Hydraulic circuit for lifting load of hoisting equipment

Abstract

The utility model belongs to the field of hydraulic systems, and particularly relates to a hydraulic circuit for a lifting load of hoisting equipment, when the hydraulic circuit operates normally, especially when a first hydraulic pipeline is intact, control pressure applied to a descending brake valve is sufficient to overcome pre-tightening force of an elastic pre-tightening piece; on the contrary, if the first hydraulic pipeline is broken and the pressure in the first hydraulic pipeline is sharply reduced, the pressure of the control end of the descending brake valve is not enough to overcome the pre-tightening force of the elastic pre-tightening piece, at the moment, the valve element of the descending brake valve is switched back to the blocking position, the second hydraulic pipeline is blocked, and the load is prevented from being further reduced; therefore, the load can be safely prevented from being out of control and falling.

Description

Technical Field

[0001] The present application relates to the technical field of hydraulic systems, and in particular to a hydraulic circuit for lifting loads in lifting equipment. Background Art

[0002] On many lifting equipment, the hoisting winch is hydraulically driven. The hydraulic winch is mainly composed of a hydraulic pump, a hydraulic motor (a bidirectional hydraulic motor), a main control valve, a reducer, a capstan, and other parts. The hydraulic motor is connected to the main control valve through a hydraulic pipeline. The main control valve measures the flow of hydraulic oil from the hydraulic pump and determines its delivery direction, thereby determining whether the load is lifted or lowered. When the hydraulic pump is working, the hydraulic oil is transmitted to the hydraulic motor through the hydraulic pipeline, driving the hydraulic motor to rotate. When the hydraulic motor rotates, the reducer drives the capstan to perform the load lifting operation, lifting the load (such as items or equipment) to the required height. In actual application, when the hydraulic pipeline leading to the hydraulic motor breaks, the load will drop uncontrollably, seriously affecting the safety of the equipment. Utility Model Content

[0003] An embodiment of the present application provides a hydraulic circuit for lifting loads in lifting equipment, aiming to prevent the load from falling uncontrollably when a hydraulic line breaks, thereby improving the safety of the equipment.

[0004] To achieve the above objectives, the present application provides a hydraulic circuit for lifting a load in a lifting device, comprising:

[0005] Hydraulic drive unit;

[0006] a first hydraulic pipeline connected to the hydraulic drive device, the first hydraulic pipeline serving as an oil supply pipeline when lowering a load and serving as an oil return pipeline when lifting a load;

[0007] a second hydraulic pipeline connected to the hydraulic drive device, the second hydraulic pipeline serving as an oil return pipeline when lowering a load and serving as an oil supply pipeline when lifting a load;

[0008] a descent brake valve disposed in the second hydraulic pipeline, wherein a valve core of the descent brake valve is pushed by an elastic preload member to a blocking position that prevents hydraulic oil from flowing out through the second hydraulic pipeline, and when a pressure applied to a control end of the descent brake valve exceeds a preload force of the elastic preload member, the valve core of the descent brake valve can be switched to an open position that allows hydraulic oil to flow out through the second hydraulic pipeline; and

[0009] A control valve is arranged in the connecting pipeline between the first hydraulic pipeline and the control end of the descent brake valve, the valve core of the control valve is biased by the biasing device to a blocking position blocking the connecting pipeline, and the pressure of the first hydraulic pipeline is applied to the first control end of the control valve so that the valve core of the control valve can push the biasing device and switch to an open position that connects the connecting pipeline, wherein the opening cross-section of the control valve changes with the pressure applied to the first control end.

[0010] Optionally, the elastic preload member includes a preload spring, and the preload spring acts on one end of the valve core of the descent brake valve relative to the control end.

[0011] Optionally, the control pressure applied to the control end of the descent brake valve is applied to a second control end of the control valve opposite to the first control end.

[0012] Optionally, the biasing means of the control valve comprises a preload spring acting on the second control end.

[0013] Optionally, the force of the preload spring is adjustable.

[0014] Optionally, an additional spring is also included, which is used to offset the preload spring acting on the second control end of the control valve. When the valve core of the control valve is in the open position, the pressure of the first hydraulic pipeline does not act on the first control end, and the pressure of the first hydraulic pipeline acts on the control surface opposite to the additional spring.

[0015] Optionally, the output section of the connecting pipeline between the control valve and the control end of the descent brake valve is connected to the first hydraulic pipeline through a check valve, and the check valve opens in the flow direction from the output section to the first hydraulic pipeline and closes in the opposite flow direction.

[0016] Optionally, a one-way valve is provided in the second hydraulic pipeline in parallel with the descent brake valve, and the one-way valve opens in the flow direction toward the hydraulic drive device and closes in the opposite flow direction.

[0017] Optionally, the hydraulic drive device includes a hydraulic motor.

[0018] The beneficial effect of the hydraulic circuit for lifting loads in lifting equipment provided by the present application is that: compared with the prior art, the hydraulic circuit of the present application has a control valve installed in the connecting pipeline between the control end of the descent brake valve in the first hydraulic pipeline and the second hydraulic pipeline, and the control valve includes a biasing device for biasing the valve core to a blocking position. In the blocking position, the control valve blocks the connecting pipeline, so that the pressure from the first hydraulic pipeline cannot act on the control end of the descent brake valve. The valve core of the control valve can be switched from the blocking position to the open position. In the open position, the control valve opens the connecting pipeline. When the control valve is opened, the pressure from the first hydraulic pipeline acts on the control end of the descent brake valve. When the pressure is large enough (that is, when the pressure exceeds the preload force of the elastic preload member), the valve core of the descent brake valve can be switched from the blocking position to the open position, allowing the hydraulic oil to flow out through the second hydraulic pipeline, thereby reducing the load. In this case, the oil supply pressure of the first hydraulic pipeline serving as the oil supply pipe is applied to the first control end of the control valve during the descent process. When the hydraulic circuit operates normally, especially when the first hydraulic pipeline is intact, the control pressure applied to the descent brake valve is sufficient to overcome the preload force of the elastic preload member; on the contrary, if the first hydraulic pipeline breaks, causing the pressure in the first hydraulic pipeline to drop sharply, the pressure at the control end of the descent brake valve is insufficient to overcome the preload force of the elastic preload member. At this time, the valve core of the descent brake valve switches back to the blocking position, blocking the second hydraulic pipeline to prevent the load from further descending, thereby safely preventing the load from falling out of control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] in:

[0021] Figure 1 This is a schematic diagram showing the principle of a hydraulic circuit for lifting loads in a lifting device according to an embodiment of the present application;

[0022] Figure 2 This is a schematic diagram of the principle of another hydraulic circuit for lifting loads in lifting equipment shown in an embodiment of the present application.

[0023] Description of main component symbols:

[0024] 1. Hydraulic drive device;

[0025] 2. The first hydraulic line;

[0026] 3. Second hydraulic line;

[0027] 4. Lowering brake valve; 41. Control end; 42. Elastic preload member;

[0028] 5. Connecting pipeline; 51. Output section;

[0029] 6. Control valve; 61. First control end; 62. Preload spring; 63. Additional spring; 64. Control surface;

[0030] 7. Check valve;

[0031] 8. One-way valve. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present application. However, the present application may be implemented in many other forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0033] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0036] The embodiment of the present application provides a hydraulic circuit for lifting loads in a lifting device, such as Figure 1-Figure 2As shown, the hydraulic circuit includes a hydraulic drive device 1 (such as a hydraulic motor or winch motor), a first hydraulic pipeline 2, a second hydraulic pipeline 3, a descent brake valve 4, and a control valve 6. The first hydraulic pipeline 2 is connected to the hydraulic drive device 1 and serves as an oil supply pipeline when lowering the load and as an oil return pipeline when lifting the load. The second hydraulic pipeline 3 is connected to the hydraulic drive device 1 and serves as an oil return pipeline when lowering the load and as an oil supply pipeline when lifting the load. The descent brake valve 4 is arranged in the second hydraulic pipeline 3. The valve core of the descent brake valve 4 is pushed by the elastic preload 42 to a blocking position that prevents the hydraulic oil from flowing out of the second hydraulic pipeline 3. When the pressure applied to the control end 41 of the descent brake valve 4 exceeds the preload force of the elastic preload 42, the valve core of the descent brake valve 4 can be switched to an open position to allow the hydraulic oil to flow out of the second hydraulic pipeline 3. The control valve 6 is arranged in the connecting pipeline 5 between the first hydraulic pipeline 2 and the control end 41 of the descent brake valve 4. The valve core of the control valve 6 is biased by the biasing device to a blocking position that blocks the connecting pipeline 5. The pressure of the first hydraulic pipeline 2 is applied to the first control end 61 of the control valve 6 so that the valve core of the control valve 6 can push the biasing device and switch to an open position that connects the connecting pipeline 5, wherein the opening cross-section of the control valve 6 changes with the pressure applied to the first control end 61.

[0037] The control valve 6 releases a variable opening cross section depending on the control pressure applied to its first control end 61. It is understood that the control valve 6 can release a cross section intermediate between the blocked position and the open position. In particular, the control valve 6 can release a continuous transition cross section between the blocked position (zero opening cross section) and the open position (maximum opening cross section).

[0038] Among them, the control valve 6 can be a regulating valve, a pressure control valve, etc., of course, a proportional valve or other valves can also be used, so that continuous conversion can be achieved between the blocking position (i.e., the locking position) and the opening position (i.e., the release position).

[0039] In the present application, a control valve 6 is installed in the connecting line 5 between the control end 41 of the descent brake valve 4 in the first hydraulic line 2 and the second hydraulic line 3 of the hydraulic circuit. The control valve 6 includes a biasing device for biasing the valve core to a blocking position. In the blocking position, the control valve 6 blocks the connecting line 5, so that the pressure from the first hydraulic line 2 cannot act on the control end 41 of the descent brake valve 4. The valve core of the control valve 6 can be switched from the blocking position to the open position. In the open position, the control valve 6 opens the connecting line 5. When the control valve 6 is opened, the pressure from the first hydraulic line 2 acts on the control end 41 of the descent brake valve 4. When the pressure is large enough (that is, when the pressure exceeds the preload force of the elastic preload member 42), the valve core of the descent brake valve 4 can be switched from the blocking position to the open position, allowing the hydraulic oil to flow out through the second hydraulic line 3, thereby reducing the load. In this case, the oil supply pressure of the first hydraulic pipeline 2 serving as the oil supply pipe is applied to the first control end 61 of the control valve 6 during the descent process. When the hydraulic circuit operates normally, especially when the first hydraulic pipeline 2 is intact, the control pressure applied to the descent brake valve 4 is sufficient to overcome the preload force of the elastic preload member 42; on the contrary, if the first hydraulic pipeline 2 breaks, causing the pressure in the first hydraulic pipeline 2 to drop sharply, the pressure at the control end 41 of the descent brake valve 4 is insufficient to overcome the preload force of the elastic preload member 42. At this time, the valve core of the descent brake valve 4 switches back to the blocking position, blocking the second hydraulic pipeline 3 to prevent the load from further descending, thereby safely preventing the load from falling out of control.

[0040] Furthermore, in all applications subject to vibration, it is generally desirable to reduce the damping of the lowering brake valve 4. To avoid the drawbacks of rigid damping with a fixed outlet nozzle, the control valve 6 of the present application provides self-adjusting damping with a variable opening cross-section. The control valve 6 is an automatically adjustable orifice, allowing for a minimum opening cross-section. This enables automatic damping adjustment, resulting in a lowering brake valve 4 with high dynamics, high damping, and low vibration tendency.

[0041] In one embodiment, the descent brake valve 4 can provide a variable opening cross-section based on the pilot pressure applied to its control end 41. In particular, the descent brake valve 4 can provide a continuous transition of the opening cross-section between a blocked position (i.e., a locked position) and an open position (i.e., a released position). Therefore, the descent brake valve 4 can also be a control valve 6, a proportional valve, or the like.

[0042] In one embodiment, if Figure 1-Figure 2 As shown, the elastic preload member 42 in the descending brake valve 4 includes a preload spring, which acts on one end of the valve core of the descending brake valve 4 relative to the control end 41. The preload force of the valve core is provided by the preload spring acting on the end opposite to the control end 41.

[0043] In one embodiment, if Figure 1-Figure 2 As shown, the control pressure applied to the control end 41 of the descent brake valve 4 is applied to a second control end 61 of the control valve 6 opposite the first control end. This can be part of a preload device for the control valve 6. The biasing device of the control valve 6 includes a preload spring 62 acting on the second control end. Preferably, the force of the preload spring 62 is adjustable.

[0044] The biasing device of the control valve 6 can bias the valve spool of the control valve 6 to the blocked position and maintain it in this position when there is no pressure in the first hydraulic line 2. However, as will be described in detail below, it is also conceivable to provide a spring or similar device to offset the biasing device, so that the biasing device does not bias the valve spool to the blocked position when there is no pressure in the first hydraulic line 2, but only works when the pressure increases.

[0045] Therefore, in a specific embodiment, Figure 1-Figure 2 As shown, an additional spring 63 is also included. The additional spring 63 is used to offset the preload spring 62 acting on the second control end of the control valve 6. When the valve core of the control valve 6 is in the open position, the pressure of the first hydraulic pipeline 2 does not act on the first control end 61, and the pressure of the first hydraulic pipeline 2 acts on the control surface 64 opposite to the additional spring 63.

[0046] An additional spring 63 is provided to offset the preload spring 62 acting on the second control end of the control valve 6. This ensures that when the valve core of the control valve 6 is in the open position, there is no pressure from the first hydraulic line 2 on its first control end 61, and the pressure in the first hydraulic line 2 acts on the control surface 64 that offsets the additional spring 63. The additional spring 63 offsets the preload spring 62 of the control valve 6, rendering it inactive at its home position. This means that the control valve 6 is in the open position, i.e., open in the absence of pressure in the first hydraulic line 2. The preload spring 62 of the control valve 6 only becomes effective when the supply pressure in the first hydraulic line 2 exceeds a specified value. The force of the preload spring 62 increases, typically steadily, with increasing supply pressure. This is because the supply pressure in the first hydraulic line 2 contacts the control surface 64, thereby acting on the additional spring 63. Due to the interaction between the additional spring 63 and the preload spring 62, the control valve 6 remains open. This means that the control pressure acting on the lowering brake valve 4 at the first control port 61 increases continuously starting from the supply pressure in the first hydraulic line 2 (eg 15 bar) until it reaches the full value (eg 30 bar).

[0047] In one embodiment, if Figure 1-Figure 2As shown, the output section 51 of the connecting line 5 between the control valve 6 and the control end 41 of the lowering brake valve 4 is connected to the first hydraulic line 2 through the check valve 7, and the check valve 7 opens in the flow direction from the output section 51 to the first hydraulic line 2 and closes in the opposite flow direction.

[0048] A section of connecting line 5 between control valve 6 and control port 41 of lowering brake valve 4 is connected to first hydraulic line 2 via check valve 7. The pilot pressure at control port 41 of lowering brake valve 4 never exceeds the supply pressure in first hydraulic line 2. This also applies to dynamic changes or sudden drops in supply pressure in first hydraulic line 2. Therefore, the safety function of the hydraulic circuit arrangement is guaranteed at all times. The pressure always drops to the pressure level in first hydraulic line 2, so that, in the event of a line rupture, for example, lowering brake valve 4 closes.

[0049] In one embodiment, if Figure 1-Figure 2 As shown, a one-way valve 8 is provided in parallel with the lowering brake valve 4 in the second hydraulic line 3 . The one-way valve 8 opens in the flow direction toward the hydraulic drive device 1 and closes in the opposite flow direction.

[0050] Check valve 8 is installed in a section of second hydraulic line 3 parallel to lowering brake valve 4. It serves as a bypass valve for lowering brake valve 4. During load lowering operation, check valve 8 blocks, preventing accidental bypass of lowering brake valve 4. In load raising mode, when second hydraulic line 3 serves as the oil supply line, check valve 8 opens, preventing lowering brake valve 4 from operating during load raising.

[0051] In summary, combined with Figure 1 and Figure 2 The working principle of the hydraulic circuit is explained as follows:

[0052] like Figure 1As shown, to lift a load, hydraulic oil is pumped through port B via the second hydraulic line 3 to the hydraulic drive 1. The lowering brake valve 4 is in the blocked position and therefore does not participate in the hydraulic oil flow. Hydraulic oil flows from the hydraulic drive 1 back through the first hydraulic line 2 to port A and then to the tank. This allows the load to be lifted without intervention from the lowering brake valve 4 and the control valve 6. To lower a load, hydraulic oil is pumped through port A and the first hydraulic line 2 to the hydraulic drive 1. As long as the lowering brake valve 4 is in the blocked position, hydraulic oil cannot flow from the hydraulic drive 1 to the hydraulic tank via the second hydraulic line 3. The check valve 8 also blocks this flow direction. However, once the preload of the control valve 6 is overcome, the supply pressure in the first hydraulic line 2 contacts the first control port 61 of the control valve 6, causing the control valve 6 to open. The pressure applied by the control valve 6 acts on the control port 41 of the lowering brake valve 4, causing it to switch from the blocked position to the open position. The lowering brake valve 4 can also provide different opening cross sections depending on the pilot pressure applied to the control port 41. Specifically, the descent brake valve 4 can provide a continuous transition of the opening cross section between the blocked position and the open position. Therefore, the descent brake valve 4 can also be a control valve 6 or a proportional valve, for example. Once the descent brake valve 4 is opened, hydraulic oil flows from the hydraulic drive 1 through the descent brake valve 4 to the oil tank, thereby lowering the load. For example, if a circuit breaker occurs in the first hydraulic line 2, the control valve 6 will immediately close, thereby closing the descent brake valve 4. This safely prevents the load from being lowered uncontrollably. The connection via the check valve 7 also prevents the application of an oil supply pressure higher than the supply pressure of the first hydraulic line 2 to the control end 41 of the descent brake valve 4.

[0053] Figure 2 and Figure 1 The hydraulic circuit arrangement shown is basically the same. See the above description. Figure 2 The hydraulic circuit arrangement shown is similar to Figure 1 The circuit arrangements shown differ only in the biasing of the control valve 6. Figure 2 In the example shown, the preload spring 62 of the control valve 6 is offset by the additional spring 63. The oil supply pressure of the first hydraulic line 2 is continuously applied to the control surface 64 that offsets the additional spring 63 through the line. This design means that when there is no pressure in the first hydraulic line 2, the preload spring 62 will be offset by the additional spring 63. Therefore, the control valve 6 is in the open position when there is no pressure in the first hydraulic line 2. Figure 2As shown, in this position, control valve 6 fully opens the connecting line 5 between the first hydraulic line 2 and the control end 41 of the lowering brake valve 4. The control pressure at the control end 41 of the lowering brake valve 4 is adjusted to the insufficient supply pressure in the first hydraulic line 2 via check valve 7, thereby maintaining the lowering brake valve 4 in the blocked position. The supply pressure acting on the first hydraulic line 2 now counteracts the additional spring 63 via control surface 64, allowing the preload spring 62 to maintain its prestressing effect. In this design, the preload pressure required to open the lowering brake valve 4 already exists at the control end 41 of the lowering brake valve 4 before the spring force of the preload spring 62 is exceeded. Therefore, the lowering brake valve 4 can be opened even at a relatively low supply pressure.

[0054] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A hydraulic circuit for lifting loads in lifting equipment, characterized in that: include: Hydraulic drive device (1); a first hydraulic pipeline (2) connected to the hydraulic drive device (1), the first hydraulic pipeline (2) serving as an oil supply pipeline when lowering a load and serving as an oil return pipeline when lifting a load; a second hydraulic pipeline (3) connected to the hydraulic drive device (1), the second hydraulic pipeline (3) serving as an oil return pipeline when lowering a load and serving as an oil supply pipeline when lifting a load; a descent brake valve (4) disposed in the second hydraulic pipeline (3); a valve core of the descent brake valve (4) is pushed by an elastic preload member (42) to a blocking position for preventing hydraulic oil from flowing out through the second hydraulic pipeline (3); and when the pressure applied to the control end (41) of the descent brake valve (4) exceeds the preload force of the elastic preload member (42), the valve core of the descent brake valve (4) can be switched to an open position for allowing hydraulic oil to flow out through the second hydraulic pipeline (3); and A control valve (6) is provided in a connecting line (5) between the first hydraulic line (2) and the control end (41) of the descending brake valve (4); a valve core of the control valve (6) is biased by a biasing device to a blocking position blocking the connecting line (5); the pressure of the first hydraulic line (2) is applied to the first control end (61) of the control valve (6) so that the valve core of the control valve (6) can push against the biasing device and switch to an open position connecting the connecting line (5); wherein the opening cross section of the control valve (6) changes with the pressure applied to the first control end (61).

2. The hydraulic circuit according to claim 1, characterized in that: The elastic preload member (42) comprises a preload spring, and the preload spring acts on one end of the valve core of the descending brake valve (4) relative to the control end (41).

3. The hydraulic circuit according to claim 1, characterized in that The control pressure applied to the control end (41) of the descending brake valve (4) is applied to the second control end of the control valve (6) opposite to the first control end (61).

4. The hydraulic circuit according to claim 3, characterized in that: The biasing means of the control valve (6) comprises a preload spring (62) acting on the second control end.

5. The hydraulic circuit according to claim 4, characterized in that: The acting force of the preload spring (62) is adjustable.

6. The hydraulic circuit according to claim 4 or 5, characterized in that: The invention also includes an additional spring (63), which is used to offset the preload spring (62) acting on the second control end of the control valve (6). When the valve core of the control valve (6) is in the open position, the pressure of the first hydraulic pipeline (2) does not act on the first control end (61), and the pressure of the first hydraulic pipeline (2) acts on the control surface (64) opposite to the additional spring (63).

7. The hydraulic circuit according to claim 1, characterized in that: The output section (51) of the connecting line (5) between the control valve (6) and the control end (41) of the descent brake valve (4) is connected to the first hydraulic line (2) via a check valve (7), and the check valve (7) opens in the flow direction from the output section (51) to the first hydraulic line (2) and closes in the opposite flow direction.

8. The hydraulic circuit according to claim 1, wherein: A one-way valve (8) is provided in the second hydraulic pipeline (3) in parallel with the descending brake valve (4), and the one-way valve (8) opens in the flow direction toward the hydraulic drive device (1) and closes in the opposite flow direction.

9. The hydraulic circuit according to claim 1, characterized in that The hydraulic drive device (1) comprises a hydraulic motor.

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