Scissor forklift hydraulic control system and scissor forklift

Abstract

The utility model relates to the technical field of engineering machinery, in particular to a shear forklift hydraulic control system and a shear forklift. Due to the fact that the walking reversing valve is communicated with the oil tank through the balance valve, hydraulic oil flowing out of the first motor and the second motor flows into the balance valve through the walking reversing valve, and due to the arrangement of the balance valve, it can be guaranteed that the pressure of the hydraulic oil flowing out of the walking reversing valve is adjusted when the shear forklift goes down a slope. Compared with the prior art, the balance valve arranged between the walking reversing valve and the oil tank enables the overall space size of the hydraulic system to be reduced, and an oil way is relatively simple.

Description

Technical Field

[0001] The utility model relates to the technical field of engineering machinery, in particular to a scissor lift truck hydraulic control system and a scissor lift truck. Background Art

[0002] Aerial work vehicles are special vehicles used to transport workers and equipment to the site and perform aerial work. Among them, scissor-type aerial work vehicles are widely used special equipment for aerial work. Its scissor-type mechanical structure makes the lifting platform have higher stability, a wide working platform and a higher load-bearing capacity, which makes the aerial work range larger and suitable for multiple people to work at the same time, and makes the aerial work more efficient and safer.

[0003] At present, the hydraulic control system of the scissor-type aerial work vehicle includes a lifting control oil circuit, a steering control oil circuit, a brake release control oil circuit, a travel control oil circuit, etc. The hydraulic control of the scissor-type aerial work vehicle in the prior art has the following technical defects: the travel control oil circuit has a complex structure and occupies a large space.

[0004] In its travel hydraulic system, two balancing valves are usually set after the travel reversing valve to control the speed of the scissor lift when it is working downhill. However, this solution also brings about the problem that the design of the scissor lift control valve block is complicated and the cost is slightly high. The utility model proposes a single balancing valve design, which simplifies the valve group design and reduces the cost while solving the speed controllability problem in downhill working conditions. Utility Model Content

[0005] The utility model aims to provide a scissor lift truck hydraulic control system and a scissor lift truck, which can reduce the volume of the scissor lift truck hydraulic control system and reduce the cost while ensuring that the speed of the scissor lift truck is controllable when the scissor lift truck is in downhill working conditions.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] A hydraulic control system for a scissor lift truck includes an oil tank, a travel reversing valve, a series-parallel switching valve, a first motor, a second motor and a balancing valve. Each working oil port of the travel reversing valve is directly connected to the working oil ports of the first motor and the second motor, and each oil port of the series-parallel switching valve is connected to the working oil ports of the first motor and the second motor to connect the first motor in series or in parallel. The balancing valve is arranged between the travel reversing valve and the oil tank.

[0008] As a preferred technical solution of the hydraulic control system of the scissor lift truck, the travel reversing valve is a three-position four-way solenoid valve.

[0009] As a preferred technical solution for the hydraulic control system of the above-mentioned scissor lift truck, the travel reversing valve is provided with a throttling structure. When the travel reversing valve is in a normal position state, the throttling structure is used to limit the flow rate of the hydraulic oil flowing from the first motor and / or the second motor to the oil tank.

[0010] As a preferred technical solution of the hydraulic control system of the above-mentioned scissor lift truck, the throttling structure includes a first damping hole and / or a second damping hole, the apertures of the first damping hole and the second damping hole are both smaller than the apertures of the working oil ports of the travel reversing valve, and when the travel reversing valve is in normal state, the first damping hole is used to connect the working oil port of the first motor with the travel reversing valve, and the second damping hole is used to connect the working oil port of the second motor with the travel reversing valve.

[0011] As a preferred technical solution of the above-mentioned scissor lift truck hydraulic control system, the scissor lift truck hydraulic control system also includes an oil replenishing one-way valve, and the oil tank is connected to the first motor and the second motor respectively through the oil replenishing one-way valve, and the oil replenishing one-way valve only allows hydraulic oil to flow from the oil tank to the first motor and the second motor.

[0012] As a preferred technical solution of the hydraulic control system of the above-mentioned scissor lift truck, the travel reversing valve has an oil inlet, an oil outlet, a first working oil port and a second working oil port, the oil inlet of the travel reversing valve is selectively connected or disconnected with the first working oil port of the travel reversing valve, the second working oil port of the travel reversing valve or the oil outlet of the travel reversing valve, the oil outlet of the travel reversing valve is selectively connected or disconnected with at least one of the first working oil port of the travel reversing valve and the second working oil port of the travel reversing valve, and the oil outlet of the travel reversing valve is connected with the oil inlet of the balancing valve; and / or,

[0013] The series-parallel switching valve has a first oil port, a second oil port, a third oil port and a fourth oil port. The first oil port of the series-parallel switching valve is selectively connected or disconnected with the second oil port of the series-parallel switching valve or the third oil port of the series-parallel switching valve, and the fourth oil port of the series-parallel switching valve is selectively connected or disconnected with the third oil port of the series-parallel switching valve.

[0014] As a preferred technical solution of the above-mentioned scissor lift truck hydraulic control system, the scissor lift truck hydraulic control system also includes a third reversing valve, a fourth reversing valve and a steering cylinder, the third reversing valve is connected to the oil tank, the first working oil port of the third reversing valve is respectively connected to the fourth reversing valve and the travel reversing valve, and the fourth reversing valve is used to enable the third reversing valve to selectively connect to the first chamber or the second chamber of the steering cylinder.

[0015] As a preferred technical solution for the hydraulic control system of the above-mentioned scissor lift truck, a priority flow valve is also arranged between the fourth reversing valve and the travel reversing valve, the priority oil port of the priority flow valve is connected to the fourth reversing valve, and the redundant oil port of the priority flow valve is connected to the travel reversing valve.

[0016] As a preferred technical solution for the above-mentioned scissor lift truck hydraulic control system, a first one-way valve is further arranged between the fourth reversing valve and the travel reversing valve, and the first one-way valve only allows hydraulic oil to flow from the fourth reversing valve to the travel reversing valve and / or a first throttle valve and a second throttle valve are respectively arranged between the fourth reversing valve and the steering cylinder.

[0017] As a preferred technical solution of the above-mentioned scissor lift truck hydraulic control system, the scissor lift truck hydraulic control system also includes a brake, and the oil port of the brake is connected to the oil inlet of the travel reversing valve through a throttling one-way valve.

[0018] On the other hand, the utility model further provides a scissor lift truck, comprising the scissor lift truck hydraulic control system described in any of the above solutions.

[0019] The utility model has at least the following beneficial effects:

[0020] Compared with the prior art, the balancing valve disposed between the travel reversing valve and the oil tank reduces the overall space volume of the hydraulic system and makes the oil circuit relatively simple. When the scissor lift truck travels downhill, the motor will rotate too fast due to the deadweight of the scissor lift truck, which will cause a larger amount of hydraulic oil than the supply of the travel reversing valve to be discharged, making the downhill speed of the scissor lift truck uncontrollable. Since the travel reversing valve and the oil tank are connected through the balancing valve, the hydraulic oil flowing out of the first motor and the second motor flows into the balancing valve through the travel reversing valve, and the setting of the balancing valve can ensure that the scissor lift truck adjusts the pressure of the hydraulic oil flowing out of the travel reversing valve when operating in downhill conditions, so as to avoid excessive rotation speed of the motor. This can achieve the purpose of controllable speed in downhill conditions and prevent the motor from increasing speed due to inertia. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0022] Figure 1 Hydraulic control system for scissor lift truck provided by the utility model Figure 1 ;

[0023] Figure 2 Hydraulic control system for scissor lift truck provided by the utility model Figure 2 .

[0024] In the figure:

[0025] 1. Travel reversing valve; 2. Series-parallel switching valve; 3. Balance valve; 4. First motor; 5. First damping hole; 6. Second damping hole; 7. Oil replenishing one-way valve; 8. Third reversing valve; 9. Fourth reversing valve; 10. Steering cylinder; 11. Priority flow valve; 12. First one-way valve; 13. First throttle valve; 14. Second throttle valve; 15. Brake; 16. Throttle one-way valve; 17. Second motor; 18. First overflow valve; 19. Second overflow valve. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0027] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0030] refer to Figure 1 The hydraulic control system of the scissor lift truck provided in the prior art includes a hydraulic pump, a travel reversing valve 1, a series-parallel switching valve 2, a balance valve 3 and a travel motor. The balance valve 3 is used to connect the travel reversing valve 1 with the travel motor. When the travel reversing valve 1 is in the left position or the right position (the left position and the right position respectively realize the backward and forward movement of the scissor lift truck), the hydraulic oil in the oil tank enters the travel motor through the travel reversing valve 1 and the balance valve 3, and then flows out of the travel motor and returns to the oil tank. When the scissor lift truck needs to stop braking, the travel reversing valve 1 is powered off and returns to the normal position. The hydraulic pressure flowing out of the oil tank directly returns to the oil tank through the travel reversing valve 1, and no longer supplies oil to the travel motor to control the braking of the scissor lift truck. The travel motor includes a first motor 4 and a second motor 17. The first motor 4 and the second motor 17 correspond to the two front wheels driving the scissor lift truck, respectively, and the hydraulic oil of the first motor 4 and the second motor 17 flows in the same direction, and the two move forward or backward synchronously. Specifically, each working oil port of the travel reversing valve 1 is directly connected to the working oil ports of the first motor 4 and the second motor 17, and each working oil port of the series-parallel switching valve 2 is directly connected to the working oil ports of the first motor 4 and the second motor 17 so that the first motor 4 and the second motor 17 are connected in series or in parallel.

[0031] Since two balancing valves 3 are arranged between the travel reversing valve 1 and the travel motor, the volume of the balancing valve 3 occupies a large space, resulting in a corresponding increase in the overall volume of the scissor lift truck.

[0032] In order to solve the above problem, in this embodiment, Figure 1As shown, a balancing valve 3 is provided between the travel reversing valve 1 and the oil tank, that is, the hydraulic oil of the travel reversing valve 1 flows out and enters the balancing valve 3 and then flows back to the oil tank. Since the oil outlet (i.e., the return oil outlet) of the travel reversing valve 1 is connected to the oil tank through the balancing valve 3, the number of balancing valves 3 is set to one to ensure that the pressure of the hydraulic oil flowing out through the travel reversing valve 1 is adjusted when the scissor lift truck is in downhill working conditions, so as to avoid the motor rotating too fast. In this way, the purpose of adjustable speed in downhill working conditions can be achieved, and the speed of the motor is prevented from increasing under the action of inertia. The balancing valve 3 prevents the scissor lift truck from losing control due to the rotation of the motor caused by external force. When the scissor lift truck is traveling downhill, the motor will rotate according to the deadweight of the scissor lift truck. In this case, a larger amount of hydraulic oil than the supply of the travel reversing valve 1 is discharged. The balancing valve 3 adjusts the throttling of the outlet pipeline according to the oil pressure on the inlet side, so as to adjust the travel speed of the scissor lift truck. The setting of the balancing valve 3 makes the pressure oil at the motor oil outlet more constant and has less impact.

[0033] Compared with the prior art, the balancing valve 3 disposed between the travel reversing valve 1 and the oil tank reduces the overall space volume of the hydraulic system and makes the oil circuit relatively simple.

[0034] Specifically, continue to refer to Figure 1 The balancing valve 3 includes a balancing overflow valve, a balancing check valve and a balancing throttle valve which are arranged in parallel. Specifically, when the oil flows out of the working oil port (a2, b2, a3 or b3) of the motor, it flows into the return oil port T1 through the balancing valve 3. The balancing overflow valve at the working oil port of the motor plays a role in safe overflow and keeps the pressure of the hydraulic oil flowing out of the motor balanced, thereby controlling the descending speed. The setting of the balancing throttle valve makes the pressure oil at the working oil port of the motor more constant and has less impact.

[0035] When the scissor lift truck moves forward and when the first motor 4 and the second motor 17 are connected in series, the hydraulic pressure enters the first motor 4 and the second motor 17 in sequence from the travel reversing valve 1, then flows out through the working oil port of the second motor 17 and enters the working oil port of the travel reversing valve 1, and then enters the balance valve 3 through the oil outlet of the travel reversing valve 1, and flows back to the oil tank from the balance valve 3, so that the scissor lift truck moves forward quickly.

[0036] Specifically, the travel reversing valve 1 has an oil inlet P2, an oil outlet T2, a first working oil port A and a second working oil port B, the series-parallel switching valve 2 has a first oil port a1, a second oil port b1, a third oil port c1 and a fourth oil port d1, the oil inlet P2 of the travel reversing valve 1 is connected to the main oil inlet P1, the oil inlet P2 of the travel reversing valve 1 is selectively connected or disconnected with the first working oil port A of the travel reversing valve 1, the second working oil port B of the travel reversing valve 1 or the oil outlet T2 of the travel reversing valve 1, and the oil outlet T2 of the travel reversing valve 1 is selectively connected or disconnected. The first oil port a1 of the series-parallel switching valve 2 is selectively connected or disconnected with the second oil port b1 of the series-parallel switching valve 2 or the third oil port c1 of the series-parallel switching valve 2, the fourth oil port d1 of the series-parallel switching valve 2 is selectively connected or disconnected with the third oil port c1 of the series-parallel switching valve 2, the oil outlet of the travel reversing valve 1 is connected with the oil inlet a4 of the balancing valve 3, and the oil outlet b4 of the balancing valve 3 is connected with the oil return port T1.

[0037] When the upper position of the travel reversing valve 1 is energized and the series-parallel switching valve 2 is not energized, the oil inlet P2 of the travel reversing valve 1 is connected to the second working oil port B of the travel reversing valve 1, and the first working oil port A of the travel reversing valve 1 is connected to the oil outlet T2 of the travel reversing valve 1, and the hydraulic oil passes through the first motor 4 and the second motor 17 in sequence and enters the first working oil port A of the travel reversing valve 1, and then returns to the oil return port T1 through the oil outlet T2 of the travel reversing valve 1. At this time, the rotation direction of the first motor 4 and the second motor 17 is the first direction. When the lower position of the travel reversing valve 1 is energized and the series-parallel switching valve 2 is not energized, the oil inlet P2 of the travel reversing valve 1 is connected to the first working oil port A of the travel reversing valve 1, and the second working oil port B of the travel reversing valve 1 is connected to the oil outlet of the travel reversing valve 1. The hydraulic oil flows into the second motor 17 and the first motor 4 in turn through the oil inlet of the travel reversing valve 1 through the first working oil port of the travel reversing valve 1, and then enters the travel reversing valve 1 through the second working oil port B of the travel reversing valve 1, and then returns to the oil return port T1 through the oil outlet T2 of the travel reversing valve 1. At this time, the rotation direction of the first motor 4 and the second motor 17 is the second direction, while the first direction and the second direction are opposite, that is, the travel reversing valve 1 is used to realize the forward or backward movement of the first motor 4 and the second motor 17. When the series-parallel switching valve 2 is energized, the hydraulic oil flowing out through the travel reversing valve 1 enters the first motor 4 and the second motor 17 respectively, so that the first motor 4 and the second motor 17 are connected in parallel, and the speed of the first motor 4 and the second motor 17 decreases at this time. The travel reversing valve 1 and the series-parallel switching valve 2 work together to achieve the rotation speed of the first motor 4 and the second motor 17 when they move forward or backward.

[0038] In some embodiments, the travel reversing valve 1 is a three-position four-way solenoid valve, and the series-parallel switching valve 2 is a two-position four-way solenoid valve. The specific structures of the three-position four-way solenoid valve and the two-position four-way solenoid valve are prior art and will not be described in detail here.

[0039] When the vehicle is parked, when the hydraulic oil of the first motor 4 and the second motor 17 flows out through the oil outlet of the travel reversing valve 1, impact will occur due to the large flow rate, causing the scissor lift truck to slide backward for a distance when braking during the process of going up a slope, that is, a slope sliding phenomenon. For this reason, in some embodiments, the travel reversing valve 1 is provided with a throttling structure. When the travel reversing valve 1 is in a normal position, the throttling structure is used to limit the flow of hydraulic oil flowing from the first motor 4 and / or the second motor 17 to the oil tank. When the scissor lift truck is parked and braked on a slope, the travel reversing valve 1 is in a normal position. Even if external force drives the hydraulic oil in the first motor 4 and the second motor 17 to flow back into the travel reversing valve 1, the hydraulic oil will first pass through the throttling structure and then flow into the inside of the travel reversing valve 1, and then flow back to the oil tank through the travel reversing valve 1. Since the throttling structure can limit the flow rate of the hydraulic oil flowing back from the first motor 4 and the second motor 17, the throttling structure can reduce the reflux flow rate of the hydraulic oil compared to the traditional way of flowing back through the oil outlet, thereby hindering the reverse rotation of the travel motor, achieving rapid braking of the scissor lift truck and reducing the distance of sliding down the slope.

[0040] Specifically, the throttling structure includes a first damping hole 5 and / or a second damping hole 6. The apertures of the first damping hole 5 and the second damping hole 6 are smaller than the apertures of the working oil ports of the travel reversing valve 1. When the travel reversing valve 1 is in normal state, the first damping hole 5 is used to connect the working oil port a2 of the first motor 4 with the travel reversing valve 2, and the second damping hole 6 is used to connect the working oil port b3 of the second motor 17 with the travel reversing valve 1. When the scissor lift truck is parked on a slope, the travel reversing valve 1 is powered off and returns to the normal position. Even if the external force drives the hydraulic oil in the first motor 4 and the second motor 17 to flow back into the travel reversing valve 1, the hydraulic oil will first flow through the first damping hole 5 or the second damping hole 6 and then flow back into the oil tank through the travel reversing valve 1. Since the apertures of the first damping hole 5 and the second damping hole 6 are both smaller than the apertures of each working oil port, compared with the traditional method of reflux through the oil outlet, the method of reflux through the damping hole in the present application can reduce the reflux flow of the hydraulic oil, thereby hindering the reverse rotation of the first motor 4 and the second motor 17, achieving rapid braking of the scissor lift truck and reducing the sliding distance. Among them, the first damping hole 5 can reduce the sliding distance of the scissor lift truck when braking in the uphill state with the front of the vehicle in front, and the second damping hole 6 can reduce the sliding distance of the scissor lift truck when braking in the uphill state with the rear of the vehicle in the front and back, which is suitable for two different working conditions.

[0041] Specifically, a first damping hole 5 is provided between the first working oil port P2 of the travel reversing valve 1 and the oil outlet T2 of the travel reversing valve 1, and a second damping hole 6 is provided between the second working oil port B1 of the travel reversing valve 1 and the oil outlet T2 of the travel reversing valve 1. The setting of the first damping hole 5 and the second damping hole 6 can control the flow of the oil outlets of the first motor 4 and the second motor 17, and achieve the purpose of throttling. In this way, when the scissor lift truck stops, the first damping hole 5 and the second damping hole 6 play a buffering role.

[0042] In some embodiments, the hydraulic control system of the scissor lift truck further includes an oil replenishment check valve 7, through which the oil tank (i.e., the oil return port T1) is respectively connected to the working oil port b2 of the first motor 4 and the working oil port a3 of the second motor 17, and the oil replenishment check valve 7 only allows the hydraulic oil to flow from the oil tank to the first motor 4 and the second motor 17. There are two oil replenishment check valves 7, one of which is connected to the oil tank and the first motor 4, and is used to actively replenish the hydraulic oil for the first motor 4, and the other oil replenishment check valve 7 is connected to the oil tank and the second motor 17, and is used to actively replenish the hydraulic oil for the second motor 17, so as to prevent the first motor 4 and the second motor 17 from making abnormal noises, and effectively improve the service life of the first motor 4 and the second motor 17.

[0043] In some embodiments, Figure 2 As shown, the hydraulic control system of the scissor lift truck also includes a lifting oil port CSE, a third reversing valve 8, a fourth reversing valve 9 and a steering oil cylinder 10. Specifically, the oil inlet P3 of the third reversing valve 8 is connected to the main oil inlet P1, and the oil inlet P3 and the oil outlet T3 of the third reversing valve 8 are selectively connected or disconnected with the first working oil port a5 of the third reversing valve 8 and the second working oil port b5 of the third reversing valve 8. The first working oil port a5 of the third reversing valve 8 is connected to the oil inlet P4 of the fourth reversing valve 9 and the oil inlet P2 of the travel reversing valve 1, and the second working oil port b5 of the third reversing valve 8 is selectively connected or disconnected with the first working oil port a5 of the third reversing valve 8 and the second working oil port b5 of the third reversing valve 8. The fourth reversing valve 9 is connected to the lifting oil port CSE, the oil inlet P4 of the fourth reversing valve 9 is selectively connected or disconnected with the first working oil port a6 of the fourth reversing valve 9, the second working oil port b6 of the fourth reversing valve 9 and the oil outlet of the fourth reversing valve 9, the oil outlet T4 of the fourth reversing valve 9 is selectively connected or disconnected with the first working oil port a6 of the fourth reversing valve 9 or the second working oil port b6 of the fourth reversing valve 9, the first chamber of the steering cylinder 10 is connected to the first working oil port a6 of the fourth reversing valve 9, and the second chamber of the steering cylinder 10 is connected to the second working oil port b6 of the fourth reversing valve 9. In this way, the valve core of the fourth reversing valve 9 can realize the control of the steering of the steering cylinder 10 at different positions.

[0044] When the scissor lift truck is working, it is necessary to give priority to controlling its steering to ensure the safe driving of the scissor lift truck. For this purpose, a priority flow valve 11 is also provided between the oil inlet of the fourth reversing valve 9 and the first working oil port A1 of the travel reversing valve 1. The priority oil port of the priority flow valve 11 is connected to the oil inlet of the fourth reversing valve 9, and the redundant oil port of the priority flow valve 11 is connected to the oil inlet P2 of the travel reversing valve 1. In this way, the hydraulic oil flowing into the priority flow valve 11 is preferentially supplied to the steering cylinder 10, and the steering control is prioritized, and the redundant hydraulic oil is provided to the first motor 4 and the second motor 17 to control the travel of the scissor lift truck.

[0045] In some embodiments, a first one-way valve 12 is further provided between the oil outlet T4 of the fourth reversing valve 9 and the oil inlet P2 of the travel reversing valve 1. The first one-way valve 12 only allows the hydraulic oil to flow from the oil outlet T4 of the fourth reversing valve 9 to the oil inlet P2 of the travel reversing valve 1, so that the hydraulic oil passing through the priority flow valve 11 can be fully supplied to the first motor 4 and the second motor 17, and the setting of the first one-way valve 12 can prevent the hydraulic oil from entering the oil outlet of the fourth reversing valve 9 from the redundant oil port of the priority flow valve 11, thereby ensuring the travel of the first motor 4 and the second motor 17.

[0046] Furthermore, a first overflow valve 18 is connected between the priority oil port and the redundant oil port of the priority flow valve 11. The first overflow valve 18 can control the pressure of the hydraulic oil entering the fourth reversing valve 9 to avoid damage to the fourth reversing valve 9 due to excessive pressure of the hydraulic oil entering the fourth reversing valve 9.

[0047] In order to ensure the stability of steering during the steering process, in some embodiments, a first throttle valve 13 is provided between the first working oil port of the fourth reversing valve 9 and the first chamber of the steering cylinder 10, and a second throttle valve 14 is provided between the second working oil port of the fourth reversing valve 9 and the second chamber of the steering cylinder 10. The first throttle valve 13 and the second throttle valve 14 can control the flow to the steering cylinder 10 to ensure that the steering cylinder 10 works smoothly.

[0048] For example, when the left position of the fourth reversing valve 9 is turned on, oil enters the first chamber of the steering cylinder 10, and the scissor lift truck turns left; when the right position of the fourth reversing valve 9 is turned on, oil enters the second chamber of the steering cylinder 10, and the scissor lift truck turns right; when the middle position of the fourth reversing valve 9 is turned on, the hydraulic oil flows directly to the oil outlet through the oil inlet of the fourth reversing valve 9, and the scissor lift truck moves in a straight line.

[0049] In some embodiments, the hydraulic control system of the scissor lift truck further includes a brake 15, which is used to brake the first motor 4 and the second motor 17. After the hydraulic oil passes through the main oil inlet P1, a portion of the hydraulic oil enters the brake 15. When the scissor lift truck needs to be braked, the oil port of the brake 15 is connected to the oil inlet of the travel reversing valve 1 through the throttling one-way valve 16. The setting of the brake 15 can ensure that the scissor lift truck travels more safely. The specific structure of the brake 15 is prior art and will not be described in detail here.

[0050] Preferably, the third reversing valve 8 is a two-position four-way solenoid valve, and the fourth reversing valve 9 is a three-position four-way solenoid valve.

[0051] Preferably, the main oil inlet P1 is also connected to a second overflow valve 19 , which can prevent the third reversing valve 8 from being impacted by excessive hydraulic oil pressure.

[0052] The embodiment of the utility model further provides a scissor lift truck, including the scissor lift truck hydraulic control system provided by the embodiment of the utility model.

[0053] Since the scissor lift truck includes the above-mentioned hydraulic control system, the scissor lift truck of the embodiment of the utility model has all the advantages and beneficial effects of the above-mentioned embodiments, which will not be described in detail here.

[0054] In addition, the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. Scissor lift hydraulic control system, characterized in that: The invention comprises an oil tank, a travel reversing valve (1), a series-parallel switching valve (2), a first motor (4), a second motor (17) and a balancing valve (3); each working oil port of the travel reversing valve (1) is correspondingly connected to the working oil ports of the first motor (4) and the second motor (17); each oil port of the series-parallel switching valve (2) is correspondingly connected to the working oil ports of the first motor (4) and the second motor (17) so that the first motor (4) and the second motor (17) are connected in series or in parallel; and the balancing valve (3) is arranged between the travel reversing valve (1) and the oil tank.

2. The hydraulic control system of a scissor lift truck according to claim 1, characterized in that: The travel reversing valve (1) is a three-position four-way solenoid valve.

3. The hydraulic control system of a scissor lift truck according to claim 2, characterized in that: The travel reversing valve (1) is provided with a throttling structure. When the travel reversing valve (1) is in a normal position, the throttling structure is used to limit the flow of hydraulic oil flowing from the first motor (4) and / or the second motor (17) to the oil tank.

4. The hydraulic control system of a scissor lift truck according to claim 3, characterized in that: The throttling structure comprises a first damping hole (5) and / or a second damping hole (6), the apertures of the first damping hole (5) and the second damping hole (6) are both smaller than the apertures of the working oil ports of the travel reversing valve (1), and when the travel reversing valve (1) is in a normal state, the first damping hole (5) is used to connect the working oil port of the first motor (4) with the travel reversing valve (1), and the second damping hole (6) is used to connect the working oil port of the second motor (17) with the travel reversing valve (1).

5. The hydraulic control system of a scissor lift truck according to claim 1, characterized in that: The scissor lift truck hydraulic control system further comprises an oil replenishment check valve (7), wherein the oil tank is respectively connected to the first motor (4) and the second motor (17) via the oil replenishment check valve (7), and the oil replenishment check valve (7) only allows hydraulic oil to flow from the oil tank to the first motor (4) and the second motor (17).

6. The hydraulic control system of a scissor lift truck according to claim 1, characterized in that: The travel reversing valve (1) has an oil inlet, an oil outlet, a first working oil outlet and a second working oil outlet; the oil inlet of the travel reversing valve (1) is selectively connected to or disconnected from the first working oil outlet of the travel reversing valve (1), the second working oil outlet of the travel reversing valve (1) or the oil outlet of the travel reversing valve (1); the oil outlet of the travel reversing valve (1) is selectively connected to or disconnected from at least one of the first working oil outlet of the travel reversing valve (1) and the second working oil outlet of the travel reversing valve (1); the oil outlet of the travel reversing valve (1) is connected to the oil inlet of the balance valve (3); and / or, The series-parallel switching valve (2) has a first oil port, a second oil port, a third oil port and a fourth oil port. The first oil port of the series-parallel switching valve (2) is selectively connected to or disconnected from the second oil port of the series-parallel switching valve (2) or the third oil port of the series-parallel switching valve (2), and the fourth oil port of the series-parallel switching valve (2) is selectively connected to or disconnected from the third oil port of the series-parallel switching valve (2).

7. The hydraulic control system of a scissor lift truck according to claim 1, characterized in that: The hydraulic control system of the scissor lift truck further comprises a third reversing valve (8), a fourth reversing valve (9) and a steering oil cylinder (10); the third reversing valve (8) is connected to the oil tank; the first working oil port of the third reversing valve (8) is respectively connected to the fourth reversing valve (9) and the travel reversing valve (1); the fourth reversing valve (9) is used to enable the third reversing valve (8) to selectively connect to the first chamber or the second chamber of the steering oil cylinder (10).

8. The hydraulic control system of a scissor lift truck according to claim 7, characterized in that: A priority flow valve (11) is also provided between the third reversing valve (8) and the travel reversing valve (1); a priority oil port of the priority flow valve (11) is connected to the fourth reversing valve (9), and a redundant oil port of the priority flow valve (11) is connected to the travel reversing valve (1).

9. The hydraulic control system of a scissor lift truck according to claim 7, characterized in that: A first one-way valve (12) is also provided between the fourth reversing valve (9) and the travel reversing valve (1), and the first one-way valve (12) only allows hydraulic oil to flow from the fourth reversing valve (9) to the travel reversing valve (1) and / or a first throttle valve (13) and a second throttle valve (14) are also provided between the fourth reversing valve (9) and the steering cylinder (10), respectively.

10. A scissor lift truck, characterized in that: A scissor lift truck hydraulic control system comprising any one of claims 1-9.

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