A control method for a constant tension system of a crane

Abstract

The invention provides a constant tension system of a crane, comprising a control oil port P, an oil drain port L, a lifting oil port A1 and a lifting oil port A2 connected to a lifting oil circuit of a winch motor, descending oil ports B1 and B2 connected to a descending oil circuit of a winch motor, a switch valve, a pilot relief 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 to an oil pump, and the oil drain port L is connected to an oil tank; a double insurance effect is achieved by respectively arranging a first electromagnetic valve and a second electromagnetic valve for control, and when one of the electromagnetic valves is not reversed, the constant tension valve will not be activated, thereby achieving good safety.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic systems, and in particular to a control method for a constant tension system of a crane. Background Art

[0002] The function of the constant tension hydraulic system is to keep a certain tension on the winch wire rope. When the tension is too large, the rope is released, and when the tension is too small, the rope is reeled in. The existing constant tension hydraulic system occupies a large space, resulting in a waste of installation space. In addition, when the crane does not use the constant tension hydraulic system, there is a problem that the lifting system leaks and causes the lifting system to slip.

[0003] A patent document in China with application number 202122757952.6 and publication date 2022.7.8 discloses a constant tension system for a crane, including a winch motor and a constant tension valve, the constant tension valve including a control oil port P, a lifting oil port A connected to the lifting oil circuit of the winch motor, a lowering oil 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 overflow valve, a direct-operated overflow valve and an oil drain port L; the oil drain port L is connected to the oil tank, but the constant tension valve uses an electromagnetic reversing valve to simultaneously control the reversing of the first logic valve and the second logic valve. In this way, when the electromagnetic reversing valve fails, the winch rope cannot be accurately controlled to be retracted and released. Summary of the invention

[0004] The present invention provides a control method for a constant tension system of a crane. When constant tension control is performed, a first electromagnetic reversing valve and a second electromagnetic reversing valve are simultaneously controlled to be energized, thereby achieving a double insurance effect. When one of the electromagnetic valves does not change direction, the constant tension valve will not be activated, thereby achieving good safety.

[0005] To achieve the above-mentioned purpose, the technical solution of the present invention is: a control method for a constant tension system of a crane, the constant tension system of the crane includes a control oil port P, an oil drain port L, a lifting oil port A1 and a lifting oil port A2 connected to the lifting oil circuit of the winch motor, a descending oil port B1 and B2 connected to the descending oil circuit of the winch motor, a switch valve, a pilot overflow valve, a first solenoid reversing valve, a second solenoid reversing valve, a first check valve and a second check valve; the control oil port P is connected to the oil pump, and the oil drain port L is connected to the oil tank.

[0006] The control oil port P is connected to the oil inlet of the first electromagnetic reversing valve through the first one-way valve; the oil outlet of the first electromagnetic reversing valve is connected to the external control oil port of the switch valve; one side of the switch valve is connected to the lifting oil port A1 and the lifting oil port A2.

[0007] The other side of the switch valve is connected to the oil inlet of the pilot relief valve, and the oil outlet of the pilot relief valve is connected to the descending oil port B1 and the descending oil port B2; the external control oil port of the pilot relief valve is connected to the oil outlet of the second solenoid reversing valve, and the control oil port P is connected to the oil inlet of the second solenoid reversing valve through the second one-way valve.

[0008] The control method of the constant tension system of a crane comprises the following steps:

[0009] S1, the first electromagnetic reversing valve and the second electromagnetic reversing valve are electrically switched.

[0010] S2, the pilot relief valve is connected to the oil unloading port L; the signal hydraulic oil flowing in from the control oil port P flows to the switch valve through the oil outlet of the first solenoid reversing valve, causing the switch valve to reverse.

[0011] S3. The hydraulic oil flowing in from the lifting oil port A1 and the lifting oil port A2 flows through the switch valve and enters the oil inlet of the pilot relief valve.

[0012] S4, determine whether the lifting pressure of the winch motor is greater than the constant pressure set by the pilot relief valve, if so, proceed to S6; if not, proceed to S5.

[0013] S5. The hydraulic oil entering the pilot relief valve flows from the external oil control port of the pilot relief valve to the oil drain port L and then flows into the oil tank.

[0014] S6. The oil inlet of the pilot relief valve is connected to the oil outlet of the pilot relief valve, and the hydraulic oil entering the pilot relief valve flows from the oil outlet of the pilot relief valve to the descending oil port B1 and the descending oil port B2.

[0015] In the above method, when the second solenoid reversing valve is electrically switched, the control oil port P is cut off from the second solenoid reversing valve, and the pilot relief valve is connected to the oil unloading port L; when the first solenoid reversing valve is electrically switched, the signal hydraulic oil flowing in from the control oil port P flows to the switch valve through the oil outlet of the first solenoid reversing valve, and then the switch valve is switched, and the hydraulic oil flowing in from the lifting oil port A1 and the lifting oil port A2 flows through the switch valve and enters the oil inlet of the pilot relief valve; when the lifting pressure of the winch motor is less than the constant pressure set by the pilot relief valve, the pilot relief valve enters The hydraulic oil of the valve flows from the external control oil port of the pilot relief valve to the oil drain port L and then into the oil tank, thereby realizing the retraction of the wire rope; when the lifting pressure of the winch motor is greater than the constant pressure set by the pilot relief valve, the hydraulic oil entering the pilot relief valve flows from the oil outlet of the pilot relief valve to the descending oil port B1 and the descending oil port B2, thereby lowering the rope under a certain wire rope tension. The first solenoid valve and the second solenoid valve are respectively set for control to achieve a double insurance effect. When one of the solenoid valves is not reversed, the constant tension valve will not be activated, and the safety is good.

[0016] Furthermore, the oil unloading port of the first electromagnetic reversing valve is connected to the oil unloading port L; the oil unloading port of the second electromagnetic reversing valve is connected to the oil unloading port L.

[0017] Further, the oil unloading port of the switch valve is connected to the oil unloading port L.

[0018] Furthermore, a first damper is provided between the output end of the first one-way valve and the oil inlet of the first electromagnetic reversing valve. The first damper is provided to reduce the impact of the hydraulic oil, so that the constant tension valve remains stable.

[0019] Furthermore, a second damper is provided between the first damper and the oil inlet of the first electromagnetic reversing valve. The second damper is provided to reduce the impact of the hydraulic oil, so that the constant tension valve remains stable.

[0020] Furthermore, a third damper is provided between the output end of the second one-way valve and the oil inlet of the second electromagnetic reversing valve. The third damper is provided to reduce the impact of the hydraulic oil, so that the constant tension valve remains stable.

[0021] Furthermore, a first pressure measuring point M1 is provided between the first damper and the oil inlet of the first electromagnetic reversing valve, so that the pressure of the oil inlet of the first electromagnetic reversing valve can be detected.

[0022] Furthermore, a second pressure measuring point M2 is provided between the oil outlet of the second electromagnetic reversing valve and the external oil control port of the pilot relief valve, so that the pressure of the external oil control port of the pilot relief valve can be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The hydraulic principle diagram of the constant tension system of the crane of the present invention is implemented. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, a control method for a constant tension system of a crane, the constant tension system of the crane includes a control oil port P, an oil drain port L, a lifting oil port A1 and a lifting oil port A2 connected to the lifting oil circuit of the winch motor, a descending oil port B1 and a descending oil port B2 connected to the descending oil circuit of the winch motor, a switch valve 1, a pilot relief valve 2, a first electromagnetic reversing valve 3, a second electromagnetic reversing valve 4, a first non-return valve 5 and a second non-return valve 6; the control oil port P is connected to the oil pump, and the oil drain port L is connected to the oil tank.

[0026] The control oil port P is connected to the oil inlet 31 of the first electromagnetic reversing valve through the first non-return valve 5; the oil outlet 32 ​​of the first electromagnetic reversing valve is connected to the external control oil port of the switch valve 1; one side of the switch valve 1 is connected to the lifting oil port A1 and the lifting oil port A2.

[0027] The other side of the switch valve 1 is connected to the oil inlet of the pilot relief valve 2, and the oil outlet of the pilot relief valve 2 is connected to the descending oil port B1 and the descending oil port B2; the external control oil port of the pilot relief valve 2 is connected to the oil outlet 42 of the second solenoid reversing valve, and the control oil port P is connected to the oil inlet 41 of the second solenoid reversing valve through the second check valve 6.

[0028] In this embodiment, the oil unloading port of the switch valve 1 , the oil unloading port 33 of the first electromagnetic reversing valve, and the oil unloading port 43 of the second electromagnetic reversing valve are all connected to the oil unloading port L.

[0029] In this embodiment, a first damper 7 and a second damper 8 are provided in sequence between the output end of the first check valve 5 and the oil inlet of the first electromagnetic reversing 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 electromagnetic reversing valve 4. By providing the first damper 7, the second damper 8 and the third damper 9, the impact of the hydraulic oil is reduced, so that the constant tension valve remains stable.

[0030] In this embodiment, a first pressure measuring point M1 is provided between the first damper 7 and the oil inlet of the first electromagnetic reversing valve 3 , so that the pressure of the oil inlet of the first electromagnetic reversing valve 3 can be detected.

[0031] 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 outlet of the pilot relief valve 2. In this way, the pressure of the external control oil outlet of the pilot relief valve 2 can be detected. The control method of the constant tension system of the crane includes the following steps:

[0032] S1, the first electromagnetic reversing valve and the second electromagnetic reversing valve are electrically switched.

[0033] S2, the pilot relief valve is connected to the oil unloading port L; the signal hydraulic oil flowing in from the control oil port P flows to the switch valve through the oil outlet of the first solenoid reversing valve, causing the switch valve to reverse.

[0034] S3. The hydraulic oil flowing in from the lifting oil port A1 and the lifting oil port A2 flows through the switch valve and enters the oil inlet of the pilot relief valve.

[0035] S4, determine whether the lifting pressure of the winch motor is greater than the constant pressure set by the pilot relief valve, if so, proceed to S6; if not, proceed to S5.

[0036] S5. The hydraulic oil entering the pilot relief valve flows from the external oil control port of the pilot relief valve to the oil drain port L and then flows into the oil tank.

[0037] S6. The oil inlet of the pilot relief valve is connected to the oil outlet of the pilot relief valve, and the hydraulic oil entering the pilot relief valve flows from the oil outlet of the pilot relief valve to the descending oil port B1 and the descending oil port B2.

[0038] In the above method, when the second solenoid reversing valve 4 is electrically reversed, the control oil port P is cut off from the second solenoid reversing valve 4, and the pilot relief valve 2 is connected to the oil discharge port L; when the first solenoid reversing valve 3 is electrically reversed, the signal hydraulic oil flowing in from the control oil port P flows to the switch valve 1 through the oil outlet of the first solenoid reversing valve 3, and then the switch valve 1 is reversed, and the hydraulic oil flowing in from the lifting oil port A1 and the lifting oil port A2 flows through the switch valve 1 and enters the oil inlet of the pilot relief valve 2; when the lifting pressure of the winch motor is less than the constant pressure set by the pilot relief valve 2, the pilot relief valve 2 enters. The hydraulic oil of the relief valve 2 flows from the external control oil port of the pilot relief valve 2 to the oil drain port L and then into the oil tank, thereby realizing the retraction of the wire rope; when the lifting pressure of the winch motor is greater than the constant pressure set by the pilot relief valve 2, the hydraulic oil entering the pilot relief valve 2 flows from the oil outlet of the pilot relief valve 2 to the descending oil port B1 and the descending oil port B2, thereby lowering the rope under a certain wire rope tension. The first solenoid valve and the second solenoid valve are respectively set for control to achieve a double insurance effect. When one of the solenoid valves is not reversed, the constant tension valve will not be activated, and the safety is good.

Claims

1. A control method for a constant tension system of a crane, characterized in that: The constant tension system of the crane includes a control oil port P, an oil drain port L, a lifting oil port A1 and a lifting oil port A2 connected to the lifting oil circuit of the winch motor, a descending oil port B1 and a descending oil port B2 connected to the descending oil circuit of the winch motor, a switch valve, a pilot relief valve, a first electromagnetic reversing valve, a second electromagnetic reversing valve, a first check valve and a second check valve; the control oil port P is connected to the oil pump, and the oil drain port L is connected to the oil tank; The control oil port P is connected to the oil inlet of the first electromagnetic reversing valve through the first one-way valve, a first damper is provided between the output end of the first one-way valve and the oil inlet of the first electromagnetic reversing valve, a second damper is provided between the first damper and the oil inlet of the first electromagnetic reversing valve, and a first pressure measuring point M is provided between the first damper and the oil inlet of the first electromagnetic reversing valve; the oil outlet of the first electromagnetic reversing valve is connected to the external control oil port of the switch valve, and 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 relief valve; one side of the switch valve is connected to the lifting oil port A1 and the lifting oil port A2; The other side of the switch valve is connected to the oil inlet of the pilot relief valve, and the oil outlet of the pilot relief valve is connected to the descending oil port B1 and the descending oil port B2; the external control oil port of the pilot relief valve is connected to the oil outlet of the second electromagnetic reversing valve, and the control oil port P is connected to the oil inlet of the second electromagnetic reversing valve through the second check valve; The control method of the constant tension system of a crane comprises the following steps: S1, the first electromagnetic reversing valve and the second electromagnetic reversing valve are electrically reversing; S2, the pilot relief valve is connected to the oil unloading port L; the signal hydraulic oil flowing in from the control oil port P flows to the switch valve through the oil outlet of the first solenoid reversing valve, causing the switch valve to reverse; S3, the hydraulic oil flowing in from the lifting oil port A1 and the lifting oil port A2 flows through the switch valve and enters the oil inlet of the pilot relief valve; S4, judging whether the lifting pressure of the winch motor is greater than the constant pressure set by the pilot relief valve, if so, proceed to S6; if not, proceed to S5; S5. The hydraulic oil entering the pilot relief valve flows from the external oil control port of the pilot relief valve to the oil drain port L and then flows into the oil tank; S6. The oil inlet of the pilot relief valve is connected to the oil outlet of the pilot relief valve, and the hydraulic oil entering the pilot relief valve flows from the oil outlet of the pilot relief valve to the descending oil port B1 and the descending oil port B2.

2. The control method of a constant tension system of a crane according to claim 1, characterized in that: The oil unloading port of the first electromagnetic reversing valve is connected to the oil unloading port L; the oil unloading port of the second electromagnetic reversing valve is connected to the oil unloading port L.

3. The control method of a constant tension system of a crane according to claim 1, characterized in that: The oil discharge port of the switch valve is connected to the oil discharge port L.

4. The control method of a constant tension system of a crane according to claim 1, characterized in that: A third damper is provided between the output end of the second one-way valve and the oil inlet of the second electromagnetic reversing valve.

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