JPH071543Y2 - Forklift hydraulic clutch lubrication circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to improvement of a hydraulic clutch lubrication circuit of a forklift, and more particularly, by connecting a drain circuit of an inching valve to a cooler relief valve, the hydraulic clutch of the inching valve The present invention relates to a hydraulic clutch lubrication circuit for a forklift, which increases the flow rate of the lubrication circuit by the flow rate of the line pressure circuit to sufficiently cool and lubricate the hydraulic clutch when the inching operation is repeated at low engine speed.

[Conventional technology]

As a conventional hydraulic clutch lubrication circuit for a forklift, for example, the one described in JP-A-55-76252 is known.

In this conventional circuit, the circuit that has passed through the oil cooler from the torque converter and the relief circuit from the cooler relief valve that relieves the oil when the pressure of the oil supplied to the oil cooler exceeds a predetermined level are merged to make the hydraulic pressure of the transmission. It is used as a lubrication circuit for the clutch. The inching valve is connected to the hydraulic clutch via the select valve, and the inching circuit guides the line pressure to the drain circuit of the inching valve and drains it into the transmission case to reduce the line pressure. .

[Problems to be solved by the device]

However, in such a conventional forklift hydraulic clutch lubrication circuit, the amount of oil in the lubrication circuit supplied to the hydraulic clutch is determined by the engine speed, and the lubrication amount decreases at low engine speeds. Higher rotations increase the number. The amount of lubrication is irrelevant to the front-rear traveling of the vehicle, the inching operation, and the like. Therefore, when the inching operation is performed to put the hydraulic clutch in the half-clutch state, the hydraulic clutch generates heat and a large amount of lubrication and cooling are required. However, in the conventional circuit, the amount of lubrication is determined by the engine rotation, so the amount of lubrication of the hydraulic clutch is insufficient depending on the operating conditions, such as frequent inching operation at low engine speed. was there.

The present invention has been made in view of such a conventional problem, and in particular, the lubrication amount of the hydraulic clutch of the transmission is insufficient even in an operating condition in which the inching operation is frequently performed at a low engine speed. It is an object of the present invention to provide a hydraulic clutch lubrication circuit for a forklift, which is prevented.

[Means for Solving the Problems]

Therefore, the hydraulic clutch lubrication circuit for a forklift according to the present invention is provided with a line pressure circuit that supplies the line pressure from the inching valve to the hydraulic clutch of the transmission through the select valve of the transmission, and the circuit that passes through the oil cooler from the torque converter. And a relief circuit from a cooler relief valve that relieves when the pressure of the oil supplied to the oil cooler is equal to or higher than a predetermined value, thereby forming a lubrication circuit of a hydraulic clutch of a transmission in a hydraulic clutch lubrication circuit of a forklift. , The drain circuit of the inching valve of the line pressure circuit is connected to the inlet side of the cooler relief valve so that the hydraulic fluid of the line pressure circuit is supplied to the lubrication circuit of the hydraulic clutch via the cooler relief valve during inching operation. It is characterized by having done.

[Action]

During inching operation to put the hydraulic clutch in the half-clutch state, in addition to the total amount of lubrication of the oil that has passed through the normal oil cooler and the oil that has relieved the cooler relief valve, the line pressure from the inching valve through the drain circuit is Since the relief valve is relieved to supply the oil from the lubrication circuit to the hydraulic circuit, the amount of lubrication increases by the line pressure, and especially when the inching operation is repeated frequently at low engine speed, the cooling and lubrication of the hydraulic clutch are improved. Become.

Further, when the oil cooler is clogged, oil is not supplied downstream from the oil cooler, but both the oil from the torque converter and the oil from the drain circuit pass through the relief valve and are supplied from the relief circuit to the hydraulic clutch. Therefore, also in this case, the lubrication of the hydraulic clutch is improved. Further, in this invention, since the drain circuit of the inching valve is connected to the inlet side of the cooler relief valve, the hydraulic pressure of the circuit from the drain circuit and the inching valve to the hydraulic clutch via the select valve becomes the relief pressure of the cooler relief valve. Therefore, the minimum hydraulic pressure supplied to the clutch as the line pressure is secured even during the inching operation.

〔Example〕

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

First, the configuration will be described.

In FIG. 1, oil pressure-fed from an oil pump (not shown) is connected to a regulator valve 1 that adjusts the oil pressure to a predetermined value or more. At the outlet side of the regulator valve 1, the torque converter 2 and the A torque converter inlet relief valve 3 that relieves when the inlet pressure of the torque converter 2 becomes excessive is connected.

The oil coming out of the torque converter 2 is returned to the oil cooler 4,
Also, a cooler relief valve 5 that relieves when the pressure of the oil supplied to the oil cooler 4 exceeds a predetermined value is connected. The outlet side of the oil cooler 4 and the relief circuit of the cooler relief valve 5 are merged and connected as a lubrication circuit 6 to the forward clutch 7 and the reverse clutch 8 of the transmission.

The discharge side of the oil pump is connected to an accumulator 9 that stores line pressure and suppresses its pulsation, and an inching valve 10 that is rotated by an inching pedal (not shown). The outlet side of the inching valve 10 is connected to a select valve 11 that can be switched between forward, neutral and reverse by a shift lever (not shown), and the drain circuit 12 of the inching valve 10 is described above. It is connected to the inlet side of the cooler relief valve 5. The outlet side of the select valve 11 is connected to the forward clutch 7 and the reverse clutch 8, respectively.

Next, the operation of the above embodiment will be described.

The oil pressure-fed from the oil pump is adjusted to a predetermined pressure or higher by the regulator valve 1 and is supplied to the torque converter 2 as relief oil while being relieved by the torque converter inlet relief valve 3 when the pressure becomes excessive.

The torque converter 2 transmits the rotation of the crankshaft of the engine to the input shaft of the transmission. On the other hand, the line pressure from the oil pump passes through the inching valve 10 while being accumulated in the accumulator 9 and absorbing the pulsation.
It is supplied to the select valve 11. Here, if the select lever of the transmission is operated, for example, to the forward side, the select valve 11 is rotated to the forward side, and the line pressure is changed to the select valve 11
Is supplied to the forward clutch 7 of the transmission, and the forward clutch 7 is connected. Then, if the accelerator pedal is depressed, the forward speed of the forklift becomes faster, and if the accelerator pedal is returned, the forward speed becomes slower. When the select lever is operated in the reverse direction, the select valve 11 is rotated to the reverse side, the reverse clutch 8 is engaged, and the forklift is moved in the reverse direction. If you operate the select lever neutrally,
The select valve 11 is rotated to the neutral position, and the forklift takes the neutral position.

At this time, the high-temperature oil discharged from the torque converter 2 is cooled by the oil cooler 4 while being relieved when the cooler relief valve 5 reaches a predetermined pressure or higher, and the oil and the oil cooler 4 which are relieved by the cooler relief valve 5 are relieved. The oil that has passed through is the lubrication circuit 6
Are supplied to the forward clutch 7 and the reverse clutch 8 of the transmission to cool and lubricate them.

As shown in FIG. 2, when the select valve 11 is operated in the forward direction and the forward clutch 7 is engaged and the vehicle is traveling forward, when the inching valve (not shown) is depressed to rotate the inching valve 10. The line pressure is supplied from the inching valve 10 through the drain circuit 12 to the inlet side of the cooler relief valve 5, the relief amount of the cooler relief valve 5 increases, the line pressure flows into the lubrication circuit 6, and the forward clutch 7 and the reverse clutch The amount of lubricating oil supplied to 8 increases. This allows the inching valve
The supply of the line pressure from 10 to the forward clutch 7 is reduced, the forward clutch 7 is in a half-clutch state, and the forklift travels gently. For this reason, the forward clutch 7 and the reverse clutch 8 are cooled and lubricated well, and particularly, when the inching operation is performed when the engine is running at low speed, the forward clutch 7 and the reverse clutch 8 are cooled and lubricated well. .

FIG. 3 shows the amount of lubricating oil supplied to the forward clutch 7 and the reverse clutch 8, where Qa is the amount of oil supplied to the hydraulic clutch after passing through the oil cooler 4, which is the same as in the prior art and the present invention. Is the same. Qb is the amount of oil supplied to the hydraulic clutch via the conventional lubrication circuit 6, and Qc is the amount of oil supplied to the hydraulic clutch during the inching operation in this invention. In the case of the present invention, the flow rate increases by the amount supplied from the inching valve 10 through the drain circuit 12 to the cooler relief valve 5.

Also, when the oil cooler 4 is clogged, the oil cooler 4
Although no oil is supplied downstream from the above, both the oil from the torque converter 2 and the oil from the drain circuit 12 pass through the relief valve 5 and are supplied from the relief circuit to the forward clutch 7 or the reverse clutch 8. Also in this case, the lubrication of these hydraulic clutches 7 and 8 becomes good. Further, since the drain circuit 12 of the inching valve 10 is connected to the inlet side of the cooler relief valve 5, the drain circuit 12 and the inching valve 10 select the select valve 11 from the drain circuit 12.
The hydraulic pressure of the circuit that goes to the hydraulic clutches 7 and 8 via the pressure becomes the relief pressure of the cooler relief valve 5, so that the minimum hydraulic pressure supplied to the clutches 7 and 8 as the line pressure is secured even during the inching operation.

Thus, the cooler relief valve 5 guarantees the function of allowing the clutches 7 and 8 to be lubricated even when the oil cooler 4 is clogged during the inching operation, and the minimum hydraulic pressure of the line pressure to the clutches 7 and 8 during the inching operation. It coexists with the function to do.

If the line pressure is directly introduced from the inching valve 10 to the lubrication circuit 6, the oil pressure in the lubrication circuit 6 rises too much and the cooler relief valve 5 may not operate.

[Effect of device]

As described above, according to the hydraulic clutch lubrication circuit for a forklift according to the present invention, the drain circuit of the inching valve is connected to the inlet side of the cooler relief valve to relieve the line pressure from the cooler relief valve during the inching operation. Since lubricating oil is used for the hydraulic clutch, even if the inching operation is repeated at low engine speed, the amount of lubrication for the hydraulic clutch is secured, and overheat due to insufficient lubrication of the hydraulic clutch can be prevented.

In particular, according to this invention, the cooler relief valve has
The function of allowing lubrication of the clutch even when the oil cooler is clogged during the inching operation and the function of ensuring the minimum hydraulic pressure of the line pressure to the clutch during the inching operation coexist. Therefore, when the oil cooler is clogged, the oil is not supplied downstream from the oil cooler, but the oil with the oil drain circuit from the torque converter passes through the relief valve and is supplied from the relief circuit to the hydraulic clutch. Therefore, in this case as well, the lubrication of the hydraulic clutch is good, and since the drain circuit of the inching valve is connected to the inlet side of the cooler relief valve, the circuit from the drain circuit and inching valve to the hydraulic clutch via the select valve is reached. Is the relief pressure of the cooler relief valve, so that there is an effect that the minimum hydraulic pressure supplied to the clutch as the line pressure is secured even during the inching operation.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a hydraulic clutch lubrication circuit of a forklift according to the present invention, FIG. 2 is a hydraulic circuit diagram similar to FIG. 1 for explaining the operation of the above embodiment, and FIG. The figure is a graph showing the relationship between the engine speed and the flow rate during inching. 2 ... Torque converter, 4 ... Oil cooler, 5 ... Cooler relief valve, 6 ... Lubrication circuit, 7 ... Forward clutch, 8
… Reverse clutch, 10… Inching valve, 11… Select valve.

Claims (1)

[Scope of utility model registration request] 1. A line pressure circuit for supplying a line pressure from an inching valve to a hydraulic clutch of a transmission via a select valve of the transmission, and a circuit passing through an oil cooler from a torque converter and the oil cooler. In the hydraulic clutch lubrication circuit of the forklift, which is used as the lubrication circuit of the hydraulic clutch of the transmission by merging with the relief circuit from the cooler relief valve that relieves when the oil pressure exceeds a predetermined value, the inching valve of the line pressure circuit A drain circuit is connected to the inlet side of the cooler relief valve to supply the hydraulic fluid of the line pressure circuit to the lubrication circuit of the hydraulic clutch via the cooler relief valve during inching operation. Hydraulic clutch lubrication circuit.