valves 55, 55. First to force their engagement
The outer ends of the distribution valves 55, 55 ... Are connected to each other by an eccentric wheel 57 and a force wheel 59 concentric with each other.

The eccentric wheel 57, as shown in FIGS. 2, 4, and 4A,
It is connected to the swash plate anchor 13 via a pivot 60 parallel to the input shaft 2 so as to be swingable between two positions, a hydraulic operating position n and a lockup position 1. The eccentric wheel 57 is substantially along the trunnion axis O ₁ with the center of the input shaft 2 as a reference by a control device (not shown) that engages with a protrusion 57a that is provided on the outer peripheral surface of the eccentric wheel 60 on the opposite side. The eccentricity is controlled, and the eccentricity amount is ε at the hydraulic operating position n and zero at the lockup position l (that is, the eccentric wheel 57 is concentric with the input shaft 2).
Is set to.

Thus, when the eccentric wheel 57 occupies the hydraulic operating position n (fourth
When the cylinder block 7 is rotated, the eccentric ring 57 causes each of the first distribution valves 55 to make the stroke in the first valve hole 51 twice the eccentric amount ε.
Are reciprocated between the inner and outer positions in the radial direction, and thereby the hydraulic pump P is provided with a discharge region D and a suction region S.

That is, in the discharge region D, the first distribution valve 55 moves toward the inner position side with the rotation of the cylinder block 7 to communicate the corresponding pump port a with the oil passage 53 communicating with the first outer oil chamber 46. The internal oil chamber 45 is cut off, and the pump plunger 9 during the discharge stroke is used to move the first oil from the cylinder hole 8 through the oil passage 53.
The hydraulic oil is discharged to the outer oil chamber 46. In the suction region S, the first distribution valve 55 moves on the outer position side so that the corresponding pump port a communicates with the inner oil chamber 45 and makes the oil passage 53 incommunicable, and by the pump plunger 9 during the suction stroke. Inside oil chamber
The hydraulic oil is sucked into the cylinder hole 8 from 45.

A switching neutral region is provided between the regions D and S so that the first distribution valve 55 makes the pump port a incommunicable with both the inner oil chamber 45 and the oil passage 53.

When the eccentric wheel 57 occupies the lockup position 1 (see FIG. 4A), all the first distribution valves 55 are held in the switching neutral state by the eccentric wheel 57 regardless of the rotation of the cylinder block 7. The pump port a of is closed.

Referring again to FIGS. 2 and 3, the second valve holes 52, 52 ...
Penetrates the cylinder block 7 across the first, second and third outer oil chambers 46, 47, 48, and each valve hole 52 has an intermediate portion between the first and third outer oil chambers 46, 48. The motor port b (see FIG. 2 and FIG. 7) connected to the cylinder hole 18 adjacent thereto is opened in the section.

The spool type second distribution valves 56, 56 ... Are slidably fitted in the second valve holes 52, 52. These second distribution valves 56, 56 ... Are engaged at one end with a spring force of a spring 63 into a spherical concave portion 62a of a valve swash plate 62 which is supported by the motor swash plate holder 27 via a thrust roller bearing 61. It

The valve swash plate 62 is a virtual trunnion axis O _{2 of the} motor swash plate 20.
On the other hand, the cylinder block 7 is held in a state of being inclined at a constant angle with respect to the axis of the cylinder block 7 about the second virtual trunnion axis O ₃ which is set with a 90 ° phase shift around the axis of the cylinder block 7. Motor swash plate holder
During relative rotation with respect to 27, the second distribution valves 56, 56 ... Are reciprocated in the axial direction with a predetermined stroke. The expansion region Ex and the contraction region Sh of the hydraulic motor M are determined by the positions of the second distribution valves 56, 56 ...

That is, as shown in FIG. 5, in the expansion region Ex, the second distribution valve 56 is located at the left end or near the left end, and the corresponding motor port b communicates with the first outer oil chamber 46 and the second outer valve chamber 46.
High pressure hydraulic oil is supplied from the first outer oil chamber 46 to the cylinder hole 18 of the motor plunger 19 during the expansion stroke, which is in communication with the outer oil chamber 47. In the contraction region Sh, the second distribution valve 56 is at the right limit or a position close to it and the corresponding motor port b
Is communicated with the second outer oil chamber 47 and is not communicated with the first outer oil chamber 46, and the hydraulic oil is discharged from the cylinder hole 18 to the low-pressure second outer oil chamber 47 side by the motor plunger 19 during the contraction stroke.

Each second distribution valve 56 does not prevent the communication between the second and third outer oil chambers 47, 48 by the second valve hole 52, and thus the second outer oil chamber 4
The oil discharged to the 7 side is returned to the inner oil chamber 45 via the third outer oil chamber 48 and the oil passage 49.

In the above structure, the cylinder block 7 is rotated by the power of the engine E via the input shaft 2 while the pump swash plate 10 is held at a certain tilt angle and the eccentric wheel 57 is held at the hydraulic operating position n. Then, first, in the hydraulic pump P, the pump plunger 9 performing the discharge operation pumps the working oil from the cylinder hole 8 to the first outer oil chamber 46 while passing through the discharge area D, and also performs the suction operation. The pump plunger 9 for performing the above operation sucks the working oil from the inner oil chamber 45 into the cylinder hole 8 while passing through the suction region S.

The high-pressure hydraulic oil sent to the first outer oil chamber 46 is supplied to the cylinder hole 18 of the motor plunger 19 located in the expansion region Ex of the hydraulic motor M, while the high pressure hydraulic oil is supplied to the cylinder hole 18 of the hydraulic plunger M by the motor plunger 19 located in the contraction region Sh. The hydraulic oil is discharged from 18 to the inner oil chamber 45 as described above.

The output gear 3 is the sum of the rotational torque that the cylinder block 7 gives to the motor swash plate 20 via the motor plungers 19, 19 ... Group and the rotational torque that the motor plunger 19 gives to the motor swash plate 20 during the expansion stroke. The rotation torque is transmitted to the differential device Df.

Where n _{P is} the number of pump plungers n _{M is} the number of motor plungers 19 d _{P is} the diameter of pump plunger 9 d _{M is} the diameter of motor plunger 19 D _{P is} the pitch circle diameter of pump plunger 9 groups D _{M is the} motor Pitch circle diameter of the group of plungers 19 O _P ... Inclination angle of pump swash plate 10 with respect to vertical plane O _M ... Inclination angle of motor swash plate 20 with respect to vertical plane S _P ... Stroke of pump plunger 9 S _M ... Stroke of motor plunger 19 The number of revolutions of the input shaft 2 is the number of revolutions of the output cylinder shaft 25, and the gear ratio π can be obtained by the following equation.

Therefore, when the motor swash plate 20 is fixed to a constant tilt angle θ _M as in the illustrated example, if the tilt angle θ _P of the pump swash plate 10 is set to θ _P = 0, π≈1, that is, Ni≈ No, the direct connection is obtained.

When θ _P <0, π> 1, that is, Ni <No, and a speed-up state is obtained.

Then, Ni>No> 0 and a deceleration state is obtained.

If this is set, No = 0 regardless of Ni, and a neutral state can be obtained.

If it is set to No <0, a reverse rotation state is obtained.

The above is illustrated in FIG.

By the way, even in the direct connection state, unavoidable oil leakage from sliding parts exposed to high oil pressure, such as between the plungers 9 and 19 and the cylinder holes 8 and 18, between the distribution valves 55 and 56 and the valve holes 51 and 52, etc. The transmission efficiency is unavoidably deteriorated due to, and the frequency of use of No = Ni is high while the vehicle is driving. Therefore, in such a state, if the eccentric wheel 57 is controlled to the lockup position l, all the pump ports a, a ... Are closed by all the first distribution valves 55, 55 ... Since the oil passage between the pump P and the hydraulic motor M is cut off, the sliding portion exposed to high hydraulic pressure is significantly reduced, and the reduction in transmission efficiency due to oil leakage can be suppressed.

During operation of the hydraulic pump P and the hydraulic motor M, the pump swash plate 10
, And the motor swash plate 20 receive thrust loads in the opposite directions from the pump plungers 9, 9 ... Group, and the motor plungers 19, 19 ... group, but the thrust load received by the pump swash plate 10 is the thrust roller bearing 11 and the trunnion shaft. 12,
The thrust load that is transmitted to the input shaft 2 through the swash plate anchor 13, the thrust roller bearing 37 and the first thrust support plate 35, and that the motor swash plate 20 receives is the thrust roller bearing 26, the motor swash plate holder 27, and the thrust roller bearing. 40 and the second thrust support plate 36, and the same input shaft 2
Be transmitted to. Therefore, the thrust load only causes a tensile stress in the input shaft 2 and does not act on the casing C supporting the shaft 2 at all.

By the way, the pump plungers 9, 9 ... Group and the motor plungers 19, 19 ... Group are displaced from each other in the circumferential direction of the cylinder block 7, and the motor plungers 19, 19 ...
Since the inscribed circles of the group are arranged so as to pass through the pump plungers 9, 9 ... Group, the pump plungers 9, 9 ... Group and motor while ensuring sufficient wall thickness of the partition wall between the adjacent cylinder holes 8, 18 The plungers 19, 19 ... Group can be arranged close to each other, and as a result, the axial dimension of the cylinder block 7 can be greatly reduced by only slightly increasing the diameter.

This is extremely effective for downsizing, especially in the case of the para unit U in which the engine E and the transmission T are arranged in the axial direction.

Further, by adopting the second distribution valves 56, 56 that reciprocate in the axial direction, the second diameter is increased by slightly increasing the diameter of the cylinder block 7.
It is possible to install the distribution valves 56, 56 ..., By which the axial dimension of the cylinder block 7 can be further reduced. Moreover, the valve swash plate 62 that drives the second distribution valves 56, 56 ...
Is disposed so as to surround the motor swash plate 20, so that the valve swash plate 62 does not increase the axial dimension of the transmission T.

In FIGS. 2 and 6, the cylinder block 7 includes
Further, one or a plurality of third valve holes 65 (three in the illustrated example) extending parallel to the second valve holes 52, 52 are provided. The valve hole 65 extends so as to traverse the first and second outer oil chambers 46 and 47, and the inner end is closed and the outer end is opened to the right end surface of the cylinder block 7. A spool type clutch valve 66 is slidably fitted in the valve hole 65.

The clutch valve 65 has an annular groove 67 on the outer circumference of the valve head protruding from the right end surface of the cylinder block 7, and an inner actuating member slidably fitted on the outer peripheral surface of the cylinder block 7 is engaged in the annular groove 67. The inwardly bent claw 68a of the ring 68 is engaged. An outer working ring 69 surrounding the inner working ring 68 is connected to the inner working ring 68 via a release bearing 70.
A pinion 72 is meshed with a rack 71 which is provided at one end of 69 and extends in the axial direction thereof. The pinion 72 is rotatably supported by the swash plate anchor 13, and a clutch lever 73 is fixed to one end of the pinion 72.

When the pinion 72 is rotated by the clutch lever 73 to move the outer operating ring 69 to the left or right, the clutch valve 66 is moved to the left clutch-on position via the release bearing 70 and the inner operating ring 68 even when the cylinder block 7 is rotating. It is possible to shift to the clutch-off position on the right side (the position indicated by the chain line in FIG. 2) and the position indicated by the solid line in FIG. Thus, the clutch valve 66
At the clutch-on position, the first and second outer oil chambers 46, 47 are
The two oil chambers 46, 47 are communicated with each other at the clutch-off position. When communicating between the oil chambers 46, 47, the first outer oil is passed from the hydraulic pump P through the first distribution valve 55. The high pressure hydraulic oil supplied to the chamber 46 is the low pressure second outer oil chamber 47.
Immediately, the hydraulic pump P is short-circuited and the hydraulic pump P is short-circuited. Therefore, the clutch-off state in which the hydraulic transmission from the hydraulic pump P to the hydraulic motor M is cut off is obtained.

As shown in FIG. 9, in the clutch valve 66, one or a plurality of cutouts 74 are provided at the edge of the land 66a that controls the opening and closing of the oil chambers 46, 47 between the oil chambers 46, 47. Is provided. The notch 74 is provided in both the oil chambers 46, 47 when the clutch valve 66 is switched from the clutch-off position to the clutch-on position.
It is possible to finely control the communication between the two, whereby the half-clutch state can be accurately obtained.

Referring again to FIGS. 1 and 2, at the center of the input shaft 2, a main oil passage 75 having a deep stop is bored. The open end of the main oil passage 75 communicates with an oil sump 77 at the bottom of the casing C via a replenishment pump 76, and the replenishment pump 76 is driven by a drive gear 78 formed on the outer periphery of the first thrust bearing plate 35. . Therefore, while the input shaft 2 is rotating, the oil in the oil sump 77 is constantly fed to the main oil passage 75 by the replenishment pump 76.

The main oil passage 75 is communicated with the inner oil chamber 45 via a radial first supply hole 79 formed in the input shaft 2, and the main oil passage 75 extends from the inner oil chamber 45 to the first supply hole 79. A first check valve 81 is provided to prevent oil from flowing back in the direction of. This first check valve
81 is biased in the valve closing direction by a leaf spring 83 surrounding the input shaft 2.

The main oil passage 75 is also communicated with the first outer oil chamber 46 through a second replenishing hole 80 that is formed in the input shaft 2 and the cylinder block 7 and extends in the radial direction as a whole, and is connected to the second replenishing hole 80. Is
A second check valve 82 for preventing oil from flowing backward from the first outer oil chamber 46 to the main oil passage 75 is provided, and the check valve 82 is biased in a valve closing direction by a valve spring 84. To be done.

Therefore, during a normal output operation in which the hydraulic motor P is hydraulically driven from the hydraulic pump P, the main oil passage 75 to the first supply oil passage are
When the engine is braked by supplying hydraulic oil to the low-pressure inner hydraulic pressure 45 through 79 and hydraulically driving the hydraulic pump P from the hydraulic motor M, the main oil passage 75 through the second supply oil passage 80,
The hydraulic oil can be replenished to the first outer oil chamber 46 that has changed to a low pressure, and the leakage of the hydraulic oil from the hydraulic closed circuit can be compensated.

In FIGS. 3 and 10, the trunnion shaft 12 has:
A shift control device 85 for controlling the angle of the pump swash plate 10 is connected. This shift control device 85 has a sector gear 88 fixed to the other end of the trunnion shaft 12 by a bolt 86 and a pair of knock pins 87, 87, a worm gear 89 meshing with the sector gear 88, and a drive shaft 90 attached to the worm gear 89. It is composed of a DC electric motor 91 that can be connected forward and backward.
The worm gear 89 is rotatably supported by a gear box 93 fixed to the casing C with bolts 92 via bearings 94 and 95. Further, the stator of the electric motor 91 is fixed at a proper position of the casing C.

Thus, if the electric motor 91 is rotated in the normal direction or the reverse direction, the rotation is decelerated and transmitted from the worm gear 89 to the sector gear 88, and further transmitted to the trunnion shaft 12, which is directed in the standing direction of the pump swash plate 10 or It can be rotated in the tilt direction.

Further, when the electric motor 91 is stopped and the pump swash plate 10 is held at an arbitrary angle, the pump swash plate 10 moves to the motor plungers 19,1.
9 ... Even if a moment in the standing or tilting direction is received from the group and the moment is transmitted to the sector gear 88 via the trunnion shaft 12, the worm gear 89 cannot be driven from the sector gear 88, so both gears 88 and 89 are locked. In this state, the trunnion shaft 12 is not allowed to rotate, so that the pump swash plate 10 is securely held at the current position.

The transmission T may be reversed on the input and output sides, and the hydraulic pump P may be used as a hydraulic motor and the hydraulic motor M may be used as a hydraulic pump.

C. Effects of the Invention As described above, according to the present invention, the pump plunger group and the motor plunger group are concentrically arranged so that one plunger group surrounds the other plunger group, and Since the positions of both plunger groups are shifted in the circumferential direction of the cylinder block so that the tangent circle passes through the other plunger group, the axial dimension of the cylinder block is greatly shortened and the cylinder block is formed by concentric arrangement of both plunger groups. It is possible to suppress the increase in the diameter of the transmission as much as possible, which can greatly contribute to the downsizing of the entire transmission.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical cross-sectional rear view of an essential part of a power unit for an automobile including a hydrostatic continuously variable transmission to which the present invention is applied, and FIG. Fig. 3 is a vertical plan view, Fig. 3 is a sectional view taken along the line III-III in Fig. 2, Fig. 4 is a sectional view taken along the line IV-IV in Fig. 3, and Fig. 4A is an operation diagram shown in Fig. 4.
5 is a sectional view taken along the line VV of FIG. 2, FIG. 6 is a sectional view taken along the line VI-VI of FIG. 3, FIG. 7 is a sectional view taken along the line VII-VII of FIG. 2, and FIG. 2 is a sectional view taken along line VIII-VIII, FIG. 9 is an enlarged view of the clutch valve peripheral portion shown in FIG. 2 (however, shown in a half-clutch state), FIG. 10 is a sectional view taken along line XX of FIG. FIG. 11 is a diagram viewed from the arrow XI of FIG. 3, and FIG. 12 is a diagram showing the relationship between the inclination angle of the pump swash plate and the motor swash plate and the gear ratio. T ... continuously variable transmission, M ... hydraulic motor, P ... hydraulic pump, 2 ... input shaft as a transmission shaft, 7 ... cylinder block, 8 ... cylinder hole, 9 ... pump plunger, 10 ...
… Pump swash plate, 18 …… Cylinder hole, 19 …… Motor plunger, 20 …… Motor swash plate

Claims (1)

[Claims] 1. A swash plate type hydraulic pump and a hydraulic motor are connected to each other via a hydraulic closed circuit, and a pump plunger group of the hydraulic pump and a motor plunger group of the hydraulic motor are connected to a common portion with a transmission shaft at a central portion. In a hydrostatic continuously variable transmission in which each cylinder block is annularly arranged, the pump plunger group and the motor plunger group are concentrically arranged so that one plunger group surrounds the other plunger group and one plunger group is arranged. A hydrostatic continuously variable transmission characterized in that the positions of the two plunger groups are displaced in the circumferential direction of the cylinder block so that the inscribed circle of (2) passes through the other plunger group.