A new type of luffing system

Abstract

The present invention discloses a novel amplitude-changing system, comprising a main pump, a pilot pump, a main valve, a pilot handle, an amplitude-changing balancing valve and an amplitude-changing oil cylinder connected in sequence; the main valve is provided with a main reversing valve, a compensation valve, an overflow valve, a first reversing valve and a second reversing valve. The present invention can increase the rotation speed according to the speed requirement when performing the amplitude-changing falling action, thus solving the problem of limited speed regulation range. Users can set the idle current and the maximum current at high speed, as well as the current value change slope, etc. according to their operating habits, which is more humane. Different idle currents can be set in the factory program for different products to meet the requirements of different product ranges and realize the standardization of the amplitude-changing balancing valve.

Description

Technical Field

[0001] The present invention relates to a luffing system of a truck crane, and in particular to a novel luffing system. Background Art

[0002] Truck cranes can be categorized by their control method into mechanical lever operation, pilot handle operation, and electric control handle operation. Pilot handle operation is widely used in small and medium-sized cranes. The principle behind pilot handle operation is that a pilot pump provides pilot hydraulic oil, which controls the direction of the main valve stem through the pilot handle, pilot valve, or main valve integrated solenoid valve.

[0003] The hydraulic components of a truck crane's luffing system typically include a main valve and a luffing counterbalance valve. The main valve is a directional valve that controls the luffing movement, while the luffing counterbalance valve is a key hydraulic component that maintains the boom's luffing angle. During the luffing process, the counterbalance valve must be open. Luffing can be performed by power or gravity. Truck cranes operated by a pilot handle typically use gravity.

[0004] In existing technical solutions, the upper vehicle hydraulic system is controlled by a pilot handle, with pilot oil controlling the reversal of the main valve stem. The luffing counterbalance valve is a pilot-operated type. During luffing, the pilot oil simultaneously controls the reversal of the main valve stem and opens the luffing counterbalance valve, allowing the luffing to descend through gravity. The engine speed has no effect on the luffing speed. A two-position, three-way solenoid reversing valve is installed in the luffing pilot control oil circuit. This solenoid reversing valve is an on-off solenoid valve. When energized, it operates, and when de-energized, it unloads.

[0005] However, since the luffing valve stem usually adopts gravity drop valve stem, the engine speed has no effect on the luffing drop speed, and the speed adjustment range of the handle is relatively limited. Therefore, the luffing drop speed cannot meet the needs of different users and different products, resulting in the following two deficiencies:

[0006] 1. Different specifications and models of luffing balancing valves are required for products of different tonnage levels to ensure that the luffing speed is within the appropriate range, resulting in a wide variety of specifications and models of luffing balancing valves and difficulty in standardization. 2. Different users of the same product may have different requirements for luffing speed, and existing technology cannot meet these needs, often requiring manual adjustment of the luffing balancing valve. Summary of the Invention

[0007] Purpose of the invention: In view of the shortcomings and defects of the existing technology, the present invention provides a new type of amplitude adjustment system to solve the problems in the existing technology that the amplitude adjustment speed range is limited, the speed adjustment of the amplitude adjustment balancing valve is relatively complicated, and the unified amplitude adjustment balancing valve cannot meet the needs of different users and different products.

[0008] Technical solution: A new type of luffing system of the present invention is characterized by: comprising a main pump, a pilot pump, a main valve, a pilot handle, an luffing balancing valve and an luffing cylinder connected in sequence; the main valve is provided with a main reversing valve, a compensation valve, a relief valve, a first reversing valve and a second reversing valve.

[0009] The luffing cylinder comprises a large luffing cylinder chamber and a small luffing cylinder chamber which are arranged up and down.

[0010] The system is connected to the external vehicle accelerator pedal, controller, crane arm and engine.

[0011] Wherein, the first reversing valve adopts a proportional solenoid valve; the second reversing valve adopts a switch solenoid valve.

[0012] Alternatively, the first reversing valve is a proportional pressure reducing valve.

[0013] The system includes the following steps when used:

[0014] 1) The -YA solenoid valve of the second reversing valve is energized. At this time, the second reversing valve is in the right position, and the pilot handle a2 side is opened. The pilot pump provides pilot oil, which pushes the main reversing valve to reversal through the pilot handle and the second reversing valve; the main pump provides high-pressure hydraulic oil, which flows in one direction to the large chamber of the luffing cylinder through the main valve P port, the main reversing valve, the main valve A port and the luffing balance valve; the hydraulic oil in the small chamber of the luffing cylinder returns to the hydraulic oil tank through the main valve B port, the main reversing valve and the main valve T port; the luffing cylinder extends to realize the boom luffing starting action;

[0015] 2) The -YB solenoid valve of the first reversing valve is energized. At this time, the first reversing valve is in the left position, the pilot handle b2 side is open, and the pilot pump provides pilot oil, which pushes the main reversing valve to reverse through the pilot handle and the first reversing valve; the pilot oil flows from the main valve Mb port into the luffing balancing valve X port, the luffing balancing valve opens, and the high-pressure hydraulic oil in the large chamber of the luffing cylinder returns to the hydraulic oil tank through the luffing balancing valve, the main valve A port, the main reversing valve, and the main valve T port; the boom realizes the luffing and falling action by its own gravity, and the luffing cylinder retracts. The high-pressure hydraulic oil provided by the main pump passes through the first reversing valve and the main reversing valve, and then the pressure is reduced to a fixed value through the relief valve to replenish oil to the small chamber of the luffing cylinder;

[0016] 3) The first reversing valve adopts a proportional solenoid valve, which adjusts the valve stem opening according to the current change. When the current increases, the valve stem opening increases, the pilot oil flow increases, and the opening of the main reversing valve and the variable amplitude balancing valve increases, thereby increasing the flow of the variable amplitude main oil circuit and increasing the variable amplitude falling speed;

[0017] 4) When the engine is idling, the control current of the proportional solenoid valve of the first reversing valve is the initial setting value. This initial setting value can be factory-set according to the product tonnage level, and can also be adjusted according to user needs; when the accelerator pedal is operated, the engine speed increases, the control current increases, and the amplitude of the control current increase can also be adjusted according to needs; when the engine speed increases to a certain set value, the control current reaches the upper limit, at this time the main reversing valve and the variable amplitude balancing valve are in the fully open state, and the variable amplitude falling speed reaches the peak value.

[0018] Beneficial Effects: Compared with existing technologies, this invention offers the following significant advantages: During variable-luffing and lowering operations, the speed can be increased based on speed requirements, resolving the issue of limited speed regulation ranges. Users can set idle current, maximum high-speed current, and current ramp according to their operating preferences, providing a more user-friendly experience. Different idle currents can be set in the factory program for different products to meet varying product range requirements, while also enabling standardized variable-luffing balancing valves. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the amplitude variation system of the present invention;

[0020] Figure 2 It is a structural diagram of the variable amplitude system of the prior art;

[0021] In the figure, 1 is the main pump; 2 is the pilot pump; 3 is the main valve; 31 is the main reversing valve; 32 is the compensation valve; 33 is the overflow valve; 34 is the first reversing valve; 35 is the second reversing valve; 4 is the pilot handle; 5 is the boom balancing valve; 6 is the boom cylinder; 61 is the large chamber of the boom cylinder; 62 is the small chamber of the boom cylinder. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0023] Some key terms of the present invention are defined as follows:

[0024] 1. On-off solenoid valve: The control current is a switch quantity, with only two states: energized and de-energized. This corresponds to the opening and closing of the solenoid valve, controlling the valve stem reversal. 2. Proportional solenoid valve: The control current is a variable quantity, and the valve stem reversal and opening degree are controlled by changes in the solenoid valve current. 3. Power-assisted lowering of the boom: The main pump supplies hydraulic oil to the small boom chamber through the main reversing valve. The hydraulic oil pressure retracts the boom cylinder, achieving the boom lowering action. 4. Gravity-assisted lowering of the boom: The large boom chamber is connected to the oil return line through the main reversing valve, and the boom relies on its own gravity to achieve the boom lowering action.

[0025] A novel luffing system comprises a main pump 1, a pilot pump 2, a main valve 3, a pilot handle 4, a luffing balancing valve 5, and a luffing cylinder 6, all connected in sequence. The main valve 3 is equipped with a main reversing valve 31, a compensating valve 32, a relief valve 33, a first reversing valve 34, and a second reversing valve 35. The luffing cylinder 6 comprises a large chamber 61 and a small chamber 62, arranged vertically. The system is connected to the external vehicle accelerator pedal, controller, boom, and engine. The first reversing valve 34 is a proportional solenoid valve or a proportional pressure reducing valve; the second reversing valve 35 is an on-off solenoid valve.

[0026] When in use, the first reversing valve 34 adopts a proportional solenoid valve:

[0027] 1) The -YA solenoid valve of the second reversing valve 35 is energized. At this time, the second reversing valve 35 is in the right position, and the pilot handle 4a2 side is open. The pilot pump 2 provides pilot oil, which pushes the main reversing valve 31 to change direction through the pilot handle 4 and the second reversing valve 35. The main pump 1 provides high-pressure hydraulic oil, which flows in one direction to the large chamber 61 of the luffing cylinder through the main valve 3P port, the main reversing valve 31, the main valve 3A port, and the luffing balance valve 5. The hydraulic oil in the small chamber 62 of the luffing cylinder returns to the hydraulic oil tank through the main valve 3B port, the main reversing valve 31, and the main valve 3T port. The luffing cylinder 6 extends, realizing the boom luffing start action.

[0028] 2) The -YB solenoid valve of the first reversing valve 34 is energized. At this time, the first reversing valve 34 is in the left position, the pilot handle 4b2 side is open, and the pilot pump 2 provides pilot oil, which pushes the main reversing valve 31 to reverse through the pilot handle 4 and the first reversing valve 34; the pilot oil flows from the main valve 3Ma port into the luffing balancing valve 5X port, the luffing balancing valve 5 is opened, and the high-pressure hydraulic oil in the large chamber 61 of the luffing cylinder returns to the hydraulic oil tank through the luffing balancing valve 5, the main valve 3A port, the main reversing valve 31, and the main valve 3T port; the boom realizes the luffing and falling action by its own gravity, and the luffing cylinder 6 retracts. The high-pressure hydraulic oil provided by the main pump 1 passes through the first reversing valve 34 and the main reversing valve 31, and then through the relief valve 33 to reduce the pressure to a fixed value, so as to replenish oil to the small chamber 62 of the luffing cylinder;

[0029] 3) The first reversing valve 34 uses a proportional solenoid valve, which adjusts the valve stem opening according to the current change. When the current increases, the valve stem opening increases, the pilot oil flow increases, and the opening of the main reversing valve 31 and the variable amplitude balancing valve 5 increases. This increases the flow rate of the variable amplitude main oil circuit and increases the variable amplitude falling speed.

[0030] 4) When the engine is idling, the control current of the proportional solenoid valve of the first reversing valve 34 is at the initial set value; when the accelerator pedal is operated, the engine speed increases and the control current increases; when the engine speed increases to a certain set value, the control current reaches the upper limit, at which time the main reversing valve 31 and the variable amplitude balancing valve 5 are in the fully open state, and the variable amplitude falling speed reaches the peak value.

[0031] Furthermore, when used in electronically controlled handle-operated products, the opening of the electronically controlled balancing valve can be adjusted directly according to changes in engine speed.

[0032] The solenoid valve control current of the variable amplitude drop pilot oil circuit of the present invention adopts the implementation principle of non-fixed value; the control mode of the solenoid valve control current of the variable amplitude drop pilot oil circuit is in direct proportion to the engine speed; the implementation principle that the solenoid valve control current of the variable amplitude drop pilot oil circuit can meet the requirements of different products. When performing the variable amplitude drop action, the present invention can increase the speed according to the speed requirement, solving the problem of limited speed regulation range. Users can set the idle current and the maximum current at high speed and the current value change slope according to their operating habits, which is more humane. Different idle currents can be set in the factory program for different products to meet the requirements of different product ranges and realize the standardization of variable amplitude balancing valves.

Claims

1. A new type of luffing system, characterized by: The invention comprises a main pump (1), a pilot pump (2), a main valve (3), a pilot handle (4), a variable amplitude balance valve (5) and a variable amplitude oil cylinder (6) connected in sequence; the main valve (3) is provided with a main reversing valve (31), a compensation valve (32), a relief valve (33), a first reversing valve (34) and a second reversing valve (35); The new luffing system includes the following steps when used: 1) The -YA solenoid valve of the second reversing valve (35) is energized. At this time, the second reversing valve (35) is in the right position, the pilot handle (4) a2 side is opened, and the pilot pump (2) provides pilot oil, which pushes the main reversing valve (31) to change direction through the pilot handle (4) and the second reversing valve (35); the main pump (1) provides high-pressure hydraulic oil, which flows through the main valve (3) P port, the main reversing valve (31), the main valve (3) A port and the amplitude balance valve (5) in a one-way manner to the large chamber (61) of the amplitude cylinder; the hydraulic oil in the small chamber (62) of the amplitude cylinder returns to the hydraulic oil tank through the main valve (3) B port, the main reversing valve (31) and the main valve (3) T port; the amplitude cylinder (6) extends, realizing the boom amplitude starting action; 2) The -YB solenoid valve of the first reversing valve (34) is energized. At this time, the first reversing valve (34) is in the left position, the pilot handle (4) b2 side is opened, and the pilot pump (2) provides pilot oil, which pushes the main reversing valve (31) to change direction through the pilot handle (4) and the first reversing valve (34); the pilot oil flows from the Mb port of the main valve (3) into the X port of the variable amplitude balance valve (5), and the variable amplitude balance valve (5) is opened. The high-pressure hydraulic oil in the large chamber (61) of the variable amplitude cylinder returns to the hydraulic oil tank through the variable amplitude balance valve (5), the A port of the main valve (3), the main reversing valve (31), and the T port of the main valve (3); the boom realizes the variable amplitude falling action by its own gravity, and the variable amplitude cylinder (6) retracts. The high-pressure hydraulic oil provided by the main pump (1) passes through the first reversing valve (34) and the main reversing valve (31), and then through the overflow valve (33) to reduce the pressure to a fixed value to replenish the oil in the small chamber (62) of the variable amplitude cylinder; 3) The first reversing valve (34) adopts a proportional solenoid valve, which adjusts the valve stem opening according to the change of current. When the current increases, the valve stem opening increases, the pilot oil flow increases, and the opening of the main reversing valve (31) and the variable amplitude balancing valve (5) increases, thereby increasing the flow of the variable amplitude main oil circuit and increasing the variable amplitude falling speed; 4) When the engine is idling, the control current of the proportional solenoid valve of the first reversing valve (34) is at the initial set value; when the accelerator pedal is operated, the engine speed increases and the control current increases; when the engine speed increases to a certain set value, the control current reaches the upper limit, at which time the main reversing valve (31) and the variable amplitude balancing valve (5) are in the fully open state, and the variable amplitude falling speed reaches the peak value.

2. The novel luffing system according to claim 1 is characterized in that: The amplitude-changing oil cylinder (6) comprises an amplitude-changing oil cylinder large chamber (61) and an amplitude-changing oil cylinder small chamber (62) arranged above and below.

3. The novel luffing system according to claim 1 or 2, characterized in that: The system is connected to the external vehicle accelerator pedal, controller, crane arm and engine.

4. The novel luffing system according to claim 1 is characterized in that: The first reversing valve (34) is a proportional solenoid valve; the second reversing valve (35) is a switch solenoid valve.

5. The novel luffing system according to claim 4 is characterized in that: The first reversing valve (34) is a proportional pressure reducing valve.

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