KR200182135Y1 - Hydraulic system of skid steer loader - Google Patents

Abstract

The present invention relates to a hydraulic system of the skid steer loader so that an impact does not occur during sudden start or stop.

The present invention, in the hydraulic system of the skid steer loader in which the left wheel and the right wheel are driven independently of each other, the first oil for supplying hydraulic oil to the oil tank and the first hydraulic motor for driving the left wheel through the first hydraulic line Hydraulic oil is supplied to the pump, a second oil pump for supplying hydraulic oil to the second hydraulic motor driving the right wheel through the second hydraulic line, and a control valve having a bucket spool, a boom spool and an optional spool through the third hydraulic line. The third oil pump to be supplied, the shuttle valve for pumping the hydraulic oil of the first hydraulic line and the second hydraulic line to the bypass line through the branch line, and the hydraulic oil of the set pressure discharged from the shuttle valve to the bypass line And a pressure compensation variable relief valve configured to adjust the bypass amount by gradually closing the bypass line while simultaneously passing the bypass line.

Description

Hydraulic system of skid steer loader

The present invention relates to a hydraulic system of the skid steer loader, and more particularly, to a hydraulic system of the skid steer loader to prevent the impact is generated during sudden start or stop.

The skid steer loader is a kind of heavy equipment used to move or load unshaped powder-like objects such as soil or sand to a high place. It is a bucket that can hold loads and a bucket that moves up and down. Has a boom assembly. And the lower part of the vehicle body is provided with wheels that are independently driven left and right to enable work in a small space and a small working radius.

This skid steer loader has a hydraulic system for driving the device. The hydraulic system includes an oil pump for generating the pressurized oil, a control valve for controlling the flow direction and the flow rate of the pressurized oil, a hydraulic actuator for mechanical work, and the like. 1 is a hydraulic circuit diagram showing the configuration of the hydraulic system of the skid steer loader. According to this, the hydraulic system of the skid steer loader has a first oil pump 10, a second oil pump 20, and a third oil pump 30 driven by a power source 1 such as an internal combustion engine or an electric motor. . The first oil pump 10 and the second oil pump 20 are swash plate variable hydraulic pumps in which the discharge amount and the discharge direction are controlled, and the third oil pump 30 is a gear pump in which the discharge amount and the discharge direction are constant. These first oil pump 10, the second oil pump 20 and the third oil pump 30 are so-called tandem pumps installed in series with each other.

The first oil pump 10 has a first hydraulic line 12, and the first hydraulic line 12 has a first end thereof so that the hydraulic oil discharged from the first oil pump 10 can be continuously circulated. It is connected and connected to both output terminals of the oil pump 10. The first hydraulic motor 13 and a flush valve 14 for draining a part of the hydraulic oil discharged from the first hydraulic motor 13 to the oil tank T are installed on the first hydraulic line 12. The first hydraulic motor 13 drives the left wheels of the skid steer loader. The second oil pump 20 has a second hydraulic line 22, and the second hydraulic line 22 has a second end thereof so that the hydraulic oil discharged from the second oil pump 20 can be continuously circulated. It is connected and connected to both output terminals of the oil pump 20. On the second hydraulic line 22, a second hydraulic motor 23 and a flush valve 24 for draining a part of the hydraulic oil discharged from the second hydraulic motor 23 to the oil tank T are installed. The second hydraulic motor 23 drives the right wheels of the skid steer loader.

On the other hand, the first hydraulic line 12 has a first bypass line 15 whose both ends are in communication with the first hydraulic line 12, respectively, and both ends of the first bypass line 15 are relief valves. 16 is installed. In addition, the second hydraulic line 22 also has a second bypass line 25 whose both ends are in communication with the second hydraulic line 22, and both ends of the second bypass line 25 have relief valves ( 26 are respectively installed. The relief valves 16 and 26 discharge from the first oil pump 10 and the second oil pump 20 when the hydraulic pressure in the first hydraulic line 12 and the second hydraulic line 22 is equal to or higher than the set pressure. The pressure oil is bypassed to the first bypass line 15 and the second bypass line 25 to maintain the pressure of the hydraulic oil in the first hydraulic line 12 and the second hydraulic line 22 properly. Here, the first bypass line 15 and the second bypass line 25 are of course configured to communicate with each other by the connection line 15a.

And the third oil pump 30 has a third hydraulic line 32, the control valve 33, the valve block 34, the oil cooler 35 and the oil filter 36 on the third hydraulic line (32). ) Are installed one after the other. The control valve 33 is equipped with the boom spool 33a, the bucket spool 33b, and the option spool 33c, and operates various actuators, such as the boom cylinder 37 and the bucket cylinder 38. As shown in FIG. And the valve block 34 returns a part of the hydraulic oil of the third hydraulic line 32 to the oil tank (T). On the other hand, the third hydraulic line 32 is connected to the connection line 15a connecting the first bypass line 15 and the second bypass line 25, the third hydraulic pressure through the connection line (15a) Line 32 supplies hydraulic oil in either the first hydraulic line 12 or the second hydraulic line 22. This is because the hydraulic fluid of the first hydraulic line 12 and the second hydraulic line 22 which is continuously circulated is easily overheated or contaminated, so that a part is returned to the oil tank T through the flush valves 14 and 24, and the oil This is to supply the hydraulic oil cooled and filtered by the cooler 35 and the oil filter 36 to the first hydraulic line 12 and the second hydraulic line 22 as much as the oil oil is returned to the oil tank T.

When the power source 1 is operated by such a configuration, the first, second, and third oil pumps 10, 20, and 30 are operated at the same time to generate pressure oil. At this time, the pressure oil of the first and second oil pumps 10 and 20 circulates through the first hydraulic line 12 and the second hydraulic line 22 and the first hydraulic motor 13 and the second hydraulic motor 23. This will drive the skid steer loader is capable of driving forward, backward, rotation, etc. And the pressure oil of the third oil pump 30 is introduced into the control valve 33 through the third hydraulic line 32, the pressure oil introduced into the control valve 33 is the boom spool 33a and the bucket spool 33b. And by the option spool (33c) flows into the boom cylinder 37, the bucket cylinder 38 to operate it. In addition, a part of the pressure oil passing through the control valve 33 is returned to the oil tank (T) through the valve block 34, the rest is the first hydraulic line 12 and the second hydraulic line through the connecting line (15a). Flows into (22).

On the other hand, when a load is applied to the first hydraulic motor 13 and the second hydraulic motor 23, that is, when digging or sudden stop and start by using a bucket, heavy loads such as gravel, steel, concrete, etc. When switching to the loaded state, the first hydraulic motor 13 and the second hydraulic motor 23 are subjected to a load, so that the hydraulic pressure in the first hydraulic line 12 and the second hydraulic line 22 is reduced. Relatively high. In this state, the oil pressure of the first hydraulic line 12 and the second hydraulic line 22 which maintains a high pressure passes through the relief valves 16 and 26 to the other first hydraulic line 12 and the second low pressure. Bypass to the hydraulic line 22, whereby the first hydraulic line 12 and the second hydraulic line 22 is to maintain a proper pressure at all times.

However, such a conventional hydraulic system of the skid steer loader has a problem that vibration occurs in the vehicle during sudden stop or sudden start.

That is, when the skid steer loader suddenly stops and starts quickly, a load is momentarily applied to the first hydraulic motor 13 and the second hydraulic motor 23, and the relief valves 16 and 26 are driven by the first hydraulic line. The high pressure hydraulic oil is bypassed while instantaneously communicating the 12 and the first bypass line 15, the second hydraulic line 22, and the second bypass line 25, wherein the relief valve 16, When the first and second bypass lines 25, 26, at which the high-pressure hydraulic fluid flows are momentarily interrupted, the first bypass line 15 and the second bypass line 25 are predetermined by the inertia force of the hydraulic oil. Of shock occurs. This shock is transmitted to the body through all the lines of the hydraulic system, causing the entire vehicle to vibrate. In addition, this vibration loosened the fastening portion of the vehicle body, which not only reduced the durability of the vehicle but also caused the driving feeling to be deteriorated.

Accordingly, the present invention has been made to solve the above problems, the object of which is to configure the relief valve to gradually close the first bypass line and the second bypass line to the first hydraulic line and the second It is to provide a hydraulic system of the skid steer loader to prevent the impact on the hydraulic line, the first bypass line and the second bypass line.

1 is a hydraulic circuit diagram showing the configuration of a hydraulic system of a conventional skid steer loader;

Figure 2 is a hydraulic circuit diagram showing the configuration of the hydraulic system of the skid steer loader according to the present invention,

3 is a hydraulic circuit diagram illustrating a shuttle valve and a pressure compensated variable relief valve which are features of the present invention.

♣ Explanation of symbols for the main parts of the drawing ♣

10: first oil pump 12: first hydraulic line

13: 1st hydraulic motor 17: 1st main bypass line

19: 1st sub bypass line 20: 2nd oil pump

22: 2nd hydraulic line 23: 2nd hydraulic motor

27: second main bypass line 29: second sub bypass line

30: third oil pump 33: control valve

40: shuttle valve 50: pressure compensation type variable relief valve

52: first pilot line 54: second pilot line

55: return spring 57: orifice

These objectives are the first oil for supplying the hydraulic oil to the oil tank and the first hydraulic motor driving the left wheel through the first hydraulic line in the hydraulic system of the skid steer loader in which the left wheel and the right wheel are driven independently of each other. Hydraulic oil is supplied to the pump, a second oil pump for supplying hydraulic oil to the second hydraulic motor driving the right wheel through the second hydraulic line, and a control valve having a bucket spool, a boom spool and an optional spool through the third hydraulic line. The third oil pump to be supplied, the shuttle valve for pumping the hydraulic oil of the first hydraulic line and the second hydraulic line to the bypass line through the branch line, and the hydraulic oil of the set pressure discharged from the shuttle valve to the bypass line Skis comprising a pressure compensated variable relief valve configured to adjust the bypass amount by gradually closing the bypass line while simultaneously passing the bypass line. This can be achieved by the hydraulic system of the de-steer.

Hereinafter, a preferred embodiment of the hydraulic system of the skid steer loader according to the present invention will be described in detail with reference to the accompanying drawings (the same components will be described using the same reference numerals).

2 is a hydraulic circuit diagram showing the configuration of the hydraulic system of the skid steer loader according to the present invention. According to this, the hydraulic system of the skid steer loader of the present invention has a first oil pump 10, a second oil pump 20, and a third oil pump 30 driven by the power source 1. The first oil pump 10 and the second oil pump 20 are swash plate type variable hydraulic pumps, and the third oil pump 30 is a gear pump.

The first oil pump 10 has a first hydraulic line 12, and the first hydraulic line 12 has a first end thereof so that the hydraulic oil discharged from the first oil pump 10 can be continuously circulated. It is connected and connected to both output terminals of the oil pump 10. On the first hydraulic line 12, a first hydraulic motor 13 and a flush valve 14 for draining a part of the hydraulic oil discharged from the first hydraulic motor 13 to the oil tank T are installed. On the other hand, the first hydraulic line 12 has a first main bypass line 17 connected in communication with the first hydraulic line 12 so that both ends are close to both output ends of the first oil pump 10. Check valves 17a are provided at both ends of the first main bypass line 17. This check valve 17a prevents the hydraulic oil of the first hydraulic line 12 from flowing back to the first main bypass line 17.

And on the first hydraulic line 12 is a shuttle valve 40 and the pressure compensation type variable relief valve 50 is installed. The shuttle valve 40 distributes the hydraulic oil of the first hydraulic line 12 to the pressure compensation variable relief valve 50, and is installed on the branch line 18 having both ends connected to the first hydraulic line 12. do. The pressure compensation type variable relief valve 50 is installed on the first sub bypass line 19 connecting the output terminal of the shuttle valve 40 and the first main bypass line 17. When the hydraulic fluid in 12) rises above the set pressure, it serves to bypass this hydraulic fluid to the 1st main bypass line 17. As shown in FIG.

On the other hand, the pressure compensation type variable relief valve 50 is configured to gradually close the first sub bypass line 19 to prevent the impact on the first sub bypass line 19. That is, when the relief valve momentarily closes the first sub bypass line 19 through which high-pressure hydraulic fluid flows while the first sub bypass line 19 is open, the first hydraulic line 12 is driven by the inertia force of the hydraulic oil. ), The first main bypass line 17 and the first sub bypass line 19 generate a predetermined shock. Therefore, the pressure compensating variable relief valve 50 is configured to gradually close the first sub bypass line 19 to gradually reduce the inertia force of the hydraulic oil.

The pressure compensated variable relief valve 50 has a first pilot line 52 and a second pilot line 54 branched from the first sub bypass line 19 as shown in FIG. 3. The first pilot line 52 operates the pressure compensated variable relief valve 50, and the second pilot line 54 adjusts the tension of the return spring 55 of the pressure compensated variable relief valve 50. It is to supply the oil. On the other hand, an orifice 57 is formed in the second pilot line 54, and the orifice 57 rapidly reduces the amount of hydraulic oil circulated to the second pilot line 54 to generate a load. In particular, when the pressure compensation variable relief valve 50 closes the first sub bypass line 19, the pressure compensation type variable relief valve 50 is generated by generating a load so that the return spring 55 is gradually restored. ) Gradually closes the first sub bypass line 19. Therefore, the shock is not generated in the first hydraulic line 12, the first main bypass line 17 and the first sub bypass line 19 by this action of the pressure compensation type variable relief valve 50. .

In addition, the second oil pump 20 has a second hydraulic line 22, and the second hydraulic line 22 has both ends thereof so that the hydraulic oil discharged from the second oil pump 20 can be continuously circulated. It is connected and connected to both output stages of the two oil pump 20. On the second hydraulic line 22, a second hydraulic motor 23 and a flush valve 24 for draining a part of the hydraulic oil discharged from the second hydraulic motor 23 to the oil tank T are provided. On the other hand, the second hydraulic line 22 has a second main bypass line 27 connected in communication with the second hydraulic line 22 so that both ends are close to both output ends of the second oil pump 20. Check valves 27a are provided at both ends of the second main bypass line 27.

And on the second hydraulic line 22, like the first hydraulic line 12, the shuttle valve 40 and the pressure compensation type variable relief valve 50 is installed. The shuttle valve 40 distributes the hydraulic oil of the second hydraulic line 22 to the pressure compensation variable relief valve 50, and is installed on the branch line 28 having both ends connected to the second hydraulic line 22. do. The pressure compensation type variable relief valve 50 is installed on the second sub bypass line 29 connecting the output end of the shuttle valve 40 and the second main bypass line 27 to form a second hydraulic line ( When the hydraulic oil in 22 rises above the set pressure, it serves to bypass the hydraulic oil to the second main bypass line 27.

On the other hand, the pressure-compensated variable relief valve 50 is configured to gradually close the second sub bypass line 29 to prevent the impact on the second sub bypass line 29, the first Since the same configuration and operation as the pressure compensation type variable relief valve of the hydraulic line 12, the description thereof will be omitted.

And the third oil pump 30 has a third hydraulic line 32, the control valve 33, the valve block 34, the oil cooler 35 and the oil filter 36 on the third hydraulic line (32). ) Are installed one after the other. The control valve 33 is equipped with the boom spool 33a, the bucket spool 33b, and the option spool 33c, and operates various actuators, such as the boom cylinder 37 and the bucket cylinder 38. As shown in FIG. And the valve block 34 returns a part of the hydraulic oil of the third hydraulic line 32 to the oil tank (T). On the other hand, the third hydraulic line 32 is connected and connected to the connection line 17b connecting the first main bypass line 17 and the second main bypass line 27, and through the connection line 17b The three hydraulic lines 32 supply hydraulic oil into the first hydraulic line 12 or the second hydraulic line 22.

When the power source 1 is operated by such a configuration, the first, second, and third oil pumps 10, 20, and 30 are operated at the same time to generate pressure oil. At this time, the pressure oil of the first and second oil pumps 10 and 20 circulates through the first hydraulic line 12 and the second hydraulic line 22 and the first hydraulic motor 13 and the second hydraulic motor 23. This will drive the skid steer loader is capable of driving forward, backward, rotation, etc. And the pressure oil of the third oil pump 30 is introduced into the control valve 33 through the third hydraulic line 32, the pressure oil introduced into the control valve 33 is the boom spool 33a and the bucket spool 33b. And by the option spool (33c) flows into the boom cylinder 37, the bucket cylinder 38 to operate it. In addition, a part of the pressure oil passing through the control valve 33 is returned to the oil tank (T) through the valve block 34, the rest is the first hydraulic line 12 and the second hydraulic line through the connecting line (15a). Flows into (22).

On the other hand, when a load is applied to the first hydraulic motor 13 and the second hydraulic motor 23, that is, when digging or sudden stop and start by using a bucket, heavy loads such as gravel, steel, concrete, etc. When switching to the loaded state, the first hydraulic motor 13 and the second hydraulic motor 23 are subjected to a load, and thus the pressure of the hydraulic oil in the first hydraulic line 12 and the second hydraulic line 22 is changed. Becomes relatively high. The hydraulic pressure of the first hydraulic line 12 and the second hydraulic line 22 maintaining a high pressure in such a state is the other first low pressure through the shuttle valve 40 and the pressure compensation variable relief valve 50. It is bypassed to the hydraulic line 12 and the second hydraulic line 22, whereby the first hydraulic line 12 and the second hydraulic line 22 is to maintain a proper pressure at all times.

On the other hand, the hydraulic oil which is bypassed to the first and second main bypass lines 17 and 27 along the branch lines 18 and 28 and the first and second sub bypass lines 19 and 29 are variable in pressure compensation type. By operating the relief valve 50, the first and second sub bypass lines 19 and 29 are naturally bypassed to the first and second main bypass lines 17 and 27 without causing an impact. .

The embodiments described above are merely illustrative of one embodiment of the present invention, and the scope of application of the present invention is not limited thereto, and the present invention can be appropriately changed within the scope of the same idea. For example, the shape and structure of each component specifically shown in the embodiment of the present invention can be modified.

The hydraulic system of the skid steer loader according to the present invention having such a configuration causes the pressure compensation type variable relief valve to bypass when an excessive load is applied to the first hydraulic motor and the second hydraulic motor driving the left and right wheels. By configuring the pass line to be closed gradually, there is an effect of preventing an impact on the bypass line during sudden stop or sudden start.

Claims (3)

In the hydraulic system of the skid steer loader, in which the left wheel and the right wheel are driven independently of each other, Supplying the hydraulic oil to the oil tank, the first oil pump for supplying the hydraulic oil to the first hydraulic motor for driving the left wheel through the first hydraulic line, and the second hydraulic motor for driving the right wheel through the second hydraulic line The second oil pump, the third oil pump for supplying the hydraulic oil to the control valve having the bucket spool, the boom spool and the option spool through the third hydraulic line, and the hydraulic oil of the first hydraulic line and the second hydraulic line The pressure compensating variable is configured to control the bypass amount by gradually closing the bypass line while simultaneously bypassing the shuttle valve and the hydraulic pressure discharged from the shuttle valve to the bypass line. Hydraulic system of the skid steer loader with relief valve. The pressure relief variable relief valve of claim 1, wherein the pressure relief variable relief valve has a pilot line for adjusting a return spring tension through the shuttle valve, and the pilot line has an orifice which has a time delay and attenuation effect on the pressure oil circulated. Hydraulic system of the skid steer loader, characterized in that. 3. The bypass line of claim 2, wherein both ends of the bypass line are connected to the output ends of the first oil pump and the second oil pump via a check valve, and part of the bypass line is connected to an oil tank and a part of the filter and the cooler. A first main bypass line and a second main bypass line in communication with the third hydraulic line so that the hydraulic oil flows therethrough; a first connecting the output terminal of the shuttle valve and the first and second main bypass lines; And a second sub bypass line, wherein the pressure compensation variable relief valve is installed on the first and second sub bypass lines.