Boom luffing hydraulic system and telescopic boom engineering machinery

Abstract

The present invention discloses a boom-bearing hydraulic system, comprising an oil pump, a boom-bearing electromagnetic reversing valve, a two-way balancing valve and an oil cylinder. The oil inlet and the oil return port of the boom-bearing electromagnetic reversing valve are respectively connected to the oil pump and the oil tank, the two working oil ports of the boom-bearing electromagnetic reversing valve are respectively connected to the two inlets of the two-way balancing valve, the two outlets of the two-way balancing valve are respectively connected to the rod chamber and the rodless chamber of the oil cylinder, the hydraulic control oil circuit of the two-way balancing valve is connected to the oil tank through a control valve, when the boom-bearing is boom-bearing, the control valve is closed to maintain the pressure of the hydraulic control oil circuit of the two-way balancing valve, and when the boom-bearing stops boom-bearing, the control valve is opened to connect the hydraulic control oil circuit of the two-way balancing valve to the oil tank to release the pressure. When the boom-bearing stops boom-bearing, if the boom-bearing electromagnetic reversing valve is stuck, the control oil circuit of the two-way balancing valve cannot build up enough pressure to open the two-way balancing valve due to the power failure of the control valve, and the boom will remain motionless to ensure the safety of the system. The present invention also discloses a telescopic boom engineering machinery including the above system.

Description

Technical Field

[0001] The present invention relates to the field of engineering machinery, and in particular to a boom luffing hydraulic system. In addition, the present invention also relates to a telescopic boom engineering machinery comprising the above system. Background Art

[0002] Telescopic boom engineering machinery is widely used in various fields. The boom luffing hydraulic system includes an oil pump, a reversing valve, a balancing valve and a cylinder. The reversing valve is used to control the rising and falling direction and speed of the cylinder. The main function of the balancing valve is to keep the boom moving smoothly and safely during the rising and falling process, and to keep the boom stable when the boom stops moving.

[0003] However, since the middle position of the reversing valve adopts a Y-type function, once the rodless chamber side of the balancing valve gets stuck, the hydraulic oil in the rodless chamber of the cylinder will flow out through the balancing valve, and the boom will fall uncontrollably, causing a serious safety accident; in addition, if the reversing valve gets stuck, when operating other actions, the boom will also change its amplitude, causing casualties.

[0004] Therefore, how to provide a boom luffing hydraulic system that can avoid safety accidents caused by valve sticking is a technical problem that those skilled in the art need to solve at present. Summary of the invention

[0005] The purpose of the present invention is to provide a boom luffing hydraulic system, which can prevent the boom from falling and luffing uncontrollably due to valve jamming by setting a control valve, thereby improving the safety of the system. Another purpose of the present invention is to provide a telescopic boom engineering machine including the above system.

[0006] To solve the above technical problems, the present invention provides a boom luffing hydraulic system, comprising an oil pump, an luffing electromagnetic reversing valve, a two-way balancing valve and an oil cylinder, the oil inlet and oil return port of the luffing electromagnetic reversing valve being connected to the oil pump and the oil tank respectively, the two working oil ports of the luffing electromagnetic reversing valve being connected to the two inlets of the two-way balancing valve respectively, the two outlets of the two-way balancing valve being connected to the rod chamber and the rodless chamber of the oil cylinder respectively, the hydraulic control oil circuit of the two-way balancing valve being connected to the oil tank through a control valve, when the boom luffing is performed, the control valve is closed to maintain the pressure of the hydraulic control oil circuit of the two-way balancing valve, and when the boom stops luffing, the control valve is opened to connect the hydraulic control oil circuit of the two-way balancing valve to the oil tank to release the pressure.

[0007] Preferably, the control valve is a normally open electromagnetic reversing valve, which is energized when the boom changes its amplitude, and de-energized when the boom stops changing its amplitude.

[0008] Preferably, the normally open electromagnetic reversing valve is specifically a two-position two-way electromagnetic reversing valve.

[0009] Preferably, the two-position two-way electromagnetic reversing valve is arranged at the pressure-dividing damping position of the two-way balancing valve.

[0010] Preferably, the variable amplitude electromagnetic reversing valve is specifically an O-type functional electromagnetic valve.

[0011] Preferably, the O-type functional solenoid valve is specifically an O-type functional three-position four-way solenoid reversing valve.

[0012] Preferably, the control valve further comprises a pressure sensor for detecting the pressure on the rodless cavity side, and is capable of closing the control valve when detecting that the pressure continuously exceeds a threshold value.

[0013] Preferably, the pressure sensor is arranged on a pipeline between the rodless chamber side of the bidirectional balancing valve and the variable amplitude electromagnetic reversing valve.

[0014] Preferably, the detection threshold of the pressure sensor is a pressure of 1.2 MPa lasting for 1 second.

[0015] The present invention provides a telescopic boom engineering machinery, which includes a boom luffing hydraulic system as described in any one of the above items.

[0016] The present invention provides a boom luffing hydraulic system, comprising an oil pump, a luffing electromagnetic reversing valve, a two-way balancing valve and an oil cylinder, wherein the oil inlet and oil return port of the luffing electromagnetic reversing valve are respectively connected to the oil pump and the oil tank, the two working oil ports of the luffing electromagnetic reversing valve are respectively connected to the two inlets of the two-way balancing valve, the two outlets of the two-way balancing valve are respectively connected to the rod chamber and the rodless chamber of the oil cylinder, the hydraulic control oil circuit of the two-way balancing valve is connected to the oil tank through a control valve, when the boom luffing is performed, the control valve is closed to maintain the pressure of the hydraulic control oil circuit of the two-way balancing valve, and when the boom stops luffing, the control valve is opened to connect the hydraulic control oil circuit of the two-way balancing valve to the oil tank for pressure relief.

[0017] Under normal working conditions, when the boom is extended or retracted, the speed of the cylinder's rise and fall is controlled by the luffing electromagnetic reversing valve. At this time, the control valve is closed, and the hydraulic control oil circuit of the two-way balancing valve generates enough pressure to open the other side of the two-way balancing valve and allow the hydraulic oil in the cylinder to flow back. When the boom stops, the luffing electromagnetic reversing valve returns to the middle position, and the control valve opens, and the hydraulic control oil circuit of the two-way balancing valve is depressurized, and it is impossible to build up enough pressure to open the two-way balancing valve, ensuring that the hydraulic oil in the cylinder cannot flow back and the boom remains stationary. When the boom remains stationary, if the luffing electromagnetic reversing valve is stuck and cannot return to the middle position, the pressure is released by the control valve, and the two-way balancing valve cannot be opened, ensuring that the hydraulic oil in the cylinder cannot flow back, preventing the boom from falling uncontrollably, thereby ensuring system safety.

[0018] The present invention also provides a telescopic boom engineering machinery including the above-mentioned system. Since the above-mentioned system has the above-mentioned technical effects, the above-mentioned telescopic boom engineering machinery should also have the same technical effects, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention provides a hydraulic principle diagram of a specific implementation of the boom luffing hydraulic system provided by the present invention. DETAILED DESCRIPTION

[0020] The core of the present invention is to provide a boom luffing hydraulic system, which prevents the boom from falling and luffing uncontrollably due to valve jamming by setting a control valve, thereby improving the safety of the system. Another core of the present invention is to provide a telescopic boom engineering machinery including the above system.

[0021] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0022] Please refer to the figure, Figure 1 The present invention provides a hydraulic principle diagram of a specific implementation of the boom luffing hydraulic system provided by the present invention.

[0023] A specific embodiment of the present invention provides a boom boom hydraulic system, comprising an oil pump, an oil tank, a boom boom electromagnetic reversing valve 1, a two-way balancing valve 2 and an oil cylinder 3. The boom boom electromagnetic reversing valve 1 has an oil inlet, an oil return port and two working oil ports, the two-way balancing valve 2 has two inlets and two outlets, the oil inlet and oil return port of the boom boom electromagnetic reversing valve 1 are respectively connected to the oil pump and the oil tank, the two working oil ports of the boom boom electromagnetic reversing valve 1 are respectively connected to the two inlets of the two-way balancing valve 2, and the two outlets of the two-way balancing valve 2 are respectively connected to the rod chamber and the rodless chamber of the oil cylinder 3, that is, the two-way balancing valve 2 is divided into a rod chamber side and a rodless chamber side, and two hydraulically controlled overflow valves are provided on both sides, and each hydraulically controlled overflow valve is connected in parallel with a one-way valve. At the same time, the hydraulic control oil circuit of the two-way balancing valve 2 leads to a branch connected to the oil tank, on which a control valve 4 is arranged. When the boom is luffed, the control valve 4 is closed to maintain the pressure of the hydraulic control oil circuit of the two-way balancing valve 2. When the boom stops luffing, the control valve 4 is opened to connect the hydraulic control oil circuit of the two-way balancing valve 2 to the oil tank to release the pressure.

[0024] Under normal working conditions, when the boom is extended or retracted, the speed of the rising and falling direction of the oil cylinder 3 is controlled by the luffing electromagnetic reversing valve 1. At this time, the control valve 4 is closed, and the hydraulic control oil circuit of the two-way balancing valve 2 generates sufficient pressure to enable the other side of the two-way balancing valve 2 to open, and the hydraulic oil in the oil cylinder 4 can flow back. When the boom stops, the luffing electromagnetic reversing valve 1 returns to the middle position, and the control valve 4 opens, and the hydraulic control oil circuit of the two-way balancing valve 2 is depressurized, and it is impossible to build up enough pressure to open the two-way balancing valve 2, ensuring that the hydraulic oil in the oil cylinder 3 cannot flow back, and the boom remains stationary. When the boom remains stationary, if the luffing electromagnetic reversing valve 1 is stuck and cannot return to the middle position, the pressure is released through the control valve 4, and the two-way balancing valve 2 cannot be opened, ensuring that the hydraulic oil in the oil cylinder 3 cannot flow back, preventing the boom from falling uncontrollably, thereby ensuring the safety of the system.

[0025] Specifically, the control valve 4 is a normally open electromagnetic reversing valve, which is powered on and closed when the boom is changing its amplitude, and is powered off and opened when the boom stops changing its amplitude. Further, the normally open electromagnetic reversing valve is a two-position two-way electromagnetic reversing valve, which is arranged at the partial pressure damping position of the two-way balancing valve 2.

[0026] On the basis of the boom boom hydraulic system provided in the above specific embodiments, the boom boom electromagnetic reversing valve 1 is an O-type functional electromagnetic valve, specifically an O-type functional three-position four-way electromagnetic reversing valve, which replaces the traditional Y-type functional electromagnetic valve and has better safety performance. Other types of valves can also be used, all within the protection scope of the present invention.

[0027] The specific working process is: under normal working conditions, when the boom needs to be extended, DT2 of the variable amplitude electromagnetic reversing valve 1 and DT3 of the control valve 4 are energized, the variable amplitude electromagnetic reversing valve 1 works and reverses, the control valve 4 is closed, and the high-pressure oil enters the rodless chamber side of the two-way balancing valve 2, and directly enters the rodless chamber of the cylinder 3 from the one-way valve on the rodless chamber side, and at the same time, the high-pressure oil enters the hydraulic control oil circuit of the two-way balancing valve 2. At this time, the control valve 4 is closed, and the hydraulic control oil circuit of the two-way balancing valve 2 generates enough pressure to open the overflow valve on the rod chamber side of the two-way balancing valve 2, and the hydraulic oil in the rod chamber of the cylinder 3 flows back to the oil tank via the two-way balancing valve 2 and the variable amplitude electromagnetic reversing valve 1, and the cylinder 3 is extended.

[0028] When the boom needs to be retracted, DT1 of the boom solenoid reversing valve 1 and DT3 of the control valve 4 are energized, the boom solenoid reversing valve 1 works and reverses, the control valve 4 is closed, and the high-pressure oil enters the rod chamber side of the two-way balancing valve 2, and directly enters the rod chamber of the cylinder 3 through the one-way valve on the rod chamber side. At the same time, the high-pressure oil enters the hydraulic control oil circuit of the two-way balancing valve 2. At this time, the control valve 4 is closed, and the hydraulic control oil circuit of the two-way balancing valve 2 generates enough pressure to open the overflow valve on the rodless chamber side of the two-way balancing valve 2, and the hydraulic oil in the rodless chamber of the cylinder 3 flows back to the oil tank via the two-way balancing valve 2 and the boom solenoid reversing valve 1, and the cylinder 3 retracts.

[0029] After the boom stops, the boom remains stationary, DT1 and DT2 of the boom electromagnetic reversing valve 1 and DT3 of the control valve 4 are all de-energized, the boom electromagnetic reversing valve 1 returns to the middle position, and the cylinder 3 remains stationary. At the same time, the control valve 4 opens, and the hydraulic control oil circuit of the two-way balance valve 2 is depressurized. Even if the high-pressure oil enters the hydraulic control oil circuit, it will directly flow back to the oil tank through the control valve 4, and it is impossible to build up enough pressure to open the two-way balance valve 2, ensuring that the hydraulic oil in the cylinder 3 cannot flow back, and the boom remains stationary.

[0030] When the boom remains stationary, if the boom solenoid directional control valve 1 is stuck and cannot return to the middle position, it is equivalent to that DT1 or DT2 of the boom solenoid directional control valve 1 is energized, but since DT3 of the control valve 4 is de-energized and opened, the pressure is released through the control valve 4, and the two-way balancing valve 2 cannot be opened, ensuring that the hydraulic oil in the cylinder 3 cannot flow back, preventing the boom from falling uncontrollably, thereby ensuring the safety of the system.

[0031] In addition, when the boom remains stationary, DT1 and DT2 of the boom solenoid directional valve 1 and DT3 of the control valve 4 all lose power. If the rodless chamber side of the two-way balancing valve 2 is stuck, the hydraulic oil in the rodless chamber will flow into the two-way balancing valve 2. However, since the middle position of the boom solenoid directional valve 1 adopts an O-type function, the hydraulic oil can only flow back to the oil tank from the damping hole of the valve block, and the boom will slowly fall.

[0032] Furthermore, a pressure sensor 5 is provided for detecting the pressure on the rodless cavity side of the system, and can close the control valve 4 when the continuous pressure exceeds the threshold. Specifically, the pressure sensor 5 is provided on the pipeline between the rodless cavity side of the two-way balancing valve 2 and the variable amplitude electromagnetic reversing valve 1, and the detection threshold of the pressure sensor 5 is a pressure of 1.2MPa for 1s, or a value adjusted according to experimental tests, which is within the protection scope of the present invention.

[0033] When the rodless chamber side of the two-way balancing valve 2 is stuck, causing the boom to fall slowly, the pressure sensor 5 will detect continuous pressure, and DT3 of the control valve 4 will be powered and closed, and the system will alarm, thereby avoiding danger.

[0034] In addition to the above-mentioned boom luffing hydraulic system, a specific embodiment of the present invention also provides a telescopic boom engineering machinery including the above-mentioned boom luffing hydraulic system. For the structures of other parts of the telescopic boom engineering machinery, please refer to the prior art and will not be described in detail herein.

[0035] The boom luffing hydraulic system and telescopic boom engineering machinery provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A boom luffing hydraulic system, comprising an oil pump, an luffing electromagnetic reversing valve (1), a two-way balancing valve (2) and an oil cylinder (3), wherein the oil inlet and the oil return port of the luffing electromagnetic reversing valve (1) are respectively connected to the oil pump and the oil tank, the two working oil ports of the luffing electromagnetic reversing valve (1) are respectively connected to the two inlets of the two-way balancing valve (2), and the two outlets of the two-way balancing valve (2) are respectively connected to the rod chamber and the rodless chamber of the oil cylinder (3), characterized in that: The hydraulic control oil circuit of the two-way balancing valve (2) is connected to the oil tank via the control valve (4); when the boom is luffing, the control valve (4) is closed to maintain the pressure of the hydraulic control oil circuit of the two-way balancing valve (2); when the boom stops luffing, the control valve (4) is opened to connect the hydraulic control oil circuit of the two-way balancing valve (2) to the oil tank to release the pressure; The control valve (4) is specifically a normally open electromagnetic reversing valve. When the boom is changing its length, the normally open electromagnetic reversing valve is energized, and when the boom stops changing its length, the normally open electromagnetic reversing valve is de-energized. The normally open electromagnetic reversing valve is specifically a two-position two-way electromagnetic reversing valve; The two-position two-way electromagnetic reversing valve is arranged at the partial pressure damping position of the two-way balancing valve (2); The variable amplitude electromagnetic reversing valve (1) is specifically an O-type functional electromagnetic valve; The O-type function solenoid valve is specifically an O-type function three-position four-way solenoid reversing valve; It also includes a pressure sensor (5) for detecting the pressure on the rodless cavity side, which can close the control valve (4) when it detects that the continuous pressure exceeds a threshold value.

2. The boom luffing hydraulic system according to claim 1, characterized in that: The pressure sensor (5) is arranged on a pipeline between one side of the bidirectional balancing valve (2) connected to the rodless chamber of the oil cylinder (3) and the variable amplitude electromagnetic reversing valve (1).

3. The boom luffing hydraulic system according to claim 2, characterized in that: The detection threshold of the pressure sensor (5) is a pressure of 1.2 MPa lasting for 1 second.

4. A telescopic boom engineering machinery, characterized in that: It comprises the boom luffing hydraulic system as claimed in any one of claims 1 to 3.

Images