JPS631700A - Hydraulic circuit for cargo-handling car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hydraulic circuit in a cargo handling vehicle such as a forklift truck, and in particular, to a hydraulic circuit in which two to three flow dividers are provided in the circuit.

One of these concerns a hydraulic circuit that efficiently supplies the required oil to various actuators as a flow divider with a load sensing function.

(Prior Art) A conventional hydraulic circuit used in this type of cargo handling vehicle is shown in FIG. 3.

In the figure, a is the first pump and b is the second pump.

C is a control valve, d is a tilt cylinder, e is a lift cylinder, and f is a brake valve.

g is the brake, h is the flow divider, i is the clutch booster, j is the steering gear box, is the power steering cylinder, 7! indicates an oil clutch. Note that m is the clutch pedal.

n is the brake pedal and p is the oil spray part.

q indicates an oil suction section, and S indicates an accumulator.

As is clear from the figure, the oil from the first pump a is directed to work machine actuators such as the lift cylinder e and the tilt cylinder d via the operating valve C.

Further, the oil from the second pump b is supplied to the brake g, the Tarasochi booster i, the power steering cylinder, the accumulator S, the oil clutch β, and other control system actuators. In this way, by using two pumps, it is possible to separately ensure optimal flow rates for each of the two systems.

(Problems to be Solved by the Invention) The hydraulic circuit described above is a so-called two-pump circuit, and the following means are available for driving these two pumps. That is, in the pump shown in FIG. 4, the first pump a is of the side PTO type, and the second pump b is of the crankshaft belt drive type. ■ indicates a V-belt and r indicates a crankshaft pulley. In this case, the second pump b is driven by a belt from the crankshaft, but the second pump b must be fixed to the vehicle body, and a mechanism for adjusting the tension of the belt must be provided, which is complicated.

In addition, in terms of space, the space is narrowed by the size of the second pump, making it difficult to arrange the various devices in small vehicles.

The pump shown in Fig. 5 is a tandem pump driven by a crankshaft, and in Fig. 2, the first pump a' and the second pump
The pump "b" is a tandem type, U is a universal joint, and ■ is a fan belt. In this case, the overall length becomes long, which again poses a difficult problem in terms of space, especially in small vehicles.

Furthermore, conventional hydraulic circuits are equipped with an accumulator to supply oil to the brake valve when the pump is stopped.
This equipment is great for.

In vehicles with small bodies, it becomes difficult to arrange each device.

Further, in order for the operator to accumulate pressure in the accumulator, it is necessary to increase the oil pressure in the circuit by turning the handle, etc., which is very troublesome.

(Means and effects for solving the problem) The present invention has been developed in view of the above points, and includes one pump and downstream thereof one flow divider with load sensing and at least two flow dividers. is configured to operate the work equipment system actuator and the control system actuator, and while following the advantages of the 2-pump circuit system, without using an accumulator, the 2-pump circuit system has a simple configuration. This is an attempt to eliminate the difficulty of arranging equipment when the vehicle body space is small.

(Example) Embodiments of the present invention will be described below based on the drawings.

In Fig. 1, 1 is a pump, 2 is a flow divider with load sensing, 3 is an operating valve, 4 is a tilt cylinder,
5 is a lift cylinder, 6 is a brake booster, 7 is a brake, 8 is a flow divider, 9 is a clutch booster,
10 is a steering gear box, 11 is a power steering cylinder, and 12 is an oil clutch. Note 1
3 is a clutch pedal, 14 is a brake pedal, 15 is an oil blowing part, 16 is an oil suction part, 17 is a flow divider, 18 is a release cylinder, 19 is a mask cylinder, and 20 is a mask cylinder.

As is clear from this figure, the third embodiment of the invention is
Compared to the conventional circuit shown in the figure, the second pump is eliminated,
A major feature is that a flow divider 2 with load sensing is incorporated instead. This flow divider 2 with load sensing allows a pilot flow to flow to the downstream control system actuators (brake 7, clutch booster 9, power steering cylinder 11, oil clutch 12, etc.), and the pressure increases only when the actuator is operated. Its role is to sense the flow rate and flow the specified flow rate.

In other words, when the control system actuators are not operated, most of the flow rate from pump 1 minus the pilot flow rate goes to the work equipment actuators (tilt cylinder 4, lift cylinder 5, etc.) to ensure the necessary oil. This allows for efficient work.

In addition, in the embodiment shown in FIG. 1, a flow divider 8 and a brake booster 6 are used instead of the conventional brake valve.
The brake booster 6 doubles the pedal force using hydraulic pressure and transmits the force to the mask cylinder 19, so even if the pump 1 stops, the pedal force does not reach the mask cylinder 19. act to apply brake 7.

Therefore, in the embodiment of the present invention, there is no need to provide a conventional accumulator, and the problems that arise when each device is arranged in a small vehicle are solved.

In the circuit of FIG. 1, if the clutch booster 6 is not used, the flow divider 17.
Thalassochi Booster 9. Mask cylinder 20. Remove the release cylinder 18.

A circuit may be used to connect the flow divider 8 and the steering gear box 10, and in this case, two flow dividers are used.

Note that when working with a forklift, when attempting to move the 5 work equipment actuators at maximum speed, it is often done with the vehicle stationary by depressing the clutch pedal 13 to disengage the clutch. In such a case, the circuit of this embodiment is In this case, the flow divider 2 with load sensing senses the pressure and causes a specified flow rate to flow, so that the speed of the 1 work equipment system actuator is slowed down by the difference between the specified flow rate and the pilot flow rate.

In this case, a circuit as shown in FIG. 2 can be used to prevent the speed of the two-work machine actuator from slowing down.

Since FIG. 2 is almost the same as FIG. 1, the same numerical symbols are used for corresponding components.

That is, the one in FIG. 2 differs from the one in FIG. 1 in that a normal flow divider 8 is provided in front of the flow divider 2 with load sensing so as to give priority to the clutch booster 9 side.

By doing so, the flow rate to the clutch booster 9 is relatively much smaller than the flow rate required by the power steering cylinder 11, so even if the clutch pedal 13 is depressed, the work equipment system actuator will reduce the speed of the work equipment. It can be operated at the required speed without

As described above, since the second pump is not used in any of the embodiments of the present invention, there is no need to drive the second pump with a belt or with a crankshaft as a tandem pump as in the past, and there is no need for an accumulator. , the degree of freedom in assembling each device increases in terms of space, which is especially effective in small vehicle classes.

In addition, one of the two or three flow dividers is of the load sensing type, so that most of the flow is directed to the work equipment actuator when the control system actuator is not operated.

Extremely efficient. In this way, although it is a single pump, an extremely efficient hydraulic circuit can be obtained by cleverly combining one flow divider with load sensing and a normal flow divider.

(Effect of the invention) This invention is constructed as described above in detail.

By having a second pump, there is no need to drive the second pump with a belt or drive it with a crankshaft as a tandem pump, and there is no need for an accumulator, so there is more freedom in connecting each device in terms of space. Increase,
This is particularly effective for vehicles with small bodies.

Also out of two or three flow dividers.

One of them is a load sensing type.

When not operating control system actuators.

Since most of the flow is directed to the work equipment actuator, efficient work is possible.

Also, if you place a normal type flow divider in front of the load sensing type flow divider, you can work without reducing the speed of the work equipment even when you operate the craft pedal.

In this way, by using only one pump and combining it with one flow divider with load sensing and a normal flow divider, an extremely efficient hydraulic circuit can be provided.

[Brief explanation of the drawing]

FIG. 1 shows a hydraulic circuit according to one embodiment of the present invention, FIG. 2 shows a hydraulic circuit according to another embodiment, FIG. 3 shows a conventional two-pump hydraulic circuit, and FIGS. 4 and 5 show a conventional hydraulic circuit. This figure schematically shows two methods for driving the two pumps of the two-pump hydraulic circuit. 1...Pump. 2...Flow divider with load sensing. 6...Brake booster. 8...Flow divider. 9...Clutch booster. 17...Flow divider.

Claims (3)

[Claims] (1) One pump, one flow divider with load sensing and at least two flow dividers downstream of the one pump are respectively provided to operate the work equipment system actuator and the control system actuator. A hydraulic circuit for a cargo handling vehicle, characterized by: (2) A hydraulic circuit for a cargo handling vehicle according to claim 1, wherein the flow divider is provided downstream of the one flow divider with load sensing. (3) The hydraulic circuit for a cargo handling vehicle according to claim 1, wherein the one flow divider with load sensing is provided downstream of one of the flow dividers.