CN103883571B - The many pumps of loading machine electrichydraulic control are the hydraulic system at interflow quantitatively - Google Patents

Abstract

A loader electro-hydraulic control hydraulic system with quantitative confluence of multiple pumps, the steering system is provided with a first auxiliary pump, and a first control unit for controlling the oil supply direction of the first auxiliary pump is provided between the first auxiliary pump and the main oil circuit of the steering system The valve group, in the middle and low speed section of the engine, is controlled by the first control valve group to supply oil to the steering system from the first auxiliary pump, and in the high speed section of the engine, is controlled by the first control valve group to supply oil to the working system from the first auxiliary pump; The working system is equipped with a second auxiliary pump. In the low speed section of the engine, the second auxiliary pump is controlled by the second control valve group to supply oil to the steering system. In the high speed section of the engine, the second auxiliary pump is controlled by the second control valve group. Supply oil to the working system; its advantage is that the application of multi-pump technology combined with electronic control technology can effectively realize energy saving, and the flow of the steering system can be controlled within the range of the flow target value no matter what the engine speed is.

Description

Hydraulic system of loader electro-hydraulic control multi-pump quantitative confluence

technical field

The invention relates to a hydraulic system of a loader, in particular to a hydraulic system of a loader electro-hydraulic controlled quantitative confluence of multiple pumps.

Background technique

The hydraulic system of the existing loader is generally composed of a working hydraulic system, a steering hydraulic system and a braking hydraulic system. The working hydraulic system is often composed of working pumps, distribution valves, pilot valves, boom cylinders, bucket cylinders and other components. The steering hydraulic system is often composed of steering pump, priority valve, steering gear (flow amplification valve), steering cylinder and other components. The brake hydraulic system is often composed of brake pump, filling valve, brake valve, accumulator and other components. At present, most of the loaders on the market still use the quantitative hydraulic system, such as Liugong, Lingong, Longgong, Xiagong and other domestic loader manufacturers, more than 90% of the loaders use the quantitative system; there are also quantitative and variable hydraulic systems. Hydraulic systems are used in combination, such as CAT938G, Liugong fixed variable hydraulic system, Xiagong fixed variable hydraulic system, etc.; in high-end loaders, almost all variable hydraulic systems are used, such as products after Carter H series, Volvo, Komatsu and other internationally renowned companies' current mainstream products. Compared with the variable hydraulic system, the quantitative hydraulic system has the advantages of high familiarity, good reliability, strong pollution resistance, and high cost performance, and the quantitative hydraulic system can fully meet the normal operation requirements of the loader, but the quantitative hydraulic system is also There are many deficiencies, such as serious energy loss, inability to perform compound action operations, poor controllability of the system, and large hydraulic shock. Adopt the scheme that the working hydraulic system and the steering hydraulic system are independent of each other. This scheme requires both the working pump and the steering pump to have a large enough displacement to make the machine work normally. Taking a 5-ton loader as an example, under normal circumstances, this The displacement of the working pump of this system is usually about 160cc, while the displacement of the steering pump is usually about 80cc, and the total displacement of the system is about 240cc. The disadvantages of this system are: 1. Serious energy loss; 2. The working system and the steering system operate at the same time under high load and the engine is easy to stall; 3. The steering system tends to flutter when the engine is at high speed, and the oil volume is not enough at low speed; 4. Oil cylinder Large hydraulic shock at the end of stroke; 5. Serious heating of the system, etc.

In order to reduce the displacement of the working pump and prevent the engine from stalling easily under high load of the hydraulic system, the double-pump confluence technology is used. Steering priority, that is, when the steering system has a steering demand, the oil of the steering pump is given priority to the steering system, and the excess oil is merged into the working system. When not turning, all the oil of the steering pump is merged into the working system. The unloading valve is set to forcibly unload the oil of the steering pump when the pressure of the working system reaches a certain value, so as to reduce the engine load and avoid stalling. The disadvantages of this system are: 1. The energy loss is improved compared with the independent system, but the loss of the steering pump passing the priority valve has always existed. When the priority valve produced at home and abroad passes the flow rate of 140L/min, most of the losses are 1-2MPa 2. Since the displacement of the steering pump cannot be reduced, the steering system also tends to flutter when the engine is at high speed, and the oil volume is not enough at low speed; 3. The hydraulic shock at the end of the cylinder stroke is large; 4. The system heats up seriously, etc.

In order to improve the problem of poor steering operability of the steering system at high and low engine speeds, a three-pump system is used. When the engine is at low speed, two pumps supply oil to the steering system at the same time, which solves the problem of insufficient oil supply to the steering system at low speeds. The problem is that when the engine is at high speed, only one pump supplies oil to the steering system, which solves the problem of high-speed steering fluttering. The disadvantages of this system are: 1. When not turning, because the oil of the steering pump flows back to the oil tank through the signal control valve, the priority valve and the neutral position of the steering gear, the energy loss here is about 3-4MPa, and the energy loss It is serious; 2. The unloading valve is not used, and the engine is easy to stall when the load is high; 3. The displacement of the working pump cannot be reduced too much, and the energy consumption of the working system is not significantly reduced; 4. When the working system works alone, the total discharge of the pump The volume is about 160cc, and the shock at the end of the cylinder stroke is severe.

The purpose of the present invention is to provide an application that adopts multi-pump technology combined with electronic control technology, automatically distributes the displacement of pumps according to the state of the system, can effectively realize energy saving, and combines electro-hydraulic control to reduce the complexity of hydraulic pipelines , reduce the hydraulic leakage point, and the wiring is easy to arrange. The three-stage flow speed regulation method of the steering system can control the flow of the steering system within the range of the flow target value no matter what the engine speed is, so as to ensure the stability of the steering system. Low-speed three-pump oil supply, medium-speed double-pump oil supply, high-speed single-pump oil supply, and a hydraulic system with electro-hydraulic control and quantitative confluence of multiple pumps for loaders with remarkable energy-saving effects.

The solution of the present invention is this:

The present invention mainly comprises a steering system and a working system, wherein the steering system includes a steering pump and a steering oil cylinder, and the working system includes a working pump, a bucket oil cylinder, and a boom oil cylinder, and is characterized in that:

(1) The steering system is equipped with a first auxiliary pump, and a first control valve group is installed between the first auxiliary pump and the main oil circuit of the steering system to control the oil supply direction of the first auxiliary pump. , the first auxiliary pump is controlled by the first control valve group to supply oil to the steering system, and in the high-speed section of the engine, the first control valve group is controlled to supply oil to the working system by the first auxiliary pump;

(2) The working system is provided with a second auxiliary pump, and a second control valve group is provided between the second auxiliary pump and the main oil circuit of the working system to control the oil supply direction of the second auxiliary pump. In the low speed section of the engine, The second control valve group controls the second auxiliary pump to supply oil to the steering system, and in the middle and high speed section of the engine, the second control valve group controls the second auxiliary pump to supply oil to the working system;

(3) A flow amplifying valve is installed in the main oil circuit of the steering system, and the priority valve port of the flow amplifying valve is connected to the main oil circuit of the working system through the electronically controlled unloading valve, which is used to The remaining oil in the steering system supplies oil to the working system through the priority valve of the flow amplification valve and the electric control unloading valve.

A more specific technical solution further includes: the first control valve group includes a first electromagnetic reversing valve and a second electromagnetic reversing valve; the first electromagnetic reversing valve is controlled by a steering signal detected by a pressure switch, so The second electromagnetic reversing valve is controlled by the signal of detecting the engine speed.

Further: the second control valve group includes a third electromagnetic reversing valve and a fourth electromagnetic reversing valve, the fourth electromagnetic reversing valve is controlled by the steering signal detected by the pressure switch, and the third electromagnetic reversing valve The direction valve is controlled by detecting the engine speed.

Further: an electromagnetic overflow valve is connected in parallel at the outlet of the working pump, which is used to directly discharge the oil of the working pump back to the oil tank by detecting the displacement signal of the oil cylinder when the oil cylinder of the working system moves close to the stroke end.

Further: the engine speed is divided into low-speed section, medium-speed section and high-speed section, the low-speed section is idling-1150rpm; the medium-speed section is 1150-1600rpm; the high-speed section is 1600-2200rpm.

The advantage of the present invention is that the application of multi-pump technology combined with electronic control technology can automatically distribute the displacement of pumps according to the state of the system, which can effectively realize energy saving, and the combination of electro-hydraulic control can reduce the complexity of hydraulic pipelines and reduce hydraulic pressure Leakage point, and the wiring is easy to arrange. The three-stage flow speed regulation method of the steering system can control the flow of the steering system within the range of the flow target value no matter what the engine speed is, ensuring the stability of the steering system. Three-pump oil supply, medium-speed double-pump oil supply, and high-speed single-pump oil supply, the energy-saving effect is remarkable.

Description of drawings

Fig. 1 is an embodiment of the present invention.

Fig. 2 is an enlarged schematic diagram of the principle near the working pump in Fig. 1 .

Fig. 3 is an enlarged schematic diagram of the principle near the steering pump in Fig. 1 .

Fig. 4 is a schematic diagram of the principle of the electronically controlled unloading valve of the present invention.

Fig. 5 is a graph showing the relationship between the engine speed and the flow entering the steering system in the present invention.

Description of drawings

In the figure, 1-shuttle valve 2-pressure switch 3-steering gear 4-pressure reducing valve 5-second electromagnetic directional valve 6-first electromagnetic directional valve 7-steering pump 8-hydraulic oil tank 9-first auxiliary pump 10-overflow valve 11-radiator 12-second auxiliary pump 13-working pump 14-electromagnetic overflow valve 15-third electromagnetic reversing valve 16-fourth electromagnetic reversing valve 17-pressure switch 18-electromagnetic unloading Valve 19-distribution valve 20-swing bucket cylinder 21-boom cylinder 22-steering cylinder 23-flow amplifying valve.

detailed description

As shown in Figure 1, the present invention mainly contains a steering system and a working system, wherein the steering system includes a steering pump 7 and a steering cylinder 22, and the working system includes a working pump 13, a bucket cylinder 20, and a boom cylinder 21, and the steering system is provided with There is a first auxiliary pump 9, and a first control valve group is set between the first auxiliary pump 9 and the main oil circuit of the steering system to control the oil supply direction of the first auxiliary pump. In the middle and low speed section of the engine, the first control valve group Control the first auxiliary pump to supply oil to the steering system, and in the high-speed section of the engine, the first control valve group controls the first auxiliary pump to supply oil to the working system;

The working system is provided with a second auxiliary pump, and a second control valve group for controlling the oil supply direction of the second auxiliary pump is arranged between the second auxiliary pump and the main oil circuit of the working system. The valve group controls the second auxiliary pump to supply oil to the steering system. In the middle and high speed section of the engine, the second control valve group controls the second auxiliary pump to supply oil to the working system;

A flow amplifying valve 23 is arranged in the main oil circuit of the steering system, and the priority valve port of the flow amplifying valve 23 is connected to the main oil circuit of the working system through the electronically controlled unloading valve 18, which is used to turn the steering The remaining oil in the system supplies oil to the working system through the priority valve of the flow amplification valve 23 and the electric control unloading valve 18 .

The first control valve group includes a first electromagnetic reversing valve 6 and a second electromagnetic reversing valve 5; the first electromagnetic reversing valve 6 is controlled by a steering signal detected by a pressure switch, and the second electromagnetic reversing valve Directional valve 5 is controlled by the signal of detecting engine speed.

The second control valve group includes a third electromagnetic reversing valve 15 and a fourth electromagnetic reversing valve 16, the fourth electromagnetic reversing valve 16 is controlled by the steering signal detected by the pressure switch, and the third electromagnetic reversing valve The direction valve 15 is controlled by detecting the engine speed.

Taking a 5-ton reloading machine as an example, the displacement of the working pump can be selected to be about 60cc, the displacement of the steering pump can be selected to be about 50cc, the displacement of the first auxiliary pump can be selected to be about 20cc, and the displacement of the second auxiliary pump can be selected to be about 30cc , The total displacement of the system is maintained at around 160cc.

The flow of the steering system is controlled in three stages. In the low-speed section of the engine (idling speed - 1150rpm), by detecting the engine speed signal, the electromagnet 4YA of the second electromagnetic reversing valve 5 and the electromagnet 3YA of the fourth electromagnetic reversing valve 16 are simultaneously energized; by detecting the steering signal of the pressure switch 2, the electromagnet 4YA of the first electromagnetic reversing valve 6 and the electromagnet 2YA of the third electromagnetic reversing valve 15 are energized at the same time, at this time, the steering pump 7, the first auxiliary The pump 9 supplies oil to the steering system together with the second auxiliary pump 12 . In the middle speed section of the engine (1150-1600rpm), by detecting the engine speed signal, the electromagnet 4YA of the second electromagnetic reversing valve 5 is energized, and the electromagnet 3YA of the fourth electromagnetic reversing valve 16 is de-energized; by detecting the pressure The steering signal of the switch 2 makes the electromagnet 4YA of the first electromagnetic reversing valve 6 and the electromagnet 2YA of the third electromagnetic reversing valve 15 energized at the same time. At this time, the steering pump 7 and the first auxiliary pump 9 give priority to the steering. The oil is supplied to the system, and the remaining oil flows into the working hydraulic system through the priority valve in the flow amplification valve 23 and the electric control unloading valve 18, and supplies oil to the working system together with the working pump 13 and the second auxiliary pump 9. In the high-speed section of the engine (1600-2200rpm), by detecting the engine speed signal, the electromagnet 4YA of the second electromagnetic reversing valve 5 and the electromagnet 3YA of the fourth electromagnetic reversing valve 16 are de-energized at the same time; The steering signal makes the electromagnet 4YA of the first electromagnetic reversing valve 6 and the electromagnet 2YA of the third electromagnetic reversing valve 15 energized at the same time. At this time, only the steering pump 7 supplies oil to the steering system alone, and the first auxiliary pump The oil flows from the right P8 port of the first electromagnetic reversing valve 6 to the left PW port of the second electromagnetic reversing valve 5 and flows into the working hydraulic system through the electronically controlled unloading valve 18, and the oil of the second auxiliary pump passes through the third The working hydraulic system flows from the right port P2 of the electromagnetic reversing valve 15 to the left port P5 of the fourth electromagnetic reversing valve 16 . So long as electromagnet 4YA and electromagnet 2YA have turning signal to respond to get electricity immediately, the response condition of electromagnet 5YA is that the engine speed is lower than 1600rpm, and the response condition of electromagnet 3YA is that the engine speed is lower than 1150rpm. Through these three stages of flow control, according to the pump displacement selected above, the flow rate of the steering system in the low-speed section is 80-115L/min (the idle speed is 800rpm); the flow rate of the steering system in the medium-speed section is 80.5-112L/min; The flow of the steering system in the high-speed section is 80-110L/min (the maximum engine speed is 2200rpm), as shown in the attached figure, no matter what the speed of the engine is, it can ensure that the flow supplied to the steering system is within a small fluctuation range In order to achieve the requirement of stable steering.

The electronically controlled unloading valve 18 is used in the system, and the function of the electromagnetic switch valve 25 is that when the pressure of the working system reaches the set value of the pressure switch 17, the electromagnet 8YA is energized, and the steering pump 7 passing through the electronically controlled unloading valve 18 1. The flow of the first auxiliary pump 9 and the second auxiliary pump 12 is unloaded, which can effectively ensure that the engine will not stall, and reduce unnecessary high-pressure and large-flow overflow losses. The function of the electromagnetic switch valve 27 is to control the flow through the electronically controlled unloading valve by detecting the displacement signal of the oil cylinder when the boom cylinder 21 or bucket cylinder 20 of the working system moves to the end of the stroke. The pump flow is unloaded, while reducing the impact at the end of the cylinder stroke, it avoids unnecessary overflow loss of high pressure and large flow. When the boom cylinder 21 or bucket cylinder 20 is at the limit position, the electromagnet 6YA is energized due to the signal from the displacement sensor of the cylinder, and the oil in the spring chamber of the external control unloading valve 24 will flow back to the T port and make the oil flowing through this unloading valve The oil of the unloading valve is unloaded. At this time, when operating another group of oil cylinders, the flow through the electronically controlled unloading valve 18 has been unloaded, resulting in insufficient flow. The role of setting the electromagnetic switch valve 26 is to operate under these extreme conditions , the oil in the spring cavity of the unloading valve 24 is not allowed to be unloaded back to the oil tank through the solenoid valve switch valve 27, the electromagnet 7YA is powered on, and the 7YA is powered off when the extreme working condition occurs, and the electronically controlled unloading valve 18 cannot unload effect.

An electromagnetic overflow valve 14 is connected in parallel at the outlet of the working pump 13. Its function is to detect the displacement signal of the oil cylinder when the oil cylinder of the working system moves close to the end of the stroke, so that the electromagnet 1YA is energized, and the pressure of the working pump 13 is directly energized. The oil is discharged back to the oil tank 8, and 6YA is also powered on at the same time, so that when the oil cylinder is close to the end of the stroke, only the second auxiliary pump 12 supplies oil to the working system, which greatly reduces the impact of the end of the stroke of the oil cylinder and avoids high pressure and large flow overflow. When the engine speed is in the low-speed section, since both 2YA and 3YA are powered on, in order to ensure the work of the working system, 1YA cannot be powered on at low speeds, and 3YA is used to lock 1YA from being powered on.

Claims (5)

1. A loader electro-hydraulic control hydraulic system with quantitative confluence of multiple pumps, mainly including a steering system and a working system, wherein the steering system includes a steering pump and a steering cylinder, and the working system includes a working pump, a bucket cylinder, and a boom cylinder. in: (1) The steering system is equipped with a first auxiliary pump, and a first control valve group is installed between the first auxiliary pump and the main oil circuit of the steering system to control the oil supply direction of the first auxiliary pump. , the first auxiliary pump is controlled by the first control valve group to supply oil to the steering system, and in the high-speed section of the engine, the first control valve group is controlled to supply oil to the working system by the first auxiliary pump; (2) The working system is provided with a second auxiliary pump, and a second control valve group is provided between the second auxiliary pump and the main oil circuit of the working system to control the oil supply direction of the second auxiliary pump. In the low speed section of the engine, The second control valve group controls the second auxiliary pump to supply oil to the steering system, and in the middle and high speed section of the engine, the second control valve group controls the second auxiliary pump to supply oil to the working system; (3) A flow amplifying valve is installed in the main oil circuit of the steering system, and the priority valve port of the flow amplifying valve is connected to the main oil circuit of the working system through the electronically controlled unloading valve, which is used to The remaining oil in the steering system supplies oil to the working system through the priority valve of the flow amplification valve and the electric control unloading valve. 2. The hydraulic system of loader electro-hydraulic control multi-pump quantitative confluence according to claim 1, characterized in that: the first control valve group includes a first electromagnetic reversing valve and a second electromagnetic reversing valve; An electromagnetic reversing valve is controlled by the steering signal detected by the pressure switch, and the second electromagnetic reversing valve is controlled by the signal detected by the engine speed. 3. The hydraulic system of loader electro-hydraulic control multi-pump quantitative confluence according to claim 1, characterized in that: the second control valve group includes a third electromagnetic reversing valve and a fourth electromagnetic reversing valve, and the first The three electromagnetic reversing valves are controlled by the steering signal detected by the pressure switch, and the fourth electromagnetic reversing valve is controlled by detecting the engine speed. 4. The hydraulic system of loader electro-hydraulic control multi-pump quantitative confluence according to claim 1, characterized in that: an electromagnetic overflow valve is connected in parallel at the outlet of the working pump, for when the oil cylinder of the working system moves close to the stroke At the end, by detecting the displacement signal of the oil cylinder, the oil of the working pump is directly discharged back to the oil tank. 5. The hydraulic system of loader electro-hydraulic control multi-pump quantitative confluence according to claim 2 or 3, characterized in that: the engine speed is divided into low-speed section, medium-speed section, and high-speed section, and the low-speed section is The idle speed is -1150rpm; the middle speed section is 1150-1600rpm; the high speed section is 1600-2200rpm.