JP2000225864A - Neutral holding mechanism of hydraulic continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly change the leak quantity of hydraulic oil by providing a hole provided on a plunger and a hole provided on a cylinder block so as to conform to each other at the condition in which the plunger is not vertically moved by rotation of an input shaft, and releasing hydraulic oil outward. SOLUTION: A circumferential groove 23 is carvedly provided on the slide face of the plunger 21e of a hydraulic pump, and the groove 23 is connected to an oil passage 23a formed as a communicating hole to the inner circumferential face of the plunger. A cylinder block 21b is provided with an oil passage 24 formed as a hole communicating the outer circumferential face of the plunger and the plunger slide face. The groove 23 and the oil passage 24 are constituted so as to communicate to each other when a movable swash plate 21c is on the neutral position. Namely the oil passage 23a provided on the plunger and the oil passage 24 provided on the cylinder block are provided so as to conform to each other when the plunger is not vertically moved by rotation of an input shaft, and hydraulic oil is released outward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for holding a neutral position of a hydraulic continuously variable transmission by a mechanical structure or a hydraulic circuit.

[0002]

2. Description of the Related Art Conventionally, a hydraulic continuously variable transmission (hereinafter referred to as HST) has been proposed.
A configuration is known in which a movable swash plate operating lever of an HST type transmission is held at a neutral position by a detent mechanism or the like provided outside the HST type transmission. Alternatively, a configuration is known in which a shift lever or the like connected to a movable swash plate operation lever is held at a neutral position by a guide. Further, in order to maintain the neutrality of the HST type transmission, there is known a configuration in which an orifice for releasing hydraulic oil to a charge circuit or the outside is opened from an oil passage connecting a hydraulic pump side and a motor side. In this configuration, when the angle of the swash plate is small, the hydraulic oil leaks from the orifice, the pressure does not rise, and the motor is not driven. Further, there is known a neutral valve type in which a valve is opened when a flow rate from a pump side is small and hydraulic oil is released to a charge circuit or the outside to stop supply of hydraulic oil to a motor and maintain neutrality.

[0003]

When the orifice type is used in the neutral holding mechanism of the HST type transmission,
Leakage of hydraulic oil from the pump side increases, and power transmission efficiency decreases. In the case of the neutral valve type, when the shock accompanying the opening and closing of the valve occurs, or when the HST type transmission is operated in the switching range of the valve, the flow of the hydraulic oil becomes unstable.

[0004]

In order to solve the above problems, the present invention proposes the following solutions. First, in a hydraulic stepless transmission including an axial plunger pump and a motor, a hole communicating with a pressure side end face is provided on a sliding surface of a plunger on a hydraulic pump side, and the plunger is inserted. A hole is provided in the plunger sliding surface of the cylinder block, and the hole provided in the plunger and the hole provided in the cylinder block are:
The hydraulic oil is released to the outside so that the plunger does not move up and down due to the rotation of the input shaft.

According to a second aspect of the present invention, in the hydraulic continuously variable transmission including the axial plunger pump and the motor, the position of the slide surface of the plunger where the hole is provided, the hole of the slide surface of the plunger of the cylinder block. An annular groove is provided at one or both of the positions where.

According to a third aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a valve plate located between a hydraulic pump or a motor-side cylinder block and an oil passage plate has a cylinder block end face. A pump communicating with the port is provided, and the hole is formed in the charge circuit or valve plate inside the oil passage plate, and the pump is on the opposite side of the hole connecting the plunger top dead center and bottom dead center.・ Communicate with the hydraulic oil circuit between motors.

According to a fourth aspect of the present invention, in the hydraulic stepless transmission including an axial plunger pump and a motor, a hole communicating with a port on an end face of the cylinder block is provided in a valve plate between the cylinder block on the hydraulic motor side and the oil passage plate. And the hole is provided near the position corresponding to the bottom dead center of the plunger of the valve plate in a configuration in which the hole communicates with a charge circuit inside the oil passage plate.

According to a fifth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a valve plate located between the cylinder block and the oil passage plate is provided on either the hydraulic pump or the motor side. A hole communicating with the port is provided, the hole is communicated with a charge circuit inside the oil passage plate, and a shut-off valve interlocked with at least a tilt angle of about 0 ° of the pump movable swash plate in the passage communicating with the charge circuit. Arranged and opened when the angle of the swash plate is around 0 °.

According to a sixth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a passage for a hydraulic oil circuit connecting the pump and the motor is provided, and at least a slope of the pump movable swash plate is provided in the middle of the passage. Angle 0
A shutoff valve communicating near ° is installed, and the swash plate opens near 0 °.

According to a seventh aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a valve plate located between a cylinder block on either the hydraulic pump or the motor side and an oil passage plate has a cylinder block end face. Provide a hole communicating with the port, and connect the hole between the pump and motor on the other side with a line connecting the plunger top dead center and bottom dead center between the hole and the valve plate hole. A shutoff valve communicating with the oil circuit and communicating with the pump movable swash plate at least at an inclination angle of about 0 ° is provided in the middle thereof, and the shutoff valve is opened and closed according to the angle of the swash plate.

According to an eighth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, the hydraulic swash plate is branched from a hydraulic oil circuit of an oil passage plate and guided to a movable swash plate rotation bearing surface, and the swash plate angle is adjusted. A hole is provided on the shaft so as to coincide with a hole communicating with the outside at around 0 °.

According to a ninth aspect of the present invention, there is provided a hydraulic stepless transmission comprising an axial plunger pump and a motor, wherein the cradle-type pump movable swash plate is operated by an operation lever having a bearing in a pump case. The torsion coil spring positioned by the shaft and the pin on the lever is supported by the pin on the side of the pump case, and the pin is eccentrically adjusted with respect to the pin mounting portion.

According to a tenth aspect of the present invention, there is provided a hydraulic stepless transmission having a charge pump on the opposite side of the axial plunger pump and an oil passage plate for forming a working oil passage for a motor, In the gap between the O-ring for seal part on the mounting surface of
An orifice hole communicating with the hydraulic oil circuit connecting the motors,
A hole communicating with a charge circuit or a charge pump discharge port is provided.

According to an eleventh aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, an oil groove having both ends closed is provided in a valve plate or an oil passage plate provided with a valve plate. An orifice hole communicating with the pump motor operating oil circuit and a hole communicating with the charge circuit were formed in the oil passage plate from the oil passage.

According to a twelfth aspect of the present invention, in the hydraulic stepless transmission having an axial plunger pump and a motor and configured to operate the pump movable swash plate, a lever for controlling the movable swash plate is provided in a direction parallel to the lever axis. And an intermediate lever slidably engaged with the two pins by two elongated holes of different directions, and operable from the outside, and the longitudinal position of the elongated hole of the intermediate lever is determined. It is regulated by the rotation angle of the intermediate plate.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention, the HST
A description will be given using a working vehicle equipped with a transmission. 1 is a side view of a work vehicle, FIG. 2 is a side view of the same, FIG. 3 is a side cross-sectional view of an HST-type transmission in which holes are formed in a plunger and a cylinder block, and FIG. Side sectional view,
FIG. 5 is a side sectional view of the HST type transmission, FIG. 6 is a partial side sectional view showing the configuration of a cylinder block, a valve plate, and an oil passage plate. FIG. 7 is a plan sectional view showing the structure of an oil passage plate.
FIG. 9 is a bottom view showing a configuration of a housing, a hydraulic pump and a hydraulic motor, FIG. 9 is a side sectional view of an HST type transmission device provided with a spool valve, FIG. 10 is a partial side sectional view showing an arrangement of a spool valve, FIG. Is a plan sectional view showing a configuration of an oil passage plate in which a spool valve is disposed, FIG. 12 is a plan partial sectional view showing a configuration of a spool valve and a sleeve, and FIG. 13 is another configuration of an HST type transmission in which a spool valve is disposed. FIG. 14 is a partial side sectional view showing the arrangement of another spool valve, FIG. 15 is a plan sectional view showing the configuration of a spool valve and a sleeve disposed on an oil passage plate, and FIG. 16 is an oil passage. FIG. 17 is a plan sectional view showing a configuration in which a spool valve, a sleeve and a valve element are provided on a plate, FIG. 17 is a partial side sectional view showing another configuration of the sleeve, and FIG. Side cross-sectional view showing another structure of the T-type transmission device, FIG. 19 is a plan sectional view showing the configuration of a spool valve and sleeve disposed in the oil path plate, 20 is a housing,
FIG. 2 is a bottom view showing a configuration of a hydraulic pump and a hydraulic motor.
1 is a side sectional view showing a configuration of a spool valve and a sleeve, FIG. 22 is a plan sectional view showing a configuration of a spool valve and a sleeve, FIG. 23 is a partially broken sectional view showing a configuration of a trunnion shaft portion of an HST type transmission, FIG. 24 is a partially broken cross-sectional view showing an oil passage configuration of a trunnion shaft portion, FIG. 25 is a side view showing an end of a movable swash plate and a bearing configuration, FIG. 26 is a bottom cross-sectional view showing a bearing configuration, and FIG. 29 is a diagram showing the relationship between the tilt angle θ of the trunnion shaft and the output rotation speed R, which are the operating characteristics of the HST transmission, FIG. 28 is a side sectional view of the HST transmission, and FIG.
Is a side view of the neutral holding mechanism, FIG. 30 is a hydraulic circuit diagram of the HST type transmission, FIG. 31 is a side sectional view of the HST type transmission,
32 is a bottom view showing the configuration of the charge pump, FIG. 33 is a plan sectional view showing the configuration of the oil passage plate at the position where the charge pump is provided, FIG. 34 is a side sectional view of the HST type transmission, and FIG. FIG. 36 is a plan sectional view showing the configuration of the oil passage plate at the position where the valve plate is disposed, and FIG.
7 is a plan view showing the configuration when the operation amount of the detent cam plate and the intermediate plate is 0, FIG. 38 is a side sectional view showing the configuration when the operation amount of the detent cam plate and the intermediate plate is 0, and FIG.
FIG. 40 is a diagram showing the configuration when the operation amount of the detent cam plate and the intermediate plate is 0, FIG. 40 is a diagram showing the configuration when the intermediate plate is rotated, and FIG. 41 is a diagram showing the configuration when the detent cam plate and the intermediate plate are rotated. FIG. The configuration of a working vehicle equipped with a rotary cultivator will be described with reference to FIGS. 1 and 2. A rotary tiller 2 is connected to the rear of the work vehicle 1, and the rotary tiller 2 is driven by a part of the output of the engine 3 of the work vehicle 1. In this work vehicle 1, a hood 6 is disposed at a front portion of a main body that suspends a front wheel 4 and a rear wheel 5 in front and back, and an engine 3 is disposed inside the hood 6. A steering handle 7 is provided behind the hood 6, and a seat 8 is provided behind the steering handle 7. A main transmission lever is protruded from the side of the seat 8. The steering handle 7 and the seat 8 are covered by a cabin 9.

A hydraulic continuously variable transmission (HST type transmission) 10 is disposed behind the engine 3 to transmit power from the engine 3 to the rear wheels 5 for driving. However, depending on the operation, a four-wheel drive that transmits the driving force to the front wheel 4 and the rear wheel 5 at the same time is also possible.

The driving force of the engine 3 is transmitted to a PTO shaft 11 protruding from the rear end of the HST type transmission 10 to drive the PTO shaft 11 to drive the rotary tiller 2 as a working machine connected to the rear end of the machine body. It is configured to be driven. A rotary tiller 2 is connected to the rear of the work vehicle 1, and a driving force is transmitted from the PTO shaft 11 to the rotary tiller 2 to drive the rotary tiller 2. The rotary cultivator 2 is connected to the work vehicle via the connection device 12, and the vertical position and the left and right inclination angles of the rotary cultivator 2 can be adjusted by an elevating device provided in the work vehicle 1. .

Next, a first embodiment of the configuration of the HST transmission 10 will be described. 3 and 4, the variable displacement hydraulic pump 21 and the hydraulic motor 22 are included in a housing 31 and are arranged on the same surface of an oil passage plate 32. The variable displacement hydraulic pump 21 has a drive shaft 21.
a, a cylinder block 21b into which the drive shaft 21a is inserted and which rotates together with the drive shaft 21a;
The plunger 21e is slidably inserted into the plunger 21b and the movable swash plate 21c is in contact with the plunger 21e. The movable swash plate 21c is configured to regulate the sliding amount of the plunger 21e and to adjust the discharge amount of the working oil of the variable displacement hydraulic pump 21. Center section 32
Is provided with an oil passage, and the variable displacement hydraulic pump 21
More hydraulic oil is supplied to the hydraulic motor 22 via the oil passage.

The hydraulic motor 22 is a variable displacement hydraulic pump 2
1, is inserted into the oil passage plate 32, and one end is inserted into the housing 3.
1, an output shaft 22a rotatably supported by 1, a cylinder block 22b into which the output shaft 22a is inserted and rotated together with the drive shaft 22a, a plunger 22e slidably inserted into the cylinder block 22b, and the plunger 22
e of the fixed swash plate 22c. The cylinder block 22b is configured to rotate together with the output shaft 22a, and a plunger 23e is slidably inserted into the cylinder block 22b. The plunger 23e is a fixed swash plate 23 fixed to the housing 31.
c. With the above configuration, the driving force is input to the driving shaft 21a, and the hydraulic pump 21 is driven. The hydraulic oil discharged from the hydraulic pump 21 is supplied to a hydraulic motor 22 via an oil passage plate 32, the hydraulic oil 22 is driven by the hydraulic oil, and the driving force is transmitted to an output shaft 22a.

A groove 23 is formed circumferentially on the sliding surface of the plunger 21e of the hydraulic pump 21, and an oil passage 23a communicating with the inner peripheral surface of the plunger is connected to the groove 23. The cylinder block 21b is provided with an oil passage 24 that communicates the outer peripheral surface of the plunger with the sliding surface of the plunger. The groove 23 and the oil passage 24 are
When c is in the neutral position, it is configured to communicate with each other. When the groove 23 and the oil passage 24 communicate with each other, the hydraulic oil inside the plunger 21e and outside the cylinder block 21b can enter and exit freely. Also, the plunger 21e
The groove 23 is formed on the sliding surface of the plunger 21e.
To prevent the oil film from running out of the sliding surface and maintain sufficient lubrication.
The durability of the hydraulic pump 21 can be improved. For this reason, when the movable swash plate 21c is near the neutral position and is located at a position where the groove 23 and the hole 24 are connected, the hydraulic oil flows into and out of the cylinder block 21b through the groove 23 and the hole 24. Therefore, hydraulic oil is not supplied from the hydraulic pump 21 to the hydraulic motor 22, and the hydraulic motor 22 is not driven.

Further, when the movable swash plate 21c is tilted to increase the sliding amount of the plunger 21e and the hydraulic motor 22 is driven, the sliding speed of the plunger 21e is high, and the time during which the holes 23a and 24 communicate with each other is reduced. And the amount of hydraulic oil flowing out through the holes 23a and 24 decreases. Further, since a part of the holes 23a and 24 is formed to have a small diameter and is configured to generate an orifice effect, as the plunger 21e slides quickly due to the viscosity of the hydraulic oil, the holes 23a and the holes 24 are formed. At 24, the hydraulic oil flows out or hardly flows. That is, the movable swash plate 21
even if c is not in a completely neutral position.
In the range where the groove 23 of 1e and the hole 24 of the cylinder block 21b communicate with each other, the neutral position in the operation of the movable swash plate 21c can be expanded without driving the hydraulic motor 22, and the hydraulic motor 22 is driven by the hydraulic pump 21. In this case, the leakage of hydraulic oil is reduced, and a decrease in drive efficiency can be prevented. Thereby, the operability of the HST transmission 10 can be improved without separately providing a neutral maintenance device outside.

Next, a second embodiment of the configuration of the HST transmission 10 will be described. As shown in FIGS. 5 to 8,
The cylinder blocks 21b and 22b are each provided with an oil passage plate 32.
Hydraulic oil flows from the hydraulic pump 21 into and out of the main circuits 32 m and 32 m via the valve plate 41, and is disposed via the valve plate 42. Hydraulic oil flows into and out of the hydraulic motor 22 from the main circuits 32m and 32m.
Check valves 4 are provided in the main circuit 32m, respectively.
4 is connected, and when the operating oil in the main circuit 32m is insufficient, the check valve 44 is connected to the oil passage 32c.
The working oil is replenished via.

In the center of the oil passage plate 32, the oil passage 4
3 is provided, and one end of the oil passage 43 is connected to the oil passage 32c. The oil passage 43 is connected to the drive shaft 21 of the oil passage plate 32.
In the arrangement position a, a circular groove is formed along the outer periphery of the bearing outer ring 32b inserted into the oil passage plate 32.
For this reason, the oil passage 43 can be easily formed in the oil passage plate 32. The other end of the oil passage 43 is connected to an oil passage 43b provided in a right angle direction, and the oil passage 43b is provided toward an end face of the hydraulic motor 22. Oil passage 43
The end b is connected to a hole 42b provided in the valve plate 42, and the hole 42b communicates the oil passage 43 with the sliding portion of the plunger 22e of the cylinder block 22b. The hole 42b is provided near the position corresponding to the bottom dead center of the plunger 22e of the hydraulic motor 22.
A part of b is configured to have a small diameter, and is configured to exhibit an orifice effect.

Since the oil passage 43, the oil passage 43b, and the hole 42b are formed as described above, the swash plate 21c of the hydraulic pump 21 is held near the neutral position, and a small amount of hydraulic oil is supplied to the hydraulic motor 2
2, the hydraulic motor 22 rotates if the resistance received by the hydraulic motor 22 is small, but the rotation causes the sliding portion of the plunger 22 e of the cylinder block 22 b of the hydraulic motor 22 and the hole of the valve plate 42 to rotate. 42b communicates, hydraulic fluid leaks and the hydraulic motor 22
Rotation stops. Thus, the HST transmission 10
Can easily maintain the neutral position. When the swash plate 21c is tilted and the hydraulic motor 22 is rotated by the hydraulic pump 21, the timing at which the hole 22f on the end face of the plunger block and the hole 42b coincide with each other is shorter than at the time of stop. For this reason, when the motor rotates, the leakage of the hydraulic oil is small, and a decrease in drive efficiency can be prevented.

Further, by providing the hole 42b from the right or left with respect to the position corresponding to the bottom dead center of the plunger,
It is possible to eliminate the leakage of hydraulic oil at the time of turning right or left, and when the hydraulic motor 22 is driven by external force,
Even if the rotation direction is the same, since pressure is generated in the main circuit 32m on the opposite side to the case where the hydraulic motor 22 is driven by the hydraulic oil from the hydraulic pump 21, the bottom dead center of the motor-side valve plate 42 is equivalent to the plunger. Hydraulic oil does not leak from the hole 42b provided in the vicinity of the position, and the stop torque required for the work vehicle equipped with the HST transmission 10 to stay on a slope or the like can be secured.

In the above configuration, a mechanism for shutting off the oil passage 43 may be provided to open the oil passage 43 when the angle of the swash plate 21c of the hydraulic pump 21 is near 0 °. is there. This will be described as a third embodiment of the neutral holding configuration of the HST type transmission 10. As shown in FIGS. 9 to 12, a spool valve 51 that slides in the same direction as the pump 21 and the motor 22 is disposed at a substantially intermediate position between the hydraulic pump 21 and the hydraulic motor 22 on the oil passage plate 32. The spool valve 51 is inserted into a sleeve 53 provided in the middle of the oil passage 43, and is slidable in the sleeve 53. An oil passage 43 is provided on the outer peripheral surface of the sleeve 53.
Notches 53b and 53b connected to the holes and holes 53c and 5 communicating the notches 53b with the inside of the sleeve 53.
3c is provided.

A large-diameter flat portion 51b is formed on the upper portion of the spool valve 51, and a circumferential groove 51c is provided on the outer peripheral portion of the lower portion of the spool valve 51. The spool valve 51 has a spring 52 inserted therein. The spring 52 comes into contact with the sleeve 53 and the flat portion 51b of the spool valve 51 to urge the spool valve 51 upward. Further, the spool valve 51 is provided with an oil passage 51d communicating the bottom surface and the upper side surface, and eliminates a pressure difference between the housing 31 and the sleeve 53 due to the sliding of the spool valve 51. It is configured to be able to slide smoothly. The movable swash plate 21 of the hydraulic pump 21 is provided on the flat portion 51 b of the spool valve 51.
One end of the movable swash plate 21c is in contact with the movable swash plate 21c, so that the spool valve 51 slides up and down. The housing 3 is located above the spool valve 51.
1 is provided with a stopper 31b which is integrally formed with and protrudes downward.
By contacting the flat portion 51b, the sliding amount of the spool valve 51 above is regulated. Thus, the spool valve 51 does not come off the sleeve 53.

When the movable swash plate 21c is located near the neutral position, the circumferential groove 51c of the spool valve 51 and the hole 53
c and 53c communicate with each other, and the oil passage 43 communicates with the oil passage 43b by the notch 53b, the hole 53c, and the circumferential groove 51c. Further, when the movable swash plate 21 c is located near the neutral position, the oil passage 43 b is shut off by the spool valve 51, so that the working oil of the hydraulic motor 22 does not leak into the oil passage 43. Therefore, the movable swash plate 2 of the hydraulic pump 21
When 1c is near the neutral position, the hydraulic oil of the hydraulic motor 22 leaks, the hydraulic motor 22 is not driven, and when the movable swash plate 21c is other than near the neutral position, the oil passage 43 is closed. It is shut off, the hydraulic oil of the hydraulic motor 22 does not leak, and the driving efficiency does not decrease.

Another configuration using the spool valve 51 will be described as a fourth embodiment of the neutral holding configuration of the HST type transmission 10. 13 to 17, a description will be given of a configuration in which the oil passage 61 communicating the main circuits 32m and 32m of the oil passage plate 32 is opened and closed to maintain the neutral position. A sleeve 63 is provided on the oil passage plate 32, and the spool valve 51 is inserted into the sleeve 63. The spool valve 51 is provided with the movable swash plate 21c.
The vertical position is determined by the tilt of. The sleeve 63 is disposed substantially at the center of an oil passage 61 communicating with the main circuits 32m. The sleeve 63 is provided with holes 63b communicating with the oil passage 61. One end of the oil passage 61 is sealed by a screw. As described above, the spool valve 51 is provided with a circumferential groove 51c at the lower portion. The spool valve 51 slides, and the circumferential groove 51c is
3b and 63b, so that the oil passage 61 communicates. The main circuit 32m is provided by the oil passage 61.
The hydraulic oil discharged from the hydraulic pump 21 is returned to the hydraulic pump 21 via the oil passage 61 without being supplied to the hydraulic motor 22 due to the communication of 32 m.

When the movable swash plate 21c of the hydraulic pump 21 is located near the neutral position, the oil passage 61 is connected by the spool valve 51, and the main circuits 32m and 32m are short-circuited. Supply of hydraulic oil to the motor stops, and the hydraulic motor 22 is not driven. When the movable swash plate 21c is tilted, the position of the spool valve 51 moves, the oil passage 61 is shut off by the spool valve 51, and hydraulic oil can be supplied from the hydraulic pump 21 to the hydraulic motor 22. The motor 22 is driven.
Thus, when the movable swash plate 21c is near the neutral position, the hydraulic motor 22 is not driven even if a small amount of hydraulic oil is discharged from the hydraulic pump 21.

As shown in FIG. 16, a valve body 65 can be provided in the oil passage 61 to regulate the direction of the hydraulic oil passing through the oil passage 61. Accordingly, even when the hydraulic motor 21 is driven from the outside, the operating oil does not pass through the oil passage 61, and the stop torque necessary for the work vehicle equipped with the HST transmission 10 to stay on a slope or the like is reduced. Can be secured.

As shown in FIG. 17, a thread groove may be formed at one end, and a sleeve 64 configured to be externally adjustable may be screwed onto the oil passage plate 32. In this case, by adjusting the position of the sleeve 64, the position of the spool valve 51 that leaks hydraulic oil into the oil passage 61 can be adjusted.
Further, the sleeve 64 can be adjusted from outside the oil passage plate 32, so that the adjusting operation can be easily performed.
Is improved. Fine adjustment of the positional relationship between the movable swash plate 21c and the spool valve 51 can be performed. Precisely movable swash plate 2
Hydraulic oil leaks at the neutral position 1c, and the drive of the hydraulic motor 22 at the neutral position can be stopped.

Another configuration using the spool valve 51 will be described as a fifth embodiment of the HST transmission 10. 18 to 22, a description will be given of a configuration in which the spool valve 51 opens and closes the oil passage 69 and the oil passage 67 that communicate the main circuit 32m of the oil passage plate 32 and the position corresponding to the bottom dead center of the plunger of the cylinder block 22b.
A notch 66b is provided on the outer peripheral surface of the sleeve 66, and the notch 66b communicates with the inner peripheral surface of the sleeve 66 through a hole 66c. The notch 66b is connected to an oil passage 67 provided in the oil passage plate 32, and the oil passage 67
Is connected to a hole 68b provided in the valve plate 42, and the hole 68b is connected to the recess 68. The hole 68b is provided on the right or left side of a straight line connecting the axis of the drive shaft 21a and the axis of the output shaft 22a. The sleeve 66
Is provided with a hole 66d communicating the outer peripheral surface and the inner peripheral surface of the sleeve 66 toward the oil passage 69 connected to the main circuit 32m. Holes 66c and 66 provided in sleeve 66
d indicates that the movable swash plate 21c is near 0 ° and the spool valve 51
The movable oil is leaked from the cylinder block 22b through the hole 68b, the oil passage 67, the sleeve 66, and the oil passage 69 when the movable swash plate 21c is near 0 °. It has become. This allows
Neutral can be secured around 0 °. In contrast, the movable swash plate 21
By configuring the valve to open when c is inclined to some extent, the valve timing at which the pressure changes from high pressure to low pressure at a swash plate angle that is frequently used can be advanced, and high efficiency can be secured. Further, this configuration can be combined with the above-described embodiment.

Next, another configuration for holding the neutral position of the movable swash plate will be described as a sixth embodiment of the HST transmission 10. 23 to 27, both ends 72 of the movable swash plate 21c are fitted into a bearing case 81 via a bearing 72b, and a trunnion shaft 71 is fixed to one end 72. An oil passage 73 is provided astride the oil passage plate 32 and the housing 31 and connected to the main circuit 32m of the oil passage plate 32. The oil passage 73 is provided by two O-rings of a bearing case 81 mounted on the housing 31. It is connected to the inner part of the groove 81b. A through hole 81 communicating with the inside of the two O-ring grooves 81b is formed on the pressure receiving surface side of the bearing case 81.
The through hole 81c is connected to the through hole 72c provided in the bearing 72b. The drill hole 72
c is the end 7 when the movable swash plate 21c is in the neutral position.
2 has a configuration corresponding to the drill hole 72d provided in
The drill hole 72d is connected to an end 72 and an oil passage 72f provided in the movable swash plate 21c. The oil passage 72f is configured to release hydraulic oil into the housing 31.
Therefore, when the movable swash plate 21c is at the neutral position, the hydraulic oil is released from the main circuit 32m into the housing 31 through the oil passage 72f, and the driving force of the hydraulic pump 21 is not transmitted to the hydraulic motor 22. , The hydraulic motor 22 is not driven. An oil reservoir 72 is provided on the inner surface of the bearing 72b.
g is provided, and when the movable swash plate 21c is not at the neutral position, lubrication between the bearing 72b and the end portion 72 is performed.

Further, as the orifice diameter of the drill hole 72c is increased, as shown in FIG. 27, the width of the range D where the output is 0 becomes wider in the curve A showing the output rotation speed with respect to the rotation angle of the trunnion shaft 71. Become. The straight line B shows the characteristics when the orifice does not close, and the straight line C shows the characteristics when the orifice does not exist.

As another neutral position holding configuration, FIG.
As shown in FIG. 8 and FIG. 29, a neutral position holding configuration using a spring is also conceivable. A stay 91 is fixed to the trunnion shaft 71, and the stay 91 is disposed in the housing 31. A shaft 92 is fixed to the stay 91 on the axis of the trunnion shaft 71. A torsion spring 92b is inserted into the shaft 92, and both ends of the spring 92b are connected to a projection 91b fixed to a stay 91 and the housing 31.
Abuts so as to pinch a contact portion 93 eccentrically fixed to the support portion 93b attached to the support portion 93b. The projecting portion 91b and the contact portion 93 are arranged in a straight line when the movable swash plate 21c is in the neutral position, and the spring 92b is arranged so that the projecting portion 91b and the contact portion 93 are located in a straight line. It is configured to be biased. In addition, the contact portion 93 is supported by the support portion 9.
The position can be finely adjusted by rotating 3b. That is, the neutral position holding mechanism can be configured with an easy configuration.

A configuration in which hydraulic oil leaks from the main circuit 32m to the charge circuit to secure the neutral position will be described. In FIG. 30, the main circuits 32m and 32
m is supplied with hydraulic oil by the charge pump 101. The charge pump 101 is connected to main circuits 32m 32m via check valves 44. A charge circuit 101b connecting the charge pump 101 and the check valves 44 is connected by a main circuit 32m and an orifice 102. For this reason, near the neutral position where the hydraulic pump 21 discharges a small amount of hydraulic oil, the hydraulic oil leaks through the orifice 102 and the hydraulic motor 22 is not driven.

As shown in FIGS. 31 to 33, the oil passage plate 3
2, a charge pump 101 mounted on a housing 101c is provided.
Is provided with an O-ring groove 101d. The orifice hole 102a connected to the main circuit 32m of the oil passage plate 32 and the oil passage 102c communicating with the discharge port of the charge pump 101 are connected to the O-ring groove 101d. With this configuration, hydraulic oil flows from the main circuit 32m through the orifice hole 102a and further through the O-ring groove 101d to the discharge port of the charge pump 101. Thus, an oil passage for ensuring neutrality from the main circuit 32m to the charge circuit can be formed only by simple drilling. Also, the hydraulic oil can be used effectively.

As shown in FIGS. 34 to 36, an oil passage is formed by covering the groove 102h with the valve plate 41 on the surface of the oil passage plate 32, and using this, the main circuit 32m and the charge circuit 101b are used. Can also be connected. That is, the oil passage plate 32 is provided with an orifice hole 102f connected to the main circuit 32m and an orifice hole 102g connected to the charge circuit 101b at a position below the hydraulic pump 21, and the orifice hole 102f and the orifice hole 102g are The oil passage plate 32 is connected to an oil passage formed by covering the groove 102 h on the surface of the oil passage plate 32 with the valve plate 41. Therefore, hydraulic oil flows into the charge pump 101 from the main circuit 32m and the hydraulic pump 21 with a simple configuration.

Next, the neutral holding mechanism when the movable swash plate 21c is controlled by the servo mechanism will be described with reference to FIGS.
This will be described with reference to FIG. The detent mechanism 120 shown in FIG. 37 holds the neutral position of the movable swash plate 21c by a control mechanism connected to an operation lever for sliding the servo spool of the servo mechanism when the movable swash plate 21c is controlled by a servo mechanism (not shown). It is a mechanism for. Substrate 1 of detent mechanism 120
An operation shaft 122 is rotatably supported by the operation shaft 11, and an arm 121 b having a servo spool drive pin 121 is fixedly provided inside the substrate 111 of the operation shaft 122. A detent cam plate 114 is fixed to the operation shaft 122 outside the substrate 111, and pins 114b and 114c are fixed to the detent cam plate 114.

Above the detent cam plate 114, the pins 114b and 114c have elongated holes 113b and 113c, respectively.
And an intermediate plate 113 engaged with the pins 114b and 114c is provided with a stopper so that the intermediate plate 113 does not come off. A cam follower 112 disposed on the substrate 111 is in contact with the intermediate plate 113, and is configured to regulate the behavior of the intermediate plate 113.

A cam follower 115b disposed on an arm 115 urged by a spring 118 so as to rotate toward the detent cam plate 114 is in contact with the detent cam plate 114. A valley is provided on the surface of the detent cam plate 114 that abuts the cam follower 115b, and the urging force of the arm 115 urges the detent cam plate 114 so that the cam follower 115b is located at the valley. Further, the substrate 111 is provided with stoppers 117, 117, and is configured to regulate the maximum rotation amount of the detent cam plate 114. The ends of the springs 116 are connected to the detent cam plate 114 and the intermediate plate 113, respectively, and the intermediate plate 113 is urged toward the detent cam plate 114. An operation link 123 is connected to one end of the intermediate plate 113. By sliding the operation link 123, the intermediate plate 113 and the detent cam plate 114 are rotated to drive the servo spool drive pin 121. Has become.

When the operation link 123 is slid, first, the intermediate plate 113 connected to the operation link 123 is driven. The intermediate plate 113 slides on the operation link 123 due to the long holes 113b and 113c, the pins 114b and 114c, the cam follower 112, and the shape of the cam follower 112 abutting portion of the intermediate plate 113, as shown in FIG. The plate 114 is a cam follower 115
Therefore, the pin 114b is driven without being rotated until the one end pin 114b / 114c contacts the end of the long hole 113b / 113c on the side of the cam follower 112. Thereafter, by further sliding the operation link 123, the detent cam plate 1 together with the intermediate plate 113 is moved.
14 is rotated, and the servo spool drive pin 1 is moved together with the operation shaft 122 fixed to the detent cam plate 114.
21 is rotated, and the movable swash plate 21c is controlled via a servo mechanism (not shown). The detent mechanism 120 can directly drive the movable swash plate by the operation shaft 122 without using a servo mechanism.

In the above configuration, the lift amount H and the operation of the elongated hole 113c with respect to the operation shaft 122 of the intermediate plate 113 due to the shape of the intermediate plate 113 on the cam follower 112 side with respect to the rotation angle Δθ of the intermediate plate 113 about the operation shaft 122. Pins 114c and 114 when link 123 is in neutral position
The inclination angle Φ with respect to a straight line passing through the axis
Assuming that the distance between c and 114b is r, the relationship is set so that Φ = tan ⁻¹ (H / rΔθ).

With the above configuration, the range in which the movable swash plate 21c is not tilted near the neutral position when the operation link 123 is slid can be widened. That is, the movable swash plate 2 is operated by a simple mechanism with respect to the operation of the operation link 123.
Since the amount of tilt of 1c can be set non-linearly, an inexpensive HST transmission 10 with good operability can be configured.

[0047]

According to a first aspect of the present invention, in a hydraulic stepless transmission including an axial plunger pump and a motor, a hole is formed in a sliding surface of a plunger on a hydraulic pump side so as to communicate with a pressure side end surface. A hole is provided in the plunger sliding surface of the cylinder block in which the plunger is inserted, so that the hole provided in the plunger and the hole provided in the cylinder block match when the plunger does not move up and down due to rotation of the input shaft. Since the hydraulic oil is released to the low pressure side, the hydraulic oil leaks when the pump side swash plate angle is around 0 degrees,
Leakage in a large angle range can be reduced, and the amount of leakage of hydraulic oil during that time can be smoothly changed. Thus, the efficiency of the hydraulic continuously variable transmission in a high-speed range can be reduced, and the shift operation characteristics can be improved.

According to a second aspect of the present invention, in the hydraulic continuously variable transmission including the axial plunger pump and the motor, the position where the hole is provided on the sliding surface of the plunger, and the hole on the sliding surface of the plunger of the cylinder block. Since the annular groove is provided at one or both of the positions where the plunger is provided, the hole of the plunger and the hole of the cylinder block can be reliably communicated regardless of the sliding position of the plunger. It is possible to easily secure the transmission efficiency, and it is possible to reduce a decrease in transmission efficiency in a high-speed region where the swash plate angle is large.

According to a third aspect of the present invention, in the hydraulic continuously variable transmission including the axial plunger pump and the motor, the valve plate located between the hydraulic block or the cylinder block on either the motor side or the motor side and the valve plate at the end face of the cylinder block. A pump communicating with the port is provided, and the hole is formed in the charge circuit or valve plate inside the oil passage plate, and the pump is on the opposite side of the hole connecting the plunger top dead center and bottom dead center.・ Communication with the hydraulic oil circuit between the motors makes it possible to secure neutrality with a simple structure and to set the neutral width by changing the orifice diameter of the valve plate. Changes can be made easily.

According to a fourth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a hole communicating with a port on the end face of the cylinder block is provided in a valve plate between the cylinder block on the hydraulic motor side and the oil passage plate. In the configuration in which the hole is communicated with the charge circuit inside the oil passage plate, the hole is provided near the position corresponding to the bottom dead center of the plunger of the valve plate. When the motor receives driving force on the road from the output shaft side when stopping on a slope, etc.
Since the plunger can compress the hydraulic oil without leaking toward the top dead center, the danger of the vehicle rolling down can be prevented. Also,
Leakage from the hole formed in the valve plate to the charge circuit occurs only during the timing of communication with the port on the end face of the cylinder block, so that a decrease in driving force transmission efficiency at high speed can be reduced.

According to a fifth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a valve plate provided between the cylinder block and the oil passage plate is provided on either the hydraulic pump or the motor side. A hole communicating with the port is provided, the hole is communicated with a charge circuit inside the oil passage plate, and a shut-off valve interlocked at least in the vicinity of a tilt angle of 0 ° of the pump movable swash plate in a passage communicating with the charge circuit. Since the swash plate opens when the angle of the swash plate is around 0 °, there is no leakage of hydraulic oil except when the operation lever is near the neutral position, and it is possible to prevent a reduction in driving force transmission efficiency at high speed.

According to a sixth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a passage of a hydraulic oil circuit connecting the pump and the motor is provided, and at least a slope of the pump movable swash plate is provided in the middle of the passage. Angle 0
A shut-off valve that communicates near 0 ° is provided, and a shut-off valve that opens when the angle of the swash plate is near 0 °, allows hydraulic oil to escape, and closes at other times. Otherwise, since there is no leakage of hydraulic oil, it is possible to prevent the transmission efficiency of the driving force at high speed from being reduced.

According to a seventh aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, a valve plate located between a hydraulic pump or a motor-side cylinder block and an oil passage plate has a cylinder block end face. Provide a hole communicating with the port, and connect the hole between the pump and motor on the other side with a line connecting the plunger top dead center and bottom dead center between the hole and the valve plate hole. A shutoff valve communicating with the oil circuit and communicating with the pump movable swash plate at least near the inclination angle of 0 ° is provided in the middle thereof, and the shutoff valve is opened and closed according to the angle of the swash plate. Since the neutrality is reliably ensured, and there is no leakage of the hydraulic oil in other cases, it is possible to prevent a reduction in the transmission efficiency of the driving force at a high speed. It is also possible to make the opening and closing timing of the valve plate two-stage variable by connecting the hole of the valve plate to the hydraulic oil circuit on the same side and controlling the shut-off valve in the middle by the swash plate angle. Thus, a timing suitable for the output shaft speed can be set.

According to an eighth aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, the hydraulic swash plate is branched from a hydraulic oil circuit of an oil passage plate, guided to a movable swash plate rotation bearing surface, and swash plate angle is adjusted. A hole is provided on the shaft to communicate with the outside at around 0 °, and the hydraulic oil escapes, ensuring neutrality at around the swash plate angle of 0 °. A reduction in driving force transmission efficiency can be prevented. In addition, since hydraulic oil is guided to the pressure receiving surface of the swash plate rotation shaft, the frictional force of the bearing can be reduced, and the operating force of the swash plate can be reduced.

According to a ninth aspect of the present invention, there is provided a hydraulic stepless transmission having an axial plunger pump and a motor, wherein the cradle type pump movable swash plate is operated by an operation lever having a bearing in a pump case. The torsion coil spring positioned by the pin on the shaft and the lever is supported by the pin on the side of the pump case, and the pin is eccentrically adjusted with respect to the pin mounting portion, so that the neutral holding mechanism can be easily performed, and the neutral position can be easily adjusted. Fine adjustment can be performed easily.

According to a tenth aspect of the present invention, in the hydraulic stepless transmission having a charge pump on the opposite side to the axial plunger pump and an oil passage plate forming a working oil passage for the motor, An orifice hole communicating with the hydraulic oil circuit connecting the pump and motor, and a hole communicating with the charge circuit or the charge pump discharge port are provided in the gap inside the groove of the seal portion O-ring on the mounting surface of the road plate and the charge pump. The neutral position holding mechanism can be configured with a simple configuration. Further, since no new member is required to configure the mechanism, the degree of freedom in design is high and the mechanism can be configured at low cost.

According to an eleventh aspect of the present invention, in the hydraulic stepless transmission comprising an axial plunger pump and a motor, an oil groove having both ends closed is provided in a valve plate or an oil passage plate provided with a valve plate. An orifice hole communicating with the pump motor operating oil circuit and a hole communicating with the charge circuit are provided in the oil passage plate from the oil passage to the oil passage plate. Can be configured. Further, since no new member is required to configure the mechanism, the degree of freedom in design is high and the mechanism can be configured at low cost. In addition, efficient use of the hydraulic oil can be performed.

According to a twelfth aspect of the present invention, in a hydraulic stepless transmission having an axial plunger pump and a motor and configured to operate a pump movable swash plate, a lever for controlling the movable swash plate is provided in a direction parallel to the lever axis. And an intermediate lever slidably engaged with the two pins by two elongated holes of different directions, and operable from the outside, and the longitudinal position of the elongated hole of the intermediate lever is determined. Since the mechanism is restricted by the rotation angle of the intermediate plate, a mechanism that does not tilt the movable swash plate near the neutral position can be configured with an easy configuration, and the amount of tilt of the movable swash plate can be set non-linearly with respect to the speed change operation. An inexpensive HST type transmission with good operability can be configured.

[Brief description of the drawings]

FIG. 1 is a side view of a work vehicle.

FIG. 2 is a side view of the same.

FIG. 3 is a side sectional view of the HST type transmission in which holes are formed in a plunger and a cylinder block.

FIG. 4 is a partial side sectional view showing a configuration of a plunger and a cylinder block in a neutral position.

FIG. 5 is a side sectional view of the HST-type transmission.

FIG. 6 is a partial side sectional view showing a configuration of a cylinder block, a valve plate, and an oil passage plate.

FIG. 7 is a plan sectional view showing a configuration of an oil passage plate.

FIG. 8 is a bottom view showing a configuration of a housing, a hydraulic pump, and a hydraulic motor.

FIG. 9 is a side cross-sectional view of the HST type transmission equipped with a spool valve.

FIG. 10 is a partial side sectional view showing an arrangement configuration of a spool valve.

FIG. 11 is a plan sectional view showing a configuration of an oil passage plate in which a spool valve is arranged.

FIG. 12 is a partial plan sectional view showing a configuration of a spool valve and a sleeve.

FIG. 13 is a side cross-sectional view showing another configuration of the HST type transmission equipped with the spool valve.

FIG. 14 is a partial side sectional view showing an arrangement configuration of another spool valve.

FIG. 15 is a plan sectional view showing a configuration of a spool valve and a sleeve disposed on an oil passage plate.

FIG. 16 is a cross-sectional plan view showing a configuration in which a spool valve, a sleeve, and a valve element are disposed on an oil passage plate.

FIG. 17 is a partial side sectional view showing another configuration of the sleeve.

FIG. 18 is a side cross-sectional view showing another configuration of the HST type transmission equipped with the spool valve.

FIG. 19 is a plan sectional view showing the configuration of a spool valve and a sleeve disposed on an oil passage plate.

FIG. 20 is a bottom view showing a configuration of a housing, a hydraulic pump, and a hydraulic motor.

FIG. 21 is a side sectional view showing a configuration of a spool valve and a sleeve.

FIG. 22 is a plan sectional view showing the configuration of a spool valve and a sleeve.

FIG. 23 is a partially broken sectional view showing a configuration of a trunnion shaft portion of the HST-type transmission.

FIG. 24 is a partially broken sectional view showing an oil passage configuration of a trunnion shaft portion.

FIG. 25 is a side view showing the configuration of an end of a movable swash plate and a bearing.

FIG. 26 is a bottom sectional view showing the configuration of the bearing.

FIG. 27 is a diagram showing the relationship between the tilt angle θ of the trunnion shaft and the output rotation speed R, which are the operating characteristics of the HST type transmission.

FIG. 28 is a side sectional view of the HST-type transmission.

FIG. 29 is a side view of the neutral holding mechanism.

FIG. 30 is a hydraulic circuit diagram of the HST-type transmission.

FIG. 31 is a side sectional view of the HST-type transmission.

FIG. 32 is a bottom view showing the configuration of the charge pump.

FIG. 33 is a plan sectional view showing a configuration of an oil passage plate at a position where a charge pump is provided.

FIG. 34 is a side sectional view of the HST-type transmission.

FIG. 35 is a plan view showing a configuration of a valve plate.

FIG. 36 is a plan sectional view showing the configuration of an oil passage plate at a valve plate disposition position.

FIG. 37: Operation amount 0 of detent cam plate and intermediate plate
It is a top view which shows the structure at the time of.

FIG. 38: Operation amount 0 of detent cam plate and intermediate plate
FIG. 4 is a side sectional view showing the configuration at the time of FIG.

FIG. 39 is a diagram showing a configuration when the operation amounts of the detent cam plate and the intermediate plate are 0.

FIG. 40 is a diagram showing a configuration when the intermediate plate is rotated.

FIG. 41 is a diagram showing a configuration when the detent cam plate and the intermediate plate rotate.

[Explanation of symbols]

 Reference Signs List 10 HST transmission 21 Hydraulic pump 21b Cylinder block 21c Movable swash plate 21e Plunger 22 Hydraulic motor 31 Housing 32 Oil passage plate 41 Valve plate 43 Oil passage 51 Spool valve 53 Sleeve 71 Trunnion shaft 72 End 72b Bearing 93 Contact portion 92 Shaft 92b Spring 101 Charge pump 102 Orifice

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Sakata, Inventor Koji Sakatacho, Kita-ku, Osaka-shi, Osaka F-term (reference) 3D042 AA05 AB12 BA02 BA05 BC03 BC16 3J053 AA03 AB02 AB12 AB32 AB46

Claims (12)

[Claims] 1. A hydraulic stepless transmission comprising an axial plunger pump and a motor, wherein a sliding surface of a plunger on a hydraulic pump side is provided with a hole communicating with a pressure side end face, and a plunger of a cylinder block into which the plunger is inserted. A hole is provided in the sliding surface, and a hole provided in the plunger and a hole provided in the cylinder block are provided so as to coincide when the plunger does not move up and down due to rotation of the input shaft, and the hydraulic oil is released to the outside. A neutral holding mechanism for a hydraulic stepless transmission. 2. A hydraulic continuously variable transmission comprising an axial plunger pump and a motor, wherein one of a position where the hole is provided on the sliding surface of the plunger and a position where the hole is provided on the sliding surface of the plunger of the cylinder block. Alternatively, a neutral holding mechanism for a hydraulic continuously variable transmission, wherein annular grooves are provided in both. 3. A hydraulic stepless transmission comprising an axial plunger pump and a motor, wherein a hole communicating with a port on an end face of the cylinder block is provided in a valve plate between the cylinder block and the oil passage plate on either the hydraulic pump or the motor. Hydraulic oil between the pump and motor on the opposite side of the line connecting the plunger top dead center and bottom dead center with the side of the hole formed in the charge circuit or valve plate inside the oil passage plate. A neutral holding mechanism for a hydraulic stepless transmission that is connected to a circuit. 4. A hydraulic stepless transmission comprising an axial plunger pump and a motor, wherein a valve plate provided between a cylinder block on the hydraulic motor side and an oil passage plate is provided with a hole communicating with a port on an end face of the cylinder block, and the hole is formed in the valve plate. A neutral holding mechanism for a hydraulic continuously variable transmission, wherein the hole is provided near a position corresponding to a bottom dead center of a plunger of a valve plate in a configuration communicating with a charge circuit inside an oil passage plate. 5. A hydraulic stepless transmission comprising an axial plunger pump and a motor, wherein a hole communicating with a port on the end face of the cylinder block is provided on a valve plate between the cylinder block and the oil passage plate on either the hydraulic pump or the motor side. And a shut-off valve interlocked with at least a tilt angle of about 0 ° of the pump movable swash plate in the passage communicating with the charge circuit. A neutral holding mechanism for a hydraulic stepless transmission that opens at an angle of about 0 °. 6. A hydraulic continuously variable transmission comprising an axial plunger pump and a motor, wherein a passage of a hydraulic oil circuit connecting the pump and the motor is provided, and the passage is provided at least in the vicinity of an inclination angle of 0 ° of the pump movable swash plate. A neutrally holding mechanism for a hydraulic continuously variable transmission, wherein a shut-off valve is provided and the swash plate is opened near an angle of 0 °. 7. A hydraulic stepless transmission comprising an axial plunger pump and a motor, wherein a hole communicating with a port on an end face of the cylinder block is provided in a valve plate between a cylinder block on either the hydraulic pump or the motor side and an oil passage plate. The hole is in the oil passage plate, and the hole of the valve plate communicates with the hydraulic oil circuit connecting the pump and the motor on the opposite side with a line connecting the top dead center of the plunger and the bottom dead center interposed therebetween, A neutral holding mechanism for a hydraulic continuously variable transmission, wherein a shutoff valve communicating with at least the inclination angle of 0 ° of the movable swash plate of the pump is provided in the middle thereof, and the shutoff valve is opened and closed by the angle of the swash plate. . 8. In a hydraulic stepless transmission comprising an axial plunger pump and a motor, a hydraulic oil circuit of an oil passage plate branches and is guided to a movable swash plate rotation bearing surface, and a swash plate angle of 0 is provided.
A neutral holding mechanism for a hydraulic continuously variable transmission, wherein a hole is provided on a shaft so as to coincide with a hole communicating with the outside in the vicinity of °. 9. A hydraulic continuously variable transmission, comprising an axial plunger pump and a motor, wherein a cradle-type pump movable swash plate is operated by an operation lever having a bearing in a pump case, a rotating shaft of the operation lever and a pin on the lever. A neutral holding mechanism for a hydraulic continuously variable transmission, characterized in that the torsion coil spring positioned in step (1) is supported by a pin on the side of the pump case, and the pin is eccentrically adjusted with respect to a pin mounting portion. 10. A hydraulic continuously variable transmission having a charge pump on the opposite side to an axial plunger pump and an oil passage plate forming a working oil passage for a motor, wherein the oil passage plate and the charge pump are connected to each other. O for seal part of mounting surface
Neutral holding of hydraulic stepless transmission, characterized in that an orifice hole communicating with the hydraulic oil circuit connecting the pump and motor and a hole communicating with the charge circuit or discharge port of the charge pump are provided in the inner gap of the groove of the ring. mechanism. 11. A hydraulic continuously variable transmission comprising an axial plunger pump and a motor, wherein an oil groove having both ends closed is provided in a valve plate or an oil passage plate at a position where the valve plate is provided, and oil between both ends is provided. A neutral holding mechanism for a hydraulic continuously variable transmission, wherein a passage is formed, and an orifice hole communicating with a pump motor operating oil circuit and a hole communicating with a charge circuit are provided from the oil passage to an oil passage plate. 12. A hydraulic stepless transmission comprising an axial plunger pump and a motor and operating a pump movable swash plate, wherein two pins are provided on a lever for controlling the movable swash plate in a direction parallel to the lever axis. Provided two pins and two
Slidably engaged by two long holes in different directions,
A neutral holding mechanism for a hydraulic continuously variable transmission, wherein an intermediate lever which can be operated from the outside is provided, and a longitudinal position of a long hole of the intermediate lever is regulated by a rotation angle of the intermediate plate.