JPH0156305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention connects a hydraulically operated gear transmission and a hydraulically operated clutch in series, and operates a transmission valve of the transmission to transmit pressure oil from a pump to the transmission state of the transmission. connected to the pump in a state where it is supplied to an actuator for operating the transmission;
The operation valve of the clutch is linked to the transmission so that it is automatically operated to an on position when the transmission is in a transmission state, and is automatically operated to an off position when the transmission is switched, and , connected to the pump in a state in which pressurized oil from the pump is supplied to an actuator for operating the clutch when the clutch is in an engaged state, and a relief valve mechanism is provided in a connecting oil path between the pump and both actuators, Shifting can be done with the light operating force of simply switching the shift valve, and in conjunction with the shifting operation, the transmission is automatically disconnected from the drive side or from driven devices such as traveling gear, and the shift gear engagement is switched off. The actuator for operation is maintained in a pressurized state, the transmission and the clutch are maintained in the transmission state or the engagement state, and the clutch is engaged while the transmission is in the transmission state. The present invention relates to a hydraulically operated transmission configured so that surplus oil from the pump after the pump is returned to the tank via a relief valve mechanism.

In the above-mentioned transmission, conventionally, if the relief pressure of the relief valve mechanism is set so that the clutch actuator is maintained in the engaged state with the minimum amount of oil pressure required to engage the clutch, the The relief valve mechanism operates in relief while the hydraulic pressure acting on the actuator is low, resulting in a loss of oil supply to the actuator, causing the inconvenience of slowing down the operating speed of the actuator. Either the time required to be in the neutral state becomes longer and the vehicle speed decreases significantly, or the pressure-receiving area of the actuator must be increased in order to increase the actuator's operating speed even with low oil pressure. However, the actuator becomes large in size. Conversely, if the relief pressure of the relief valve mechanism is set high to avoid these inconveniences, the pressure oil from the pump will be relieved at high pressure from the relief valve mechanism to the tank during transmission, and the oil temperature will decrease. This caused the inconvenience of an early rise.

The purpose of the present invention is to reduce the relief pressure of excess oil during transmission, to quickly change the transmission without increasing the size of the actuator, and to provide a structure that is simple in structure. It's about making sure you get it.

A characteristic configuration of the present invention is that in the above-mentioned hydraulically operated transmission, the relief valve mechanism is provided with a first relief valve on the upper side of the two operating valves in the connecting oil passage, and A second relief valve whose relief pressure is lower than that of the first relief valve is provided in the oil passage connecting the operation valve and the clutch operation actuator, and its use and effects are as follows. be.

That is, during gear shifting, the clutch valve is in the off position and the connection between the second relief valve and the first relief valve is cut off, so that only the first relief valve acts on the pressure oil from the pump. As a result, the circuit pressure for the transmission actuator reaches the high pressure set by the first relief valve, and after the transmission is in the transmission state, the pressure from the pump is reduced by moving the clutch valve to the on position. Both the first and second relief valves will act on the oil, but the second relief valve will act on the oil.
Since the relief pressure of the relief valve is lower than that of the first relief valve, the circuit pressure to the clutch actuator becomes low due to the second relief valve, which is lower than that during gear shifting. When the circuit pressure increases during gear shifting, the flow loss due to relief decreases, and high-pressure oil acts on the transmission actuator, so this actuator operates quickly even if it is made small. Therefore, the relief pressure of excess oil during transmission can be made low, and the rise in oil temperature caused by excess oil reduction can be suppressed as much as possible.Moreover, the actuator for changing the transmission can be made as small as possible, and the entire transmission can be reduced in size. It has become possible to make the system more compact, and it has also been possible to quickly change the transmission, making it possible to suppress a decrease in travel speed due to the speed change as much as possible, which is advantageous. Furthermore, since the relief pressure is changed automatically, no special effort is required to adjust the relief pressure, which is advantageous in terms of operation. On top of that,
According to the relief valve mechanism configuration according to the present invention,
Since the clutch operation structure can be effectively used as the means for automatically changing the relief pressure, it is only necessary to provide both the first and second relief valves in order to advantageously perform gear shifting, excess oil relief, etc. as described above. The structure was simplified.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in Fig. 1, a main gear transmission that can be switched to four stages is connected to an input shaft 2 that is linked to an engine 1.
_M1 is interlocked, and a hydraulically operated first clutch 4 is interlocked with the output shaft 3 of this main transmission _M1 .
On the output side of the clutch 4, a forward/reverse switching gear transmission M ₂ , an auxiliary gear transmission M ₃ capable of switching to two high and low speeds, and a reduction gear transmission M ₄ capable of switching to a non-deceleration state are interlocked in that order, and,
The first output shaft 5 of the reduction transmission M ₄ is connected to the rear wheel 6.
A second output shaft 9, which is interlocked with the differential mechanism 7 of the front wheel 10 and interlocked with the first output shaft 5 via the clutch gear 8, is interlocked with the differential mechanism 11 of the front wheels 10. It constitutes a transmission gear for driving an agricultural tractor.

The input shaft 2 is connected to a gear transmission _M5 capable of changing four speeds, and the power output shaft 14 is connected to the output shaft 12 of the transmission _M5 via a hydraulically operated second clutch 13. A variable speed transmission for the working device is provided.

The operating structure of the traveling transmission is constructed as follows.

That is, as shown in FIG. 1, the two shift forks 15 and 16 of the main gear transmission M ₁ are configured to be operated by the first or second hydraulic cylinder 17 or 18, and the sub gear transmission M ₃ is operated by the first or second hydraulic cylinder 17 or 18. The shift fork 19 is configured to be operated by a third hydraulic cylinder 20, and as shown in FIG.
The transmission valve 21 is connected to the transmission case 2.
Pump 23 that supplies the lubricating oil in 2 as hydraulic oil
It is connected to. The cylinders 17, 18, 20
Shift fork 15 or 16 or 19 respectively
is energized to a neutral position, and the transmission valve 21 is moved to the main transmission cylinder at each operating position P ₁ to P ₈ where both the main and auxiliary transmissions M ₁ and M ₃ are in a transmission state. 17, 18 and the auxiliary transmission cylinder 20 from the pump 23, and a relief valve mechanism 25 is provided in the oil passage 24 connecting each of the cylinders 17, 18, 20 and the pump 23. Provided,
When the transmission valve 21 is operated to each transmission position _P1 to _P8 , the cylinders 17 or 18 and 20 are maintained in a pressurized state by the pressure oil supplied from the pump 23, and both the main and sub-transmission devices M ₁ and _M3 are maintained in a transmission state, and surplus oil from the pump 23 is relieved from the relief valve mechanism 25 and returned to the transmission case 22, and both the main and sub-transmission devices _M1 , M 8 obtained by combining ₃
The transmission valve 21 is operated to switch, and both the main and auxiliary transmissions M ₁ and M ₃ are operated to switch by hydraulic pressure so that a transmission state of stages is displayed.

As shown in Figure 1, the forward/reverse switching mechanism
M ₂ shift fork 26 to the 4th hydraulic cylinder 2
As shown in FIG.
M ₂ is operated by hydraulically switching.

As shown in FIG. 2, an operating valve 2 of a hydraulic cylinder 4a for operating the first clutch 4 on and off.
9 as the first to third valves 29a, 29b, 29
It is composed of c. And these valves 29
a, 29b, 29c to the pilot operating circuit 30
a, 30b, 30c, the cylinder 1
7, 18, and 20, which are formed to be switched in accordance with the operation thereof, and connected to the cylinder 27 through the oil passage 31 so as to be switched in accordance with the operation of the cylinder 27. The operation valve 29 is connected to the formed valve portion, and is automatically operated to the on position in the transmission state of both the main and auxiliary transmissions M ₁ , M ₃ , _{and 3}
It is linked to both main and sub-transmission devices M ₁ and M ₃ so that it is automatically operated to the cut position when switching. That is, only when either one of the main transmission cylinders 17 and 18 and the auxiliary transmission cylinder 20 is in the transmission state, the operation valve 29 is supplied from the pump 23 via the control valve 28 and the valve portion of the cylinder 27. The clutch is configured to be in a clutch engaged state in which pressurized oil is supplied to the cylinder 27. The first clutch 4 is disengaged and the operating valve 29 is configured to supply pressure oil from the cylinder 27 to the cylinder 4a when the clutch 4 is in the engaged state, and the cylinder 4a is configured to supply pressure oil from the pump 23 to the cylinder 4a. The clutch 4 is maintained in a pressurized state by pressurized oil so that the clutch 4 is maintained in an engaged state. And clutch 4
Excess oil supplied to the cylinder 4a in the closed state is relieved from the relief valve mechanism 25 and returned to the mission case 22.

More specifically, during a gear shift operation, the first clutch 4 is automatically disconnected so as to disconnect the main transmission _M1 from the wheel side, and also disconnect the auxiliary transmission _M3 from the engine side. When both the main and auxiliary transmissions M ₁ and M ₃ are in the transmission state, the first clutch 4 is automatically engaged, and both the main and auxiliary transmissions M ₁ and M ₃ and the forward/reverse switching transmission M ₂ are all in the transmission state. It is designed to remain in the entered state as long as it remains in the entered state.

As shown in FIG. 2, the relief valve mechanism 25 includes a first relief valve 32 on the upper side of the connection oil passage 24 than the main transmission valve 21 and the forward/reverse switching valve 28. A relief oil passage 33 configured as an oil passage for supplying cooling and lubrication to the first and second clutches 4 and 13 is connected to the connecting oil passage 34 between the operating valve 29 and the clutch cylinder 4a, A second relief valve 35 whose relief pressure is lower than that of the first relief valve 32 is provided, and when changing gears,
The clutch valve 29 is automatically set to the off position and the connection between the second relief valve 35 and the first relief valve 32 is cut off, thereby increasing the relief pressure by the first relief valve 32 and causing both the main and sub-side pressures to be high. When the transmissions M ₁ and M ₃ enter the transmission state, the clutch valve 29 automatically moves to the engaged position and shifts to the first position.
Both the second relief valves 32 and 35 act on the pressure oil from the pump 23, but the relief pressure of the second relief valve 35 is smaller than the relief pressure of the first relief valve 32. Accordingly, the relief pressure is switched to a low pressure by the second relief valve 35.

To configure the operating structure of _the transmission device for the working device, as shown in FIG. As shown in FIG. 2, the fifth and sixth cylinders 41 and 42 are operated by a single rotary speed change valve 43.

As shown in FIG. 2, the operating valve 44 of the second hydraulic clutch 13 is operated so that the operating oil is supplied to the second hydraulic clutch 13 only when either one of the fifth and sixth cylinders 41, 42 is in the transmission position. The second hydraulic clutch 13 is connected to the valve portions of the fifth and sixth cylinders 41, 42 so as to be automatically switched to the supply state, so that the second hydraulic clutch 13 is automatically switched only when the gear transmission _M5 is in the transmission state. It is designed so that it can be operated at the moment of entry.

The present invention can also be applied to the case where the transmission device for the work equipment incorporates the same configuration as the transmission device for traveling, and the clutch is only connected to the main and sub-transmission device.
Alternatively, the present invention can also be applied to a configuration in which the transmission is operated in conjunction with only one of the main and sub transmissions.

[Brief explanation of drawings]

The drawings show an embodiment of the hydraulically operated transmission according to the present invention, with FIG. 1 being a driving transmission system diagram and FIG. 2 being a hydraulic circuit diagram. 4... Clutch, 4a... Actuator for clutch, 17, 18, 20... Actuator for transmission, 21... Speed change valve, 23... Pump, 24, 34... Connection oil path, 25... Relief valve mechanism , 29...clutch valve, 32...
First relief valve, 35...Second relief valve, M ₁ ,
_M3 ...Transmission device.

Claims (1)

[Claims] 1 Hydraulically operated gear transmissions M ₁ , M ₃ and hydraulically operated clutch 4 are interlocked and connected in series, and the shift valves 21 of said transmissions M ₁ , M ₃ are connected to said transmissions M 1 , M ₃ .
In the transmission state of M ₃ , pressure oil from the pump 23 is transferred to the actuator 1 for operating the transmission devices M ₁ and M ₃ .
7, 18, 20, the pump 23
and the operating valve 29 of the clutch 4,
The transmission devices M ₁ , M ₃ are automatically operated to the on position in the transmission state, and the transmission devices M 1 , M ₃ are automatically operated to the engaged position;
The transmissions M _{1 and} M ₃ are linked so that when the clutch M 3 is switched, it is automatically operated to the off position, and when the clutch ₄ is engaged, pressure oil from the pump 23 is applied to the clutch 4. A connecting oil passage 24 between the pump 23 and both the actuators 17, 18, 19, 4a is connected to the pump 23 in a state where it is supplied to the actuator 4a for use.
The hydraulically operated transmission is equipped with a relief valve mechanism 25, and the relief valve mechanism 25 includes a first relief valve 32 on the side of the connection oil passage 24 above both operation valves 21 and 29.
and a second relief valve 35 whose relief pressure is smaller than the relief pressure of the first relief valve 32 is provided in the oil passage 34 connecting the clutch operation valve 29 and the clutch operation actuator 4a. Operated transmission.