JP2515984B2 - Gear ratio control device for hydraulic continuously variable transmission for vehicle - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle hydraulic continuously variable transmission, and more particularly to a hydraulic circuit including a hydraulic pump connected to an input shaft and a variable displacement hydraulic motor connected to an output shaft. The present invention relates to a hydraulic continuously variable transmission that is connected with.

<Prior Art> As a continuously variable transmission of an automobile, a hydraulic cylinder formed by sliding a plurality of annularly arranged pump plungers surrounding a rotation center of a pump cylinder connected to an input shaft is connected to an output shaft. A motor cylinder is connected to a hydraulic motor that surrounds the center of rotation of the motor cylinder by sliding a large number of motor plungers arranged in a ring, and the motor cylinder and the pump cylinder are rotated relative to each other. A pump swash plate that reciprocates the pump plunger is provided on the motor cylinder, and the tilt angle is adjusted so as to reciprocate the motor plunger as the motor cylinder rotates and adjust the reciprocating stroke steplessly. 2. Description of the Related Art There is known a hydraulic continuously variable transmission in which a motor swash plate that can be changed steplessly is tiltably provided on a body frame.

In such a transmission, as disclosed in JP-B-32-7159 or JP-B-56-50142, the inclination angle of the motor swash plate is set to the minimum, that is, 0, and the gear ratio is reduced. Is controlled to be 1: 1.

At this time, by closing the hydraulic circuit that connects the discharge port of the hydraulic pump and the suction port of the hydraulic motor, the pump plunger is locked in the pump cylinder and the motor cylinder is mechanically driven via the pump swash plate. can do. By doing so, the discharge pressure of the hydraulic pump is prevented from acting on the motor plunger to reduce the thrust load on the motor swash plate, and at the same time,
It is possible to reduce oil leakage between the motor plunger and the motor cylinder.

Further, even when a shoe is provided at the tip of the motor plunger and hydraulic pressure is introduced to the sliding surface of the shoe to achieve hydraulic balance, the hydraulic pressure introduced to the sliding surface of the shoe is reduced by closing the hydraulic circuit described above. Further, oil leakage can be reduced.

That is, by closing the hydraulic circuit between the hydraulic pump and the hydraulic motor as described above, it is possible to improve not only the power transmission efficiency of the transmission but also the durability.
Conventionally, it is publicly known.

On the other hand, for example, JP-A-54-134252 or JP-A-
As disclosed in Japanese Laid-Open Patent Publication No. 55-14312, in order to achieve smooth and economical operation of a vehicle, the relationship between the throttle opening and the engine rotation speed should be kept in a certain predetermined proportional relationship. It is known that gear shift control is effective.

<Problems to be Solved by the Invention> However, as described above, if the hydraulic circuit is closed at the time of the minimum gear ratio by using the disconnecting device of the hydraulic circuit, the volumetric efficiency is improved as compared with before the closing. As shown in the equation, the phenomenon of decrease in engine rotation speed occurs.

That is, Therefore, in a vehicle in which gear shift control is performed by a function of the throttle opening and the engine speed, when the throttle opening is kept substantially the same, the following phenomenon will be repeated.

 The gear ratio becomes 1 (minimum tilt angle of the motor swash plate).

 The hydraulic circuit interrupter operates to close the circuit.

The engine speed decreases due to the improvement in volumetric efficiency.

The tilt angle of the motor swash plate is controlled so that the gear ratio is increased.

 The hydraulic circuit is closed.

 The gear ratio becomes 1 again.

To repeat the above operations 1 to 6 within a short time,
It is conceivable that the disconnecting device of the hydraulic circuit may cause a hunting operation and hinder the smooth running feeling of the vehicle.

The same thing may occur when the shift control is performed with the engine torque as the reference so that the minimum fuel ratio is obtained. That is, when the engine rotation speed decreases, the engine torque increases, and the inclination angle of the motor swash plate is controlled in the same manner as described above, and the hydraulic circuit interrupting device causes a hunting phenomenon accordingly.

In view of such inconveniences of the prior art, a main object of the present invention is to provide a hydraulic continuously variable transmission for a vehicle capable of suppressing the occurrence of the above-mentioned hunting phenomenon.

<Means for Solving Problems> According to the present invention, such an object is achieved by sliding a plurality of pump plungers annularly arranged around a rotation center of a pump cylinder connected to the input shaft. And a hydraulic motor comprising a motor cylinder connected to the output shaft, and a large number of annular motor plungers surrounding the center of rotation of the motor cylinder that are slidably engaged with each other and connected to the hydraulic pump by a hydraulic closed circuit. A cam mechanism that reciprocates the pump plunger according to the relative rotation of the motor cylinder and the pump cylinder; and a reciprocating motion of the motor plunger that causes the motor cylinder to rotate with the reciprocating copper of the motor plunger. A motor swash plate which is pivotally supported by a body frame so as to adjust the stroke steplessly and can change the tilt angle steplessly; Driving means for varying the tilt angle of the motor swash plate in response to the rotational speed of the engine driving the input shaft and the throttle opening, and the tilt angle of the motor swash plate in conjunction with the tilting motion of the motor swash plate. In a gear ratio control device for a hydraulic continuously variable transmission for a vehicle having a hydraulic circuit connecting / disconnecting means for closing a discharge port of the hydraulic pump and a suction port of the hydraulic motor when A swash plate angle sensor for detecting the vehicle inclination angle, a vehicle speed sensor for detecting the vehicle speed, and a swash plate angle sensor and a vehicle speed sensor based on signals from the swash plate angle sensor. And a holding means for holding the operation of the motor swash plate driving means when the vehicle is running at a speed equal to or higher than a predetermined vehicle speed suitable for running in a vehicle, and a gear ratio control device for a hydraulic continuously variable transmission for a vehicle is provided. Achieved by That.

<Operation> With this configuration, when the motor swash plate has a minimum inclination angle, that is, when the vehicle is in a traveling state with a minimum gear ratio (so-called stop traveling), the inclination angle of the motor swash plate varies even if the engine rotation speed changes. Since it can be controlled so as not to change, it is possible to avoid the occurrence of a hunting phenomenon that obstructs a smooth driving feeling and that the hydraulic circuit interrupting means repeats closing and opening in a short cycle.

<Embodiment> A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a hydraulic continuously variable transmission to which the present invention is applied. Case halves 1a are formed separately in the longitudinal direction,
A hydraulic pump P and a hydraulic motor M, which constitute a transmission, are built in the transmission case 1 formed by connecting the 1b.

The hydraulic pump P includes a pump cylinder 4 spline-coupled to an end 3 of the input shaft 2, and a large number of pump cylinders 4 provided on the pump cylinder 4 concentrically with the input shaft 2 in parallel with the input shaft 2. It has a cylinder hole 5 and a large number of pump plungers 6 slidably fitted in the cylinder hole 5, and is rotationally driven by the power of an engine (not shown) transmitted via a flywheel 7 connected to the input shaft 2. It

The hydraulic motor M includes a motor cylinder 8 which is provided so as to surround the pump cylinder 4, and a large number of cylinders which are provided in parallel with the input shaft 2 on a circumference concentric with the input side 2 of the motor cylinder 8. It has a hole 9 and a large number of motor plungers 10 slidably fitted in the cylinder hole 9, respectively, and is configured to be rotatable relative to the pump cylinder 4 concentrically.

A pair of support shafts 11 is provided at both ends of the motor cylinder 8 in the axial direction.
a and 11b are projected, and one support shaft 11a has a ball bearing 12
Is supported on the end wall of the right case half body 1b, and the other support shaft 11b is supported on the end wall of the left case half body 1a via a needle bearing 13.

One support shaft 1 protruding from the inner race 12a of the ball bearing 12
A stop ring 14 is attached to the outer end of 1a, and another stop ring 1 is attached to the outer end of the outer race 12b.
5 is mounted so as to engage with an annular recess 16 formed on the outer surface of the end wall, and further, a holding plate 17 that abuts the outer end surface of the outer race 12b is fixed to the axial end surface of the right case half body 1b by using a bolt 18. Has been done. In this way, the ball bearing 12 and the support shaft
11a is assembled integrally with the right case half body 1b while being prevented from moving in the axial direction.

A gear 19 is integrally formed on the other support shaft 11b, and a floating gear that meshes the output of the hydraulic motor M with the gear 19 is provided.
It can be transmitted to the differential gear device 21 via 20.

Inside the motor cylinder 8, each pump plunger 6
A pump swash plate 22 inclined at a predetermined angle with respect to is fixed to the pump shoe having an annular shape on the inclined surface.
23 is rotatably supported.

Each pump plunger 6 is formed with a bottomed hole 24 that opens toward the pump swash plate 22, and the connecting rod 25 inserted into this hole 24 is pumped via a ball joint 26a at its inner end. It is connected to the plunger 6 so as to be able to swing to some extent. Further, the connecting rod 25 projects from the bottomed hole 24 to the outside of the pump plunger 6, and is connected to the pump shoe 23 described above via a ball joint 26b formed at the projecting end thereof so as to be swingable. .

The annular pump shoe 23 has an outer peripheral surface supported inside the motor cylinder 8 via a needle bearing 27, and a step portion 23a formed on the inner peripheral portion of the pump shoe 23 on the pump plunger side. A spring in which a pressing ring 28 that abuts is compressed around the input shaft 2 via a spring holder 29.
Upon receiving the elastic force of 30, the pump shoe 23 is pressed against the pump swash plate 22. The spring holder 29 is slidably fitted to a spline portion 31 formed on the input shaft 2,
A spherical surface is in contact with the presser ring 28. Therefore,
The spring holder 29 can evenly contact the pressing ring 28 at any mounting position to transmit the elastic force of the spring 30.

In this way, the pump shoe 23 can always rotate and slide on the pump swash plate 22 at a fixed position.

Bevel gears 32 and 33 meshing with each other are fixed to the end faces of the pump cylinder 4 and the pump shoe 23, which mesh with each other, with the same number of teeth. These bevel gears 32, 33
When the pump cylinder 4 is driven from the input shaft 2 by the engagement of the above, the pump cylinder 4 rotationally drives the pump shoe 23 synchronously. With these rotations, the pump plunger 6 running on the upside of the inclined surface of the pump swash plate 22.
Is given a discharge stroke from the pump swash plate 22 via the pump shoe 23 and the connecting rod 25, and the pump plunger 6 running on the downward side of the inclined surface is given a suction stroke. That is, the pump swash plate 22 acts as a cam mechanism that reciprocates the pump plunger 6.

During this operation, due to the inclination of the pump swash plate 22, that is, the pump shoe 23, the ball joints 26a, 2 at both ends of the connecting rod 25 are
The rotation trajectories of the centers of 6b do not fit on the same cylindrical surface, but the connecting rod 25 moves the pump plunger 6 depending on the deviation of both rotation trajectories.
Since the ball joint 26a swings in the bottomed hole 24, the pump plunger 6 can be slid smoothly. Also, almost half of the many pump plungers 6 are always in the discharge stroke, and the high hydraulic pressure of the pump oil chambers on the back side of the pump plungers 6 presses the half circumference of the pump shoe 23 against the pump swash plate 22 via the connecting rod 25. The pressing force extends to the other half of the pump shoe 23. Therefore, the entire sliding surface of the pump shoe 23 is constantly pressed against the pump swash plate 22, and even if a sudden pressure drop occurs in the pump oil chamber on the suction stroke side for some reason, the pump shoe 23 A part of 23 is not lifted from the pump swash plate 22.

The pump shoe 23 has a recessed hydraulic pocket 34 at a position corresponding to each connecting rod 25 on the contact surface with the pump swash plate 22. In order to communicate the hydraulic pocket 34 with the oil chamber in the pump cylinder 4. In addition, the pump plunger 6, the connecting rod 25, and the pump shoe 23 are provided with a series of oil holes 35, 36, and 37. Therefore, during the operation of the pump cylinder 4, the pressure oil therein is supplied to the hydraulic pocket 34, and the pressure oil pressurizes the pump shoe 23 so as to bear the thrust applied to the pump shoe 23 from the pump plunger 6. Therefore, the pump shoe 23 can reduce the contact pressure with the pump swash plate 22, and at the same time, can lubricate the sliding surface between the pump shoe 23 and the pump swash plate 22.

Inside the mission case 1, each motor plunger is
The motor swash plate 38 is tiltably supported via a pair of trunnion shafts 39 protruding from both outer sides thereof so as to face the motor 10, and a motor shoe 40 slidingly contacting the inclined surface of the motor swash plate 38 is provided. A ball joint 10a formed at the outer end of each motor plunger 10 is swingably coupled.

Each motor plunger 10 reciprocates similarly to the pump plunger 6 described above, and rotates the motor cylinder 8 while repeating the expansion and contraction strokes. At this time, the stroke of the motor plunger 10 depends on the motor swash plate 38.
The inclination angle of 0 can be adjusted steplessly from 0 to maximum by changing from the upright position perpendicular to each motor plunger 10 to the maximum inclination position shown in the drawing, as will be described later.

The motor cylinder 8 is divided into the first divided into the axial direction.
-It is comprised from the 4th part 8a-8d. First part 8a
The support shaft 11b and the pump swash plate 22 are provided in the
Further, the second portion 8b is provided with a guide hole 41 for guiding the sliding of the motor plunger 10 in the cylinder hole 9, and the third and fourth portions 8c and 8d are provided with the cylinder portion. A series of oil chambers 42 having a diameter slightly larger than that of the guide holes 41 in the holes 9 are provided, and the third portion 8c is provided with a distributor plate 43 provided with oil passages to the cylinder holes 5 and 9. Make up and fourth
The above-mentioned one support shaft 11a is formed in the portion.

A coupling flange 44 is integrally formed at the end of the first portion 8a facing the second portion 8b, and a positioning hole formed at the end face of the second portion 8b facing the flange 44. 45
Is relatively tightly fitted to the second portion 8b by a plurality of bolts 46. Further, the second, third and fourth portions 8b, 8c, 8d are fitted with knock pins 47 at their joints to be positioned relative to each other, and are integrally joined by a plurality of bolts 48. There is.

The above-mentioned input shaft 2 has its outer end portion in the center of the other support shaft 11b of the motor cylinder 8 via the needle bearing 49,
The inner ends thereof are supported by the center of the distribution board 43 via needle bearings 50, respectively.

As described above, the spring 30 is contracted between the pump cylinder 4 and the spring holder 29, and the elastic force of the spring 30 presses the pump cylinder 4 against the distribution board 43 so that Of oil is prevented from rotating and sliding parts of the motor cylinder 8 and the spring holding member 29, the pressing ring 28, the pump shoe 23 and the pump swash plate 22 are supported inside the motor cylinder 8 by the elastic reaction force. are doing.

One support shaft 11a of the motor cylinder 8 is formed in a hollow shape, and a fixed shaft 51 is inserted in the center of the support shaft 11a.
A distribution ring 52 is fluid-tightly fitted to the inner end of the fixed shaft 51 via an O-ring, and the axial end surface of the distribution ring 52 is eccentrically slidably contactable with the distribution plate 43. There is. The distribution ring 52 divides the hollow portion 53 formed in the fourth portion 8d of the motor cylinder 8 into an inner oil chamber 53a and an outer oil chamber 53b.

The distribution board 43 is provided with a discharge port 54 and a suction port 55. The discharge port 54 communicates between the cylinder hole 5 of the pump plunger 6 in the discharge stroke and the inner oil chamber 53a, and also the suction port. By 55, the cylinder hole 5 of the pump plunger 6 in the suction stroke and the outer oil chamber 53b are communicated with each other. Further, a large number of communication ports 56 are formed in the distribution board 43 so that the cylinder hole 9 of the motor cylinder 8 is communicated with the hollow portion 53 in the fourth portion 8d.

In this way, a hydraulic closed circuit is formed between the hydraulic pump P and the hydraulic motor M via the distribution board 43 and the distribution ring 52. Therefore, when the pump cylinder 4 is driven from the input shaft 2, the high-pressure hydraulic oil generated by the discharge stroke of the pump plunger 6 is discharged from the discharge port 54 to the inner oil chamber 53a.
And through a communication port 56 in communication with this, into the cylinder hole 9 of the motor plunger 10 in the expansion stroke,
A thrust force is applied to the motor plunger 10. On the other hand, the hydraulic oil discharged by the motor plunger 10 in the contraction stroke flows into the cylinder hole 5 of the pump plunger 6 in the suction stroke through the communication port 56 communicating with the outer oil chamber 53b and the suction port 55. Due to such circulation of hydraulic oil, the sum of the reaction torque that the pump plunger 6 in the discharge stroke gives to the motor cylinder 8 through the pump swash plate 22 and the reaction torque that the motor plunger 10 in the expansion stroke receives from the motor swash plate 22. The motor cylinder 8 is driven by.

In this case, the gear ratio of the motor cylinder 8 to the pump cylinder 4 is given by the following equation.

From the above equation, it can be understood that the gear ratio can be changed from 1 to a required value by changing the capacity of the hydraulic motor M from 0 to a certain value.

By the way, the capacity of the hydraulic motor M depends on the motor plunger.
Since it is determined by 10 strokes, the motor swash plate
By inclining 38 from the upright position to a certain inclination angle as described above, the gear ratio can be continuously adjusted from 1 to a certain value.

A hydraulic change servomotor S1 as a first servomotor for tilting the motor swash plate 38 is provided in the upper part of the mission case 1. The change servomotor S1 includes a servo cylinder 58 fixed to the mission case 1, and a left side oil chamber 59 and a right side oil chamber 60 inside the servo cylinder 58.
Servo piston 61 that is divided into two parts, a piston rod 62 integrally formed with servo piston 61, and a valve hole formed from the end surface of servo piston 61 to piston rod 62.
It is composed of a first pilot valve 64 slidably fitted into the inside of 63.

The piston rod 62, which is integral with the servo piston 61, penetrates the servo cylinder 58 and has its end portion in the mission case 1.
The protruding end is pin-connected to the motor swash plate 38 via a connecting member 65.

A land portion 64a is formed at a tip portion of the first pilot valve 64 so that the land portion 64a can be closely fitted to the valve hole 63, and two diagonal surfaces are formed behind the land portion 64a in a certain axial direction. The recesses 64b are formed by being cut off along the dimension. A retaining ring 66 is fitted behind the concave portion 64b and comes into contact with a retaining ring 67 fitted on the inner peripheral surface of the servo piston 61 to prevent the retaining.

The servo piston 61 including the piston rod 62 has a first
The right oil chamber 60 has a valve hole according to the rightward movement of the pilot valve 64.
A drain passage 68 that can be opened to an oil tank (not shown) via 63, and a communication passage 69 that can communicate the right oil chamber 60 with the left oil chamber 59 according to the leftward movement of the first pilot valve 64 are provided. ing.

The left oil chamber 59 of the servo cylinder 58 is
It is communicated with the hollow portion 53 via an oil passage 70 formed in the peripheral wall of the above and an oil passage 71 formed in the holding plate 17, and pressure oil can be introduced from the hydraulic pump P.

From this state, when the first pilot valve 64 is moved to the right,
The land portion 64a closes the upper connecting path 69 and simultaneously opens the lower discharging path 68. Therefore, the pressure oil flowing in via the oil passages 70 and 71 acts only on the left-side oil chamber 59 and moves the servo piston 61 to the right.

Next, when the first pilot valve 64 is moved to the left 2, the land portion 64
Contrary to the above, a communicates the communication path 69 with the right oil chamber 60 and closes the discharge path 68 (the state shown in FIG. 1). Therefore, the pressure oil acts on both the left and right oil chambers 59 and 60, but the servo piston 61 is moved to the left due to the difference in pressure receiving area.

Also, if the first pilot valve 64 is stopped halfway, the servo piston 61 will move due to the pressure balance between the left and right oil chambers 59 and 60.
Becomes a hydraulic floating state and stops at that position.

In this way, the servo piston 61 is amplified by the operating hydraulic pressure from the hollow portion 53 so as to follow the movement of the first pilot valve 64, which causes the motor swash plate 38 to move to the first position.
From the maximum tilt position shown by the solid line in the figure, that is, the maximum gear ratio,
It is possible to shift steplessly to the minimum tilt position shown by an imaginary line in FIG. 1, that is, the minimum gear ratio.

A first link arm 72 is connected to an outer end portion of the first pilot valve 64 that protrudes through the holding plate 17. The first link arm 72 is connected to a cam mechanism C1 described later, and is remotely operated by a separate control signal.

As best shown in FIG. 2, a cylindrical bearing member 74 is coupled to the outer peripheral surface of the outer end portion of the fixed shaft 51 with a spline 73 having a relatively loose tolerance in the radial direction. . The minute gap formed between the outer peripheral surface of the bearing member 74 and the inner peripheral surface of the support shaft 11a is made uniform over the entire circumference by the oil film pressure of the operating oil, so that the bearing member 74 is supported with respect to the support shaft 11a. There is floating support.

On the fixed shaft 51, an annular projection 75 is provided over the entire circumference at a position facing the inner end of the bearing member 74 in the axial direction, and the projection 75 and the right case half 1b of the mission case 1 are provided. The axial movement of the bearing member 74 is regulated between the inner surface of the pressing plate 17 fixed to the outer end surface of the bearing member 74 and the inner surface of the holding plate 17.

At the portion near the annular protrusion 75, the bearing member 74 and the fixed shaft
No splice 73 is provided between the fixed shaft 51 and
An annular groove 76 is provided on the side. An O-ring 77 and a backup ring 78 as a sealing material are fitted in the annular groove 76.

The fixed shaft 51 is formed in a hollow shape, and its peripheral wall has short-circuit ports 79a, 7 that can communicate between the inner oil chamber 53a and the outer oil chamber 53b.
9b is projected. A cylindrical clutch valve 80 is fitted in the hollow portion of the fixed shaft 51 to open and close the ports 79a and 79b.

The clutch valve 80 is fixed after being radially and axially positioned by the radial needle bearing 81 for the fixed shaft 51 and the thrust needle bearing 82 for the holding plate 17. It is assembled so that it can freely rotate relative to the shaft 51, and on the inner wall of the inner wall,
Short-circuit holes 83a and 83b that can be aligned with the short-circuit ports 79a and 79b of the fixed shaft 51 are provided, and a rotation link 84 that is connected to a clutch control device (not shown) is formed at the outer end portion. By rotating this rotating link 84,
By changing the relative positions of the short-circuit holes 83a, 83b and the short-circuit ports 79a, 79b, the clutch-off state is set when the short-circuit ports 79a, 79b are fully opened, and the short-circuit ports 83a, 83b are displaced to open the short-circuit ports 79a, 79b. When the clutch is half-opened, the clutch is in the half-clutched state, and when the short-circuit ports 79a and 79b are fully closed, the clutch is in the fully-clutched state.
The ON state can be obtained respectively. That is,
In the illustrated clutch-off state, the discharge port 54
The hydraulic oil discharged from the internal oil chamber 53a from the short-circuit port 79
The hydraulic motor M is deactivated by directly flowing into the suction port 55 from the outer oil chamber 53b via a and 79b, and when the clutch is in the ON state, the above-mentioned short-circuit flow of hydraulic oil is blocked and the hydraulic pump P Circulates to the hydraulic motor M, and normal power transmission is performed.

An escape groove 85 is provided near the radial needle bearing 81 on the outer peripheral surface of the clutch valve 80, and the fixed shaft 51
It is designed so that no twisting or the like occurs even when the is bent.

At the center of the hollow clutch valve 80, a hydraulic circuit connecting / disconnecting servomotor S2 as a second servomotor is provided. The piston shaft 86 of the servomotor S2 is slidably fitted in the hollow hole of the clutch valve 80, and a valve rod 87 is screwed to the tip of the piston shaft 86. Valve rod
The tip of 87 is partially spherical, and the shoe 88
Are connected so that they can be swung freely.

When the piston shaft 86 slides to the left in FIG. 1, the shoe 88 liquid-tightly closes the open end of the discharge port 54 formed in the distribution board 43, and the oil inside the discharge port 54 is closed. The flow of hydraulic oil to the chamber 53a can be blocked. In this cut-off state, the pump plunger 6 is hydraulically locked, the hydraulic pump P and the hydraulic motor M are directly connected, and the pump cylinder 4 passes through the pump plunger 6 and the pump swash plate 22 and then the motor cylinder. 8 will be mechanically driven. This hydraulic pump P and hydraulic motor M
The direct connection state with the motor swash plate 38 is carried out at the minimum gear ratio with the motor swash plate 38 in the upright state, that is, at the top position. The thrust exerted on the plate 38 can be reduced, and the load applied to each member such as the bearing can be reduced.

The outer diameter of the piston shaft 86 is reduced by a step, and an oil chamber 89 is formed between the piston shaft 86 and the inner member 82a of the thrust needle bearing 82 that supports the clutch valve 80. The oil chamber 89 is normally provided with an oil passage 90 bored along the axial direction of the piston shaft 86, and an oil passage 91 bored at the center of the valve rod 87 so as to communicate with the passage 90. Through to communicate with the inside oil chamber 53a. When the engine is driven, part of the high-pressure hydraulic oil circulating between the hydraulic pump P and the hydraulic motor M is constantly supplied into the oil chamber 89 via the series of passages described above.

A piston portion 92 is integrally formed at an axially intermediate portion of the piston shaft 86. To the left of the piston portion 92, the inner surface of the hollow hole of the clutch valve 80 and the outer peripheral surface of the piston shaft 86 are formed. An annular chamber 93 is formed between them. Further piston shaft
At the center of 86, a blind hole 94 is formed from the outer end surface beyond the piston portion 92, and a clearance groove 95 is formed on the innermost surface of the blind hole 94. The non-stop hole 94 and the annular chamber 93 can be communicated with each other via a through hole 96a formed in the piston shaft 86 and the piston portion 92 in the vicinity of the inner end thereof in the radial direction. Further, in the vicinity of the outer end surface of the piston portion 92, a through hole 96 that allows the oil chamber 89 and the stop hole 94 to communicate with each other.
b is drilled.

A rod-shaped second pilot valve penetrating the holding plate 17 fixed to the end wall of the mission case 1 into the stop hole 94.
97 has been inserted. At the tip of the second pilot valve 97, a land portion 98 that is in close contact with the inner peripheral surface of the non-stop hole 94 and slides.
Is formed, and a small diameter portion 99 is formed on the right side of the land portion 98 with an appropriate axial dimension. Further, at the center of the second pilot valve 97, an atmosphere communication hole 100 that communicates the inside of the stop hole 94 with the atmosphere is formed. The outer end side of the second pilot valve 97 from the intermediate portion in the axial direction is stepped to reduce the diameter, and the stop ring 101 fitted to the inner peripheral surface of the outer end portion of the piston shaft 86 is brought into contact with the step portion. The contact defines the outward sliding distance of the second pilot valve 97. This second pilot valve 97 has a second link arm attached to its outermost end.
By the operation of the cam mechanism C1 coupled with the first pilot valve 64 of the change servomotor S1 via 102, the sliding operation is performed in the left-right direction.

 In the above configuration, the dimensions of each part are as follows: Pressure receiving area of the end face of the shoe 88: A Cross-sectional area of the piston part 92: B Inner end side pressure receiving area of the piston shaft 86: C Reduced diameter part of the piston shaft 86 It is set so that the inequality of A> B-D B-D> C is satisfied when the cross-sectional area: D.

When the second pilot valve 97 is moved to the left in FIGS. 1 and 2, the small diameter portion 99 of the second pilot valve 97 is located inside the stop hole 94 inside the right end surface 103 of the piston portion 92. Since the high pressure hydraulic oil from the discharge port 54 flows into the oil chamber 89 through the oil passages 91 and 90, its hydraulic pressure acts on the right end surface 103 of the piston portion 92 and at the same time, Five
It also acts on the left end face of the piston shaft 86 from the 3a side. This time,
The pressure receiving area of the right end surface 103 of the piston portion 92 is BD.
Further, since the pressure receiving area of the inner end face of the piston shaft 86 is C, from the relation of the inequality BD> C described above,
86 will move to the left. With the movement of the piston shaft 86, the shoe 88 comes into contact with the discharge port 54 of the distribution board 43, and the direct connection state between the hydraulic pump P and the hydraulic motor M is realized.

In this state, the high-pressure hydraulic oil from the discharge port 54 (equal pressure to the oil pressure in the oil chamber 89) acts on the end surface of the shoe 88 having the pressure receiving area A, while the pressure receiving area B of the piston portion 92 is applied.
The high-pressure hydraulic oil in the oil chamber 89 acts on the right end surface 103 having -D. By the way, both pressure receiving areas are
Because of the BD relationship, a force that moves the shoe 88 to the right acts on the shoe 88. When the shoe 88 slightly moves to the right, the hydraulic pressure on the end surface of the shoe 88 is released, and the shoe 88 is pressed against the end surface of the distribution board 43 again. In this way,
By setting the pressure receiving areas of A, B, and C to predetermined values so as to satisfy the above-mentioned inequalities, a so-called hydraulic floating state can be maintained, and the operation between the shoe 88 and the discharge port 54 can be maintained. It is possible to keep oil leakage to a minimum and maintain a good oil-tight state between them. Next, when the second pilot valve 97 is moved to the right, the small diameter portion 99 of the second pilot valve 97 comes out of the right end surface 103 of the piston portion 92 and the through hole 96 formed in the small diameter portion of the piston shaft 86.
communicate with b. As a result, high-pressure hydraulic oil
At the same time as the right end face 103 of the second, it acts on the inner end face of the piston shaft 86, and also acts on the left end face of the piston portion 92 through the through hole 96b, the small diameter portion 99, the communicating hole 96a and the annular chamber 93. Become.
At this time, the pressure receiving area for moving the piston shaft 86 to the left is B
In contrast to −D, the pressure receiving area for moving the piston shaft 86 to the right is B, and since B> B−D, the piston shaft 86 moves to the right, and the hydraulic motor M and the hydraulic pump P are separated. The locked state is released.

By the way, the supply of the hydraulic oil to the change servo motor S1 is performed by the first oil passage 10 formed in the fixed shaft 51.
The outer oil is passed through a passage communicating with the inner oil chamber 53a via the second oil passage 105 formed in the holding plate 17 and a third oil passage 106 separately formed in the fixed shaft 51. By switching a passage communicating with the chamber 53b with a shaft valve 107 made of a ball, the operation is performed from either the inner oil chamber 53a or the outer oil chamber 53b.

During acceleration and when the discharge port 54 of the hydraulic pump P is not closed, the pressure on the inner oil chamber 53a side is higher than that on the outer oil chamber 53b side. It is pressed against the opening of the passage 105, only the first oil passage 104 communicates with the oil passage 71, and the working oil on the inner oil chamber 53a side is supplied to the change servomotor S1.

When the discharge port 54 is closed during deceleration or acceleration, the pressure on the outer oil chamber 53b side becomes higher than that on the inner oil chamber 53a side. The second and third oil passages 1 are pressed against the opening of the first oil passage 104.
Only 05 and 106 communicate with the oil passage 71, and the hydraulic oil on the outer oil chamber 53b side is supplied to the change servomotor S1.

In this way, the supply of hydraulic oil to the change servomotor S1 is performed from the high pressure side in the hydraulic closed circuit, and a sufficient operating force can always be secured.

On the other hand, a supply pump F is provided outside the left case half 1a. The replenishment pump F is driven by the input shaft 2 to feed the working oil sucked from an oil tank (not shown) at a constant pressure, and its discharge port 108 is located at the center of the input shaft 2. It communicates with the discharge port 54 of the distribution board 43 and the outer oil chamber 53b via the drilled oil passage 109 and check valves 110 and 111, respectively. As a result, even if the hydraulic oil leaks from the closed hydraulic circuit of the hydraulic pump P and the hydraulic motor M, that portion can be automatically replenished from the replenishment pump F.

The right side surface of the transmission is covered with an end cover 112 to accommodate the cam mechanism C1 and the like.

Next, the control portion of the transmission will be described in detail mainly with reference to FIG.

The base end portion of the first link arm 72 connected to the first pilot valve 64 of the change servomotor S1 that tilts the motor swash plate 38 is fixed to the drive shaft 120. Drive shaft 1
The bearing 20 is rotatably supported at its both ends by bearings 121, 122 fixed to the pressing plate 17, and a drive cam 123 and a drive link arm 124 are fixed to both sides of the first link arm 72. It is set up.

Second pilot valve of servomotor S2 for hydraulic circuit disconnection 97
The base end portion of the second link arm 102 connected to is fixed to the driven shaft 125 arranged in parallel with the drive shaft 120 below the drive shaft 120. The driven shaft 125 is rotatably supported at both ends by bearings 122 and 126 fixed to the pressing plate 17, and includes a driven cam 127 that engages with the drive cam 123. Further, a stopper member 128 is fixedly provided on the holding plate 17 so that it can be brought into contact with the proper position of the second link arm 102, whereby the second ring arm 1
The arc movement range of 02 is specified.

The piston rod 129 of the hydraulic cylinder J is connected to the free end of the drive link arm 124. This hydraulic cylinder J is a cylinder 130 having a cylindrical shape with both ends closed.
And a partitioning of the inside of the cylinder 130 into a head chamber 131 and a rod chamber 132, a piston 133 slidably fitted in the cylinder, and a piston 133 formed integrally with the piston 133 and on the rod chamber 132 side. A piston rod 129 penetrating the end wall so as to be liquid-tight and movable in the axial direction. The piston rod 129 is moved together with the piston 133 by the action of the pressure oil supplied separately, whereby the drive shaft 1
It gives a rotational movement to 20.

The control valve DV for controlling the hydraulic cylinder J can change the direction and at the same time continuously change the degree of throttling, and has a neutral position. Hydraulic cylinder J
It is designed to control the amount of oil supplied and discharged.

This control valve DV includes a pump port Pp, a tank port Pt,
And a pair of output ports Pa and Pb.
Pa and Pb are connected to the input ports 135 and 136 of the head chamber 131 and the rod chamber 132 of the hydraulic cylinder J through pipes 137 and 138, respectively. The pump port Pp is connected to, for example, the gear pump 139 (which may be the replenishment pump F) with a pipe line 140, and the tank port Pt is connected to the oil tank 142 with a pipe line 141. Furthermore, the gear pump 139
Between the pump port Pp and the pump port Pp, a relief pipe line 143 that recirculates to the oil tank 142 is formed, and a relief valve 144 is provided in the pipe line 143, so that the pressure oil pumped from the gear pump 139 is supplied. By relieving the tank 142 as needed, the hydraulic pressure in the pipeline can be maintained within a predetermined range.

The gear pump 139 is connected to the engine E, pressure-feeds the working oil sucked from the oil tank 142, and the hydraulic governor 145 is connected to one end of the pump rotation shaft.

The hydraulic governor 145 has a gear pump 1 with its input port 145a.
The discharge port 140 of 39 is connected, and its output port 145b and the governor pressure input port Pg of the control valve DV are connected by a line 146. The governor oil pressure proportional to the rotation speed of the engine E is controlled by the control valve DV. It can be given to.

On the other hand, the control valve DV is equipped with a spool valve body 147 that is slidable back and forth in order to switch the flow direction of the pressure oil, and one end of the spool valve body 147 receives the discharge pressure of the gear pump 139 from the pump pressure input port Pi. It is made available for introduction.

Discharge pipe line 140 of gear pump 139 and pump pressure input port Pi
A switching solenoid valve EV is provided in a pipe line 148 that connects between and. This switching solenoid valve EV is a two-position three-way valve, and normally has a pump pressure input port Pi and an oil tank 142.
And the discharge line 140 of the gear pump 139 and the pump pressure input port Pi communicate with each other in an excited state.
The switching solenoid valve EV operates by inputting a signal from a control circuit Cc, which will be described later, to the solenoid 149.

The spool valve element 147 has an inner cylindrical surface 150 provided inside the control valve DV.
Three land portions 151 that are in close contact with each other, and the small-diameter portion 1 through which the hydraulic oil formed between the land portions 151 can flow.
52 and the above-mentioned ports Pa, Pb, Pp, and Pt are changed in relative positional relationship to change the flow rate and direction of the hydraulic oil, and the coil springs 153 having different spring constants are provided at both ends thereof. , 154 have been reduced.

One end portion 147a of the spool valve body 147 is reduced in diameter from the land portion 151, extends in the axial direction, and is in close contact with a guide hole 155 provided in the control valve DV. The pump oil chamber 156 formed between the one end 147a and the guide hole 155 communicates with the pump pressure input port Pi, and the end surface 151a of the land 151 on this side and the control valve DV are connected to each other. A governor oil chamber 157 formed between the inner cylinder surface 150 and the inner cylindrical surface 150 communicates with the governor pressure input port Pg. The oil pressures from these input ports Pi and Pg and the biasing force of the one coil spring 153 described above exert a rightward acting force Fr on the spool valve element 147.

Further, the coil spring 154 interposed on the other end side of the spool valve body 147 is configured so that the cam lever 158 connected to the accelerator pedal 159 can compress the flexure of the coil spring 154. The left acting force Fl on the spool valve element 147 increases as the valve is opened.

By the way, when the spool valve element 147 moves to the left in FIG. 3, it makes the pump port Pp and one of the output ports Pb connected to the rod chamber 132 communicate with each other, and at the same time makes the head chamber 131 and the tank port Pt communicate with each other. When the piston rod 129 of the hydraulic cylinder J is moved to the left to increase the inclination angle of the motor swash plate 38, and conversely to the right, the head chamber of the pump port Pp is moved.
The other output port Pa connected to 131 is communicated with the rod chamber 132 and the tank port Pt at the same time, and the piston rod 129 is moved to the right so as to reduce the inclination angle of the motor swash plate 38. . And as mentioned above,
The acting force Fl that moves the spool valve element 147 to the left increases in proportion to the throttle opening, and the acting force Fr that moves it to the right increases in proportion to the engine rotation speed. Therefore, the left acting force Fl
And the right acting force Fr are equal, the spool valve element 14
7 becomes neutral, hydraulic oil does not flow, the angle of the motor swash plate 38 is fixed, and in the state of Fr> Fl, the spool valve body 147 moves right and the tilt angle of the motor swash plate 38 decreases. When the gear ratio is reduced and Fr <Fl, the spool valve element 147 moves to the left and the tilt angle of the motor swash plate 38 increases,
The gear ratio is increased. That is, by the change servo motor S1, the hydraulic cylinder J, and the control valve DV described above, the motor swash plate 38 is adjusted according to the engine speed and the throttle opening.
Drive means for tilting and driving.

 Table 1 shows the relationship of the above operations.

The control circuit Cc for controlling the switching solenoid valve EV is, as shown in FIG. 4 well, an NPN connected in series to a solenoid 149.
Type transistor 170 and a resistor at the base of the transistor 170
A comparator 173 connected via 171 and 172, and a frequency-voltage converter connected to the non-inverting input terminal (+) of the comparator 173.
174, a reference value setting circuit 175 connected to the inverting input terminal (-) of the comparator 173, and a relay unit 176 for connecting / disconnecting the output signal from the comparator 173 to the ground.

A vehicle speed sensor 178 is connected to the frequency-voltage converter 174 via a waveform shaper 177.
An electric signal corresponding to the vehicle speed output from the waveform shaper 17
After molding at 7, the frequency-voltage converter 174 converts the voltage signal Ev proportional to the vehicle speed as shown in FIG.

The reference value setting circuit 175 includes a first voltage dividing resistor 180 connected to the reference power supply terminal 179 and a second voltage dividing resistor 180 connected in series to the resistor 180.
It consists of a voltage dividing resistor 181. And relay unit 1
Reference numeral 76 cuts off the contact 183 of the coil 182 in accordance with conduction to the coil 182. The coil 182 is interlocked with the hydraulic cylinder J for operation of the motor swash plate 38, and the inclination angle of the motor swash plate 38 is substantially minimum. Inclination sensor 1 consisting of contact point 184 that conducts when
It is connected to the + side power supply terminal 186 via 85.

The reference voltage of the comparator 173 is a value Eo obtained by dividing the voltage applied to the reference power supply terminal 179 by the voltage dividing resistors 180 and 181. The reference voltage Eo corresponds to the predetermined vehicle speed Vh on the relatively high speed side. (Fig. 5). Therefore, the voltage Ev corresponding to the vehicle speed is applied to the non-inverting input terminal (+) of the comparator 173, and the comparator 173 reaches the predetermined vehicle speed or more when the voltage Ev becomes the reference voltage Eo or more. Sometimes transistor 170 is conducting,
The current is output so as to excite the solenoid 149. On the other hand, when the tilt angle of the motor swash plate 38 is not substantially minimum, the contact 184 of the tilt angle sensor 185 does not close, so the contact 183 of the relay unit 176 remains closed, and the comparator 17
Even if current is output from 3, it will conduct to the ground,
The transistor 170 cannot be turned on and the solenoid 1
49 cannot be illustrated.

In this way, the inclination angle of the motor swash plate 38 is substantially minimized, and when the vehicle speed reaches a predetermined speed or higher, the solenoid 149 of the switching electromagnetic valve EV is excited.

As described above, the cam mechanism C1 includes the drive cam 123 that rotates integrally with the first link arm 72 connected to the first pilot valve 64 of the change servomotor S1 that operates the motor swash plate 38, and the hydraulic circuit. It is composed of a second link arm 102 connected to the second pilot valve 97 of the intermittent servomotor S2 and a driven cam 127 which rotates integrally with the second link arm 102.

As shown in FIG. 6, the drive cam 123 has a semi-circular portion 123a having a semi-circular arc centered on the drive shaft 120, a convex portion 123b partially protruding outward from the radius of the semi-circular portion 123a, and a semi-circular portion 123b. Circle part 123a
And a concave portion 123c that is partially recessed inward from the radius of, and has a contour that smoothly connects these three portions.

The driven cam 127 includes an arcuate portion 127a having a concave surface with a curvature substantially equal to that of the semicircular portion 123a, and a straight portion 127b extending from the arcuate portion 127a in a substantially tangential direction.

Next, the operation of the cam will be described with reference to FIGS. 6 to 8.

First, the case where the discharge port 54 is changed from the open state to the closed state will be described. In FIG. 6, the first pilot valve 64 is moved to the left, and accordingly, the motor swash plate 38 is changed servo. Motor S1 piston rod 62
To the maximum tilt position, that is, the maximum gear ratio.

In this state, the semi-circular portion 123a of the drive cam 123 and the arcuate portion 127a of the driven cam 127 are in contact with each other, and the second link arm 102 is in contact with the stopper member 128. 125 cannot rotate in either direction, and the second pilot valve of the servomotor S2 for hydraulic circuit disconnection
97 is held on the right side, and the discharge port 54 is held open.

Next, when the piston rod 129 of the hydraulic cylinder J is moved to the right, the drive cam 123 also rotates in the same direction as the drive shaft 120 rotates clockwise, but as shown in FIG. The driven cam 127 is not rotated until the 123b and the straight portion 127b of the driven cam 127 come into contact with each other, so that the second pilot valve 97 does not move and the opening of the discharge port 54 is maintained.

When the piston rod 129 further moves to the right, the convex portion 123b of the drive cam 123 pushes down the straight portion 127b of the driven cam 127, whereby the second link arm 102 rotates clockwise together with the driven shaft 125, and the second Move pilot valve 97 to the left. As a result, due to the action of hydraulic pressure as described above, the piston shaft 86 of the hydraulic circuit intermittent servomotor S2 moves to the left and the discharge port
54 is blocked.

In this state, the first pilot valve 64 of the change servomotor S1 is moved to the right, and therefore, as described above, the motor swash plate 38 is in the vertical state, that is, the minimum gear ratio,
Both ends of the driven cam 127 have a convex portion 123b and a concave portion 12b of the drive cam 123.
Rotation in either direction is blocked by 3c,
The closed state of the discharge port 54 is maintained. That is, the hydraulic circuit intermittent servomotor S2 and the cam mechanism C1 are interlocked with the tilting motion of the motor swash plate 38, and when the tilt angle of the motor swash plate 38 is substantially minimum, the discharge port 54 of the hydraulic pump P is A hydraulic circuit connecting / disconnecting means for closing the connection port 56 as the suction port of the hydraulic motor M is configured.

Conversely, when the drive cam 123 rotates counterclockwise, the recess 123c contacts the end 127c of the driven cam 127 and the second link arm moves the second pilot valve 97 to the right.
Rotate 102. During the transition from FIG. 8 to FIG. 7, the contours of both cams are determined so that the convex portion 123b and the straight portion 127b are not in contact with each other, so that when the gear ratio tends to increase, Immediately, the closure of the discharge port 54 can be released.

Next, the operation of the hydraulic continuously variable transmission shown in the above embodiment will be described mainly with reference to FIG.

When the accelerator pedal 159 is stepped on to start the vehicle from the stopped state, the throttle valve is opened according to the amount of stepping on the accelerator pedal 159, and the cam lever 158 interlocked with the accelerator pedal 159 causes the coil spring 154 of the control valve DV to move. Is compressed, and the left acting force F on the spool valve element 147 is
l increases. At this time, since the motor swash plate 38 has the maximum inclination angle (the maximum gear ratio), the switching solenoid valve EV is not excited and the governor oil pressure corresponding to the engine speed acts only on the governor pressure input port Pg. However, since the engine speed has not yet risen, the acting force on the spool valve element 147 is Fr <Fl, and the motor swash plate 38 is controlled in the tilt angle increasing direction. When the clutch valve 80 is closed here, the discharge oil of the hydraulic pump P starts to be supplied to the hydraulic motor M, and the vehicle starts.

When the governor oil pressure rises as the engine speed increases and the acting force on the spool valve body 147 becomes Fr> Fl, the spool valve body 147 of the control valve DV moves right and the piston rod 129 of the hydraulic cylinder J moves to the right. To move. As a result, the motor swash plate 38 includes the first link arm 72 and the first pilot valve.
64, and the change servomotor S1 is used to displace in a direction in which the gear ratio is decreased, and the traveling speed is increased.

Then, as the reduction ratio decreases, the engine load increases, and the increase in engine speed is suppressed.
The acting force on 147 is Fr ≦ Fl, but the gear ratio is controlled so that the engine rotation speed becomes substantially constant according to the opening degree of the throttle valve while repeating the operation shown in Table 1 within a minute time. .

Then, when the inclination angle of the motor swash plate 38 becomes the minimum (the gear ratio is minimum), the cam circuit C1 operates the hydraulic circuit connecting / disconnecting servomotor S2, and the discharge port 54 of the hydraulic pump P is closed.

At this time, if the vehicle speed is equal to or higher than the predetermined vehicle speed value Vh suitable for traveling with the minimum gear ratio, the solenoid 149 of the switching solenoid valve EV is excited by the action of the control circuit Cc described above, and the discharge pressure of the gear pump 139 is controlled. It is led to the pump oil chamber 156 of the valve DV.
As a result, the acting force on the spool valve element 147 is maintained at Fr <Fl regardless of the change in the engine rotation speed.
The minimum gear ratio position of the motor swash plate 38 is also held. Therefore,
The hunting operation of the servomotor S2 for intermittent hydraulic circuit does not occur. That is, the switching solenoid valve EV and the control circuit Cc described above actuate the motor swash plate driving means in the traveling state in which the tilt angle of the motor swash plate 38 is substantially minimum based on the signals of the swash plate angle sensor 185 and the vehicle speed sensor 178. A holding means for holding is configured.

If the traveling speed is lower than the specified value Vh, the switching solenoid valve EV
Since the solenoid 149 of the is demagnetized, the pump discharge pressure is not added to the right acting force Fr on the spool valve element 147, and the motor swash plate 38 is not locked, but the engine speed due to the closing of the hydraulic circuit Because the rate of decline is low,
Hunting operation of servo motor S2 for hydraulic circuit disconnection does not occur.

Note that the switching solenoid valve EV may cause hunting due to chattering of the contacts, but this can be avoided by adding a hysteresis circuit to the control circuit Cc.

FIG. 9 shows a second embodiment of the present invention. The parts corresponding to those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment, the governor oil pressure is constantly added from the governor pressure input port Pg as the right acting force Fr of the spool valve element 147, and the pump discharge pressure is switched under the condition where the predetermined conditions are met. The solenoid valve EV is actuated to add it to the right acting force Fr, but in this embodiment, the governor oil pressure and the pump discharge pressure are switched by the switching solenoid valve EV, and the spool valve element is input from the input port Pgi. It is designed to be added to the left end of 147.

Outside the specified operating condition range, only the governor oil pressure is added to the spool valve element 147, and when the specified condition is met, the switching solenoid valve EV is activated by the signal of the control circuit Cc and only the pump discharge pressure is spool valve. Add to body 147.

When adding governor oil pressure in this way, Fr ≤ Fl
Is set so that when the pump discharge pressure is applied, Fr
By setting so that> Fl, the same effect as that of the first embodiment can be obtained.

FIG. 10 shows a third embodiment of the present invention. The parts corresponding to those of the first and second embodiments described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, the cam lever 158 in the above embodiment is used.
In place of the left acting force Fl added by, the hydraulic pressure control valve 161 connected to the accelerator pedal 159 adds the throttle hydraulic pressure corresponding to the throttle opening to the right end of the spool valve body 147 from the throttle hydraulic pressure port Ps. The governor hydraulic pressure is always added as the right acting force Fr. In the case of the present embodiment, the switching solenoid valve EV, which is controlled in the same manner as in the above-mentioned embodiment, is adapted to connect and disconnect the throttle hydraulic line 160.

In the case of the present embodiment, outside the predetermined operating condition range, both the governor hydraulic pressure and the throttle hydraulic pressure act on the spool valve element 147 so that Fr ≦ Fl, but when the predetermined operating state is reached, The operation of the switching solenoid valve EV cuts off the throttle oil pressure to maintain the state of Fr> Fl, and the same effects as those of the first and second embodiments can be obtained.

As described above, when the vehicle speed is equal to or lower than the predetermined vehicle speed, the motor swash plate 38 is controlled according to the function of the throttle opening and the engine rotation speed, and when the vehicle speed is equal to or higher than the predetermined vehicle speed, regardless of fluctuations in the engine rotation speed. By holding the minimum tilt position of the motor swash plate 38, it is possible to prevent the servo actuator S2 for hydraulic circuit interruption from following the motor swash plate 38 and causing a hunting operation.

In the above embodiment, the spool valve element 147 of the control valve DV is controlled by the balance between the coil spring and the hydraulic pressure.
The motor swash plate 38 is thereby controlled, but this can be replaced with map control using a CPU, for example, and the hydraulic cylinder J is used as the actuator of the motor swash plate 38. However, it can be electrically controlled using a pulse motor or an electric linear actuator.

Further, the cam mechanism C1 for interlocking the change servo motor S1 and the hydraulic circuit connecting / disconnecting servo motor S2 is not limited to the above embodiment, and the interlocking operation can be performed in various modes. In addition to the interlocking operation by, the actuator for operating the motor swash plate and the actuator for disconnecting the hydraulic circuit may be separately provided.

Further, as the index indicating the driver's intention to accelerate or decelerate, not only the above-mentioned throttle opening or the stroke of the accelerator pedal but also the intake pipe negative pressure of the engine, the fuel supply amount, etc. may be detected.

The case where the shift control is performed based on the engine speed has been described above, but the present invention can be similarly applied to the case where the control is performed by the engine torque.

<Effects of the Invention> As described above, according to the present invention, the hunting operation of the motor swash plate can be prevented when the gear ratio is minimum, that is, when the vehicle is traveling at a constant speed at the so-called top. It is possible to avoid the occurrence of the hatching phenomenon, and it is very effective in further improving the running smoothness of the vehicle by the hydraulic continuously variable transmission.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hydraulic continuously variable transmission to which the present invention is applied. FIG. 2 is an enlarged view of the servomotor S2 for connecting and disconnecting the hydraulic circuit shown in FIG. FIG. 3 is a system diagram of the control device. FIG. 4 is a developed view of the control circuit shown in FIG. FIG. 5 is a graph showing the relationship between vehicle speed and output voltage. 6 to 8 are operation explanatory views of the cam mechanism. FIG. 9 is a hydraulic circuit diagram according to the second embodiment. FIG. 10 is a hydraulic circuit diagram according to the third embodiment. P …… hydraulic pump, M …… hydraulic motor S1 …… change servomotor S2 …… hydraulic circuit interrupting servomotor C1 …… cam mechanism, F …… replenishing pump CP …… control unit, J …… hydraulic cylinder DV… ... Control valve, EV ... Switching solenoid valve E ... Engine, Cc ... Control circuit 1 ... Mission case, 1a, 1b ... Case half 2 ... Input shaft, 3 ... End 4 ... Pump cylinder 5 ... Cylinder hole 6 ... Pump plunger, 7 ... Flywheel 8 ... Motor cylinder, 8a ... 1st part 8b ... 2nd part, 8c ... 3rd part 8d ... 4th , 9 …… Cylinder hole 10 …… Motor plunger 10a …… Ball joint 11a, 11b …… Spindle, 12 …… Ball bearing 12a …… Inner race, 12b …… Outer race 13 …… Needle bearing 14,15… … Stop ring 16 …… Annular recess, 17 …… Holding plate 18 …… Bolt 19 …… Gear 20 …… Floating gear, 21 …… Differential gear device 22 …… Pump swash plate, 23 …… Pump shoe 23a …… Step portion, 24 …… Bottomed hole 25 …… Connecting rod 26a, 26b… … Ball joint 27 …… Needle bearing, 28 …… Pressing ring 29 …… Spring holder, 30 …… Spring 31 …… Spline part, 32,33 …… Bevel gear 34 …… Hydraulic pocket, 35,36,37… … Oil hole 38 …… Motor swash plate, 39 …… Trunnion shaft 40 …… Motor shoe, 41 …… Guide hole 42 …… Oil chamber, 43 …… Distribution board 44 …… Connection flange, 45 …… Positioning hole 46… … Bolts, 47 …… Knock pins 48 …… Bolts, 49, 50 …… Needle bearings 51 …… Fixed shafts, 52 …… Distribution rings 53 …… Hollow part, 53a …… Inside oil chamber 53b …… Outside oil chamber, 54 …… Discharge port 55 …… Suction port, 56 …… Connection port 58 …… Servo cylinder, 59 …… Left oil chamber 60 …… Right oil chamber, 61 …… Servo piston 62 …… Pis Rod 63, valve hole 64, first pilot valve 64a, land portion, 64b, concave portion 65, connecting member, 66, 67, retaining ring 68, discharge passage, 69, connecting passage 70, 71 ... Oil passage, 72 ... First link arm 73 ... Spline, 74 ... Bearing member 75 ... Annular ridge, 76 ... Annular groove 77 ... O-ring, 78 ... Backup ring 79a, 79b ... … Short-circuit port 80 …… Clutch valve 81 …… Radial needle bearing 82 …… Thrust needle bearing 83a, 83b …… Short-circuit hole 84 …… Rotating link, 85 …… Escape groove 86 …… Piston shaft, 87 …… Valve rod 88 …… shoe, 89 …… oil chamber 90, 91 …… oil passage, 92 …… piston section 93 …… annular chamber, 94 …… stop hole 95 …… escape groove, 96a, 96b …… through hole 97… … Second pilot valve 98 …… Land part, 99 …… Small diameter part 100 …… Atmosphere communication hole, 101 …… Retaining ring 102 …… Link arm, 103 …… Right end surface 104 …… First Oil passage, 105 …… Second oil passage 106 …… Third oil passage, 107 …… Shuttle valve 108 …… Discharge port, 109 …… Oil passage 110,111 …… Check valve 112 …… End cover, 120 …… Drive shaft 121,122 …… Bearing, 123 …… Drive cam 123a …… Semi-circular part, 123b …… Convex part 123c …… Concave part, 124 …… Drive link arm 125 …… Drive shaft, 126 …… Bearing 127 …… driven cam, 127a …… arc-shaped part 127b …… straight part, 127c …… end part 128 …… stopper member, 129 …… piston rod 130 …… cylinder, 131 …… head chamber 132 …… rod chamber, 133 …… Piston 134 …… Solenoid 135,136 …… Input port 137,138 …… Pipe line, 139 …… Gear pump 140,141 …… Pipe line, 142 …… Oil tank 143 …… Relief line, 144 …… Relief valve 145 …… hydraulic governor, 145a …… input port 145b …… output port, 146 …… pipe line 147 …… spool valve, 147a …… end 148 …… pipe line, 149… 150 …… Inner cylinder surface 151 …… Land portion, 151a …… End surface 152 …… Small diameter portion 153,154 …… Coil spring 155 …… Guide hole, 156 …… Pilot oil chamber 157 …… Governor oil chamber, 158 …… Cam lever 159 ...... Accelerator pedal 160 ...... Throttle hydraulic line 161 ...... Hydraulic pressure control valve 170 ...... NPN transistor 171, 172 ...... Resistance, 173 ...... Comparator 174 ...... Frequency-voltage converter 175 ...... Reference value setting circuit 176 ...... Relay unit 177 …… Wave shaper, 178 …… Vehicle speed sensor 179 …… Reference voltage terminal, 180,181 …… Voltage resistance 182 …… Coil, 183,184 …… Contact 185 …… Swash plate angle sensor, 186 ... Power supply terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuya Maki 1-4-1 Chuo, Wako-shi, Saitama Honda R & D Co., Ltd. (56) References Japanese Patent Publication Sho 56-50142 (JP, B2)

Claims (1)

(57) [Claims] 1. A hydraulic pump comprising a pump cylinder connected to an input shaft and a plurality of annularly arranged pump plungers surrounding the center of rotation, and a motor cylinder connected to the output shaft. A plurality of annularly arranged motor plungers are slidably engaged with each other, and the hydraulic motor is connected to the hydraulic pump by a hydraulic closed circuit, and the motor cylinder and the pump cylinder are rotated relative to each other. A cam mechanism that gives a reciprocating motion to the pump plunger,
The motor cylinder is rotated in accordance with the reciprocating movement of the motor plunger, and the reciprocating stroke of the motor plunger is adjusted steplessly. A motor swash plate that can be driven, drive means that changes the tilt angle of the motor swash plate in response to the rotational speed of the engine that drives the input shaft, and the throttle opening, and tilting motion of the motor swash plate Gear shift of a hydraulic continuously variable transmission for a vehicle having a hydraulic circuit connecting / disconnecting means for closing a discharge port of the hydraulic pump and a suction port of the hydraulic motor when the inclination angle of the motor swash plate is substantially minimum. In the ratio control device, a swash plate angle sensor that detects an inclination angle of the motor swash plate, a vehicle speed sensor that detects a vehicle speed, and the motor based on signals of the swash plate angle sensor and the vehicle speed sensor. A vehicle provided with holding means for holding the operation of the motor swash plate driving means in a traveling state at a predetermined vehicle speed or more suitable for traveling with a minimum swash plate inclination angle and a minimum gear ratio. Gear ratio control device for hydraulic continuously variable transmission.