JP2000220737A - Hydraulic continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a hydraulic continuously variable transmission, and reduce a cost in the transmission installed with two hydraulic motors together to an axial type hydraulic pump so as to circulate hydraulic oil in a closed oil hydraulic circuit. SOLUTION: A variable capacity hydraulic pump 21, a first hydraulic motor 22, and a second hydraulic motor 23 are arranged on a central section 32, thereby a HST type transmission 10 is constituted. Both the first hydraulic motor 22 and the second hydraulic motor 23 are formed in a variable capacity type, and gear change is made by capacity control. The first hydraulic motor 22 is formed in a variable capacity type, the second hydraulic motor 23 is formed in a fixed capacity type, and changing gear operation is performed by controlling the capacity of the first hydraulic motor 22. Either or both the first hydraulic motor and the second hydraulic are formed as a double variable capacity hydraulic motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tractor, a combine, a rice transplanter, a ship, a power shovel, a backhoe, a drag line, a clamshell, a crane, a shovel loader, a bulldozer, a scraper, a grader, a road roller, a tire roller, a crawler carrier. The present invention relates to a configuration of a hydraulic continuously variable transmission mounted on the like.

[0002]

2. Description of the Related Art Conventionally, a power transmission device for traveling of a work vehicle such as an agricultural tractor or the like transmits power to driving wheels and the like after reducing the output rotation speed of the engine at one kind of speed ratio using gears or the like. As can be seen from FIG. 29 showing the relationship between the output and the number of revolutions, since the output at a low speed, which is the work area, is small, a plurality of speed ratios are conventionally selectively engaged by a clutch. In other words, by setting a large reduction ratio when working at a low speed and setting a small reduction ratio when traveling on a road at a high speed, as shown in FIG. Regardless, the maximum output of the engine is made available.
However, since the area that can be used also by this method is the shaded area in FIG. 30, not only the maximum output cannot be used depending on the work speed, but also the load increases during the work and the engine speed decreases, causing the stall. It is necessary to switch the speed ratio during the operation in order to prevent this. This switching of the speed ratio involves a time lag before transmission of the driving force. Leads to deterioration. In order to use the engine output as effectively as possible, it is effective to increase the number of speed ratio stages. However, this causes an increase in manufacturing cost, an increase in size, an increase in mechanical loss, and a frequency of switching. Therefore, the number of speed ratio stages cannot be increased without limitation. Accordingly, by using a hydraulic continuously variable transmission (HST type transmission) that combines a variable displacement hydraulic pump and a constant displacement hydraulic motor, a power capable of continuously changing the speed ratio. There is also a transmission device. As a result, it is possible to prevent the work accuracy from deteriorating and the occurrence of a shock due to the shift during the work. However, a torque characteristic as shown in FIG. 31 showing the relationship between the output torque and the output rotation due to the shift using the HST type transmission. Output torque and output rotation speed maximum value N of the HST transmission
The ratio Nb / Na between b and the output torque maximum rotation speed Na is about 1.5 to 2.0. In this case, it is not possible to satisfy the general speed ratio of 3.5 to 4.0 at the time of operation with respect to high-speed running. Have been done. Such a power transmission device not only has a complicated structure and causes an increase in manufacturing cost, but also has a shock when the speed ratio is switched.

[0003] In a combine transmission,
Since a constant drive speed is required for a fluctuating load during work, a transmission that can perform a smooth shift operation is required. In a rice transplanter, it is necessary to perform work while keeping the vehicle speed constant under a running condition in which the load fluctuates rapidly, and a sudden decrease in the vehicle speed causes a decrease in work accuracy. For this reason, there is a demand for a transmission capable of performing a smooth shift operation.

[0004] The above-mentioned problem also exists in a transmission mounted on a ship or the like. For fishing boats and the like at the fishing ground, the maneuvering performance of the fishing boat is required, and it is required that the turning performance and the operation of moving the propulsion engine forward and backward are simple, fast and reliable. High-speed power is required for movement in fishing grounds and casting of seine nets, and dragnets are required for dragnets. The transmission requires a transmission having a wide shift range, and the transmission needs to shift smoothly.

[0005] The same applies to construction machines used for leveling of plazas, construction of roads and gutters, repair of gravel roads, snow removal work, and the like. Excavators, backhoes,
Drag lines, clamshells, cranes, shovel loaders, bulldozers, scrapers, graders, road rollers, tire rollers, crawler carriers, etc. need to slow down while receiving high loads during work, and move quickly between work sites. There is a need to.

[0006]

In the prior art, when using a mechanical transmission or an HST-type transmission, it is necessary to provide a shift stage using a clutch and a gear, and a shift using a clutch is performed. In this case, the vehicle speed rapidly decreases, and the work accuracy and the riding comfort of the work vehicle deteriorate.
Also, in order to realize a general speed ratio of 3.5 to 4.0 when working with high speed traveling by using the HST type transmission, the motor capacity of the HST type transmission is set to about 2 to the pump maximum capacity. It needs to be about twice as large. However, in order to increase the capacity of the motor, it is necessary to increase the size of the motor, which makes it difficult to share parts of the pump and the motor, and increases the manufacturing cost. In addition, a large-capacity motor is disadvantageous for high rotation, and because of its large size, mountability is reduced.

[0007] Agricultural machines are used only for a suitable period of time during the operation of a year, which is different from the use of the same machine every day by a skilled driver like a factory. Furthermore, just as the soil conditions of the fields differ one by one, the conditions of use of the machine are slightly different. For this reason, there is a need for a vehicle which can meet various conditions and which can be easily handled by an unfamiliar driver. Machines that are easy to operate and easy to operate are desired, especially in countries such as Japan, where most of the farmers are part-time farmers, and there are relatively many women and the elderly among farmers.

[0008]

Means for Solving the Problems In order to solve the above problems, the following means are used. First, as described in claim 1, with respect to the axial hydraulic pump,
In a hydraulic continuously variable transmission in which hydraulic oil is circulated in a closed hydraulic circuit, the axial hydraulic pump is a variable displacement hydraulic pump, and one of the hydraulic motors is a fixed displacement hydraulic pump. The other one of the motors is configured as a variable displacement hydraulic motor, and the speed is changed by controlling the discharge amount of the variable displacement hydraulic pump and the suction amount of the working oil of the variable displacement hydraulic motor. .

According to a second aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial hydraulic pump. And the constant displacement hydraulic motor and the variable displacement hydraulic motor are integrated such that they share an oil passage plate communicating with each other in a closed hydraulic passage.

According to a third aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial type hydraulic pump. The variable displacement hydraulic motor and the variable displacement hydraulic motor are tandemly arranged on the same surface of the oil passage plate, and the constant displacement hydraulic motor is arranged on the opposite surface in tandem.

According to a fourth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial hydraulic pump. And a variable displacement hydraulic motor on the same surface of the oil passage plate, and a constant displacement hydraulic motor on the opposite surface of the oil passage plate. The hydraulic motor and the fixed displacement hydraulic motor are shared.

According to a fifth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to a variable displacement hydraulic pump. One was configured as a fixed displacement hydraulic motor and the other was configured as a variable displacement hydraulic motor, and the suction and discharge directions of the working oil of the variable displacement hydraulic motor were configured to be reversible.

According to a sixth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided together with an axial type hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. Type hydraulic pump and two variable displacement type hydraulic motors are integrated by sharing one oil path plate.

According to a seventh aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to an axial hydraulic pump. The mounting housing for the hydraulic pump and one variable displacement hydraulic motor was shared, and arranged on one surface of the oil passage plate, and one variable motor was formed on the opposite surface of the oil passage plate.

According to an eighth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two variable displacement hydraulic motors are provided for an axial hydraulic pump in such a manner that hydraulic oil circulates in a closed hydraulic circuit. Two variable hydraulic motors were configured in tandem in a closed hydraulic circuit.

According to a ninth aspect of the present invention, in a hydraulic continuously variable transmission in which two hydraulic motors are driven by an axial hydraulic pump, two minimum values of swash plate angles of the two hydraulic motors are set. The maximum and minimum were respectively combined, and four types of capacities were set.

According to a tenth aspect of the present invention, in a hydraulic continuously variable transmission in which two hydraulic motors are driven by an axial hydraulic pump, two minimum values of the swash plate angle of the two hydraulic motors are set, Combine maximum and minimum respectively, 4
Seed capacity was set.

According to an eleventh aspect of the present invention, there is provided a continuously variable hydraulic transmission in which two variable displacement hydraulic motors are provided for one axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. Two kinds of minimum values of the swash plate angle of the two hydraulic motors are set, and the swash plate is driven by a driving mechanism such as a hydraulic piston or an electric actuator, and can be set at two minimum and maximum positions. 4 corresponding to
Seed capacity was set.

According to a twelfth aspect of the present invention, in the hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial type hydraulic pump, After the swash plate position reaches the maximum position in the plus direction or the maximum position in the minus direction, the swash plate position of the variable displacement motor can be operated to the maximum position.

According to a thirteenth aspect of the present invention, in the hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to an axial type hydraulic pump, one motor is used. A variable displacement hydraulic motor and another 1
Each of them is a hydraulic motor of a type capable of adjusting the capacity in two stages, the upper limit and the lower limit of the swash plate angle.

[0021]

Next, an embodiment of the present invention will be described. The present invention relates to a tractor, a combine, a rice transplanter, a ship,
The present invention relates to the configuration of a transmission mounted on a power shovel, a backhoe, a drag line, a clamshell, a crane, a shovel loader, a bulldozer, a scraper, a grader, a road roller, a tire roller, a crawler carrier, and the like. As an example, a transmission mounted on a tractor is used. 1 is a side view of a working vehicle according to an embodiment of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a schematic diagram showing a transmission mechanism of a transmission, and FIG. 4 is a schematic diagram showing an example of an operation mechanism of the transmission. , FIG. 5 is a side sectional view of the transmission, FIG. 6 is a front view of the transmission, FIG. 7 is a plan view showing the configuration of an oil passage plate of the transmission, and FIG. 8 shows an operation mechanism using two levers of the transmission. FIG. 9 is a diagram showing an operation mechanism using one lever of the transmission, FIG. 10 is a side view showing the configuration of a lever base of the operation mechanism in FIG. 9, FIG. 11 is a front sectional view thereof, and FIG. FIG. 13 is a front view showing a configuration of a transmission in a delta arrangement, FIG. 14 is a side view thereof, FIG. 15 is a rear view thereof, and FIG. 16 is a plan view thereof. FIG. 17 is a front view showing the configuration of a transmission having a Z-type arrangement, FIG. 18 is a side view thereof, and FIG. Rear view, FIG. 20 is plan view of the same, FIG. 21 is a schematic diagram showing the configuration of two using the transmission of the two-stage variable displacement hydraulic motor, 22 one variable displacement hydraulic motor, 2
FIG. 23 is a schematic diagram showing an operation mechanism of a transmission using one stage variable displacement hydraulic motor, FIG. 23 is a schematic diagram showing a mechanism of a swash plate tilting means of a two stage switching displacement type hydraulic motor, and FIG. FIG. 25 is a schematic diagram showing an operation configuration of a transmission using two hydraulic motors, FIG. 25 is a schematic diagram showing a shift stage switching mechanism of the transmission in FIG. 24, and FIG. 26 is an operation of a two-stage variable displacement hydraulic motor by a cam. FIG. 27 is a schematic diagram showing the configuration, FIG. 27 is a diagram showing the relationship between the output rotation and the displacement of the hydraulic pump and the hydraulic motor, and FIG. 28 is a hydraulic system composed of one variable displacement hydraulic pump and two variable displacement hydraulic motors. FIG. 29 is a diagram showing the relationship between the output of the engine and the number of revolutions, FIG. 30 is a diagram showing the relationship between the vehicle speed due to shifting and the output of the engine, and FIG. 31 is a diagram showing the HST type transmission. Output torque due to shifting Is a diagram showing an output rotational speed of the relationship between.

The construction of a working vehicle equipped with a rotary cultivator will be described with reference to FIGS. A rotary cultivator 2 is connected to the rear of the work vehicle 1.
Part of the output of the engine 3 of the rotary tiller 2
Is driven. 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.
The engine 3 is arranged 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.
Is arranged. 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 (hereinafter referred to as an HST type transmission) 10 is provided behind the engine 3, and the power from the engine 3 is transmitted to the rear wheels 5 to be driven. However, depending on the operation, the front wheel 4
Alternatively, a four-wheel drive that transmits the driving force simultaneously with the rear wheel 5 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 transmission 10,
The TO shaft 11 is driven, and the rotary tiller 2 which is a working machine connected to the rear end of the machine is driven. A rotary tiller 2 is connected to the rear of the work vehicle 1,
A driving force is transmitted to the rotary tiller 2 from the PTO shaft 11, and the rotary tiller 2 is driven. 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. .

Referring to FIG. 3, the structure of the HST type transmission 10 will be described. The HST transmission 10 includes a variable displacement hydraulic pump 21, a first hydraulic motor 22, and a second hydraulic motor 23.
It consists of. The variable displacement hydraulic pump 21 is connected to the engine 3 and is configured to suck and discharge hydraulic oil by the driving force of the engine 3. The variable displacement hydraulic pump 21 is connected to the first hydraulic motor 22 and the second hydraulic motor 23 via an oil passage 25 and an oil passage 26. The motor 22 and the second hydraulic motor 23 are driven. In addition, the first hydraulic motor 22 and the second hydraulic motor 23
And the second hydraulic motor 23 rotates at a fixed ratio with respect to the rotation of the first hydraulic motor 22. The driving force transmission mechanism 27 can be constituted by a gear or the like, but the output shafts of the first hydraulic motor 22 and the second hydraulic motor 23 can be directly connected. The output shaft 24 is connected to the second hydraulic motor 23, and the driving force generated by the first hydraulic motor 22 and the second hydraulic motor 23 is transmitted to the output shaft 24.

In the above configuration, the driving force transmission mechanism 27
When the first hydraulic motor 22 and the second hydraulic motor 23 are connected so as to rotate at a ratio of one to one, the discharge amount of the working oil of the variable displacement hydraulic pump 21 and the first hydraulic motor 2
The rotation output of the output shaft 24 is determined by the ratio of the hydraulic oil suction amount of the second hydraulic motor 23 to the second hydraulic motor 23. That is, when the sum of the suction amounts of the first hydraulic motor 22 and the second hydraulic motor 23 is small, the rotation speed of the output shaft 24 increases,
When the sum of the suction amounts of the hydraulic motor 22 and the second hydraulic motor 23 is large, the rotation speed of the output shaft 24 becomes small. Therefore, the capacity of one or both of the first hydraulic motor 22 and the first hydraulic motor 22 is made variable, the capacities of the first hydraulic motor 22 and the first hydraulic motor 22 are adjusted, and the suction amount of hydraulic oil is reduced. By controlling, the rotation speed of the output shaft 24 can be adjusted.

Next, a structure for operating the HST type transmission 10 using two operation handles will be described. As shown in FIG. 4, a case will be described in which the variable displacement hydraulic pump 21 is operated by the main shift lever 21a and the first hydraulic motor 22 and the second hydraulic motor 23 are operated by the sub shift lever 22a. Variable displacement hydraulic pump 2 by engine 3
1 is driven, and hydraulic oil is supplied to the first hydraulic motor 22 and the second hydraulic motor 22.
The first hydraulic motor 22 and the second hydraulic motor 23 that are supplied to the hydraulic motor 23 and connected by the output shaft 24 are driven. The output shaft 24 drives the rear wheel 5 via a differential gear 5a. In this configuration, a main shift lever 21a is connected to the variable displacement hydraulic pump 21, and both the first hydraulic motor 22 and the second hydraulic motor 23 are connected to an auxiliary shift lever 22a. The discharge amount of hydraulic oil of the variable displacement hydraulic pump 21 can be adjusted by the main shift lever 21a, and the capacity of the first hydraulic motor 22 and the second hydraulic motor 23 can be adjusted by the auxiliary shift lever 22a. That is, by operating the main transmission lever 21a and the auxiliary transmission lever 22a, the capacity of the variable displacement hydraulic pump 21 and the capacities of the first hydraulic motor 22 and the second hydraulic motor 23 can be controlled to perform a shift operation. . This makes it possible to configure a hydraulic continuously variable transmission mechanism that can cope with a high rotation speed and has a wide range of speed ratios.

Also, according to another configuration, the first hydraulic motor 2
By setting the angle of the swash plate in the negative direction to one of the second and second hydraulic motors 23,
When the discharge and discharge directions are reversed with respect to the other hydraulic motor, the rotation speed is determined by the difference in capacity between the first hydraulic motor 22 and the second hydraulic motor 23. For example,
The swash plate angle of the first hydraulic motor 22 is reversed with respect to the swash plate angle of the second hydraulic motor 23 so that the variable displacement hydraulic pump 21
When the first hydraulic motor 22 operates as a hydraulic pump by driving the second hydraulic motor 23 by the supply of the hydraulic oil, the variable displacement hydraulic pump 21 and the first hydraulic motor 22 discharge. The hydraulic oil is sucked by the second hydraulic motor 23. That is, the first hydraulic motor 2 with respect to the discharge of the operating oil of the variable displacement hydraulic pump 21
The rotation output of the output shaft 24 is determined by the difference between the capacity of the second hydraulic motor 23 and the capacity of the second hydraulic motor 23. In addition, the variable displacement hydraulic pump 2
When the hydraulic pump 1 is constituted by a hydraulic pump that changes the capacity by a movable swash plate, the suction and discharge directions of the hydraulic oil can be reversed by the inclination angle of the movable swash plate of the variable displacement hydraulic pump 21. , The forward rotation and the reverse rotation of the rotation direction of the output shaft 24 can be controlled.

Thus, in the HST type transmission 10, the capacity ratio of the hydraulic motor constituted by the first hydraulic motor 22 and the second hydraulic motor 23 to the variable displacement type hydraulic pump 21 can be increased. The range of the transmission ratio of the transmission 10 can be configured to be large.
That is, the HST type transmission 10 is made compact because the hydraulic motor that drives the output shaft 24 by the two hydraulic pumps, the first hydraulic motor 22 and the second hydraulic motor 23, is used without increasing the size of the hydraulic pump. Configurable,
By sharing parts, the HST transmission 10
Manufacturing cost can be reduced.

Next, another embodiment of the HST type transmission 10 will be described. 5 to 7, the HST transmission 1
Reference numeral 0 denotes a variable displacement hydraulic pump 21, which is an axial piston pump, a first displacement variable displacement hydraulic motor 22, and a fixed displacement second hydraulic motor 23. The variable displacement hydraulic pump 21 and the first hydraulic motor 22 are included in a housing 31 and are arranged on the same surface of an oil passage plate 32. The second hydraulic motor 23 is provided on the opposite side of the oil passage plate 32 on which the variable displacement hydraulic pump 21 and the first hydraulic motor 22 are provided. It is arranged. That is, the variable displacement hydraulic pump 21 and the first hydraulic motor 22 are disposed on the front surface of the oil passage plate 32 and are covered by the housing 31, and the second hydraulic motor 23 is mounted on the rear surface of the oil passage plate 32. It is arranged and provided with a housing 33.

The variable displacement type hydraulic pump 21 is
The first hydraulic motor 22 and the second hydraulic motor 23 are disposed on the upper part of the HST type transmission 10.
It is arranged at the lower part. The variable displacement hydraulic pump 21 includes a drive shaft 21a in which the housing 31, the oil passage plate 32, and the housing 33 are inserted, a cylinder block 21b in which the drive shaft 21a is inserted, and which rotates together with the drive shaft 21a, and slides on the cylinder block 21b. Plunger 21e movably inserted and movable swash plate 2 in contact with plunger 21e
1c. The movable swash plate 21c regulates the sliding amount of the plunger 21e, and the variable displacement hydraulic pump 2
It is configured such that the discharge amount of the first working oil can be adjusted. The oil passage plate 32 is provided with an oil passage 26 and an oil passage 27,
The variable displacement hydraulic pump 21 is connected to the oil passage 26 or the oil passage 2.
Hydraulic oil is sucked in from 7, and the hydraulic oil is discharged to an oil path different from the sucked oil path.

The oil passage 26 and the oil passage 27 are connected to the first hydraulic motor 22 and the second hydraulic motor 23. The first hydraulic motor 22 is, like the variable displacement hydraulic pump 21, inserted into the housing 31 and the oil passage plate 32, and has an output shaft 22 a rotatably supported at one end by the housing 33.
It comprises a cylinder block 22b into which the output shaft 22a is inserted and rotates together with the output shaft 22a, a plunger 22e slidably inserted into the cylinder block 22b, and a movable swash plate 22c abutting on the plunger 22e. I have. The output shaft 22a is integrally formed,
2a is fitted with a cylinder block 22b of the first hydraulic motor 22 and a cylinder block 23b of the second hydraulic motor 23. That is, the output shaft 22a is connected to the oil passage plate 32.
And the cylinder block 22b of the first hydraulic motor 22 and the cylinder block 23b of the second hydraulic motor 23 are fitted on both sides of the oil passage plate 32, respectively. The cylinder block 23b is configured to rotate together with the output shaft 22a, and a plunger 23e is slidably inserted into the cylinder block 23b. The plunger 23e is connected to the housing 33.
Abuts on the fixed swash plate 23c fixed to the swash plate. With the above configuration, the first hydraulic motor 22, the oil passage plate 32 and the second
HST transmission 10 determined by hydraulic motor 23
, The overall length of the HST type transmission 10 can be improved.

The movable swash plate 21c and the movable swash plate 22c are controlled by a swash plate control mechanism 31a and a swash plate control mechanism 31b provided on the side surface of the housing 31, and the inclination angles of the movable swash plates 21c and 22c are changed. Controlled. The swash plate control mechanisms 31a and 31b are both
1 and a servo mechanism 42. The hydraulic servo mechanism 42 includes a support piston 43 and a sliding swash plate angle control valve 44 disposed inside the support piston 43. The control lever 41
By sliding the swash plate angle control valve 44, the support piston 43 slides hydraulically, and the tilt angle of the movable swash plate is controlled by the support piston 43.
That is, the tilt angles of the movable swash plates 21c and 22c are controlled by the swash plate control mechanisms 31a and 31b disposed on the sides of the variable displacement hydraulic pump 21 and the first hydraulic motor 22, respectively. .

In the above configuration, the swash plates of the variable displacement hydraulic pump 21 and the first hydraulic motor 22 are movable,
The swash plate of the second hydraulic motor 23 is of a fixed type. First
When the capacity of the hydraulic motor 22 is fixed, a gear change operation can be performed by changing the capacity of the variable displacement hydraulic pump 21. By increasing the discharge amount of hydraulic oil by the variable displacement hydraulic pump 21, the output shaft 22
The number of rotations can be reduced by increasing the number of rotations of a and decreasing the discharge amount. In addition, when the displacement of the variable displacement hydraulic pump 21 is fixed, the speed change operation can be performed by changing the displacement of the first hydraulic motor 22. By reducing the capacity of the first hydraulic motor 22, the rotation speed of the output shaft 22a increases, and by increasing the capacity of the first hydraulic motor 22, the output shaft 2a increases.
The rotation speed of 2a decreases.

The capacity of the first hydraulic motor 22 can be adjusted by a movable swash plate 22c, and the discharge direction of hydraulic oil can be controlled. Therefore, when hydraulic oil is discharged to the oil passage 26 by the variable displacement hydraulic pump 21,
When the first swash plate 22c of the first hydraulic motor 22 causes the first hydraulic motor 22 to discharge hydraulic oil to the oil passage 26 as well, the discharge amount of hydraulic oil of the first hydraulic motor 22 and the variable displacement The second hydraulic motor 23 is driven by the sum of the discharge amounts of the hydraulic oil from the hydraulic pump 21. That is, the first
Since the capacity of the hydraulic motor 22 is variably configured, the hydraulic motor 22 can be used as the first hydraulic motor 22 and a hydraulic motor, and can also be used as a hydraulic pump. That is, since the capacity of the first hydraulic motor 22 is configured to be variable, the capacity of the first hydraulic motor 22 and the second hydraulic motor 23 with respect to the variable capacity hydraulic pump 21 or the capacity of the variable capacity hydraulic pump 21 Since the shift operation is performed by the displacement of the second hydraulic motor 23 with respect to the discharge amount of the one hydraulic motor 22, the shift range of the HST type transmission 10 can be configured to be wide.

In the above configuration, the variable displacement hydraulic pump 21, the first hydraulic motor 22, and the second hydraulic motor 23 are connected by the same oil passage plate 32.
The variable displacement hydraulic pump 21, the first hydraulic motor 22, and the second hydraulic motor 23 are connected by an oil path provided at the first position.
This eliminates the need for hydraulic piping between the variable displacement hydraulic pump 21 and the first hydraulic motor 22 and the second hydraulic motor 23, reduces parts and processing costs, and reduces the cost of the HST transmission 1.
The configuration of No. 0 becomes compact, and the mountability to the working machine is improved.

The HST type transmission 10 has a variable displacement hydraulic pump 21 and a variable displacement first hydraulic motor 22 disposed on the front surface of an oil passage plate 32. HST operation mechanism of hydraulic motor 22
In addition to being able to concentrate on the front portion of the transmission 10, the assemblability can be improved, and the mountability to the working machine is improved. Also, H
As another configuration of the ST-type transmission 10, as shown in FIG. 28, the second hydraulic motor 23 is a variable displacement hydraulic motor 23v.
Can also be configured. Variable displacement hydraulic motor 23v
Is a variable displacement hydraulic pump 21 and a first hydraulic motor 22
The variable displacement hydraulic motor 23v is configured to have a variable capacity by a movable swash plate 23s. Variable displacement hydraulic motor 23
The v output shaft 23x is connected to the rear end of the output shaft 22a of the first hydraulic motor 22 by a connecting member 23z at a position where the output shaft 23x is inserted into the oil passage plate 32, and the output shaft 22a and the output shaft 23x are Both are configured to rotate. As a result, a hydraulic continuously variable transmission can be configured with one variable displacement hydraulic pump and two variable displacement hydraulic motors, and the distance between the input shaft and the output shaft in the height direction can be reduced. For this reason, the hydraulic continuously variable transmission can be configured to be compact, and the mountability to the working machine can be improved.

Next, referring to FIG.
The operation configuration of the HST transmission 10 when the hydraulic pump 21 is a variable displacement type, the first hydraulic motor 22 is a variable displacement type, and the second hydraulic motor 23 is a fixed displacement type will be described. The variable displacement hydraulic pump 21 is driven by the engine 3, discharges hydraulic oil by the driving force, and drives the first hydraulic motor 22 and the second hydraulic motor 23. The first hydraulic motor 22 and the second hydraulic motor 23 have an output shaft 24.
The driving force is transmitted to the differential gear 5a via the output shaft 24, and the rear wheel 5 is driven. An operation handle 21a for controlling the angle of the movable swash plate of the variable displacement hydraulic pump 21 is connected to the variable displacement hydraulic pump 21, and the rotation of the first hydraulic motor 22 is connected to the first hydraulic motor 22. An operation handle 22a for controlling the angle of the moving swash plate is connected.

The speed and forward / backward movement can be controlled by controlling the capacity of the variable displacement hydraulic pump 21 and the discharge amount of hydraulic oil by the operation handle 21a. By operating the operation handle 22a, the first hydraulic motor 2
By controlling the sum of the hydraulic oil suction amounts of the second and second hydraulic motors 23, the rotation ratio of the output shaft 24 to the hydraulic oil discharge amount of the variable displacement hydraulic pump 21 can be controlled. That is, the operation handle 22a is operated, and the first hydraulic motor 22
By controlling the hydraulic oil to be discharged to the hydraulic oil suction side of the hydraulic motor 23, the sum of the hydraulic oil suction amounts of the first hydraulic motor 22 and the second hydraulic motor 23 is reduced, and the variable displacement hydraulic pump 21 is controlled. Of the output shaft 24 can be increased. With the operation handle 21a and the operation handle 22a, a shift operation with a wide shift range can be performed.

As shown in FIG. 9, the movable swash plate of the variable displacement hydraulic pump 21 and the movable swash plate of the first hydraulic motor 22 can be controlled by one operating handle 22b. It is connected to the variable displacement hydraulic pump 21 and the first hydraulic motor 22 via a link of the operation handle 22b, so that the capacity of the variable displacement hydraulic pump 21 and the first hydraulic motor 22 can be controlled. By performing a shift operation with the operation handle 22b, there is no need for an auxiliary shift, and the shift operation can be simplified.

As shown in FIGS. 10 and 11, a cam plate 22c is fixed to the base of the operation handle 22b, and is tilted in accordance with the tilt of the operation handle 22b. The cam plate 22c has grooved cams 2 on both sides.
1d and 22d are provided. The grooved cam 21d-2
2d is loosely fitted with a cam follower 29, 29,
The cam follower 29 is a variable displacement hydraulic pump 2
1 and the first hydraulic motor 2
2 is connected to the link mechanism 22b. The cam followers 29, 29 are configured to be movable only up and down along the grooved cams 21d, 22d by tilting the operation handle 22b, and the link mechanisms 29a, 29b are moved up and down by the vertical movement. Swash plate and the first swash plate of the variable displacement hydraulic pump 21
The swash plate of the hydraulic motor 22 is controlled to change the capacity.

The grooved cams 21d and 22d are connected to the operation handle 2.
2b is in the neutral position, the variable displacement hydraulic pump 21
Also, the movable swash plate of the first hydraulic motor 22 is configured to be in the neutral position. When the operation handle 22b is tilted forward, the cam follower 29 is raised by the grooved cam 21d, and the link mechanism 29a connected to the variable displacement hydraulic pump 21 is raised. By raising the link mechanism 29a, the hydraulic oil of the variable displacement hydraulic pump 21 is discharged, and the second hydraulic motor 23 is driven. When the operation handle 22b is further tilted forward, the link mechanism 29a is maintained at a constant height, and the cam follower 29 connected to the link mechanism 29b by the grooved cam 22d is lowered. As the link mechanism 29b moves, the first
The movable swash plate of the hydraulic motor 22 is tilted, discharges hydraulic oil to the hydraulic oil suction side of the second hydraulic motor 23, and the rotation of the output shaft increases. As a result, the speed increase on the forward side is performed.

When the operation handle 22b is tilted backward, the cam follower 29 is lowered by the grooved cam 21d, and the link mechanism 29a is lowered. The link mechanism 29a
As a result, the movable swash plate of the variable displacement hydraulic pump 21 is tilted to the opposite side from the advanced state, and the discharge direction of the hydraulic oil is reversed. As a result, the first hydraulic motor 22 is driven in a direction opposite to the forward side, and the rear wheel 5 is driven to the reverse side. When the operation handle 22b is further tilted backward,
By the cam follower 29 loosely fitted to the grooved cam 21d,
Further, the link mechanism 29b is lowered, and the link mechanism 29b is lowered by the cam follower 29 loosely fitted to the grooved cam 22d. For this reason, the discharge amount of the hydraulic oil to the second hydraulic motor 23 increases, and the speed increases to the reverse side.

As described above, the variable displacement hydraulic pump 2 is driven by the cam plate 22c linked to the operating handle 22b.
It is possible to control the first and first hydraulic motors 22 to perform a shift operation. Therefore, the speed change operation of the transmission having a wide gear ratio range can be easily performed without the need for the auxiliary speed change.

As shown in FIG. 12, a swash plate control mechanism 21 is connected to the operation handle 21h and controls the displacement of the variable displacement hydraulic pump 21 and the first hydraulic motor 22.
With g, a gear change operation can be performed. The swash plate control mechanism 21g is configured to tilt the corresponding swash plate of the variable displacement hydraulic pump 21 or the first hydraulic motor 22 according to the position of the operation handle 21h. As the configuration of the swash plate control mechanism 21g, the position of the operation handle 21h is detected by a position sensor, and the swash plate of the variable displacement hydraulic pump 21 and the first hydraulic motor 22 is moved by a linear solenoid in accordance with the detected position. A configuration for controlling is conceivable. As described above, by configuring the transmission, the variable displacement hydraulic pump 21 can be easily configured.
In contrast, a transmission mechanism having a large capacity of the hydraulic motor can be configured, and the transmission can be easily shifted by the operation handle 21h.

13 to 16, another configuration of the HST type transmission constituted by one hydraulic pump and two hydraulic motors will be described. HST transmission 5
In 5, a hydraulic pump 47 is provided on one surface of the oil passage plate 41.
A first hydraulic motor 48 and a second hydraulic motor 49 are provided, and are covered by a housing 42 fixed to the oil passage plate 41. The input shaft 43 of the hydraulic pump 47 is configured to protrude from the housing 42,
The driving force is transmitted to the input shaft 43, and the hydraulic pump 47 is driven. The hydraulic pump 47 is provided with the aforementioned HST transmission 1
0, the first hydraulic motor 48 and the second hydraulic motor 49 are connected to each other by an oil passage provided in the oil passage plate 41, and the first hydraulic motor 48 The configuration is such that the second hydraulic motor 49 is driven.

The output shaft 44 of the first hydraulic motor 48 and the output shaft 51 of the second hydraulic motor 49 project from the side of the oil passage plate 41 opposite to the side surface on which the housing 42 is provided. A gear 45 and a gear 46 are inserted and fixed to the output shaft 51, respectively. The gear 45 and the gear 46 are meshed with each other, and are configured so that the rotation of the output shaft 51 becomes constant with respect to the rotation of the output shaft 44. In the HST transmission 55, the hydraulic pump 47
The first hydraulic motor 48 may be of a variable displacement type, and the second hydraulic motor 49 may be of a fixed displacement type.

As described above, the hydraulic pump 47, the first hydraulic motor 48, and the second hydraulic motor 49 are disposed on one surface of the oil passage plate 41, and are covered by the housing 42 fixed to the oil passage plate 41. By configuring the HST type transmission 55 to be mounted, the hydraulic pump 47, the first hydraulic motor 48, and the second hydraulic motor 49 are disposed on the same surface on the oil passage plate 41. The front-rear length can be reduced. Also, the hydraulic pump 47 and the first
Since only one housing 42 is required to cover the hydraulic motor 48 and the second hydraulic motor 49, the assemblability of the HST transmission 55 is good and the manufacturing cost can be reduced.

Next, referring to FIG. 17 to FIG.
The configuration of the transmission 75 will be described. In the HST type transmission 75, the hydraulic pump 6
5, the hydraulic pump 65 is connected to the housing 6
2 is covered. An input shaft 64 of the hydraulic pump 65 protrudes from the housing 62, and a driving force is input to the hydraulic pump 65 via the input shaft 64. Oil passage plate 6
A first hydraulic motor 71 and a second hydraulic motor 72 are provided on a surface opposite to the surface on which the one hydraulic pump 65 is provided, and are mounted on the housing 63. Also,
An output shaft 67 of the first hydraulic motor 71 and an output shaft 68 of the second hydraulic motor 72 protrude from the housing 63,
A gear 67b and a gear 68b are inserted and fixed to the output shaft 67 and the output shaft 68, respectively. The gear 67b
The gear 68b and the gear 68b are meshed with each other so that the output shaft 67 and the output shaft 66 have a constant rotation ratio.

As described above, the HST type transmission 75 in which the hydraulic pump 65 and the hydraulic motors 71 and 72 are disposed on the opposite side via the oil passage plate 61 constitutes the shaft of the input shaft and the output shaft. The distance between them can be reduced. As a result, the height of the HST transmission 75 can be reduced.

Further, in the above configuration, the first hydraulic motor 71 and the second hydraulic motor 72 are constituted by variable displacement hydraulic motors, and the first hydraulic motor 71 and the second hydraulic motor 72 are tandemly mounted in a hydraulic closed circuit. Can be configured. First hydraulic motor 71 and second hydraulic motor 72
The first hydraulic motor 71 and the second hydraulic motor 72 can be connected in parallel to the hydraulic pump 65 by the oil passage provided in the oil passage plate 61 to which the oil passage is connected. In this configuration, a shift operation can be performed by changing the capacities of the first hydraulic motor 71 and the second hydraulic motor 72 with respect to the hydraulic pump 65.
Further, the first hydraulic motor 7 is provided by an oil passage provided in the oil passage plate 61.
Since the first and second hydraulic motors 72 are connected, HST
Since the main hydraulic circuit of the transmission 75 is formed in the oil passage plate 61, there is no need to connect the hydraulic pump 65, the first hydraulic motor 71, and the second hydraulic motor 72 by hydraulic piping. 75 can be made compact.

Next, the configuration of an HST type transmission in which the hydraulic pump is of a variable displacement type and two hydraulic motors are of a two-stage variable displacement type will be described. In FIG. 21, the HST transmission 81 includes a variable displacement hydraulic pump 82, a first hydraulic motor 83 connected to the variable displacement hydraulic pump 82 by an oil passage 85, and a second hydraulic motor 84. The first hydraulic motor 83 and the second hydraulic motor 84 are connected by an output shaft 87, and the first hydraulic motor 83 and the second hydraulic motor 84 rotate in the same direction and at the same rotational speed.

Each of the first hydraulic motor 83 and the second hydraulic motor 84 is a hydraulic motor that adjusts the capacity according to the inclination angle of the swash plate, and is a two-stage variable motor that adjusts the inclination angle of the swash plate in two stages. It is constituted by a displacement type hydraulic motor.
The capacity of the first hydraulic motor 83 is adjusted to two levels of Vacc / rev or 0 cc / rev, and the capacity of the second hydraulic motor 84 is adjusted to two levels of Vb1cc / rev or Vb2cc / rev. It has a configuration. That is, the capacity Va of the first hydraulic motor 83
The capacity of the second hydraulic motor 84 is Vb1cc / rev or Vb2cc / rev with respect to cc / rev, and the capacity of the second hydraulic motor 84 is Vb1cc / with respect to the capacity 0cc / rev of the first hydraulic motor 83. By adjusting the value to rev or Vb2cc / rev, a four-step shift operation can be performed. First hydraulic motor 83
When it is considered that one hydraulic motor is constituted by the second hydraulic motor 84 and the second hydraulic motor 84, the capacity of the hydraulic motor constituted by the first hydraulic motor 83 and the second hydraulic The sub-transmission mechanism having four speed ratios can be configured by the configuration. Therefore, the variable displacement hydraulic pump 82
The HST type transmission 81 having a main transmission unit and a four-stage auxiliary transmission unit by adjusting the capacity of the HST type transmission can be configured.

Since each of the first hydraulic motor 83 and the second hydraulic motor 84 is controlled in two stages, the control mechanism of the first hydraulic motor 83 and the second hydraulic motor 84 can be easily performed. Also, the first hydraulic motor 83 and the second
The cost required for the hydraulic motor 84 can be reduced and the HS
A T-type transmission 85 can be configured.

In the above configuration, Va is the maximum capacity of the first hydraulic motor 83, Vb1 is the maximum capacity of the second hydraulic motor 84, and Vb2 is the minimum capacity of the second hydraulic motor 84. And the second hydraulic motor 84
May be configured to be switchable between two levels of maximum and minimum. In this case, it is assumed that Vb2 is not zero. Also, the minimum capacity of the first hydraulic motor 83 is set to 0c
It is also possible to configure a capacitance other than c / rev, Vb1 and Vb2. Accordingly, the HST type transmission 81 can be configured compactly and at low cost, and the operation mechanism of the HST type transmission 81 can be simply configured.

Further, a hydraulic actuator or an electric actuator may be mounted on the HST type transmission 81 to operate the above-described four-stage gear ratio.

As shown in FIG. 24, the movable swash plate of the variable displacement hydraulic pump 82 is operated by an operation handle 82a.
The first and second hydraulic motors 83 and 84 are
It is also possible to implement a mechanism controlled by a · 84a. As shown in FIG. 23, the actuators 83a and 84a include a swash plate operating piston 91 and an oil passage switching valve 92. The oil passage switching valve 92 includes a hydraulic pump 93.
Hydraulic oil is supplied, and the swash plate operation piston 91 is operated by sliding the oil path switching valve 92. The swash plate operating piston 91 is separately connected to the swash plates of the first and second hydraulic motors 83 and 84 via a link mechanism, respectively. The inclination angles of the swash plates of the hydraulic motors 83 and 84 are controlled. The oil passage switching valve 92 is provided with two kinds of oil passages, and is configured to control the inclination angle of the swash plate of the second hydraulic motor 84 in two stages. The sliding of the oil passage switching valve 92 can be switched by an electromagnetic solenoid or the like, and the swash plate control of the first and second hydraulic motors 83 and 84 can be performed.

As shown in FIG. 25, the first hydraulic motor 83
The swash plate operating piston 101 is connected to the swash plate via a link mechanism.
The operation piston 101 is connected to an oil passage switching electromagnetic valve 102. By controlling the direction of hydraulic oil supplied from a hydraulic pump by the electromagnetic valve 102, the operating piston 101 is expanded and contracted, and the swash plate of the first hydraulic motor 83 is controlled. The swash plate of the second hydraulic motor 84 is controlled by a swash plate operation piston 91 connected to an oil passage switching solenoid valve 92. The oil passage switching solenoid valve 102 and the oil passage switching solenoid valve 92 are connected to a switchboard 94.
The switchboard 94 is connected to speed changeover switches 96, 96, 96, 96 and a power supply 95. In the switchboard 94, the oil passage switching solenoid valve 1 of the power supply 95
02, power supply to the oil passage switching electromagnetic valve 92 is controlled.
The switchboard 94 can control two-stage switching of the capacity of the first hydraulic motor 83 and two-stage switching of the capacity of the second hydraulic motor 84,
The control is performed by a speed changeover switch 96 connected to a switchboard 94.
・ 96 ・ 96 ・ 96

Four speed changeover switches 96, 96, 96
The oil passage switching solenoid valve 102 and the oil passage switching solenoid valve 92 are both off, the oil passage switching solenoid valve 102 is on, the oil passage switching solenoid valve 92 is on, the oil passage switching solenoid valve 1
02 and the oil passage switching solenoid valve 92 correspond to four kinds of ON controls. That is, four speed changeover switches 9
By selecting any of 6, 96, 96, 96,
Four-stage shifting can be performed.

As shown in FIG. 26, the first hydraulic motor 8 is driven by a cam 114 and oil passage switching valves 112 and 113.
3. The second hydraulic motor 84 can also be controlled. An oil passage switching valve 113 for controlling the sliding of the swash plate operating piston 91,
Oil passage switching valve 1 for controlling sliding of swash plate operating piston 101
Numeral 12 is configured to abut on a cam 114 connected to a speed gear change gear shift operation handle 115. The oil passage switching valve 112 and the oil passage switching valve 113
The oil passage switching valve 112 and the oil passage switching valve 113 are configured to switch the oil passage depending on the contact position with the cam 114. That is, the cam 114
Oil passage switching valves 112 and 113
The oil passage switching valves 112 and 113 are slid in a direction away from the cam 114 by a portion other than the concave portion of the cam 114. The on / off of the oil passage switching valves 112 and 113 can be controlled by a concave portion provided in the cam 114. In the cam 114, both the oil passage switching valve 112 and the oil passage switching valve 113 are off, only the oil passage switching valve 112 is on, only the oil passage switching valve 113 is on, and both the oil passage switching valve 112 and the oil passage switching valve 113 are on. Recesses corresponding to the four types of control are formed, and the slide of the cam 114 enables switching of the oil passage switching valves 112 and 113. That is, the cam 114 slides by operating the speed stage switching gearshift operation handle 115 to switch the oil passage switching valves 112 and 113, and the first hydraulic motor 83 and the second hydraulic motor 8 are switched.
With respect to 4, the above four types of control can be performed.

Next, in FIG. 27, in the hydraulic type continuously variable transmission in which two hydraulic motors M1 and M2 are provided in parallel with the axial hydraulic pump P so that the hydraulic oil is lubricated in the closed hydraulic circuit. An embodiment of an operation configuration in the case of performing a shift operation by changing the capacity of the hydraulic pump P and the capacity of the hydraulic motors M1 and M2 will be described. In the embodiments described herein, the hydraulic motors M1 and M2 are configured to have the same rotational speed as described above. FIG. 27 shows the relationship between the output rotation R and the displacement of the hydraulic pump P and the hydraulic motor M1. In the graph PV,
The capacity of the hydraulic pump P is increased from 0 in proportion to the time axis t, and increases at time t1 to the capacity Pmax, and the capacity is maintained at Pmax. In the graph M1V,
The capacity of the hydraulic motor M1 is maintained at M1max until time t1, and thereafter, the capacity is reduced in proportion to the time axis t. The rotational output R of the hydraulic continuously variable transmission is determined by changing the capacity of the hydraulic pump P by P
v, when the capacity of the hydraulic motor M1 is M1v and the capacity of the hydraulic motor M2 is M2v, it is simply expressed as R = Pv / (M1v + M2v). That is, the capacity of the hydraulic motor M2 is set to M2b.
As described above, the hydraulic pump P and the hydraulic motor M1
Is operated, the rotational output of the hydraulic continuously variable transmission increases as indicated by R1. When the capacity of the hydraulic motor M2 is set to M2s and the capacities of the hydraulic pump P and the hydraulic motor M1 are operated as described above, the rotational output of the hydraulic continuously variable transmission increases as indicated by R2. Here, the relationship between M2b and M2s is M2b> M2s as shown in the graph M2V.

The displacement operation of the hydraulic pump P and the hydraulic motor M1 is performed by moving the hydraulic motor M1 from the maximum position to the minimum position after the swash plate position of the hydraulic pump P reaches the maximum position. It corresponds to. This allows
After the swash plate position of the hydraulic pump P reaches the maximum position, the rotation output operation indicated by R1 or R2 can be performed by performing the swash plate position of the hydraulic motor M1 in the direction from the maximum position to the minimum position. Also, as mentioned above,
By decreasing the capacity of the hydraulic motor M2, the rate of increase of the rotational output can be increased, and by increasing the capacity, the rate of increase of the rotational output can be reduced. That is, the rotation output R can be controlled by variably operating the capacity of the hydraulic motor M2 in two stages.

The hydraulic pump P and the hydraulic motors M1 and M
2 can be realized by using the embodiment described in the detailed description of the present invention, and links the continuously variable hydraulic transmission with the shift operation lever, the hydraulic pump P, and the hydraulic motors M1 and M2. By operating through a mechanism or the like, a shift operation can be performed as if using one shift operation lever. In addition, by setting the lower limit capacity of the variable displacement motor in the hydraulic motor M2 to 0 or more, it is possible to prevent a decrease in efficiency when the lower limit becomes negative. That is, it is possible to reduce an overlapped operation portion in the speed change operation of the hydraulic pump M1 and the hydraulic motor M2, and to improve the operation efficiency. In addition, it is possible to prevent a decrease in drive efficiency that would otherwise occur when the lower limit of the capacity of the hydraulic motor M2 becomes negative.

[0063]

According to a first aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are provided in an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. The axial hydraulic pump is a variable displacement hydraulic pump, one of the hydraulic motors is configured as a fixed displacement hydraulic motor, and the other is configured as a variable displacement hydraulic motor. Since the speed is changed by controlling the suction amount of the working oil of the variable displacement hydraulic motor, a separate auxiliary transmission is not required, and the mountability of the transmission on a working machine or the like is improved. Further, a compact transmission having a large gear ratio can be configured.

According to a second aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial type hydraulic pump. And the fixed displacement hydraulic motor and the variable displacement hydraulic motor are integrated so as to share an oil passage plate communicating with each other in the closed hydraulic passage, so that only one swash plate variable mechanism of the motor is required, and the hydraulic pump and The need for hydraulic piping between hydraulic motors is eliminated, the number of components can be reduced, and manufacturing costs can be reduced. Also, since the transmission can be configured simply, it can be easily mounted on work machines.

According to a third aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial type hydraulic pump. The variable displacement hydraulic motor and the variable displacement hydraulic motor are arranged in tandem on the same surface of the oil passage plate, and the constant displacement hydraulic motor is arranged on the opposite surface in tandem. The degree of freedom of connection from the hydraulic pumps and the hydraulic motors configured on both sides is large, and assemblability and mountability to work machines are improved.

According to a fourth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to the axial hydraulic pump. And a variable displacement hydraulic motor on the same surface of the oil passage plate, and a constant displacement hydraulic motor on the opposite surface of the oil passage plate. Since the hydraulic motor and the constant displacement hydraulic motor are shared, there is no need to connect the output shaft of the variable displacement hydraulic motor and the output shaft of the constant displacement hydraulic motor with a boss, etc. The structure can be shortened, the cost can be reduced, and the mountability is improved.

According to a fifth aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are connected to a variable displacement hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. One is configured as a fixed displacement hydraulic motor and the other is configured as a variable displacement hydraulic motor, and the suction and discharge directions of the hydraulic oil of the variable displacement hydraulic motor are configured to be reversible, so that the range of the gear ratio is increased. In addition, the auxiliary transmission mechanism can be omitted.

According to a sixth aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to an axial hydraulic pump. Type hydraulic pump and two variable displacement hydraulic motors are integrated by sharing one oil passage plate.
When mounted on a mobile work machine such as a tractor, there is no need to connect an additional hydraulic pipe to the transmission. In addition, since the gear ratio can be increased, the auxiliary gear is not required.

According to a seventh aspect of the present invention, there is provided a hydraulic stepless transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to an axial hydraulic pump. A common mounting housing for the hydraulic pump and one variable displacement hydraulic motor is shared and disposed on one surface of the oil passage plate, and one variable motor is configured on the opposite surface of the oil passage plate. The cost can be reduced by sharing the housing with the hydraulic motor. Also,
Since the gear ratio can be increased, the auxiliary gear is not required.

According to an eighth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two variable displacement hydraulic motors and an axial hydraulic pump are provided so that hydraulic oil circulates in a closed hydraulic circuit. Since the two variable hydraulic motors are configured in tandem within the hydraulic closed circuit, the width of the transmission can be made compact, and the configuration of the hydraulic circuit can be simplified. Also,
Friction loss of the output shaft of the hydraulic motor can be reduced.

According to a ninth aspect of the present invention, in the hydraulic continuously variable transmission in which two variable displacement hydraulic motors are driven by an axial hydraulic pump, the two hydraulic motors have different lower limit capacities different from each other. Since the lower limit of the plate angle is set and the capacity of the hydraulic motor is adjusted in two stages, the upper limit and the lower limit, the transmission mechanism can be configured with a simple configuration, and the transmission can be easily shifted.

According to a tenth aspect, in a hydraulic continuously variable transmission in which two hydraulic motors are driven by an axial hydraulic pump, two minimum values of swash plate angles of the two hydraulic motors are set, Combine maximum and minimum respectively, 4
Since various types of capacities are set, the capacity variable mechanism can be simply configured, and the shift operation mechanism can also be simply configured. As a result, the mountability of the transmission is improved, and the operating mechanism can be made compact and low in cost.

According to an eleventh aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two variable displacement hydraulic motors are provided for one axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. Two kinds of minimum values of the swash plate angle of the two hydraulic motors are set, and the swash plate is driven by a driving mechanism such as a hydraulic piston or an electric actuator, and can be set at two minimum and maximum positions. 4 corresponding to
Since the different capacities are set, the operation of the transmission can be easily performed. In addition, the operation mechanism is simplified and the cost can be reduced, so that the transmission can be made compact and the mountability can be improved.

According to a twelfth aspect of the present invention, there is provided a hydraulic continuously variable transmission in which two hydraulic motors are provided so as to circulate hydraulic oil in a closed hydraulic circuit with respect to an axial hydraulic pump. After the swash plate position reaches the maximum position in the plus direction or the maximum position in the minus direction, the swash plate position of the variable displacement motor is configured to be operable at the maximum position. The speed change operation can be performed smoothly. Therefore, the load on the hydraulic pump and the hydraulic motor constituting the hydraulic continuously variable transmission can be reduced, and the hydraulic continuously variable transmission with good operability and durability can be constructed. Further, since the hydraulic continuously variable transmission can be easily operated by using a single operation lever, easy operation can be realized by using a single operation lever.

According to a thirteenth aspect of the present invention, in the hydraulic continuously variable transmission in which two hydraulic motors are provided together with the axial hydraulic pump so that hydraulic oil circulates in the closed hydraulic circuit, one motor is used. A variable displacement hydraulic motor and another 1
Since each of them is a hydraulic motor capable of adjusting the capacity in two steps of the upper limit and the lower limit of the swash plate angle, by setting the lower limit capacity of the variable displacement motor to 0 or more, the lower limit becomes negative. Efficiency reduction can be prevented. That is, 2
In the shifting operation of the two hydraulic pumps, the overlapping operation portion can be reduced, and the operating efficiency can be improved. Further, it is possible to prevent a decrease in drive efficiency that would otherwise occur when the lower limit of the capacity of one hydraulic motor becomes negative.

[Brief description of the drawings]

FIG. 1 is a side view of a working vehicle according to an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a schematic diagram showing a transmission mechanism of the transmission.

FIG. 4 is a schematic diagram illustrating an example of an operation mechanism of a transmission.

FIG. 5 is a side sectional view of the transmission.

FIG. 6 is a front view of the transmission.

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

FIG. 8 is a diagram showing an operation mechanism using two levers of the transmission.

FIG. 9 is a diagram showing an operation mechanism using one lever of the transmission.

FIG. 10 is a side view showing a configuration of a lever base of the operation mechanism in FIG. 9;

FIG. 11 is a front sectional view of the same.

FIG. 12 is a diagram showing another configuration of the operation mechanism using one lever of the transmission.

FIG. 13 is a front view showing the configuration of a transmission having a delta arrangement.

FIG. 14 is a side view of the same.

FIG. 15 is a rear view of the same.

FIG. 16 is a plan view of the same.

FIG. 17 is a front view showing a configuration of a transmission in a Z-type arrangement.

FIG. 18 is a side view of the same.

FIG. 19 is a rear view of the same.

FIG. 20 is a plan view of the same.

FIG. 21 is a schematic diagram showing a configuration of a transmission using two two-stage variable displacement hydraulic motors.

FIG. 22 is a schematic diagram showing an operation mechanism of a transmission using one variable displacement hydraulic motor and one two-stage variable displacement hydraulic motor.

FIG. 23 is a schematic view showing a mechanism of a swash plate tilting means of the two-stage switching displacement type hydraulic motor.

FIG. 24 is a schematic diagram showing an operation configuration of a transmission using two two-stage variable displacement hydraulic motors.

FIG. 25 is a schematic diagram showing a speed change mechanism of the transmission shown in FIG. 24;

FIG. 26 is a schematic diagram showing an operation configuration of a two-stage variable hydraulic motor using a cam.

FIG. 27 is a diagram illustrating a relationship between output rotation and a change in capacity of a hydraulic pump and a hydraulic motor.

FIG. 28 is a side sectional view showing a hydraulic continuously variable transmission mechanism constituted by one variable displacement hydraulic pump and two variable displacement hydraulic motors.

FIG. 29 is a diagram showing the relationship between the output of the engine and the number of revolutions.

FIG. 30 is a diagram showing a relationship between a vehicle speed due to a shift and an engine output.

FIG. 31 is a diagram showing a relationship between output torque and output rotation speed due to gear shifting using an HST type transmission.

[Explanation of symbols]

 Reference Signs List 3 engine 10 HST transmission 21 variable displacement hydraulic pump 22 first hydraulic motor 23 second hydraulic motor 24 output shaft 27 transmission mechanism 31 housing 32 oil passage plate 33 housing

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kunihiko Sakamoto 1-32 Chayacho, Kita-ku, Osaka, Osaka Inside Yanmar Diesel Corporation (72) Inventor Katsuyuki Shiota 1-32, Chayacho, Kita-ku, Osaka, Osaka F-term (reference) in Yanmar Diesel Co., Ltd.

Claims (13)

[Claims] 1. A hydraulic continuously variable transmission in which two hydraulic motors are connected to an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. The hydraulic pump is configured such that one of the hydraulic motors is configured as a fixed displacement hydraulic motor, and the other is configured as a variable displacement hydraulic motor. A hydraulic continuously variable transmission characterized by shifting by controlling the suction amount. 2. A hydraulic type continuously variable transmission in which two hydraulic motors are provided in parallel with an axial type hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. And a variable displacement hydraulic motor integrated so as to share an oil passage plate communicating with each other in a closed hydraulic passage. 3. A hydraulic continuously variable transmission in which two hydraulic motors are provided in parallel with an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. The hydraulic continuously variable transmission according to claim 1 or 2, wherein a fixed displacement hydraulic motor and a fixed displacement hydraulic motor are configured in tandem on the same surface of the oil passage plate and on the opposite surface, respectively. 4. A hydraulic continuously variable transmission in which two hydraulic motors are provided in parallel with an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit, the axial hydraulic pump and the variable displacement hydraulic motor Are formed on the same surface of the oil passage plate, and a constant displacement hydraulic motor is formed on the opposite surface of the oil passage plate. A hydraulic continuously variable transmission shared by hydraulic motors. 5. A hydraulic continuously variable transmission in which two hydraulic motors are connected to a variable displacement hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit, wherein one of the hydraulic motors is of a fixed displacement type. A hydraulic continuously variable transmission, wherein another one of the hydraulic motors is configured as a variable displacement hydraulic motor, and the suction and discharge directions of hydraulic oil of the variable displacement hydraulic motor are configured to be reversible. 6. A variable displacement hydraulic pump in which two hydraulic motors are connected to an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. A hydraulic continuously variable transmission characterized in that the variable displacement hydraulic motor described above is integrated with a single oil passage plate. 7. A hydraulic continuously variable transmission in which two hydraulic motors are connected to an axial type hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit, wherein one variable displacement hydraulic pump and one A hydraulic continuously variable transmission characterized in that a mounting housing for a variable displacement hydraulic motor is shared and disposed on one surface of an oil passage plate, and one variable motor is formed on the opposite surface of the oil passage plate. 8. A hydraulic continuously variable transmission in which two variable displacement hydraulic motors are provided in parallel with an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. A hydraulic continuously variable transmission, which is configured in tandem within a hydraulic closed circuit. 9. In a hydraulic continuously variable transmission in which two variable displacement hydraulic motors are driven by an axial hydraulic pump, the lower limit of the swash plate angle is set so that the lower capacities of the two hydraulic motors are different from each other. A hydraulic continuously variable transmission characterized in that the hydraulic motor is subjected to two-stage capacity adjustment of an upper limit and a lower limit. 10. A hydraulic continuously variable transmission in which two hydraulic motors are driven by an axial hydraulic pump, wherein two minimum values of the swash plate angle of the two hydraulic motors are set, and the maximum and the minimum are combined. A hydraulic continuously variable transmission characterized in that four types of capacities are set. 11. A hydraulic continuously variable transmission in which two variable displacement hydraulic motors are provided for one axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. Two kinds of minimum values of the swash plate angle are set, and the swash plate is driven by a drive mechanism such as a hydraulic piston or an electric actuator, and can be set at two positions of minimum and maximum. A hydraulic continuously variable transmission characterized in that the capacity of the hydraulic stepless transmission is set. 12. A hydraulic continuously variable transmission in which two hydraulic motors are connected to an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit. A hydraulic continuously variable transmission characterized in that the swash plate position of the variable displacement motor can be operated to the maximum position after reaching the maximum position or the maximum position in the minus direction. 13. A hydraulic continuously variable transmission in which two hydraulic motors are provided in parallel with an axial hydraulic pump so that hydraulic oil circulates in a closed hydraulic circuit, wherein one motor is a variable displacement hydraulic motor. A hydraulic continuously variable transmission characterized in that the other one is a hydraulic motor of a type capable of adjusting the capacity in two stages, the upper limit and the lower limit of the swash plate angle.