Crane luffing control system and control method thereof

Abstract

The present application relates to the technical field of engineering machinery, and discloses a luffing control system of a crane and a control method thereof, which comprises a luffing oil cylinder, a luffing handle, a hydraulic oil tank, an oil pump, a balance valve, a pressure sensor and a controller; a rodless cavity of the luffing oil cylinder is connected with a C port of the balance valve; an A1 port of the balance valve is connected with the oil pump and the hydraulic oil tank in sequence; the pressure sensor is connected with the rodless cavity of the luffing oil cylinder, is used for detecting the oil pressure P of the rodless cavity of the luffing oil cylinder, and sends the collected oil pressure value P to the controller; the controller is used for receiving a working signal transmitted by the luffing handle and the oil pressure value P monitored by the pressure sensor in real time, and realizes real-time control of the oil pump displacement and the balance valve opening degree according to a preset control strategy. The present application has the beneficial effects that real-time and accurate control of the balance valve opening degree in the luffing falling process is realized, the stability and safety of the luffing falling are improved, and the luffing efficiency of the crane is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering machinery, and relates to a crane luffing control system and a control method thereof, in particular to a crane luffing and falling control system and a control method thereof. BACKGROUND

[0002] The luffing balance valve is generally installed in the rodless cavity of the luffing cylinder, is used for load holding, and enables the luffing cylinder to be locked at any position, and meanwhile, the speed of luffing and falling can be controlled by changing the opening size of the luffing balance valve.

[0003] The crane is an important equipment widely used in engineering construction, and the superstructure of the crane mainly includes lifting, telescoping, luffing, slewing and other actions, in which the luffing refers to the rotary motion of the crane boom around the rear hinge point shaft of the slewing ring under the driving action of the cylinder, so as to realize the change of the boom angle.

[0004] The luffing mechanism hydraulic system of the crane mainly includes a luffing cylinder, a balance valve, a pump and a control valve, in which the luffing cylinder drives the boom to rise or fall by its telescoping; the balance valve is generally installed in the rodless cavity of the luffing cylinder, is used for load holding, and enables the luffing cylinder to be locked at any position, and meanwhile, the speed of luffing and falling is controlled by using the reverse opening control system of the balance valve; the pump is used to provide a pressure oil source; and the control valve is used to control the oil inlet and return of the cylinder.

[0005] At present, there are two ways for luffing and falling, i.e., power luffing and falling control and gravity luffing and falling control, and the hydraulic principles of the two control modes are shown in Figure 1 and Figure 2 As shown in Figure 1 , the luffing control mode of power luffing and falling is adopted, in which when the luffing and falling action is performed, the pressure oil punched by the oil pump (not shown in the figure) enters the rod cavity and the control port of the balance valve 2, the pressure oil is input into the rod cavity of the luffing cylinder 1 by the oil pump to pressurize and reverse open the balance valve 2 (i.e., when the pressure of the rod cavity of the luffing cylinder 1 is increased to be sufficient to open the balance valve 2), and the luffing and falling is realized. As shown in Figure 2 , the luffing control mode of gravity luffing and falling is adopted, in which when the luffing and falling action is performed, the pilot pressure oil enters the control port of the balance valve 2 to reverse open the balance valve 2, and the boom can realize luffing and falling under the action of its own gravity and the gravity of the heavy object.

[0006] Although the above two control modes can realize amplitude falling, for the system adopting power falling amplitude control mode, since a stable external oil source is not used to control the balance valve, it is more sensitive to load changes, and the response characteristics of the balance valve and its matching with the system are required to be higher, and slight deviation will lead to unstable amplitude falling, such as jitter; in addition, when the amplitude falling is performed in this control mode, the operator needs to constantly adjust the control handle or the throttle to control the amplitude falling speed, and the stability and safety are poor. For the system adopting gravity falling amplitude control mode, since a stable pressure oil source is used to control the balance valve, the opening of the balance valve is not affected by the load change, but when the control pressure is constant, the boom angle and the weight of the load have a greater impact on the amplitude falling speed, and the amplitude falling speed is uncontrollable, which requires the operator to accurately control, and when the load is empty or the boom angle is large, the amplitude speed is slow, which affects the work efficiency. SUMMARY

[0007] In view of the problems of unstable amplitude falling and uncontrollable speed in the existing amplitude falling control system, the present application provides a crane amplitude control system and a control method thereof, which realizes real-time and accurate control of the opening of the balance valve during amplitude falling, improves the stability and safety of amplitude falling, and further improves the efficiency of crane amplitude.

[0008] To achieve the above object, the present application provides the following technical scheme:

[0009] In a first aspect, a crane amplitude control system includes an amplitude cylinder, an amplitude handle, a hydraulic oil tank, an oil pump, a balance valve, a pressure sensor, and a controller. The rodless cavity of the amplitude cylinder is connected to the C port of the balance valve. The A1 port of the balance valve is connected to the oil pump and the hydraulic oil tank in sequence. The pressure sensor is connected to the rodless cavity of the amplitude cylinder for detecting the oil pressure P of the rodless cavity of the amplitude cylinder and sending the collected oil pressure value P to the controller. The controller is electrically connected to the amplitude handle, the oil pump, the balance valve, and the pressure sensor for receiving the working signal transmitted by the amplitude handle and the real-time monitored oil pressure value P by the pressure sensor, and realizing real-time control of the oil pump displacement and the balance valve opening according to the preset control strategy.

[0010] In combination with the first aspect, further, the balance valve is an electrically controlled balance valve.

[0011] In combination with the first aspect, further, the balance valve comprises an electric proportional pressure reducing valve, a dynamic balance valve and an overflow valve; the opening degree of the dynamic balance valve is controlled by controlling the current value of the electric proportional pressure reducing valve; the electric proportional pressure reducing valve is a two-position three-way electric proportional pressure reducing valve, when the control end Y1 of the electric proportional pressure reducing valve is not electrified, it is in the lower position, the leakage port is connected, and the balance valve is not opened; when the control end Y1 of the electric proportional pressure reducing valve is electrified, it is switched to the upper position, the constant pressure pilot oil port X1 is connected with the pilot cavity of the dynamic balance valve through the electric proportional pressure reducing valve, and the balance valve is opened; the oil inlet of the overflow valve is connected with the rodless cavity of the luffing cylinder, and the overflow port is connected with the oil tank; the overflow valve is arranged to prevent the pressure of the rodless cavity of the luffing cylinder from being too high, and has a protection effect.

[0012] In combination with the first aspect, further, a torque limiter can be selected to replace the controller.

[0013] The second aspect is a control method of a luffing control system of a crane, which adopts the control system, and comprises the following steps:

[0014] Step S1: the luffing handle is controlled to luff and fall, and the luffing handle sends a working signal to the controller;

[0015] Step S2: the pressure sensor sends the pressure value P of the rodless cavity of the luffing cylinder to the controller;

[0016] Step S3: the controller receives the pressure value P and compares the pressure value P with the preset pressure value in the preset control strategy;

[0017] Step S4: according to the comparison result of the pressure value and the preset control strategy, the controller automatically selects the corresponding luffing and falling mode in the corresponding control strategy, and controls the oil pump displacement and the maximum opening degree of the balance valve.

[0018] In combination with the second aspect, further, the luffing and falling mode comprises a luffing and power falling mode and a luffing and gravity falling mode.

[0019] In combination with the second aspect, further, in the step S4, when the controller automatically selects the luffing and power falling mode, the oil pump displacement is controlled to be associated with the pressure of the rodless cavity of the luffing cylinder in real time, the luffing handle is controlled to control the opening degree of the balance valve in real time, and the controller does not limit the maximum opening degree of the balance valve; when the controller automatically selects the luffing and gravity falling mode, the oil pump displacement is controlled to be 0, the luffing handle is controlled to control the opening degree of the balance valve, and the maximum opening degree of the balance valve is associated with the pressure of the rodless cavity of the luffing cylinder.

[0020] In combination with the second aspect, further, the specific steps of the preset control strategy in the step S4 are as follows:

[0021] When the controller detects that the amplitude cylinder rodless cavity pressure value P≤P1, the controller automatically selects the amplitude power falling mode, and then detects whether the engine gives a throttle signal. If no throttle signal is given, the oil pump is started and the oil pump displacement is kept at V1, and the maximum opening of the balance valve is not limited. If a throttle signal is given, the oil pump displacement V is set according to a certain coefficient proportion between the oil pump displacement V and the engine speed, and the maximum opening of the balance valve is not limited.

[0022] When the controller detects that the amplitude cylinder rodless cavity pressure P≤P2, the controller automatically selects the amplitude power falling mode, and then detects whether the engine gives a throttle signal. If no throttle signal is given, the oil pump displacement V is controlled according to the set program, and the maximum opening of the balance valve is not limited. If a throttle signal is given, the oil pump displacement V is set according to a certain coefficient proportion between the oil pump displacement V and the engine speed, and the maximum opening of the balance valve is not limited.

[0023] When the controller detects that the amplitude cylinder rodless cavity pressure P≤P3, the controller automatically selects the amplitude gravity falling mode, and keeps the oil pump displacement at 0, and the maximum opening of the balance valve is not limited.

[0024] When the controller detects that the amplitude cylinder rodless cavity pressure P≤P4, the controller automatically selects the amplitude gravity falling mode, keeps the oil pump displacement at 0, and controls the maximum opening K of the balance valve according to the set program.

[0025] When the controller detects that the amplitude cylinder rodless cavity pressure P>P4, the controller automatically selects the amplitude gravity falling mode, keeps the oil pump displacement at 0, and controls the maximum opening of the balance valve to K1, which is the maximum opening value of the balance valve itself.

[0026] In combination with the second aspect, further, in the same working condition, the above-mentioned pressures P1

[0027] In combination with the second aspect, further, the set program for controlling the oil pump displacement is: oil pump displacement V=V1(P-P2) / (P1-P2).

[0028] In combination with the second aspect, further, the set program for controlling the maximum opening K of the balance valve is: control the maximum opening K of the balance valve=(P-P3)(1-K1) / (P3-P4)+1.

[0029] Compared with the prior art, the crane amplitude control system and the control method thereof provided by the present application have the following beneficial effects:

[0030] (1) The control system of the present application realizes real-time accurate control of the balance valve opening degree in the luffing-down process, improves the stability and safety of luffing-down; in order to further improve the efficiency of the crane luffing, the preset control strategy is used to realize accurate control of the balance valve opening degree in the luffing-down process, and further improve the efficiency and stability of luffing-down.

[0031] (2)) The control method of the present application combines the advantages of power down and gravity down, mainly applied in the luffing mechanism, through the preset control strategy, the pressure of the rodless cavity of the luffing cylinder is detected in real time to realize automatic judgment of the luffing-down mode, and the control curve of the oil pump displacement and the balance valve opening degree is associated with the pressure of the rodless cavity of the luffing cylinder in real time, realizing real-time accurate control of the balance valve opening degree and the luffing-down speed, improving the stability, safety and efficiency of luffing-down, and improving the efficiency of crane operation. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a hydraulic principle diagram of the power down luffing control mode in the prior art, wherein 1 is a luffing cylinder, and 2 is a balance valve;

[0033] Figure 2 It is a hydraulic principle diagram of the gravity down luffing control mode in the prior art, wherein 1 is a luffing cylinder, and 2 is a balance valve;

[0034] Figure 3 It is a hydraulic system principle diagram of the luffing-down in the present application;

[0035] Figure 4 It is a flow chart of the luffing-down control method in the present application.

[0036] The meanings of the reference signs in the drawings are as follows:

[0037] 11-pressure sensor; 12-luffing cylinder; 13-balance valve. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] The relative arrangement of parts and steps, numerical expressions, and values set forth in the examples herein are not intended to limit the scope of the application unless otherwise specifically stated. It is to be understood that the drawings are not necessarily to scale as the dimensions of the parts shown are for the purpose of illustration and description only and can not reflect the actual proportions on the invention. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail but can be assumed by those of ordinary skill in the art to be part of the specification. In all examples shown and discussed herein, any specific value should be interpreted as merely an example and not a limitation. Thus, other examples of the example embodiments can include different values. It is noted that like numbers and letters refer to like elements throughout the several views of the drawings and as such, discussion of the same will not be repeated herein.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application.

[0041] As shown in Figure 3 The crane luffing control system of the present application includes a luffing cylinder 12, a luffing handle, a hydraulic oil tank, an oil pump, a balance valve 13, a pressure sensor 11 and a controller; the rodless cavity of the luffing cylinder 12 is connected with the C port of the balance valve 13; the A1 port of the balance valve 13 is connected with the oil pump and the hydraulic oil tank in turn; the pressure sensor 11 is connected with the rodless cavity of the luffing cylinder 12 for detecting the oil pressure P of the rodless cavity of the luffing cylinder 12 and sending the collected oil pressure value P to the controller; the controller is electrically connected with the luffing handle, the oil pump, the balance valve 13 and the pressure sensor 11 for receiving the working signal transmitted by the luffing handle and the oil pressure value P monitored by the pressure sensor in real time, and realizing real-time control of the oil pump displacement and the opening of the balance valve 13 according to the preset control strategy.

[0042] In one specific embodiment of the present embodiment, the balance valve 13 is an electrically controlled balance valve, including an electric proportional pressure reducing valve, a dynamic balance valve, and an overflow valve; the opening degree of the dynamic balance valve is controlled by controlling the current value of the electric proportional pressure reducing valve; the electric proportional pressure reducing valve is a two-position three-way electric proportional pressure reducing valve, when the control end Y1 of the electric proportional pressure reducing valve is not electrified, it is in the lower position, the leakage port is connected, and the balance valve is not opened; when the control end Y1 of the electric proportional pressure reducing valve is electrified, it is switched to the upper position, the constant pressure pilot oil port X1 is connected with the pilot cavity of the dynamic balance valve through the electric proportional pressure reducing valve, and the balance valve 13 is opened; the oil inlet of the overflow valve is connected with the rodless cavity of the luffing cylinder 12, and the overflow port is connected with the oil tank; the overflow valve is provided to prevent the pressure of the rodless cavity of the luffing cylinder 12 from being too high, and has a protection effect.

[0043] In one specific embodiment of the present embodiment, a torque limiter can be selected to replace the controller.

[0044] As shown in Figure 4 The control method of the present application adopts the above-mentioned control system and comprises the following steps:

[0045] Step S1: The luffing handle is operated to perform luffing and falling, and the luffing handle sends a working signal to the controller;

[0046] Step S2: The pressure sensor sends the pressure value P of the rodless cavity of the luffing cylinder 12 to the controller;

[0047] Step S3: The controller receives the pressure value P and compares the pressure value P with the preset pressure value in the preset control strategy;

[0048] Step S4: According to the comparison result of the pressure value and the preset control strategy, the controller automatically selects the corresponding luffing and falling mode in the corresponding control strategy, and controls the oil pump displacement and the maximum opening degree of the balance valve 13.

[0049] In one specific embodiment of the present embodiment, the luffing and falling mode includes a luffing power falling mode and a luffing gravity falling mode.

[0050] In one specific embodiment of the present embodiment, the preset control strategy in step S4 is that when the controller automatically selects the luffing power falling mode, the oil pump displacement is controlled to be associated with the pressure of the rodless cavity of the luffing cylinder 12 in real time, the luffing handle is operated to control the opening degree of the balance valve 13 in real time, and the controller does not limit the maximum opening degree of the balance valve 13; when the controller automatically selects the luffing gravity falling mode, the oil pump displacement is controlled to be 0, the luffing handle is operated to control the opening degree of the balance valve 13, and the maximum opening degree of the balance valve 13 is associated with the pressure of the rodless cavity of the luffing cylinder 12.

[0051] In one specific embodiment of the present embodiment, the specific steps of the preset control strategy in step S4 are:

[0052] When the controller detects that the rodless chamber pressure value P of the luffing cylinder 12 is P≤P1, the controller automatically selects the luffing power falling mode, and then detects whether the engine gives a throttle signal. If no throttle signal is given, the oil pump is started and the oil pump displacement is kept at V1, and the maximum opening of the balance valve 13 is not limited. If a throttle signal is given, the oil pump displacement V is set according to a certain coefficient proportion between the oil pump displacement V and the engine speed, and the maximum opening of the balance valve 13 is not limited.

[0053] When the controller detects that the rodless chamber pressure P of the luffing cylinder 12 is P≤P2, the controller automatically selects the luffing power falling mode, and then detects whether the engine gives a throttle signal. If no throttle signal is given, the oil pump displacement V is controlled according to a set program, and the maximum opening of the balance valve 13 is not limited. If a throttle signal is given, the oil pump displacement V is set according to a certain coefficient proportion between the oil pump displacement V and the engine speed, and the maximum opening of the balance valve 13 is not limited.

[0054] When the controller detects that the rodless chamber pressure P of the luffing cylinder 12 is P≤P3, the controller automatically selects the luffing gravity falling mode, and keeps the oil pump displacement at 0, and the maximum opening of the balance valve 13 is not limited.

[0055] When the controller detects that the rodless chamber pressure P of the luffing cylinder 12 is P≤P4, the controller automatically selects the luffing gravity falling mode, keeps the oil pump displacement at 0, and controls the maximum opening K of the balance valve 13 according to a set program.

[0056] When the controller detects that the rodless chamber pressure P of the luffing cylinder 12 is P>P4, the controller automatically selects the luffing gravity falling mode, keeps the oil pump displacement at 0, and controls the maximum opening of the balance valve 13 to K1, which is the maximum opening value of the balance valve 13 itself.

[0057] In one specific embodiment of the present embodiment, the above pressures P1

[0058] In one specific embodiment of the present embodiment, the set program for controlling the oil pump displacement is: oil pump displacement V=V1(P-P2) / (P1-P2).

[0059] In one specific embodiment of the present embodiment, the set program for controlling the maximum opening K of the balance valve 13 is: control the maximum opening K of the balance valve 13=(P-P3)(1-K1) / (P3-P4)+1.

[0060] It has to be noted that, in the present application, the terms "comprising", "including", and "having" should be interpreted as specifying the presence of the stated features but not precluding the presence of one or more additional features. It should also be noted that, in the description of the application given above, any reference signs do not preclude the presence of more than one element or structure bearing the same reference sign, with different reference signs being used where appropriate. Furthermore, the conjunction "or" is used herein in the inclusive sense, i.e. the meaning of "and / or", unless specifically indicated otherwise.

[0061] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, alternatives, and variations can be made in the embodiments without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents.

Claims

1. A control method of a crane luffing control system, characterized by, The method comprises the following steps: Step S1: operating the amplitude-changing handle to perform amplitude-changing falling, and the amplitude-changing handle sends a working signal to the controller; Step S2: the pressure sensor sends the pressure value P of the rodless cavity of the amplitude-changing cylinder to the controller; Step S3: the controller receives the pressure value P and compares the pressure value P with a preset pressure value in a preset control strategy; Step S4: according to the comparison result of the pressure value P and the preset control strategy, the controller automatically selects a corresponding amplitude-changing falling mode in the corresponding control strategy and controls the oil pump displacement and the maximum opening of the balance valve; the amplitude-changing falling mode comprises an amplitude-changing power falling mode and an amplitude-changing gravity falling mode; The step S4 is specifically as follows: When the controller detects that the pressure value P of the rodless cavity of the amplitude-changing cylinder is less than or equal to P1, the controller automatically selects the amplitude-changing power falling mode, then detects whether the engine gives a throttle signal, if no throttle signal is given, the oil pump is started and the oil pump displacement is kept as V1, and the maximum opening of the balance valve is not limited; if the throttle signal is given, the oil pump displacement V is set according to a certain coefficient proportion between the oil pump displacement V and the engine speed, and the maximum opening of the balance valve is not limited; When the controller detects that the pressure value P of the rodless cavity of the amplitude-changing cylinder is less than or equal to P2, the controller automatically selects the amplitude-changing power falling mode, then detects whether the engine gives a throttle signal, if no throttle signal is given, the oil pump displacement V is controlled according to a set program, and the maximum opening of the balance valve is not limited; if the throttle signal is given, the oil pump displacement V is set according to a certain coefficient proportion between the oil pump displacement V and the engine speed, and the maximum opening of the balance valve is not limited; When the controller detects that the pressure value P of the rodless cavity of the amplitude-changing cylinder is less than or equal to P3, the controller automatically selects the amplitude-changing gravity falling mode, the oil pump displacement is kept as 0, and the maximum opening of the balance valve is not limited; When the controller detects that the pressure value P of the rodless cavity of the amplitude-changing cylinder is less than or equal to P4, the controller automatically selects the amplitude-changing gravity falling mode, the oil pump displacement is kept as 0, and the maximum opening K of the balance valve is controlled according to a set program; When the controller detects that the pressure value P of the rodless cavity of the amplitude-changing cylinder is greater than P4, the controller automatically selects the amplitude-changing gravity falling mode, the oil pump displacement is kept as 0, and the maximum opening of the balance valve is controlled as K1, K1 being the maximum opening value of the balance valve itself; The pressure values P1, P2, P3 and P4 are obtained according to the amplitude angle; The set program for controlling the oil pump displacement V is: oil pump displacement V=V1(P-P2) / (P1-P2); The set program for controlling the maximum opening K of the balance valve is: maximum opening K of the balance valve=(P-P3)(1-K1) / (P3-P4)+1.

2. A control method of a crane luffing control system according to claim 1, characterized in that: The control system comprises a luffing oil cylinder, a luffing handle, a hydraulic oil tank, an oil pump, a balance valve, a pressure sensor and a controller; the rodless cavity of the luffing oil cylinder is connected with the C port of the balance valve; the A1 port of the balance valve is connected with the oil pump and the hydraulic oil tank in sequence; the pressure sensor is connected with the rodless cavity of the luffing oil cylinder, used for detecting the pressure value P of the rodless cavity of the luffing oil cylinder and sending the collected pressure value P to the controller; the controller is electrically connected with the luffing handle, the oil pump, the balance valve and the pressure sensor, used for receiving the working signal transmitted by the luffing handle and the pressure value P monitored by the pressure sensor in real time, and realizing real-time control of the oil pump displacement and the opening degree of the balance valve according to a preset control strategy; The preset control strategy is that when the controller automatically selects the luffing power falling mode, the oil pump displacement is controlled to be associated with the pressure of the rodless cavity of the luffing oil cylinder in real time, the luffing handle is controlled to control the opening degree of the balance valve in real time, and the controller does not limit the maximum opening degree of the balance valve; when the controller automatically selects the luffing gravity falling mode, the oil pump displacement is controlled to be 0, the luffing handle is controlled to control the opening degree of the balance valve, and the maximum opening degree of the balance valve is associated with the pressure of the rodless cavity of the luffing oil cylinder.

3. A control method of a crane luffing control system according to claim 2, characterized in that: The balance valve is an electric control balance valve.

4. A control method of a crane luffing control system according to claim 3, characterized in that: The balance valve comprises an electric proportional pressure reducing valve, a dynamic balance valve and an overflow valve; the opening degree of the dynamic balance valve is controlled by controlling the current value of the electric proportional pressure reducing valve; the electric proportional pressure reducing valve is a two-position three-way electric proportional pressure reducing valve, when the control end Y1 of the electric proportional pressure reducing valve is not electrified, the balance valve is not opened; when the control end Y1 of the electric proportional pressure reducing valve is electrified, the balance valve is opened; the inlet of the overflow valve is connected with the rodless cavity of the luffing oil cylinder, and the overflow port is connected with the oil tank; the overflow valve is used for preventing the pressure of the rodless cavity of the luffing oil cylinder from being too high, and plays a protection role.

5. A control method of a crane luffing control system according to claim 2, characterized in that: The torque limiter can be selected to replace the controller.

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