JPS6218110Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a freight vehicle.

A pair of left and right jack cylinders is installed immediately behind the driver's cab, and the loading platform is tilted backwards by the extension drive of the jack cylinders. Alternatively, in the case of vehicles equipped with a crane, freight vehicles that use the crane's power system to pull up construction machinery, etc. are widely used today, but the method for controlling the jack cylinder is As shown in Fig. 1, the hydraulic circuit is formed to connect two valves connected in parallel to each cylinder, so the operating levers of the two independent valves can be operated with both hands. It was necessary to control the expansion and contraction of the jack cylinder without tilting the loading platform left or right by simultaneously operating the truck. This not only gives the operator a sense of anxiety, but if the operator is a novice, this anxiety may cause the vehicle to overturn.

The present invention was developed in view of the current situation, and is capable of independently controlling the expansion and contraction of a pair of left and right jack cylinders using two switching valves, and simultaneously controlling the expansion and contraction speeds of these cylinders. Therefore, it is an object of the present invention to provide a freight vehicle in which the occurrence of a difference in the amount of expansion and contraction between these cylinders is prevented as much as possible.

Next, the configuration of the present invention will be explained in detail based on one specific embodiment.

Reference numerals 1 and 2 denote a pair of left and right jack cylinders located immediately behind the driver's cab of a freight vehicle. 1',
Reference numerals 2' and 2' denote pressure oil chambers on the extension side of the cylinders 1 and 2, respectively, and pressure oil chambers 1'' and 2'' on the contraction side of the cylinders 1 and 2, respectively. 3 supplies the discharge oil from the pump 4 to the above-mentioned jack cylinders 1 and 2 via a selection valve 5, which will be described later, and also supplies the discharge oil from the jack cylinders 1 and 2 to the tank 6 via a tank circuit 8. This is a directional switching valve that has two switching positions, forward and reverse, which allow the flow to flow back, and a neutral position which blocks the oil passages between the cylinders 1 and 2, the pump 4, and the tank 6.

The selection valve 5 is a 3-position 8-port selection valve,
In this position, the oil passage 9 communicating with the directional control valve 3 is connected to the extension operation side pressure oil chambers 1', 2' of the jack cylinders 1, 2, and the oil passage 10 is connected to the extension operation side pressure oil chambers 1', 2' of the jack cylinders 1, 2.
Oil passages 11 and 1 are connected to the reduction operation side pressure oil chambers 1'' and 2'', respectively.
6, 12, and 17.

Therefore, when the selection valve 5 is in this position, the oil passage 9 is connected to the discharge oil passage 18 of the pump 4 by switching and controlling the directional switching valve 3, and the oil passage 1 is connected to the discharge oil passage 18 of the pump 4.
0 is connected to the tank circuit 8, the jack cylinders 1 and 2 can be extended at the same time, and the oil line 1 can be extended simultaneously.
When the oil passage 9 is connected to the discharge oil passage 18 of the pump 4 and the oil passage 9 is connected to the tank circuit 8, the cylinders 1 and 2 can be simultaneously compressed. Since this expansion/contraction speed can be simultaneously controlled by the directional control valve 3, the operation is extremely simple, and it is possible to prevent the loading platform from tilting unbalanced to the left or right and tipping over as much as possible. be able to.

When the selection valve 5 is in the position, the oil passage 9 out of the oil passages 9 and 10 communicating with the directional control valve 3 is connected to the extension operation side pressure oil chamber 1' of the jack cylinder 1, and the oil passage 1
0 to the reduction operation side pressure oil chamber 1'', oil passages 11 and 12, respectively.
I'm trying to connect via .

Therefore, when the selection valve 5 is in this position, the oil passage 9 is connected to the discharge oil passage 18 of the pump 4 and the oil passage 10 is connected to the tank circuit 8 by switching and controlling the directional switching valve 3. When this is done, the jack cylinder 1 can be extended, and when the oil passage 10 is connected to the discharge oil passage 18 of the pump 4 and the oil passage 9 is connected to the tank circuit 8, the jack cylinder 1 can be contracted.

When the selection valve 5 is in the position, the oil passage 9 of the oil passages 9 and 10 communicating with the directional control valve 3 is connected to the oil passage 10 to the extension operation side pressure oil chamber 2' of the jack cylinder 2.
are connected to the reduction operation side pressure oil chamber 2'' via oil passages 16 and 17, respectively.

Therefore, when the selection valve 5 is in this position, the oil passage 9 is connected to the discharge oil passage 18 of the pump 4 and the oil passage 10 is connected to the tank circuit 8 by switching and controlling the directional switching valve 3. When this happens, the jack cylinder 2 can be extended, and when the oil passage 10 is connected to the discharge oil passage 18 of the pump 4 and the oil passage 9 is connected to the tank circuit 8, the jack cylinder 2 can be contracted.

In this way, when the selection valve 5 occupies both positions, the left and right jack cylinders can be independently controlled to expand and contract.For example, when you want to perform crane work on a slope,
This is useful because the extension stroke of each jack cylinder can be changed.

In one embodiment of the present invention shown in FIG. 2, the oil discharged from the pump 4 is passed through the oil passage 13 and then through the selection valve 5 in this order when the selection valve 5 is in the position. In addition to supplying
Two switching positions, forward and reverse, allow the discharged oil from the jack cylinder 2 to pass through the selection valve 5 and the oil path 14 and then return to the tank 6, and an oil path between the jack cylinder 2, the pump 4, and the tank 6. A directional control valve 7 having a neutral position that shuts off the directional control valve 3
When the selection valve 5 is in the position, the directional control valve 7 can independently control the expansion and contraction of the jack cylinder 2. The reason for arranging it in this way is that by blocking the connecting ports between the oil passages 13 and 14 and the selection valve 5, it is possible to operate other hydraulic actuators as an option. The selection valve 5 may be a 3-position, 6-port valve if it is not necessary to provide this option. Of course.

In summary, the present invention provides a freight vehicle that is equipped with a jack cylinder on the left and right sides immediately behind the driver's cab, and is equipped with a directional control valve and a selection valve for controlling expansion and contraction of the jack cylinder. Two oil passages are arranged between the valve and the directional switching valve, and these two oil passages are independently switched to either the pump discharge oil passage or the tank oil passage by switching the directional switching valve. one of the two oil passages is simultaneously connected to the extension operation side pressure oil chamber of the left and right jack cylinders, and the other oil passage is connected to the left and right jack cylinders. a position where the oil passages are connected to the oil chambers of one of the cylinders at the same time, a position where the oil passages are connected to the oil chambers of the other cylinder; and a position where the oil passages are connected to the oil chambers of the other cylinder. Since the configuration allows the two switching valves to independently control the expansion and contraction of the pair of left and right jack cylinders, the expansion and contraction speeds of these cylinders can be simultaneously controlled to reduce the difference in the amount of expansion and contraction between these cylinders. Since this can be prevented as much as possible, it is possible to safely tilt the vehicle on a flat or sloping ground.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional jack cylinder.
FIG. 2 is a circuit diagram of a jack cylinder showing one embodiment of the present invention. 1, 2...Judge cylinder, 3...Directional switching valve, 5...Selection valve, 9...Oil passage, 10...Oil passage,
1', 2'...Extension operation side pressure oil chamber, 1'', 2''...Reduction operation side pressure oil chamber.

Claims (1)

[Scope of utility model registration request] A freight vehicle is provided with a directional control valve and a selection valve for controlling the expansion and contraction of the jack cylinders, with the jack cylinders arranged on the left and right sides immediately behind the driver's cab, and the space between the selection valve and the directional control valve. two oil passages are arranged in the area, and these two oil passages are each independently connected to either the discharge oil passage of the pump or the tank oil passage by switching the directional control valve, and the selection At the same time, one of the two oil passages of the valve is connected to the extension operation side pressure oil chambers of the left and right jack cylinders, and the other oil passage is connected to the contraction operation side pressure oil chambers of the left and right jack cylinders. A position where the oil passages are connected to each oil chamber of one of the cylinders at the same time, a position where the oil passages are connected to each oil chamber of the other cylinder, and a position where the oil passages are connected to the oil chambers of the other cylinder. A freight vehicle characterized by: