JP3205597B2 - Hydrostatic continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block having a pump cylinder of a hydraulic pump and a motor cylinder of a hydraulic motor arranged coaxially and rotatably supported on a casing. The present invention relates to a hydrostatic continuously variable transmission in which at least one annular oil passage is formed on an inner peripheral side of a block.

[0002]

2. Description of the Related Art Conventionally, such a continuously variable transmission has been already known as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-237165.

[0003]

By the way, in the continuously variable transmission disclosed in the above publication, the annular oil is inserted between the cylinder block inserted and fixed in the center hole provided in the cylinder block and the cylinder block. Not only is the path formed, the structure of fixing the cylinder to the cylinder block is complicated,
A seal member for preventing leakage of hydraulic oil from the annular oil passage needs to be mounted on the outer surface of the cylindrical body. Therefore, it is conceivable to press-fit the cylinder into the cylinder block to simplify the fixing structure and reduce the number of parts by eliminating the need for a sealing member. However, when the cylinder is pressed into the cylinder block, a large force is applied. Is required, and it is hard to say that the assemblability is excellent.

The present invention has been made in view of such circumstances, and has as its object to provide a hydrostatic continuously variable transmission that facilitates dimensional control of a cylindrical body and improves assemblability. I do.

[0005]

According to the present invention, there is provided a cylinder block comprising a pump cylinder of a hydraulic pump and a motor cylinder of a hydraulic motor integrally and coaxially integrated with each other. Case made of metal
In a hydrostatic continuously variable transmission in which at least one annular oil passage is formed on the inner peripheral side of the cylinder block, both ends of the cylinder block
The axes that support the block on the casing are coaxial
A central hole is formed coaxially at the center of the cylinder block, and at least two annular protrusions are formed on the outer periphery of a cylindrical body formed of a non-ferrous metal having a larger thermal expansion coefficient than an iron-based metal. Parts are provided by forming an annular groove between each other, the outer diameter of the annular ridge at one end along the axial direction of the cylindrical body is set to a value that can be pressed into the center hole, and the remaining annular ridge is formed. The outer diameter creates a gap between the inner surface of the center hole at the time of assembly, but is set to a value close to the inner surface of the center hole in a use state, and the one annular ridge is press-fitted and inserted into the center hole. At least one annular oil passage is formed between the fixed cylinder and the cylinder block by the annular groove.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hydrostatic continuously variable transmission for a motorcycle will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. FIG. 1 is an enlarged cross-sectional plan view of a hydrostatic continuously variable transmission, and FIG.
3 is a sectional view taken along line 2-2 of FIG. 1, FIG. 3 is a sectional view taken along line 3-3 of FIG. 1, FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, FIG. FIG. 4 is a diagram showing thermal expansion characteristics of a cylinder block and a cylindrical body.

Referring to FIG. 1, a hydrostatic continuously variable transmission includes a constant displacement type swash plate type hydraulic pump P and a variable displacement type swash plate type hydraulic motor M which are connected to a low pressure passage during a normal load operation. The inner annular oil passage 1 becomes a high pressure passage during reverse load operation.
1, and is connected to form a closed hydraulic circuit via an outer annular oil passage 12 which becomes a high pressure path during normal load operation but becomes a low pressure path during reverse load operation.

The swash plate type hydraulic pump P includes an input cylinder shaft 14 having an input gear 13, a pump cylinder 16 rotatably supported on the inner peripheral wall of the input cylinder shaft 14 via a ball bearing 15, and a pump cylinder 16. A plurality of pump plungers 18 slidably fitted into a large number and an odd number of pump cylinder holes 17 provided in an annular arrangement around the rotation axis of the pump cylinder 16, respectively. Pump swash plate 1 that engages and abuts the front surface on the outer end
9 and a thrust bearing 20 and a radial bearing 21 to hold the pump swash plate 19 at a fixed angle with respect to the axis of the pump cylinder 16 about a virtual trunnion axis O ₁ orthogonal to the axis of the pump cylinder 16. And a pump swash plate holder 22 that supports the swash plate 19 through the swash plate. Thus, the pump swash plate holder 22
Are formed integrally with the input cylinder shaft 14.

When the input cylinder shaft 14 rotates, the pump swash plate 19 reciprocates the pump plungers 18 so that the suction and discharge strokes can be repeated.

The hydraulic motor M includes a motor cylinder 27 disposed coaxially with the pump cylinder 16 on the left side of FIG.
A plurality of motor plungers 29 are respectively slidably fitted in motor cylinder holes 28 provided in the motor cylinder 27 so as to surround the rotation axis thereof, and a front surface is engaged with an outer end of each motor plunger 29. In this case, the motor swash plate 30 to be contacted, the motor swash plate holder 33 for supporting the motor swash plate 30 via the thrust bearing 31 and the radial bearing 32, and the casing 44 for supporting the back surface of the motor swash plate holder 33. And a motor swash plate anchor 34 fixed to the motor. The motor cylinder hole 28 ...
Are formed in the motor cylinder 27 in the same number as the pump cylinder holes 17 in the hydraulic pump P. The opposing abutment surfaces of the motor swash plate holder 33 and the motor swash plate anchor 34 that are in contact with each other form a trunnion axis O ₂ parallel to the axis of the motor cylinder 27 and the virtual trunnion axis O _1.
Is formed in a spherical shape centering on the intersection with Moreover the motor swash plate holder 33 is supported on the motor swash plate anchor 34 as allow relative rotation around the trunnion axis O _2.

The motor cylinder 2 of the motor swash plate anchor 34
A cylindrical cylinder holder 35 is connected to the end on the 7 side, and a ball bearing 36 is interposed between the cylinder holder 35 and the outer periphery of the motor cylinder 27.

The motor swash plate 30 is rotated perpendicularly to the axis of the motor cylinder 27 by rotating the motor swash plate holder 33 around the trunnion axis O ₂ by a ball screw mechanism 38 connected to the pulse motor 37. Between the upright position and the maximum tilt position in which the motor plunger 29 tilts at a certain angle. Can be repeated.

The pump cylinder 16 and the motor cylinder 27 are integrally connected to each other to form a cylinder block B. The cylinder block B is provided with a coaxial output shaft 41 and a shaft 42 integrally. That is, the output shaft 41 is integrally provided from the center of the portion of the motor block 27 facing the motor swash plate 30 in the cylinder block B, and the center of the portion of the cylinder block B facing the pump swash plate 19 of the pump cylinder 16 is located. A shaft 42 is integrally formed with the output shaft 41 to protrude integrally therefrom.

The shaft 42 penetrates through the pump swash plate 19 and the pump swash plate holder 22, and has an angular contact ball bearing 43 between the shaft 42 and the pump swash plate holder 22, and the pump swash plate holder 22 and the casing 44. A ball bearing 45 is interposed between the two.

The output shaft 41 extends to penetrate the motor swash plate 30, the motor swash plate holder 33, and the motor swash plate anchor 34. The output sprocket 46 is fixed. An angular contact ball bearing 47 is interposed between the motor swash plate anchor 34 and the output shaft 41.

In the cylinder block B, a center hole 49 forming a replenishing oil passage 48 is provided coaxially through the shaft 42 and the output shaft 41, and one end of the center hole 49 is closed by a screw plug 50. Is done.

Pump cylinder hole 1 of pump cylinder 16
7 ... group and motor cylinder hole 28 of motor cylinder 27 ...
Between the group, an inner annular oil passage 11 is formed on the inner peripheral side of the cylinder block B, and an outer annular oil passage 12 concentrically surrounding the inner annular oil passage 11 is formed on the outer peripheral side of the cylinder block B. It is formed.

The inner annular oil passage 11 is provided with a cylinder block B
Is formed between the cylinder 51 and the cylinder block B which are inserted and fixed in the center hole 49. Also, the outer annular oil passage 12
The annular recess 5 provided on the outer periphery of the cylinder block B at a portion near the group of the pump cylinder holes 17 between the groups of the pump cylinder holes 17 and the group of the motor cylinder holes
2a, the pump cylinder holes 17 and the motor cylinder holes 28 between the groups are provided on the outer periphery of the cylinder block B at positions corresponding to the motor cylinder holes 28. A large number of individual concave portions 52b ... which are connected to the concave portion 52a in common,
Ring body 5 brazed to the outer periphery of cylinder block B
3 to form a common covering.

2 and 3, the inner peripheral annular oil passage 11 of the cylinder block B between the group of pump cylinder holes 17 of the pump cylinder 16 and the group of motor cylinder holes 28 of the motor cylinder 27. The same number of first and second valve holes 57 as the pump cylinder holes 17 are provided so as to radially penetrate the annular partition wall between the outer annular oil passage 12 and the ring body 53.
Moreover, the first valve holes 57 are arranged on the pump cylinder hole 17 group side, and the second valve holes 58 are arranged on the motor cylinder hole 28 group side.

The first valve holes 57 are provided with a spool type first.
A distribution valve 61 is fitted in the second valve hole 56, and a spool-type second distribution valve 62 is fitted in the second valve hole 56 in a slidable manner. A first eccentric wheel 63 surrounding the first distribution valves 61 is provided at an outer end of the first distribution valves 61, and a second eccentric surrounding the 62 is provided at an outer end of the second distribution valves 62. Wheel 6
4 are engaged via ball bear rigs 65 and 66, respectively. Moreover, the outer ends of the first distribution valves 61 are mutually connected by a first forcing wheel 67 concentric with the first eccentric ring 63, and the outer ends of the second distribution valves 62 are connected to the second eccentric ring 64. They are interconnected by a second concentric second forcing wheel 68.

The first eccentric wheel 63 is provided integrally with the input cylinder shaft 14.
Virtual trunnion as shown in FIG.
Axis O₁A predetermined distance from the center of cylinder block B along
Separation ε ₁Only placed eccentrically. Also, the second eccentric wheel 64
It is connected to the cylinder holder 35 and shown in FIG.
The trunnion axis O_TwoAlong the cylinder block
A predetermined distance ε from the center of B_TwoOnly eccentrically arranged.

Here, the operation of the first distribution valve 61 will be described. When relative rotation occurs between the input cylinder shaft 14 and the pump cylinder 16, ie, the cylinder block B, each first distribution valve 61 will be described.
Dispensing valve 61 is reciprocated between the radially inner position and outer position of the pump cylinder 16 to twice the eccentric distance epsilon ₁ as a stroke in the first valve hole 57 by the first eccentric ring 63. Then, as shown in FIG.
In the discharge region D, the first distribution valve 61 moves on the inward position side to communicate the corresponding pump cylinder hole 17 with the outer annular oil passage 12 and with the inner annular oil passage 11, thereby The operating oil is pumped from the pump cylinder hole 17 to the outer annular oil passage 12 by the pump plunger 18 during the discharge stroke. Further, in the suction area S of the hydraulic pump P, the first distribution valve 61 moves on the outer position side to connect the corresponding pump cylinder hole 17 to the inner peripheral annular oil passage 11 and to disconnect from the outer peripheral annular oil passage 12. Accordingly, the operating oil is sucked into the pump cylinder hole 17 from the inner annular oil passage 11 by the pump plunger 18 during the suction stroke.

The operation of the second distribution valve 62 will now be described.
Rotates, each second distribution valve 62 is moved by the second eccentric ring 64 between the radially inner position and the outer position of the cylinder block B in the second valve hole 58 with a stroke of a distance twice the eccentricity ε ₂ in the second valve hole 58. Is reciprocated. Thus, as shown in FIG. 3, in the expansion region Ex of the hydraulic motor M, the second distribution valve 6
2 moves on the inward position side, connects the corresponding motor cylinder hole 28 to the outer peripheral annular oil passage 12 and makes the motor cylinder hole 28 and the inner peripheral annular oil passage 11 non-communicable,
Thereby, high-pressure hydraulic oil is supplied from the outer peripheral annular oil passage 12 to the motor cylinder hole 28 of the motor plunger 29 during the expansion stroke. Further, in the contraction region Sh of the hydraulic motor M, the second distribution valve 62 moves to the outer position side to connect the corresponding motor cylinder hole 28 to the inner peripheral annular oil passage 11 and to connect the motor cylinder hole 28 and the outer peripheral annular passage. The motor plunger 2 during the contraction stroke is cut off between the oil passages 12.
Hydraulic oil is discharged from the motor cylinder hole 28 to the inner peripheral annular oil passage 12.

Thus, the cylinder block B is provided with a reaction torque that the pump cylinder 16 receives from the pump swash plate 19 via the pump plunger 18 during the discharge stroke, and a motor swash plate 30 via the motor plunger 29 during the expansion stroke. , And the rotation torque is output from an output sprocket 46 of the output shaft 41.

In this case, the output shaft 4 with respect to the input cylinder shaft 14
The speed ratio of 1 is: ｛speed ratio = 1 + (capacity of hydraulic motor M /
(The capacity of the hydraulic pump P). Therefore, if the capacity of the hydraulic motor M is changed from zero to a certain value, the gear ratio becomes 1
To some required value. In addition, since the capacity of the hydraulic motor M is determined by the stroke of the motor plunger 29, the speed ratio is set to 1 by tilting the motor swash plate 30 from the upright position to a certain tilt position.
From a certain value to a certain value.

Referring also to FIG. 4, on the outer peripheral portion of the cylinder block B, the first valve holes 57, which are adjacent to each other at equal circumferential intervals of, for example, 120 degrees.
57 and between the second valve holes 58, 58, the clutch valves 69 are reciprocally movable in a direction parallel to the axis of the cylinder block B and across the annular recess 52a of the outer annular oil passage 12. Is done. That is, three sliding holes 70... For slidably fitting the clutch valve 69 which is basically formed in a rod shape are formed in the outer peripheral portion of the cylinder block B in parallel with the axis of the cylinder block B. It is drilled at equal intervals in the circumferential direction. The cylinder block B has three communication ports extending in the radial direction such that the inner end is opened to the inner peripheral annular oil passage 11 and the outer end is closed by a ring body 53, and traverses the sliding holes 70. Hole 7
And three concave portions 72 formed by digging down the annular concave portion 52a of the outer peripheral annular oil passage 12 in a semicircular shape by spot facing.

One end of each of the clutch valves 69 is connected to the inner periphery of an operating wheel 73 surrounding the motor cylinder 27 in the cylinder block B. An operation shaft 74 movable along the axial direction of the cylinder block B is supported on the motor swash plate anchor 334.
The operation wheel 73 is connected to one end of the wheel 4 via a ball bearing 75.
Are linked. Further, the other end of the operation shaft 74 is connected to a rotation shaft 76 having an axis perpendicular to the axis of the cylinder block B and rotating in response to operation of a clutch lever (not shown).

The clutch valves 69 are provided with a clutch-on position for disconnecting between the communication holes 71 communicating with the inner annular oil passage 11 and the outer annular oil passage 12 by operating the clutch lever, and a clutch-on position. 4 to the right in FIG. 4 to communicate between the communication holes 71... And the outer annular oil passage 12, and further from the clutch off position to further advance the communication holes 71.
.. And the communication / discharge position where the communication holes 71... And the outer annular oil passage 12 are opened to the outside.

Referring again to FIG. 1, an oil filter 77 is fitted and fixed to the other end of the center hole 49 of which one end is closed by the screw plug 50 in the cylinder block B. The supply oil is supplied from the supply pump 79, and the supply pump 77 is driven by a gear 80 provided on the input cylinder shaft 14.

The cylinder block B is made of an iron-based metal such as SACM645.
The cylindrical body 51 inserted and fixed in the center hole 49 of the cylinder block B is made of a non-ferrous metal, such as an aluminum alloy, which is softer and has a larger thermal expansion coefficient than the ferrous metal.

In FIG. 5, first, second and third annular ridges 82, 83 and 84 are provided on the outer periphery of the cylindrical body 51, and between the first and second annular ridges 82 and 83. The first annular groove 85 and the second and third annular ridges 8
A second annular groove 86 is formed between the third and third grooves 84, respectively.
In addition, the outer diameter of the third annular ridge 84 located at one end of the cylindrical body 51 on the rear side in the insertion direction into the center hole 49 among the annular ridges 82 to 84 is set when the cylinder block B is assembled. It is set to a value that can be pressed into the center hole 49 in the normal temperature state. The remaining first and second annular ridges 82, 8
As shown in FIG. 6, the outer diameter of No. 3 causes a gap δ between the inner surface of the center hole 49 in the normal temperature state at the time of assembly, but the difference in the amount of thermal expansion in the temperature in the used state after the assembly is completed. Is set to a value close to the inner surface of the center hole 49.

Therefore, when inserting and fixing the cylindrical body 51 into the center hole 49, only the third annular raised portion 84 may be pressed into the center hole 49.

By inserting and fixing the cylindrical body 51 into the center hole 49, the first annular groove 85 forms the inner annular oil passage 11 between the cylindrical body 51 and the cylinder block B. With the second annular groove 86, the annular communication oil passage 8
7 will be formed. Moreover, cylinder block B
The pump cylinder 16 is provided with a communication passage 88 for communicating the annular concave portion 52 a in the outer annular oil passage 12 with the annular communication oil passage 87.

In the cylindrical body 51, a communication hole 89 for avoiding the partitioning of the replenishing oil passage 48 by the cylindrical body 51 is formed at an eccentric position in an axial direction between both ends.

In the cylindrical body 51, an inner annular oil passage 11 is provided.
A first check valve 91 for preventing the backflow of the hydraulic oil from the oil supply passage 48 to the supply oil passage 48, and a second check valve 91 for preventing the backflow of the hydraulic oil from the outer peripheral oil passage 12 to the supply oil passage 48 from the annular communication oil passage 87
The check valve 92 and the outer annular oil passage 12, that is, the annular connecting oil passage 8,
7 and a pressure regulating valve 93 interposed between the inner peripheral annular oil passage 11
Are provided.

The first check valve 91 includes a valve seat member 94 fitted and substantially fixed in one end (the left end in FIG. 5) of the cylindrical body 51, the valve seat member 94 and the valve seat. Member 9
The valve seat member 9 housed between the retainers 97 connected to
4, a spherical valve element 95 which can be seated on the inner end side, and a valve seat member 9
4 and a valve spring 96 contracted between the retainer 97.

The second check valve 92 includes a valve seat member 98 fitted and substantially fixed in the other end (the right end in FIG. 5) of the cylindrical body 51, the valve seat member 98 and the valve. Seat member 9
8, a spherical valve element 99 housed between the retainers 101 and seated on the inner end side of the valve seat member 98, and a valve spring 100 contracted between the valve seat member 98 and the retainer 101.
And

The pressure regulating valve 93 forms an annular chamber 102 with the inner surface of the cylindrical body 51 and fits and is fixed in the cylindrical body 51. The valve housing 103 is slidably fitted in the valve housing 103 in the axial direction. It comprises a valve element 104 to be fitted, and a valve spring 105 contracted between the retainer 97 and the valve housing 103.

The valve seat member 98 of the second check valve 92 is prevented from coming out in the axial direction outward by a retaining ring 106 fitted to the inner surface of the other end of the cylindrical body 51 so as to be inside the cylindrical body 51. Is fitted to. The retainer 101 of the second check valve 92 and the valve housing 103 of the pressure regulating valve 93 are
The valve seat member 98 is sandwiched between a step provided on an inner surface of an intermediate portion in the cylindrical body 51 and the valve seat member 98. Thus, retainer 101
An oil chamber 107 is formed between the valve housing 103 and the annular communication oil passage 87. Also, the valve housing 103
An annular chamber 102 formed around the inner peripheral annular oil passage 11
Is communicated to. Thus, the second check valve 92 opens when the hydraulic pressure in the outer peripheral annular oil passage 12, that is, the annular communication oil passage 87 is reduced during engine braking, and supplies the operating oil in the supply oil passage 48 to the annular communication oil passage 87, The outer annular oil passage 12 is replenished. The pressure regulating valve 93 is connected to the annular communication oil passage 8.
7, that is, when the oil pressure of the outer annular oil passage 12 becomes equal to or higher than a predetermined value, the valve is opened, and the oil pressure of the annular communication oil passage 87 is reduced to the annular chamber 1
The valve body 104 has a function of allowing the valve body 104 to escape to the inner peripheral annular oil passage 11, and the valve body 104 penetrates the valve housing 103 slidably in the axial direction so that one end thereof faces the oil chamber 107.

The valve seat member 94 of the first check valve 91 is inserted into the cylindrical body 51 so as to be prevented from coming out in the axial direction outward by a retaining ring 108 fitted to the inner surface of one end of the cylindrical body 51. Mated. Moreover, the retainer 97 abutting on the cylindrical body 51 and the valve body 1 penetrating through the valve housing 103
Since the valve spring 105 is interposed between the cylinder 51 and the valve body 04, the valve spring 105 is substantially fixed in the cylindrical body 51. Further, an oil chamber 109 communicating with the inner annular oil passage 11 is formed between the valve housing 103 and the retainer 97. Thus, the first
The check valve 91 opens when the oil pressure in the inner peripheral oil passage 11 decreases, and supplies the hydraulic oil in the supply oil passage 48 to the inner annular oil passage 1.
Works to refill one.

Incidentally, the valve seat member 94 and the valve body 95 of the first check valve 91 and the valve seat member 9 of the second check valve 92 are provided.
8 and the valve body 99, and the valve housing 103 and the valve body 104 of the pressure regulating valve 93 are formed of a hard iron-based metal different from the cylindrical body 51 made of an aluminum alloy. 91, 92, 9
The generation of chips and abrasion powder due to the operation of 3 is prevented.

Next, the operation of this embodiment will be described. The inner peripheral annular oil passage 11 and the annular communication oil passage 87 are formed between the cylinder block B, and are inserted and fixed in the center hole 49 of the cylinder block B. Since the cylindrical body 51 is made of a relatively soft material such as an aluminum alloy, the cutting of the cylindrical body 51 becomes easy.

Further, only the third annular ridge 84 of the first, second and third annular ridges 82 to 84 provided on the outer periphery of the cylindrical body 51 is press-fitted into the center hole 49 to thereby provide a cylindrical body. Since 51 is inserted and fixed in the center hole 49,
The frictional resistance at the time of press-fitting can be kept relatively small, and the assemblability can be improved.

The first and second annular ridges 82, 83
Is in close contact with the inner surface of the center hole 49 due to the difference in thermal expansion from the cylinder block B when the hydrostatic continuously variable transmission M is in use.
Like that. That is, the first and second annular ridges
When assembling the outer diameter of 82 and 83 and the inner diameter of center hole 49
Is the difference between the two thermal expansions when the transmission is in use.
Because it is set to be smaller than the difference,
When standing, the first and second annular ridges 82 and 83 have center holes.
A gap is created between the inner surface and the center hole in use.
49 It is possible to make
In use state the required sealing property between the inner peripheral annular oil passage 11 and the annular communication oil passage 87 can be secure. In addition, hydrostatic
In the normal temperature state of the continuously variable transmission M, the internal
Many sealing properties between the peripheral annular oil passage 11 and the annular connecting oil passage 87
Although slightly reduced, as described above, when the transmission M is in use.
There is no practical problem because the required sealing properties are ensured.

Further, the first check valve 9 is provided in the cylindrical body 51.
By providing the first and second check valves 92 and the pressure regulating valve 93, the valves 91, 92, and 93 can be unitized, and the unitization facilitates the operation check of each of the valves 91 to 93. As compared with the cylinder block B disposed at another position, assemblability and workability can be improved.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various small design changes can be made without departing from the present invention described in the appended claims. Can be performed.

[0048]

As described above, according to the present invention, a center hole is provided coaxially at the center of the cylinder block, and the outer periphery of the cylindrical body formed of a non-ferrous metal having a larger thermal expansion coefficient than an iron-based metal. At least two annular ridges are formed so as to form an annular groove therebetween, and the outer diameter of the annular ridge at one end along the axial direction of the cylindrical body is set to a value capable of being press-fit into the center hole. The outer diameter of the remaining annular ridge causes a gap with the inner surface of the center hole during assembly, but is set to a value close to the inner surface of the center hole in a used state, and the one annular ridge is press-fitted. inserted into the center hole Te, between the cylindrical body and the cylinder block to be fixed, at least one annular oil passage is formed by the annular grooves, a plurality of annular ridge
Only the one end of the raised portion is pressed into the center hole.
The required sealing of the remaining annular ridge in use is
The frictional resistance during press-fitting of the cylinder is relatively
It is possible to improve the assemblability while keeping the size small.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional plan view of a hydrostatic continuously variable transmission.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is an enlarged view of a main part of FIG. 1;

FIG. 6 is a diagram showing thermal expansion characteristics of a cylinder block and a cylindrical body.

[Explanation of symbols]

 11 ... inner peripheral annular oil passage 16 ... pump cylinder 27 ... motor cylinder 49 ... central hole 51 ... cylindrical body 82, 83, 84 ································· Circular block M ···· Hydraulic motor P: Hydraulic pump

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isamu Isao 2-110 Kakuda-shi Gyukan, Kakuda City, Miyagi Prefecture (72) Inventor Hideki Sasaki 9-5, Nanikamachi, Furukawa City, Miyagi Prefecture (56) References JP Akira JP-A-63-163064 (JP, A) JP-A-63-140172 (JP, A) JP-A-62-237165 (JP, A) JP-A-4-95650 (JP, A) JP-A-4-203552 (JP, A) A) JP-A-4-203554 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 61/40 F04B 1/22

Claims (1)

(57) [Claims] 1. A pump cylinder (1) of a hydraulic pump (P).
6) A cylinder block (B) in which a hydraulic motor (M) and a motor cylinder (27) are coaxially and integrally connected.
Is made of iron-based metal and can rotate freely on the casing (44)
And at least one annular oil passage (11, 87) is formed on the inner peripheral side of the cylinder block (B), the both ends of the cylinder block (B) , The block
Shafts (41, 4) for supporting (B) on the casing (44);
2) are integrally formed coaxially, and a central hole (49) is provided coaxially at the center of the cylinder block (B), and is formed of a non-ferrous metal having a larger thermal expansion coefficient than an iron-based metal. At least 2
The two annular ridges (82, 83, 84) are formed so as to form annular grooves (85, 86) therebetween, and are provided outside the annular ridge (84) at one end along the axial direction of the cylindrical body (51). The diameter is set to a value that can be pressed into the center hole (49), and the outer diameter of the remaining annular ridges (82, 83) creates a gap between the inner surface of the center hole (49) during assembly. Is set to a value close to the inner surface of the center hole (49) in the use state, and the one annular protrusion (84) is pressed into the center hole (49).
At least one annular oil passage (1) is provided between the cylinder (51) inserted and fixed in the cylinder and the cylinder block (B).
1,87) are formed by the annular grooves (85,86).