Constant tension system for a crane

Abstract

The application provides a constant tension system of a crane, which comprises a control oil port P, a leakage oil port L, a hoisting oil port A1 and a hoisting oil port A2 connected with a hoisting oil way of a winch motor, a lowering oil port B1 and B2 connected with a lowering oil way of the winch motor, a switch valve, a pilot overflow valve, a first electromagnetic reversing valve, a second electromagnetic reversing valve, a first check valve, a second check valve and a third check valve; the control oil port P is connected with an oil pump, and the leakage oil port L is connected with an oil tank; the double insurance effect is achieved by controlling through respectively setting the first electromagnetic valve and the second electromagnetic valve, and the constant tension valve cannot be activated when one of the electromagnetic valves does not reverse, and the safety is good.

Description

Technical Field

[0001] This invention relates to the field of hydraulic system technology, and more specifically to a constant tension system for a crane. Background Technology

[0002] The function of a constant tension hydraulic system is to maintain a certain tension in the winch wire rope. When the tension is too high, the rope is released; when the tension is too low, the rope is retrieved. Existing constant tension hydraulic systems occupy a lot of space, resulting in a waste of installation space. In addition, when the crane does not use a constant tension hydraulic system, there is a risk of leakage in the hoisting system, which can lead to the hoisting system slipping.

[0003] Chinese patent application number 202122757952.6, published on July 8, 2022, discloses a constant tension system for a crane, including a winch motor and a constant tension valve. The constant tension valve includes a control port P, a lifting port A connected to the lifting oil circuit of the winch motor, a lowering port B connected to the lowering oil circuit of the winch motor, an electromagnetic reversing valve, a first logic valve, a second logic valve, a pilot-operated relief valve, a direct-operated relief valve, and a drain port L. The drain port L is connected to the oil tank. However, this constant tension valve uses a single electromagnetic reversing valve to simultaneously control the reversing of the first logic valve and the second logic valve. Thus, when the electromagnetic reversing valve malfunctions, it cannot accurately control the winch's rope winding and unwinding. Summary of the Invention

[0004] This invention provides a constant tension system for a crane, which controls the switching valve to switch direction through a first electromagnetic reversing valve and controls the opening and closing of a pilot-operated relief valve through a second electromagnetic reversing valve, thereby accurately controlling the winding and unwinding of the winch.

[0005] To achieve the above objectives, the technical solution of the present invention is: a constant tension system for a crane, comprising a control port P, a drain port L, lifting ports A1 and A2 connected to the lifting oil circuit of the winch motor, lowering ports B1 and B2 connected to the lowering oil circuit of the winch motor, a switching valve, a pilot-operated relief valve, a first solenoid directional valve, a second solenoid directional valve, a first check valve, and a second check valve; the control port P is connected to an oil pump, and the drain port L is connected to an oil tank.

[0006] The control port P is connected to the inlet of the first solenoid directional valve via the first check valve; the outlet of the first solenoid directional valve is connected to the external control port of the switching valve; one side of the switching valve is connected to the lifting port A1 and the lifting port A2.

[0007] The other side of the switching valve is connected to the inlet of the pilot-operated relief valve, and the outlet of the pilot-operated relief valve is connected to the downcomer port B1 and downcomer port B2; the external control port of the pilot-operated relief valve is connected to the outlet of the second solenoid directional valve, and the control port P is connected to the inlet of the second solenoid directional valve through the second check valve.

[0008] In the above configuration, when the second solenoid directional valve is energized and reverses, the control port P is cut off from the second solenoid directional valve, and the pilot-operated relief valve is connected to the unloading port L. When the first solenoid directional valve is energized and reverses, the signal hydraulic oil flowing in from the control port P flows through the outlet of the first solenoid directional valve to the switching valve, thereby reversing the switching valve. The hydraulic oil flowing in from the lifting ports A1 and A2 flows through the switching valve into the inlet of the pilot-operated relief valve. When the lifting pressure of the winch motor is less than the constant pressure set by the pilot-operated relief valve, it enters the pilot-operated relief valve. The hydraulic oil in the valve flows from the external control port of the pilot-operated relief valve to the drain port L and then into the oil tank, thereby realizing the winding of the wire rope. When the lifting pressure of the winch motor is greater than the constant pressure set by the pilot-operated relief valve, the hydraulic oil entering the pilot-operated relief valve flows from the outlet of the pilot-operated relief valve to the lowering ports B1 and B2, thereby releasing the rope under a certain wire rope tension. The first and second solenoid valves are set separately to achieve a double insurance effect. When one of the solenoid valves does not switch, the constant tension valve will not be activated, ensuring good safety.

[0009] Furthermore, the unloading port of the first solenoid directional valve is connected to the unloading port L; the unloading port of the second solenoid directional valve is also connected to the unloading port L.

[0010] Furthermore, the oil discharge port of the switching valve is connected to the oil discharge port L.

[0011] Furthermore, a first damper is provided between the output end of the first check valve and the oil inlet of the first solenoid directional valve. By setting the first damper, the impact of hydraulic oil is reduced, thus keeping the constant tension valve stable.

[0012] Furthermore, a second damper is provided between the first damper and the oil inlet of the first solenoid directional valve. By setting the second damper, the impact of hydraulic oil is reduced, thus keeping the constant tension valve stable.

[0013] Furthermore, a third damper is provided between the output end of the second check valve and the inlet of the second solenoid directional valve. By setting the third damper, the impact of hydraulic oil is reduced, thus keeping the constant tension valve stable.

[0014] Furthermore, a first pressure measuring point M1 is provided between the first damper and the oil inlet of the first solenoid directional valve. This allows for the detection of the pressure at the oil inlet of the first solenoid directional valve.

[0015] Furthermore, a second pressure testing point M2 is provided between the oil outlet of the second solenoid directional valve and the external control port of the pilot-operated relief valve. This allows for the detection of the pressure at the external control port of the pilot-operated relief valve. Attached Figure Description

[0016] Figure 1 This is a hydraulic schematic diagram of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, a constant tension system for a crane includes a control port P, a drain port L, lifting ports A1 and A2 connected to the lifting oil circuit of the winch motor, lowering ports B1 and B2 connected to the lowering oil circuit of the winch motor, a switching valve 1, a pilot-operated relief valve 2, a first solenoid directional valve 3, a second solenoid directional valve 4, a first check valve 5, and a second check valve 6; the control port P is connected to the oil pump, and the drain port L is connected to the oil tank.

[0019] The control port P is connected to the inlet port 31 of the first solenoid directional valve via the first check valve 5; the outlet port 32 of the first solenoid directional valve is connected to the external control port of the switch valve 1; one side of the switch valve 1 is connected to the lifting port A1 and the lifting port A2.

[0020] The other side of the switching valve 1 is connected to the oil inlet of the pilot-operated relief valve 2. The oil outlet of the pilot-operated relief valve 2 is connected to the downcomer port B1 and downcomer port B2. The external control port of the pilot-operated relief valve 2 is connected to the oil outlet 42 of the second solenoid directional valve. The control port P is connected to the oil inlet 41 of the second solenoid directional valve through the second check valve 6.

[0021] In the above configuration, when the second solenoid directional valve 4 is energized and reversed, the control port P is cut off from the second solenoid directional valve 4, and the pilot-operated relief valve 2 is connected to the unloading port L; when the first solenoid directional valve 3 is energized and reversed, the signal hydraulic oil flowing in from the control port P flows through the outlet of the first solenoid directional valve 3 to the switching valve 1, and then the switching valve 1 reverses, and the hydraulic oil flowing in from the lifting ports A1 and A2 flows through the switching valve 1 into the inlet of the pilot-operated relief valve 2; when the lifting pressure of the winch motor is less than the constant pressure set by the pilot-operated relief valve 2, it enters the pilot-operated relief valve 2. The hydraulic oil in the relief valve 2 flows from the external control port of the pilot-operated relief valve 2 to the drain port L and then into the oil tank, thereby realizing the winding of the wire rope. When the lifting pressure of the winch motor is greater than the constant pressure set by the pilot-operated relief valve 2, the hydraulic oil entering the pilot-operated relief valve 2 flows from the outlet of the pilot-operated relief valve 2 to the lowering port B1 and the lowering port B2, thereby releasing the rope under a certain wire rope tension. The first solenoid valve and the second solenoid valve are set to control the double insurance effect. When one of the solenoid valves does not switch, the constant tension valve will not be activated, which ensures good safety.

[0022] In this embodiment, the oil discharge port of the switching valve 1, the oil discharge port 33 of the first solenoid directional valve, and the oil discharge port 43 of the second solenoid directional valve are all connected to the oil discharge port L.

[0023] In this embodiment, a first damper 7 and a second damper 8 are sequentially provided between the output end of the first check valve 5 and the oil inlet of the first solenoid directional valve 3; a third damper 9 is provided between the output end of the second check valve 6 and the oil inlet of the second solenoid directional valve 4. By setting the first damper 7, the second damper 8 and the third damper 9, the impact of hydraulic oil is reduced, and the constant tension valve remains stable.

[0024] In this embodiment, a first pressure measuring point M1 is provided between the first damper 7 and the oil inlet of the first solenoid directional valve 3. This allows for the detection of the pressure at the oil inlet of the first solenoid directional valve 3.

[0025] In this embodiment, a second pressure measuring point M2 is provided between the oil outlet of the second electromagnetic reversing valve 4 and the external control oil port of the pilot-operated relief valve 2. This allows for the detection of the pressure at the external control oil port of the pilot-operated relief valve 2.

Claims

1. A constant tension system for a crane, characterized in that: It includes a control port P, a drain port L, lifting ports A1 and A2 connected to the lifting oil circuit of the winch motor, lowering ports B1 and B2 connected to the lowering oil circuit of the winch motor, a switching valve, a pilot-operated relief valve, a first solenoid directional valve, a second solenoid directional valve, a first check valve, and a second check valve; the control port P is connected to the oil pump, and the drain port L is connected to the oil tank; The control port P is connected to the inlet of the first solenoid directional valve via the first check valve; the outlet of the first solenoid directional valve is connected to the external control port of the switching valve; one side of the switching valve is connected to the lifting port A1 and the lifting port A2. The other side of the switching valve is connected to the inlet of the pilot-operated relief valve, and the outlet of the pilot-operated relief valve is connected to the downcomer port B1 and downcomer port B2; the external control port of the pilot-operated relief valve is connected to the outlet of the second solenoid directional valve, and the control port P is connected to the inlet of the second solenoid directional valve through the second check valve. The discharge port of the first solenoid directional valve is connected to discharge port L; the discharge port of the second solenoid directional valve is connected to discharge port L; the discharge port of the switching valve is connected to discharge port L.

2. The constant tension system for a crane according to claim 1, characterized in that: A first damper is provided between the output end of the first check valve and the oil inlet of the first solenoid directional valve.

3. The constant tension system for a crane according to claim 2, characterized in that: A second damper is provided between the first damper and the oil inlet of the first solenoid directional valve.

4. The constant tension system for a crane according to claim 1, characterized in that: A third damper is provided between the output end of the second check valve and the oil inlet of the second solenoid directional valve.

5. The constant tension system for a crane according to claim 3, characterized in that: A first pressure measuring point M is provided between the first damper and the oil inlet of the first solenoid directional valve.

6. The constant tension system for a crane according to claim 1, characterized in that: A second pressure measuring point M2 is provided between the oil outlet of the second electromagnetic reversing valve and the external control oil port of the pilot-operated relief valve.

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