JPS6137540A - Travelling transmission unit - Google Patents

Abstract

PURPOSE:To restrain shocks upon starting and upon deceleration, by automatically operating a pair of shut-off valves in accordance with data from a swash plate angle sensor. CONSTITUTION:When the swash plate angle of a hydraulic pump 6 has a set value corresponding to its neutral position or a position near thereto, a pair of shut-off valves 14a, 14b are controlled to be opened. Then, hydraulic oil fed from the pump 6 is returned into a speed change gear casing 11 from one of oil discharge passages 12a, 12b to stop a motor 7 from which return hydraulic oil is discharged into the speed gear casing 11 through one of the oil discharge passages 12a, 12b. When the swash plate angle has a high speed side value which is higher than the set value, one of the shut-off valves 14a, 14b associated with one of a pair of oil passages 10a, 10b which serves as the supply side, is closed while the other shut-ff valve associated with the other passage which serves as the return side, is opened. Therefore, hydraulic oil from the pump 6 is fed into the motor 7 from which return oil is discharged into the speed change gear casing 11 through one of the oil discharge passages 12a, 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a continuously variable transmission for traveling consisting of a hydraulic pump and a hydraulic motor, and a pair of oil passages connecting the pump and the motor. The present invention relates to a traveling transmission device including an on-off valve that can be freely switched between an open position where the oil passage communicates with a tank and a closed position where the communication is cut off, with a throttle υ portion provided in the open position.

[Conventional technology]

Although the above-mentioned continuously variable transmission has a self-restoring force to neutral, this restoring force decreases as the swash plate approaches the neutral position. In order to make the motor drive stop when the swash plate angle does not return to the neutral position, or returns to the neutral position, in other words, the actual neutral position is set so that the swash plate angle corresponds to the value corresponding to the original neutral position or near the neutral position. In order to obtain the desired value, conventionally, the configuration was as shown in FIG. That is, the on-off valve (14a),
(14b) respectively with spring (15M) or (15M)
b) to the open position (O), and the on-off valve (1
Connect the pilot operating circuits (22&) or (22b) for each of 4a) and (14b) to the connecting oil passage (1oa) or (10b) of the hydraulic pump (6) and hydraulic motor (7), so that the swash plate angle is If the value is on the high-speed side than the setting value corresponding to neutral or the vicinity thereof, the on-off valve (14K).

(14b) each of the oil passage (1oa) or (10b)
When the swash plate angle reaches the set value, the on-off valves (14m) and (14b) are automatically switched to the closed position M (C) by pressure oil from the opening device (O). Even if the swash plate is at an angle slightly away from neutral, the supply pressure oil from the pump (6) is automatically switched to the on-off valve (14B).
) or (14b) to return to tank (6).

[Problem that the invention seeks to solve]

In the case of the conventional neutral setting configuration, when starting, the on-off valve (
14m) or (14b), some of the pressure oil supplied from the pump (6) flows into the tank 0υ, causing the swash plate angle to move beyond the neutral setting range at high speed. After the value exceeds the side, open/close valve (14m) or (14b)
Since the motor (7) is switched to the closed position (C), the motor (7) is suddenly started to be driven by relatively high-pressure oil, causing a sudden start-up shock. Furthermore, when decelerating,
A motor (7) is driven by a traveling device that rotates due to inertia,
The oil pressure of the oil return side of the pair of connecting oil passages (10 &) + (10b) increases, and the on-off valve (14a) or (14b) on this oil passage side moves to the closed position (C). As a result, a large deceleration shock was generated without the motor (7) being suddenly braked.

An object of the present invention is to enable the above-mentioned neutral setting to be performed while minimizing shocks during starting and deceleration.

[Means for solving problems]

The present invention is characterized by providing the above-mentioned traveling transmission with a sensor for detecting the swash plate angle.
When the swash plate angle is at a set value corresponding to neutral or around this, the pair of oil passages are automatically connected to the tank, and the swash plate angle is set at a higher speed side than the set value. Based on the information from the sensor, the pair of opening/closing valves are automatically set so that the supply side of the pair of oil passages is in a non-tank communication state and the return side is in a tank communication state when A mechanism is provided to automatically operate the system, and its functions and effects are as follows.

[For production]

When the swashplate reaches an angle corresponding to near its original neutral position,
The operating mechanism automatically operates both of the pair of on-off valves to the open position, and maintains the open position even if the pressure in the return side oil path becomes high, so that the pressure oil supplied from the pump returns to the tank; , allowing return oil from the motor to return to the tank when decelerating to neutral. Then, when the swash plate changes to an angle that deviates from the set value to the high speed side, the operating mechanism automatically operates the on-off valve for the supply side oil passage to the closed position with good responsiveness without delay to the swash plate angle change. , the hydraulic pressure applied to the motor can be gradually increased from a low pressure determined by the set neutral position, and the operating mechanism automatically operates the on-off valve for the return oil passage to the open position, even if the oil passage pressure is high. This allows the return oil from the motor to pass through the on-off valve and return to the tank relatively smoothly when the motor is decelerated.

〔Effect of the invention〕

Therefore, when the swash plate angle returns to the vicinity of the original neutral position, the motor drive is stopped, so that the neutral position can be set to have a range rather than a point, and the motor can rapidly rotate when starting. The shock caused by the start of the motor and the shock caused by the sudden stop of the motor during deceleration can be suppressed as much as possible, making it possible to operate extremely safely and comfortably.

〔Example〕

As shown in Figure 4, a pair of left and right steering type front wheels (1)
, (1) and non-steering punched wheels (2) I (2). A lift arm (3) connects a working device such as a rotary tiller so that it can be raised and lowered to the rear of the traveling machine that is capable of driving each of I (2) and the non-steering punched wheels (2). ), and a power take-off shaft (4) that transmits power to the connected working device, thereby constructing a riding type agricultural tractor.

A hydraulic pump (6) and a hydraulic motor (7) are provided between the engine (5) and a sub-gear transmission (not shown) for the front and rear wheels (1), (2), and
A continuously variable transmission (8) for driving that can be switched between the forward side and the reverse side with the neutral state in between is installed inside the transmission case (9).

As shown in Fig. 1, a pair of oil passages (10m) and (10b) connect the hydraulic pump (6) and the hydraulic motor (7).
An oil drain path (t2m) or (12b) connecting this oil path (10M) or (lob) and the continuously variable transmission case circuit as a hydraulic oil tank is connected to each of these oil drain paths (10M) or (lob). 12a) t (12b) is provided with an on-off valve (14m) equipped with a throttle part 03 in the open position (O), and an on-off valve (1d04b), and these on-off valves (14a),
(141)), the pair of oil passages (10h) + (1
0b) can be switched separately between a state in which it communicates with the transmission case (6) and a state in which this communication is cut off. And a pair of said on-off valves (14&), (14
Each of b) is configured as an electromagnetic operated valve biased to the open position (O) by a spring (15m) or (15b), and an operating circuit for these on-off valves (14 &) + (14b) q0 is the hydraulic pump (
6) The swash plate (not shown) is connected to the potentiometer αη which is linked to detect the swash plate angle via the swash plate operating rotation shaft (not shown), and this potentiometer aη
A pair of on-off valves (14 m), (1
4b) is configured to be automatically operated, so that the continuously variable transmission (8) is reliably brought into a neutral state, and shocks at the time of starting and deceleration are suppressed.

That is, if the output value from the potentiometer (171) is at the set value, it is determined that the swash plate angle is at the neutral angle, and there is a difference between the output value from the potentiometer aη and the set value. Then, in order to judge that the swash plate angle is on the transmission side, we also need to know whether the output value by the potentiometer Qη is larger or smaller than the set value, and then determine the swash plate angle on the forward side. It is designed to judge whether the object is on the opposite side or on the backward side.

Then, the operation circuit 01 controls the potentiometer Q.
η, a pair of on-off valves (141), (14b), and the respective electromagnetic solenoid operating parts (18m) or (18b) are connected as shown in FIG. Consists of a pair of on-off valves (14m).

(14b) is configured to operate as follows.

That is, when the swash plate angle is at a set value corresponding to neutral or around this, the pair of oil passages (1
0a) and (10b) are in communication with the transmission case 91, and the pressure oil supplied from the pump (6) returns to the transmission case αυ from the oil drain path (12m) or (12b) to the motor (
A pair of on-off valves (14 m
) and (14b) to the open position (O). When the swash plate angle is on the higher speed side than the set value, as shown in FIG. , the supply side of the pair of oil passages (10m) and (10b) so that the return oil from the motor (7) is discharged to the transmission case αυ through the oil drainage passage (xga) or (12b). thing(
ioa) or (10b) to the closed position (C), and the one on the return υ side (l) of the pair of oil passages (10m) and (10b)
on-off valve (14b) for ob) or (log) or (
14&) to the open position (O).

[Another embodiment] The potentiometer ση may be replaced with a mechanical detection configuration, and the operation circuit QQ may be replaced with a mechanical interlocking configuration, where the potentiometer αη is referred to as a sensor aη, and the operation circuit aQ is replaced with an automatic operation mechanism CIe. It is called.

In addition to agricultural tractors, the present invention can also be applied to various vehicles such as various agricultural vehicles and transport vehicles such as the Con7 (Inn).

[Brief explanation of drawings]

The first page shows an embodiment of the driving transmission device according to the present invention, FIG. 1 is a hydraulic circuit diagram of the continuously variable transmission in the neutral state, FIG. 2 is a hydraulic circuit diagram of the continuously variable transmission in the transmission state, and FIG. 3 is a hydraulic circuit diagram of the continuously variable transmission in the transmission state. is an electric circuit diagram, and FIG. 4 is an overall side view of the agricultural tractor. FIG. 5 is a hydraulic circuit diagram of a conventional transmission. (6)...Hydraulic pump, (7)...Hydraulic motor, (8)...Continuously variable transmission, (101
), (101+)... oil road, (b)...
Tank, l... Throttle part, (14m), (14b
)...Opening/closing valve, IJQ...Automatic operation mechanism, αη...Sensor. Agent Patent Attorney Shudai Kitamura 1
figure

Claims (1)

[Claims] [1] A continuously variable transmission device (8) for traveling consisting of a hydraulic pump (6) and a hydraulic motor (7) is provided, and the pump (6) and the motor (7) are connected. A pair of oil passages (10
a), (10b) respectively, this oil passage (10a) or (1
An on-off valve (1
4a) or (14b) with the constriction part (13) in the open position.
The transmission device is equipped with a sensor (17) for detecting the swash plate angle, and automatically detects when the swash plate angle is at a set value corresponding to neutral or around this. When the pair of oil passages (10a) and (10b) are both in communication with the tank, and the swash plate angle is at a value corresponding to the higher speed side than the set value, the pair of oil passages (10a) and (10b) are automatically opened. The supply side of the paths (10a) and (10b) is in communication with the tank, and the return side is in communication with the tank.
a mechanism (16) that automatically operates the pair of on-off valves (14a) and (14b) based on information from the sensor (17);
) is a traveling transmission device. [2] The traveling transmission device according to claim [1], wherein the automatic operation mechanism (16) is an electric mechanism.