Aerial work equipment and hydraulic luffing system thereof

Abstract

The application discloses a hydraulic amplitude-variable system, which comprises an amplitude-variable multi-way valve group and an amplitude-variable oil cylinder, the amplitude-variable multi-way valve group is internally provided with a rising-amplitude oil outlet and a falling-amplitude oil outlet, and further comprises a balance valve; the rising-amplitude oil outlet of the amplitude-variable multi-way valve group is communicated with a rodless cavity of the amplitude-variable oil cylinder; an oil inlet of the balance valve is communicated with the rodless cavity of the amplitude-variable oil cylinder, an oil outlet of the balance valve is simultaneously communicated with a rod cavity of the amplitude-variable oil cylinder and an oil tank, and a pilot control oil port of the balance valve is communicated with a control oil port of the amplitude-variable multi-way valve group. Thus, during the falling-amplitude process, part of oil in the rodless cavity of the amplitude-variable oil cylinder enters the rod cavity, so that pressure oil is not needed to be additionally led out from the falling-amplitude oil outlet, pressure oil is saved, the oil in the rodless cavity of the amplitude-variable oil cylinder is reused, and thus the energy consumption during the amplitude-variable operation process can be reduced, the oil circuit is simplified, and the cost is reduced. The application further discloses a high-altitude operation equipment, and the beneficial effects are as above.

Description

Technical Field

[0001] This invention relates to the field of engineering equipment technology, and in particular to a hydraulic luffing system. This invention also relates to an aerial work platform. Background Technology

[0002] With the development of engineering technology, all kinds of engineering equipment have been widely used.

[0003] Aerial work platforms, such as aerial work trucks, frequently require their booms to be luffed during operation to change the position of materials being handled. These platforms are equipped with a luffing mechanism, which is the main working mechanism used to change the boom's amplitude—that is, the horizontal distance from the center of the hook (or grab bucket) to the axis of rotation of the platform—to adapt to loading and unloading operations under different conditions. The luffing mechanism primarily operates through a hydraulic luffing system.

[0004] Currently, the hydraulic luffing system of aerial work platforms is usually equipped with a three- or multi-way luffing valve group. This luffing valve group is mainly used to input pressure oil into the rod chamber or rodless chamber of the luffing cylinder, so that the piston rod of the luffing cylinder extends or retracts, thereby driving the main boom of the aerial work platform to perform luffing or lowering movements.

[0005] In existing technologies, the hydraulic luffing system of aerial work platforms specifically includes two types of oil outlets within the luffing multi-way valve assembly: a boom-starting outlet and a boom-ending outlet. The boom-starting outlet connects to the rodless chamber of the luffing cylinder, allowing hydraulic fluid to extend the piston rod and initiate the boom's boom-starting action. Simultaneously, the boom-ending outlet connects to the rod chamber of the luffing cylinder, allowing hydraulic fluid to retract the piston rod and initiate the boom's boom-ending action. However, since both boom-starting and boom-ending actions require separate pressure oil outputs from the luffing multi-way valve assembly, this results in high oil and energy consumption. Furthermore, the separate connections between the boom-starting and boom-ending outlets to the luffing cylinder create a complex hydraulic circuit and increase costs.

[0006] Therefore, how to reduce energy consumption during luffing operations, while simplifying the hydraulic circuit and reducing costs, is a technical problem faced by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a hydraulic luffing system that reduces energy consumption during luffing operations, simplifies the hydraulic circuit, and lowers costs. Another purpose of this invention is to provide an aerial work platform.

[0008] To solve the above-mentioned technical problems, the present invention provides a hydraulic luffing system, including a luffing multi-way valve group and a luffing cylinder. The luffing multi-way valve group is provided with a starting outlet and a falling outlet, and also includes a balance valve.

[0009] The starting oil outlet of the luffing multi-way valve group is connected to the rodless chamber of the luffing cylinder;

[0010] The oil inlet of the balance valve is connected to the rodless chamber of the luffing cylinder, and the oil outlet of the balance valve is simultaneously connected to the rod chamber of the luffing cylinder and the oil tank. The pilot control oil port of the balance valve is connected to the control oil port of the luffing multi-way valve group.

[0011] Preferably, it also includes a one-way valve;

[0012] The one-way valve is connected between the starting oil outlet of the luffing multi-way valve assembly and the rodless chamber of the luffing cylinder, and is used to allow oil to flow unidirectionally from the starting oil outlet to the rodless chamber of the luffing cylinder.

[0013] Preferably, the control end of the balancing valve is connected to the outside atmosphere.

[0014] Preferably, the control end of the balance valve is connected to the oil tank.

[0015] Preferably, the balance valve has a built-in bypass check valve, and the bypass check valve is used to allow the oil to flow back from the oil outlet of the balance valve to its oil inlet in one direction.

[0016] Preferably, it also includes a pressure compensation valve;

[0017] The oil inlet of the pressure compensation valve is connected to the oil outlet of the balance valve. The oil outlet of the pressure compensation valve is also connected to the rod chamber of the luffing cylinder and the oil tank. The first control port of the pressure compensation valve is connected to the rodless chamber of the luffing cylinder. The second control port of the pressure compensation valve is connected to the oil outlet of the balance valve.

[0018] Preferably, it also includes a back pressure valve;

[0019] The back pressure valve is connected between the oil outlet of the pressure compensation valve and the oil tank.

[0020] Preferably, the lubrication outlet of the variable amplitude multi-way valve group is shut off.

[0021] Preferably, it also includes an overflow valve;

[0022] The inlet of the overflow valve is connected to the outlet of the variable amplitude multi-way valve group, and the outlet of the overflow valve is connected to the oil tank.

[0023] The present invention also provides an aerial work platform, including a frame and a hydraulic luffing system disposed on the frame, wherein the hydraulic luffing system is specifically the hydraulic luffing system described in any of the above claims.

[0024] The hydraulic luffing system provided by this invention mainly includes a luffing multi-way valve assembly, a luffing cylinder, and a balance valve. The luffing multi-way valve assembly has a starting outlet and a ending outlet, primarily used to supply pressurized oil to the luffing cylinder and control oil to the balance valve. The luffing cylinder is the actuator, mainly used to realize the luffing and ending movements of the aerial work platform's main boom through the extension and retraction of the piston rod. The rodless chamber of the luffing cylinder is connected to the starting outlet of the luffing multi-way valve assembly. The balance valve is specifically connected between the rodless chamber of the luffing cylinder and the oil tank, mainly serving to maintain load and throttle flow. The inlet of the balance valve is connected to the rodless chamber of the luffing cylinder, while the outlet of the balance valve is connected to both the rod chamber of the luffing cylinder and the oil tank. Importantly, a pilot control valve is provided inside the balance valve, and the pilot control port of the balance valve is connected to the control port (or control end) of the luffing multi-way valve group, so that the control oil in the control port of the luffing multi-way valve group can enter the pilot control port of the balance valve, provide pilot control pressure for the balance valve, open the opening of the balance valve, and make the inlet and outlet of the balance valve bidirectionally connected.

[0025] Thus, during the boom-starting process of the aerial work platform, the luffing multi-way valve assembly outputs pressurized oil directly to the rodless chamber of the luffing cylinder through the boom-starting oil outlet, driving the piston rod of the luffing cylinder to gradually extend, thereby realizing the boom-starting action. At the same time, the oil in the rod chamber of the luffing cylinder flows directly back to the oil tank. During the lowering process of the aerial work platform, the luffing multi-way valve assembly no longer outputs pressurized oil to the rod chamber of the luffing cylinder through (and cannot output) the luffing oil outlet. Instead, it generates pilot pressure on the pilot control port of the balance valve through the control port, causing the balance valve to open and the inlet and outlet ports to be interconnected. At this time, the oil in the rodless chamber of the luffing cylinder automatically (and with the assistance of the weight of the boom) flows out into the balance valve. After passing through the inlet and outlet ports of the balance valve, part of it flows directly back to the oil tank, while the other part enters the rod chamber of the luffing cylinder, which is equivalent to the pressurized oil entering the rod chamber of the luffing cylinder, assisting in driving the piston rod to retract, thereby realizing the lowering action of the boom.

[0026] In summary, the hydraulic luffing system provided by this invention, during the lowering process of the aerial work platform, allows some of the oil in the rodless chamber of the luffing cylinder to enter the rod chamber, driving the piston rod to retract. Therefore, it eliminates the need to draw pressure oil from the lowering outlet of the luffing multi-way valve group into the rod chamber of the luffing cylinder during the lowering process, saving pressure oil and enabling the reuse of oil in the rodless chamber of the luffing cylinder, thereby reducing energy consumption during the luffing operation. Compared to existing technologies, it eliminates the need to lay an oil circuit between the lowering outlet of the luffing multi-way valve group and the luffing cylinder; only the opening outlet of the luffing multi-way valve group needs to be maintained, thus simplifying the oil circuit and reducing costs. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a system schematic diagram of a specific embodiment of the present invention.

[0029] Figure 2 for Figure 1 A partial diagram of the upper half of the image.

[0030] Figure 3 for Figure 2 The diagram shows another structural schematic of the balancing valve.

[0031] Figure 4 for Figure 1 A partial diagram of the lower half of the image.

[0032] in, Figure 1 — Figure 4 middle:

[0033] Luffing multi-way valve group—1, Luffing cylinder—2, Balance valve—3, Check valve—4, Pressure compensation valve—5, Back pressure valve—6, Relief valve—7;

[0034] Oil outlet at the start of the stroke -11, oil outlet at the end of the stroke -12;

[0035] Bypass check valve - 31. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Please refer to Figure 1 , Figure 1 This is a system schematic diagram of a specific embodiment of the present invention.

[0038] In one specific embodiment provided by the present invention, the hydraulic luffing system mainly includes a luffing multi-way valve group 1, a luffing cylinder 2, and a balance valve 3.

[0039] The luffing multi-way valve group 1 is equipped with a starting outlet 11 and a falling outlet 12, mainly used to provide pressure oil to the luffing cylinder 2 and control oil to the balance valve 3. Generally, three or more luffing multi-way valve groups 1 are installed in the hydraulic luffing system, and each luffing multi-way valve group 1 includes multiple functional valve components, among which the core components are mainly electro-hydraulic proportional pressure reducing valves, etc.

[0040] The luffing cylinder 2 is the actuator, mainly used to realize the luffing action of the main boom of the aerial work platform by the extension and retraction of the piston rod. The rodless chamber of the luffing cylinder 2 is connected to the luffing outlet 11 of the luffing multi-way valve group 1. The rod chamber of the luffing cylinder 2 will be explained later.

[0041] The balance valve 3 is specifically connected between the rodless chamber of the luffing cylinder 2 and the oil tank, mainly serving the functions of load holding and throttling. The oil inlet of the balance valve 3 is connected to the rodless chamber of the luffing cylinder 2, while the oil outlet of the balance valve 3 is connected to both the rod chamber of the luffing cylinder 2 and the oil tank. Importantly, a pilot control valve is provided inside the balance valve 3, and the pilot control port of the balance valve 3 is connected to the control port (or control end) of the luffing multi-way valve group 1. This allows the control oil in the control port of the luffing multi-way valve group 1 to enter the pilot control port of the balance valve 3, providing pilot control pressure to the balance valve 3, opening the opening of the balance valve 3, and enabling bidirectional flow between the oil inlet and outlet of the balance valve 3. Generally, the greater the pilot pressure provided by the control port of the luffing multi-way valve group 1, the larger the opening of the balance valve 3, and the greater the oil flow through the balance valve 3, which in turn makes the boom lowering speed faster. The specific pilot pressure of the control port of the luffing multi-way valve group 1 needs to be controlled according to the actual situation.

[0042] Thus, during the boom-starting process of the aerial work platform, the luffing multi-way valve group 1 outputs pressurized oil directly to the rodless chamber of the luffing cylinder 2 through the boom-starting oil outlet 11, driving the piston rod of the luffing cylinder 2 to gradually extend, thereby realizing the boom-starting action. At the same time, the oil in the rod chamber of the luffing cylinder 2 flows directly back to the oil tank. During the descent process of the aerial work platform, the luffing multi-way valve group 1 no longer outputs pressurized oil to the rod chamber of the luffing cylinder 2 through (and cannot output) the descent oil outlet 12, but only through the control oil... The pilot pressure generated at the pilot control port of the balance valve 3 causes the balance valve 3 to open and the inlet and outlet ports to communicate with each other. At this time, the oil in the rodless chamber of the luffing cylinder 2 automatically (and with the assistance of the main boom's gravity) flows out into the balance valve 3. After passing through the inlet and outlet ports of the balance valve 3, part of it flows directly back to the oil tank, and the other part enters the rod chamber of the luffing cylinder 2. This is equivalent to the pressurized oil entering the rod chamber of the luffing cylinder 2, which assists in driving the piston rod to retract, thereby realizing the luffing action of the main boom.

[0043] In summary, the hydraulic luffing system provided in this embodiment eliminates the need for additional pressurized oil to be drawn from the luffing outlet 12 of the luffing multi-way valve group 1 into the rod chamber during the luffing process, thus saving pressurized oil and enabling the reuse of the oil in the rodless chamber of the luffing cylinder 2, thereby reducing energy consumption during the luffing operation. Compared to existing technologies, it eliminates the need to lay an oil circuit between the luffing outlet 12 of the luffing multi-way valve group 1 and the luffing cylinder 2; only the oil circuit between the opening outlet 11 of the luffing multi-way valve group 1 and the luffing cylinder 2 needs to be maintained, thus simplifying the oil circuit and reducing costs.

[0044] Considering that during the lowering process of the aerial work platform, the oil in the rodless chamber of the luffing cylinder 2 will flow out, and the rodless chamber of the luffing cylinder 2 is not only connected to the oil inlet of the balance valve 3, but also connected to the luffing outlet 11 of the luffing multi-way valve group 1, in order to prevent the oil in the rodless chamber of the luffing cylinder 2 from flowing back into the luffing multi-way valve group 1 through the luffing outlet 11, a one-way valve 4 is added in this embodiment. Specifically, the one-way valve 4 is connected between the starting outlet 11 of the luffing multi-way valve group 1 and the rodless chamber of the luffing cylinder 2, and the one-way flow direction is from the starting outlet 11 of the luffing multi-way valve group 1 to the rodless chamber of the luffing cylinder 2. That is, oil is only allowed to flow from the starting outlet 11 of the luffing multi-way valve group 1 to the rodless chamber of the luffing cylinder 2 in one direction, and the oil is not allowed to flow in the reverse direction. In this way, the oil in the rodless chamber of the luffing cylinder 2 can be effectively prevented from flowing back to the luffing multi-way valve group 1 during the lowering process of the aerial work platform.

[0045] like Figure 2 As shown, Figure 2for Figure 1 A partial diagram of the upper half of the image.

[0046] In one alternative embodiment of the balance valve 3, the control end (or regulating end) of the balance valve 3 is connected to the outside atmosphere to form an atmospheric balance valve, so that the pressure at the control end of the balance valve 3 is maintained at atmospheric pressure or relative zero pressure, thereby conveniently forming a 1:0 pilot ratio, so that the pilot pressure provided by the control port of the variable amplitude multi-way valve group 1 can directly control the opening size of the balance valve 3, and theoretically it is close to a linear relationship.

[0047] like Figure 3 As shown, Figure 3 for Figure 2 Another structural schematic diagram of the balance valve 3 shown.

[0048] In another optional embodiment of the balance valve 3, the control end (or adjustment end) of the balance valve 3 is connected to the oil tank to form an atmospheric balance valve, so that the pressure at the control end of the balance valve 3 is kept at zero, thereby conveniently forming a 1:0 pilot ratio, so that the pilot pressure provided by the control port of the variable amplitude multi-way valve group 1 can directly control the opening size of the balance valve 3, and theoretically it is close to a linear relationship.

[0049] Furthermore, regardless of the structural variations of the balance valve 3, it is always equipped with a bypass check valve 31. Specifically, this bypass check valve 31 is connected in parallel to the main body of the balance valve 3, with its two ends connected to the inlet and outlet ports of the balance valve 3, respectively. The unidirectional flow direction of the bypass check valve 31 is from the outlet port of the balance valve 3 to its inlet port. With this configuration, when the control port of the luffing multi-way valve group 1 does not provide pilot pressure to the pilot control port of the balance valve 3, the opening of the balance valve 3 remains closed, the inlet and outlet ports are not bidirectionally connected, and the oil in the rodless chamber of the luffing cylinder 2 cannot flow out, thus maintaining the load on the luffing cylinder 2.

[0050] Furthermore, this embodiment also includes a pressure compensation valve 5 (or pressure compensator). The pressure compensation valve 5 is essentially a proportional flow regulating valve, whose main function is to eliminate the pressure difference caused by the load change of the luffing cylinder 2 and ensure the flow rate of oil flowing out of the rodless chamber of the luffing cylinder 2. It is basically only related to the opening size of the balance valve 3, and not related to the load change of the luffing cylinder 2.

[0051] Specifically, the pressure compensation valve 5 has two positions. The inlet and outlet of one position are interconnected, allowing for normal oil flow. The inlet and outlet of the other position are disconnected, effectively halting oil flow. Furthermore, the inlet of the pressure compensation valve 5 is connected to the outlet of the balance valve 3, and the outlet of the pressure compensation valve 5 is simultaneously connected to the rod chamber of the luffing cylinder 2 and the oil tank. In addition, the pressure compensation valve 5 has two control ports. The first control port of the pressure compensation valve 5 is connected to the rodless chamber of the luffing cylinder 2, and the second control port is connected to the outlet of the balance valve 3. With this setup, during the lowering process of the aerial work platform, if the pressure in the rodless chamber of the luffing cylinder 2 suddenly increases, i.e., the load suddenly increases, the oil flow through the pressure compensation valve 5 will be too large. At this time, the control pressure of the first control port of the pressure compensation valve 5 is greater than the control pressure of the first control port, causing the pressure compensation valve 5 to operate in the first position, thereby reducing the current oil flow and preventing a sudden increase in the oil flow into the rod chamber of the luffing cylinder 2. This prevents the main boom from shaking during the lowering process and ensures the stability of the luffing action. The same applies to the case where the pressure in the rodless chamber of the luffing cylinder 2 suddenly decreases, i.e., the load suddenly decreases.

[0052] In addition, during the lowering motion of the aerial work platform, a back pressure valve 6 is added in this embodiment to facilitate the flow of oil from the rodless chamber of the luffing cylinder 2 into the rod chamber. Specifically, the back pressure valve 6 is essentially a one-way valve 4, connected between the outlet of the pressure compensation valve 5 and the oil tank. It is mainly used to create an outlet back pressure before entering the oil tank, so that when the oil flows out of the rodless chamber of the luffing cylinder 2, it needs to overcome a certain pressure to flow back into the oil tank, thus making it easier for the oil to flow into the rod chamber of the luffing cylinder 2.

[0053] like Figure 4 As shown, Figure 4 for Figure 1 A partial diagram of the lower half of the image.

[0054] Considering that during the lowering process of the aerial work platform, this embodiment does not require drawing pressurized oil from the lowering oil outlet 12 within the luffing multi-way valve assembly 1 to the rod chamber of the luffing cylinder 2, the lowering oil outlet 12 of the luffing multi-way valve assembly 1 is in a closed state in this embodiment. Of course, if necessary, the lowering oil outlet 12 of the luffing multi-way valve assembly 1 can be connected to other components.

[0055] Furthermore, considering that although the wringing outlet 12 of the luffing multi-way valve assembly 1 is shut off, the oil in the luffing multi-way valve assembly 1 is prone to being under high pressure during the wringing operation due to the shut-off of the wringing outlet 12, a relief valve 7 is added in this embodiment. Specifically, the inlet of the relief valve 7 is connected to the wringing outlet 12 of the luffing multi-way valve assembly 1, while the outlet of the relief valve 7 is connected to the oil tank. At the same time, the overflow pressure of the relief valve 7 is usually low. With this configuration, when some of the oil in the luffing multi-way valve assembly 1 flows to the wringing outlet 12, it can flow back to the oil tank through the relief valve 7, thereby maintaining the oil pressure in the luffing multi-way valve assembly 1 at a low pressure.

[0056] This embodiment also provides an aerial work platform, which mainly includes a frame and a hydraulic luffing system installed on the frame. The specific details of the hydraulic luffing system are the same as those described above, and will not be repeated here.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulic luffing system, comprising a luffing multi-way valve assembly (1) and a luffing cylinder (2), wherein the luffing multi-way valve assembly (1) is provided with a starting outlet (11) and a falling outlet (12), characterized in that, It also includes a balancing valve (3); The starting oil outlet (11) of the luffing multi-way valve group (1) is connected to the rodless chamber of the luffing cylinder (2); The oil inlet of the balance valve (3) is connected to the rodless chamber of the luffing cylinder (2), and the oil outlet of the balance valve (3) is simultaneously connected to the rod chamber of the luffing cylinder (2) and the oil tank. The pilot control oil port of the balance valve (3) is connected to the control oil port of the luffing multi-way valve group (1). When the boom lowering action of the aerial work equipment is performed, the luffing multi-way valve group (1) generates pilot pressure on the pilot control port of the balance valve (3) through the control port. The opening of the balance valve (3) is opened and the inlet and outlet ports are connected to each other. The oil in the rodless chamber of the luffing cylinder (2) flows out into the balance valve (3) so that some oil enters the rod chamber of the luffing cylinder (2) to realize the boom lowering action. It also includes a pressure compensation valve (5); The inlet of the pressure compensation valve (5) is connected to the outlet of the balance valve (3). The outlet of the pressure compensation valve (5) is simultaneously connected to the rod chamber of the luffing cylinder (2) and the oil tank. The first control port of the pressure compensation valve (5) is connected to the rodless chamber of the luffing cylinder (2). The second control port of the pressure compensation valve (5) is connected to the outlet of the balance valve (3). The lubrication outlet (12) of the variable amplitude multi-way valve group (1) is shut off.

2. The hydraulic luffing system according to claim 1, characterized in that, It also includes a check valve (4); The one-way valve (4) is connected between the starting oil outlet (11) of the luffing multi-way valve group (1) and the rodless chamber of the luffing cylinder (2), and is used to allow the oil to flow unidirectionally from the starting oil outlet (11) to the rodless chamber of the luffing cylinder (2).

3. The hydraulic luffing system according to claim 1, characterized in that, The control end of the balance valve (3) is connected to the outside atmosphere.

4. The hydraulic luffing system according to claim 1, characterized in that, The control end of the balance valve (3) is connected to the oil tank.

5. The hydraulic luffing system according to claim 3 or 4, characterized in that, The balance valve (3) has a built-in bypass check valve (31), and the bypass check valve (31) is used to allow the oil to flow back from the oil outlet of the balance valve (3) to its oil inlet in one direction.

6. The hydraulic luffing system according to claim 5, characterized in that, It also includes a back pressure valve (6); The back pressure valve (6) is connected between the oil outlet of the pressure compensation valve (5) and the oil tank.

7. The hydraulic luffing system according to claim 1, characterized in that, It also includes an overflow valve (7); The oil inlet of the overflow valve (7) is connected to the drooping oil outlet (12) of the variable amplitude multi-way valve group (1), and the oil outlet of the overflow valve (7) is connected to the oil tank.

8. An aerial work platform, comprising a frame and a hydraulic luffing system mounted on the frame, characterized in that, The hydraulic luffing system is specifically the hydraulic luffing system described in any one of claims 1-7.

Images