JPS6360263B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a transmission shaft for transmission mounted on a transmission case, which is equipped with a hydraulic cylinder for stepped height shifting, and a hydraulic cylinder for transmitting pressure oil from a hydraulic pump through a control valve. The present invention relates to a hydraulic power transmission for a work vehicle configured to supply oil to the hydraulic cylinder and return waste oil from the hydraulic cylinder to a tank via a control valve thereof.

In the above, for example, when shifting from the lowest forward speed state, that is, the first forward speed state, to the second forward speed state, which is one step higher, the cylinder for the first forward speed is switched to the oil draining state. As a result, the speed is greatly decelerated, and then the cylinder for the second forward speed is operated to shift to a high speed state, and the speed difference caused by the shift is large, causing a so-called shaki phenomenon, which causes a relatively large shock to the driver. There was an additional drawback. Especially in crawler traveling equipment,
As the cylinder for the first forward speed was switched to the oil draining state, travel was almost stopped, and the above-mentioned shock was large and dangerous.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to reduce the number of shocks required to shift from a low speed state to a high speed state while driving, and to enable smooth shifting from a high speed state to a low speed state.

In order to achieve the above object, the present invention provides the above-mentioned hydraulic power transmission for a working vehicle, in which the control valve is configured in a rotary type, and the input/output ports for each of the hydraulic cylinders are configured as a rotary valve. are formed on the valve case at equal intervals along the rotational direction of the rotor,
A pressure oil supply oil passage formed in the rotor connects each of the input/output ports and each of the hydraulic cylinders so that pressure oil is sequentially supplied to the hydraulic cylinders on the high speed side as the rotor rotates. Drain oil from a hydraulic cylinder that is one step slower than the hydraulic cylinder that is supplying pressure oil to the rotor portion that corresponds to the input/output port that is one step before the input/output port in the speed increasing operation direction than the input/output port selected by . It is characterized by forming an oil drain groove with a throttle flow path that provides oil flow resistance.

The effects of the above configuration are as follows.

In other words, when shifting from a low speed state to a high speed state while driving, even if the low speed cylinder is switched to the oil drain state, resistance is applied to the oil drain, and there is no significant deceleration immediately after switching, and the so-called half-clutch state is reached. appears and the gear is shifted to a high speed state,
On the other hand, when shifting from a high-speed state to a low-speed state, pressure oil is supplied to the low-speed cylinder while decelerating immediately after the changeover, without providing a resistance hole to the oil discharged from the high-speed cylinder.

The effects of the above action are as follows.

In other words, when shifting from a low speed state to a high speed state while driving, it is possible to suppress the deceleration caused by switching the low speed side cylinder to the oil drain state, and it is now possible to shift to a high speed state with a small speed difference and less shock. Furthermore, when shifting from a high speed side to a low speed side, there is no resistance to oil discharged from the high speed side cylinder, and the speed change can be smoothly performed without unnecessarily continuing a high speed state.

Moreover, since the configuration for performing the above-mentioned speed change action is simply to provide a throttle channel in the rotor of the rotary valve, for example, two supply channels each having a throttle channel and a free flow channel to the shift cylinder may be used. In addition to providing a position switching valve, a device is attached to the speed change operation tool to detect the direction of its operation, and oil is drained from the low speed cylinder through a throttle flow path based on the detection of the speed change operation state to the high speed side by the detection device. Compared to adopting a configuration in which a two-position switching valve is automatically switched so as to change the position, the structure has the advantage of being extremely simple.

Hereinafter, embodiments of the present invention will be described in detail based on illustrative drawings.

A reaping unit 2 raises and reaps planted stem culms in the field, transports the cut stem culms to the rear of the machine, changes its posture to a sideways posture, and transfers the cut stem culms to the feed chain 1; A threshing device 3 that performs threshing while holding and transporting grains at 1 is connected to a traveling vehicle body equipped with a crawler traveling device 4 and provided with a control section 5, and the reaping section 2 can be driven up and down via a hydraulic cylinder 2a. A combine harvester is constructed.

To drive the traveling device 4, the power from the engine 6 is transferred to a gear-type transmission mechanism 7 that can freely change three speeds for the auxiliary transmission, and a hydraulic type that can freely change the speeds to three forward speeds and one reverse speed for the main speed change. power transmission 8
As a whole, the transmission is configured to be able to freely change gears to nine forward speeds and three reverse speeds, and will be described in detail below.

That is, the engine 6 is placed in the transmission case 9.
an input shaft 10 interlocked with the driving gear, first to third transmission shafts 11, 12, 13 for traveling speed change, a steering clutch 14,
14, a left and right running drive shaft 16, 16, a fourth transmission shaft 17 for transmitting power to the reaping section 2 and the threshing device 3, and an output shaft 18, respectively, are mounted on a shaft, and the input shaft 10 and The gear-type sub-transmission mechanism 7 is provided between the first transmission shaft 11 and the gear-type transmission mechanism 19, which is capable of shifting in two stages, is provided between the fourth transmission shaft 17 and the output shaft 18. Said second transmission shaft 1
2, first and second hydraulic clutches 21 for shifting;
23, and third and fourth hydraulic clutches 20 and 22 are attached to the third transmission shaft 13, respectively, and are connected to be integrally rotatable by engaging the clutches 20, 21, 22, and 23, respectively. Transmission gears 24 are loosely fitted into the second and third transmission shafts 12 and 13, and the first
or fourth hydraulic clutch 20, 21, 22, 23
Each cylinder 20a, 21a, 22a, 23a
It is configured to supply pressure oil to.

The hydraulic cylinders 20a, 21a, 22a, 2
As shown in FIG. 3, the hydraulic circuit for 3a is configured to supply gear oil in the transmission case 9 via an oil filter 25, a hydraulic pump 26, and a rotary control valve 27. By switching the control valves 27, a neutral state N, a reverse state R, and forward first to third speed states F ₁ , F ₂ , and F ₃ can be selectively obtained. An accumulator 28 is connected in communication with the pressure oil supply path to the control valve 27, and is configured to prevent sudden start when switching from a neutral state to a first forward speed state or a reverse state. .
Further, a return oil passage 30 having a relief valve 29 interposed therein is connected in the middle of the pressure oil supply passage to the control valve 27, and the return oil passage 30 is supplied to the hydraulic clutches 20, 21, 22, and 23. The hydraulic clutches 20, 21, 22, and 23 are cooled by using the relieved oil.

The control valve 27 is provided in the transmission case 9 with its longitudinal direction parallel to the transmission shaft 11, and as shown in FIG. An accumulator 28 is provided in abutting state. Moreover, the oil filter 25
are also provided with their longitudinal direction parallel to the transmission shaft 11..., and the oil filter 25,
Hydraulic pump 26, control valve 27, accumulator 28, and cylinders 20a, 21
The in-shaft oil passages communicating with each of a, 22a, and 23a are connected through oil passages formed in the mating surfaces of the transmission case 9 and the hydraulic plate 31 attached thereto.

To configure the control valve 27, as shown in FIG. 5, a pressure oil supply oil passage 33 extending in the radial direction is formed in a cylindrical rotor 32, and oil is supplied to the inside of the rotor 32 by rotation of the rotor 32. The pressure oil
Input/output port R formed in the valve case 34,
configured to selectively supply F ₁ , F ₂ , and F ₃ ;
In addition, a return communication groove 35 is formed on the outer circumferential surface of the rotor 32 over almost the entire circumference excluding the pressure oil supply passage 33, and all except the input/output ports communicating with the pressure oil supply passage 33 are formed. The input/output port is connected to a return path 36 into the mission case 9 via a communication groove 35.

A throttle passage 35a having a smaller cross-sectional area than the other portion is provided at the end of the communication passage 35 located on the upper side than the pressure oil supply oil passage 33 in the rotational direction of the rotor 32 toward the high-speed transmission side in the forward state. When shifting from the first forward speed state to the second forward speed state or from the second forward speed state to the third forward speed state, the rotor 32 is rotated to complete the speed change operation, that is, the forward speed state. While communicating with input/output port F ₂ for 2nd speed or port F ₃ for 3rd forward speed, port F ₁ for 1st forward speed or port F ₂ for 2nd forward speed, which is one step lower, is connected to the throttle. It is located corresponding to the flow path 35a, and is configured to provide resistance to oil discharged from the cylinder 21a or 22a, and to prevent the hydraulic clutch 21 or 22 from being immediately disengaged upon gear change.

Each of the clutches 20, 21, 22, 23... has a piston member 37 as shown in FIG.
A relief hole 38 is formed at a predetermined location of the clutch 20, and is configured to allow a portion of the supplied pressure oil to escape through the relief hole 38 during a gear change operation, thereby preventing the clutch 20 from suddenly engaging. .

An operating tool 3 interlockingly connected to the valve rotor 32
To configure the lever guide 40 of No. 9, as shown in FIGS. 4 and 6, the forward operation path A and the reverse operation path B are made to have different phases, and both paths A and B are A guide groove 41 is formed so as to be continuous at a neutral position via a path C having a width slightly larger than the diameter of the tool 39, and in the middle of the operating tool 39, it is displaced to the forward operating path A side. The vehicle is provided with a leaf spring 42 that urges the vehicle to move forward, and is configured to prevent accidental reverse operation when the vehicle is operated toward a neutral position to stop traveling during forward travel.

Also, a recess 43 is provided at the neutral end of the reverse operation path B.
is formed, so that when the vehicle is operated to the neutral position side to stop traveling in the middle of traveling backwards, it is locked in the recess 43, and by cooperating with the path C, it is better to prevent accidental forward operation. It is designed to prevent this.

To configure the power transmission 8, for example, a transmission gear 24 is loosely fitted to the transmission shafts 12, 13, and a connecting pin is provided in the transmission shafts 12, 13 for connecting or disconnecting the transmission gear 24. It may be provided so as to be movable in the radial direction, and may be provided with a cylinder for operating the connecting pin to move in and out.

The present invention is applicable not only to a combine harvester equipped with a crawler traveling device but also to various work vehicles such as a riding-type tiller equipped with a tire-type traveling device.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the hydraulic power transmission for a working vehicle according to the present invention, in which Fig. 1 is an overall side view of a combine harvester, Fig. 2 is a schematic longitudinal sectional view of a transmission case, and Fig. 3 is a hydraulic circuit. 4 is a longitudinal cross-sectional view of the main parts, FIG. 5 is a cross-sectional view of the rotary valve together with a vertical cross-sectional view of the hydraulic clutch, and FIG. 6 is a cross-sectional view taken along the line -- in FIG. 4. 9...Mission case, 12, 13...Transmission transmission shaft, 20a, 21a, 22a, 23a...
Hydraulic cylinder, 26... Hydraulic pump, 27... Control valve, 32... Rotor, 35... Return communication groove, 35a... Throttle channel, R, F ₁ , F ₂ ,
_F3 ...I/O port.

Claims (1)

[Claims] 1. Hydraulic cylinders 21a, 22a, 23a for stepped height shifting are attached to transmission shafts 12, 13 for transmission mounted on the transmission case 9, and pressure oil from a hydraulic pump 26 is supplied via a control valve 27. It is supplied to the hydraulic cylinders 21a, 22a, 23a, and the hydraulic cylinders 21a, 22a, 23a are supplied via the control valve 27.
In the hydraulic power transmission for a work vehicle configured to return waste oil from the hydraulic cylinders 21a, 22a, 23a to the tank, the control valve 27 is configured in a rotary type, and
Input/output ports F ₁ , F ₂ , F ₃ are formed in the valve case 34 at equal intervals along the rotational direction of the rotor 32 constituting the rotary valve, and as the rotor 32 rotates, the high speed increases in sequence. Each of the input/output ports F ₁ , F ₂ , F ₃ and each of the hydraulic cylinders 21a, so that pressure oil is supplied to each hydraulic cylinder,
22a, 23a, and one port before the input/output ports F ₁ , F ₂ , F ₃ in the speed increasing operation direction selected by the pressure oil supply oil passage 33 formed in the rotor 32 . A throttle passage 35a is provided in the portion of the rotor 32 corresponding to the input/output ports F ₁ , F ₂ , and F ₃ to provide oil passage resistance to drained oil from a hydraulic cylinder that is one step slower than the hydraulic cylinder that is supplying pressure oil. A hydraulic power transmission for a work vehicle, characterized by having an oil drainage groove formed therein.