Pilot brake hydraulic system and fork truck
Patent Information
- Application Number
- CN202522319442.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-31
- Publication Date
- 2026-10-16
- Estimated Expiration
- 2035-10-31
AI Technical Summary
然而，此方案同样存在分流压力损失大、能耗大的问题
本实用新型中，先导制动液压系统采用单泵供油控制，并且系统中的先导控制支路能够于主回路和油箱间形成用于控制工作装置动作的控制回路，即在该先导控制支路的控制下，能够实现工作装置的起升、伸缩和倾斜等动作，同时，制动回路于主回路和油箱间形成用于实现驻车制动器和行车制动器制动的制动回路，这样利用单泵供油控制可以灵活调整压力和流量，满足制动和先导油源需求，提高工作效率，减少能源浪费，实现叉车在不同使用工况下对油压及流量的使用需求。本实用新型中，该系统中的各回路设置，可以利用蓄能器的压力油，解决停机后，工作装置的缓慢移动放下，坡道制动解除拖车的要求；同时，在整车设计时，可以更灵活地进行系统布局，节省空间。
Smart Images
Figure CN224859798U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of forklift technology, specifically to a pilot braking hydraulic system and a forklift. Background Technology
[0002] Most existing industrial vehicles use a single pump source to supply oil to the braking, steering, and working devices. Because the pressure and flow requirements of each action differ, especially in the braking and pilot circuits where pressure and flow are low, using a single pump source (i.e., a split-flow method to meet the pressure and flow requirements of each actuator) means the system still operates at maximum power, inevitably leading to power loss and energy waste. This problem is actually caused by an unreasonable power matching within the system.
[0003] Vehicles typically have two braking systems: a service brake (operated by the driver via the brake pedal, also known as the foot brake) and a parking brake (operated by the driver via the brake pedal, which only activates when the pedal is depressed and releases when released). The parking brake (operated by the driver via the brake lever, also known as the handbrake) ensures the vehicle remains reliably stationary. Currently, some industrial vehicles in China use a spring-loaded braking system. When parked, the wheel brakes apply a force from a high-preload spring in the spring-loaded cylinder, pressing the brake pads against the brake disc. When moving, pressurized oil flows into the spring-loaded cylinder to counteract the spring force, releasing the parking brake. The oil supply for both braking systems is generally provided by a main pump with multi-stage pressure reduction and diversion, which results in significant pressure loss during diversion, high energy consumption, and system overheating.
[0004] Furthermore, as industrial vehicles demand increasingly higher handling performance, multi-way valves mostly employ pilot hydraulic proportional control to achieve precise flow control. The pilot hydraulic source for the proportional valve is typically housed in a multi-way valve with a pressure reducing valve, branching off the main pump's hydraulic circuit to meet the pilot hydraulic source's needs. However, this approach also suffers from significant pressure loss and high energy consumption due to the diversion. Utility Model Content
[0005] This utility model provides a pilot braking hydraulic system and forklift, which adopts single pump oil supply control, and can flexibly adjust pressure and flow to meet the oil source requirements of braking and pilot braking, improve work efficiency and reduce energy waste.
[0006] A pilot-operated braking hydraulic system includes a tank and an accumulator, and further includes: An oil pump is installed in the main circuit between the oil tank and the accumulator; Pilot control branch, which forms a control loop between the main circuit and the oil tank for controlling the operation of the working device; and A braking branch is provided on the main circuit on the side of the pilot control branch away from the fuel tank. The braking branch includes a parking brake, a service brake, and a braking circuit provided between the two and forming a braking circuit between the main circuit and the fuel tank for realizing the braking of the parking brake and / or the service brake.
[0007] Preferably, the main circuit includes a first four-way pipe, an overflow valve, a check valve, a first three-way pipe, and a second four-way pipe. The first port of the first four-way pipe is connected to the oil pump outlet, the third port of the first four-way pipe is connected to the oil inlet of the overflow valve, the oil outlet of the overflow valve is connected to the oil tank, the fourth port of the first four-way pipe is connected to the inlet of the check valve, the outlet of the check valve is connected to the first port of the second four-way pipe through the first three-way pipe, and the third port of the second four-way pipe is connected to the accumulator.
[0008] Preferably, the pilot control branch is located on the main circuit on the side of the oil pump away from the oil tank.
[0009] Preferably, the pilot control branch includes a first solenoid valve, a third four-way pipe, a pilot control valve, and a second solenoid valve. The second port of the first four-way pipe is connected to the oil inlet P1 of the first solenoid valve. The oil return port T1 of the first solenoid valve is connected to the oil tank through the first port of the third four-way pipe. The outlet of the check valve is also connected to the oil inlet P2 of the second solenoid valve through a first three-way pipe. The working port A2 of the second solenoid valve is connected to the oil inlet P5 of the pilot control valve. The oil return port T2 of the second solenoid valve is connected to the oil tank through the second port of the third four-way pipe. The oil return port T5 of the pilot control valve is connected to the oil tank through the third port of the third four-way pipe.
[0010] Preferably, the first solenoid valve is a two-position two-way solenoid valve, and the second solenoid valve is a two-position three-way solenoid valve.
[0011] Preferably, the braking branch further includes a third solenoid valve and a service brake valve. The second port of the second four-way pipe is connected to the oil inlet P3 of the third solenoid valve, the fourth port of the second four-way pipe is connected to the oil inlet P4 of the service brake valve, the working port of the service brake valve is connected to the service brake, the working port A3 of the third solenoid valve is connected to the parking brake, and the return port T3 of the third solenoid valve is connected to the oil tank through the second port of the third four-way pipe.
[0012] Preferably, the third solenoid valve is a two-position three-way solenoid valve.
[0013] Preferably, the pilot braking hydraulic system further includes a low-pressure alarm switch and a system unloading switch.
[0014] A forklift comprising the aforementioned pilot brake hydraulic system.
[0015] As can be seen from the above technical solutions, this utility model has the following beneficial effects: In this invention, the pilot braking hydraulic system employs a single-pump oil supply control. The pilot control branch within the system forms a control loop between the main circuit and the oil tank to control the movement of the working device. Under the control of this pilot control branch, the working device can perform actions such as lifting, extending, and tilting. Simultaneously, the braking circuit between the main circuit and the oil tank forms a braking loop to activate the parking brake and service brake. This single-pump oil supply control allows for flexible adjustment of pressure and flow to meet the braking and pilot oil supply requirements, improving work efficiency, reducing energy waste, and fulfilling the forklift's oil pressure and flow requirements under different operating conditions. Furthermore, the circuit setup in this system utilizes the accumulator's pressurized oil to address the requirements for slow lowering of the working device after shutdown and for releasing the trailer on slopes. Additionally, the overall vehicle design allows for more flexible system layout and saves space. Attached Figure Description Figure 1 This is a schematic diagram of the present invention.
[0016] In the diagram: 10, fuel tank; 20, accumulator; 30, fuel pump; 410, first four-way pipe; 420, overflow valve; 430, check valve; 440, first three-way pipe; 450, second four-way pipe; 510, first solenoid valve; 520, third four-way pipe; 530, pilot control valve; 540, second solenoid valve; 610, parking brake; 620, service brake; 630, third solenoid valve; 640, service brake valve; 70, low-pressure alarm switch; 80, system unloading switch. Detailed Implementation
[0017] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.
[0018] To achieve the above objectives, the embodiments of this utility model adopt the following technical solutions: (Refer to...) Figure 1A pilot-operated braking hydraulic system includes an oil tank 10, an accumulator 20, an oil pump 30, a pilot control branch, and a braking branch. A main circuit is provided between the oil tank 10 and the accumulator 20. Specifically, the oil pump is located on the main circuit between the oil tank 10 and the accumulator 20. The pilot control branch forms a control circuit between the main circuit and the oil tank 10 for controlling the operation of the working device. Under the control of this pilot control branch, the working device can perform actions such as lifting, extending, and tilting. Furthermore, the braking branch is located on the main circuit away from the oil tank 10, and includes a parking brake 610, a service brake 620, and a braking circuit. This braking circuit is located between the parking brake 610 and the service brake 620, and forms a braking circuit between the main circuit and the oil tank 10 for braking the parking brake 610 and / or the service brake 620.
[0019] Furthermore, the pilot brake hydraulic system also includes a low-pressure alarm switch 70 and a system unloading switch 80.
[0020] As a preferred technical solution in this embodiment, the main circuit includes a first four-way pipe 410, an overflow valve 420, a check valve 430, a first three-way pipe 440, and a second four-way pipe 450. It should be noted that the first four-way pipe 410 and the second four-way pipe 450 are pipes with four ports, and the first three-way pipe 440 is a pipe with three ports. These pipes can collect and distribute fluid to different directions. The main function of the overflow valve 420 is to limit the maximum pressure of the hydraulic system. Specifically, the first port of the first four-way pipe 410 is connected to the oil outlet of the oil pump 30. The third port of 410 is connected to the oil inlet of the overflow valve 420, and the oil outlet of the overflow valve is connected to the oil tank 10. The fourth port of the first four-way pipe 410 is connected to the inlet of the one-way valve 430, and the outlet of the one-way valve is connected to the first port of the second four-way pipe 450 through the first three-way pipe 440. The third port of the second four-way pipe is connected to the accumulator 20. In this way, a circulating connection loop is formed between the oil tank 10 and the accumulator 20 using this main circuit. This main circuit can be used as the main connection pipeline. The pilot control branch and the braking branch can be set at the corresponding positions of this main circuit.
[0021] Reference Figure 1In some embodiments, the pilot control branch is located on the main circuit of the oil pump 30 on the side away from the oil tank 10. Further, the pilot control branch includes a first solenoid valve 510, a third four-way pipe 520, a pilot control valve 530, and a second solenoid valve 540. The first solenoid valve 510 is a two-position, two-way solenoid valve, and the second solenoid valve 540 is a two-position, three-way solenoid valve. The third four-way pipe 520 is also a pipe with four ports, which serves to collect and distribute fluid in different directions. Specifically, the second port of the first four-way pipe 520 is connected to... The first solenoid valve 510 has an inlet port P1 that is connected to the oil tank. The return port T1 of the first solenoid valve 510 is connected to the oil tank through the first interface of the third four-way pipe 520. The outlet of the one-way valve 430 is also connected to the inlet port P2 of the second solenoid valve 540 through the first three-way pipe 440. The working port A2 of the second solenoid valve is connected to the inlet port P5 of the pilot control valve 530. The return port T2 of the second solenoid valve is connected to the oil tank 10 through the second interface of the third four-way pipe 520. The return port T5 of the pilot control valve is connected to the oil tank 10 through the third interface of the third four-way pipe.
[0022] It should be noted that when the first solenoid valve 510 is in the neutral position, its oil inlet P1 port is connected to its oil return port T1; when the first solenoid valve 510 is energized and in the reversing position, its oil inlet P1 port is disconnected from its oil return port T1.
[0023] Meanwhile, when the second solenoid valve 540 is in the neutral position, the working oil port A2 is connected to the return oil port T2; when the second solenoid valve 540 is in the reversing position, the oil inlet port P2 is connected to the working oil port A2, and the working oil port A2 is closed to the return oil port T2.
[0024] In some embodiments, the braking branch includes a third solenoid valve 630 and a service brake valve 640. The third solenoid valve 630 is a two-position three-way solenoid valve. Specifically, the second port of the second four-way pipe 450 is connected to the oil inlet P3 of the third solenoid valve 630, the fourth port of the second four-way pipe is connected to the oil inlet P4 of the service brake valve 640, the working port of the service brake valve is connected to the service brake 620, the working port A3 of the third solenoid valve 630 is connected to the parking brake 610, and the return port T3 of the third solenoid valve is connected to the oil tank 10 through the second port of the third four-way pipe 520.
[0025] It should be noted that when the third solenoid valve 630 is in the neutral position, the working oil port A3 is connected to the return oil port T3; when the third solenoid valve 630 is in the reversing position, the oil inlet port P3 is connected to the working oil port A3, and the working oil port A3 is closed to the return oil port T3.
[0026] Working principle: When the forklift is started but not moving, if the system detects that the pressure of the accumulator 20 is lower than the set value of the low-pressure alarm switch 70, the first solenoid valve 510 is energized and reversed, disconnecting the oil inlet P1 from the oil return port T1. The oil pump 30 starts working, and the pressurized oil output by the oil pump fills the accumulator 20 through the one-way valve 430. When the filling pressure of the accumulator 20 reaches the set pressure of the system unloading switch 80, the first solenoid valve 510 is de-energized, connecting its oil inlet P1 to the oil return port T1, and the oil pump 30 is unloaded.
[0027] When the forklift starts and is ready to drive, the third solenoid valve 630 is energized and reversed, connecting its oil inlet P3 port to the working oil port A3. The pressurized oil in the accumulator 20 enters the parking brake 610 through the third solenoid valve 630, counteracting the spring force and releasing the parking brake to ensure that the vehicle can drive normally.
[0028] When the forklift encounters an obstacle and needs to slow down and brake, the driver presses the service brake valve 640. The pressurized oil in the accumulator 20 enters the service brake 620 through the service brake valve 640 to achieve service braking.
[0029] When the forklift's working device is operating, the second solenoid valve 540 is energized and reverses direction, connecting its oil inlet P2 port to the working oil port A2. The pressurized oil in the accumulator 20 enters the pilot control valve 530 through the second solenoid valve 540, controlling the main valve core to reverse direction, thus realizing the lifting, extension, and tilting actions of the working device. When the forklift's working device stops operating, the second solenoid valve 540 is de-energized, the pilot control valve 530 returns to the neutral position, and the return oil from the pilot control valve 530 flows back to the oil tank 10 through the return port T5 and the third four-way pipe 520.
[0030] During forklift operation, when the pressure in the accumulator 20 falls below the set value of the low-pressure alarm switch 70, the first solenoid valve 510 is energized and reversed, disconnecting its inlet port P1 from its return port T1. The pressurized oil output from the oil pump 30, through the check valve 430 and the second four-way pipe 450, simultaneously fills the accumulator 20 and replenishes the pressurized oil required by the parking brake 610. When the accumulator 20's filling pressure reaches the set pressure of the system unloading switch 80, the first solenoid valve 510 is de-energized, connecting its inlet port P1 to its return port T1, and the oil pump 30 is unloaded.
[0031] When the vehicle is parked, the third solenoid valve 630 is de-energized and returns to the neutral position. The pressurized oil in the parking brake 610 returns to the oil tank 10 through the working oil port A3 and the return oil port T3 of the third solenoid valve 630. The parking brake 610 then applies the parking brake under the action of the spring force.
[0032] The above-described embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made by those skilled in the art to the technical solutions of the present utility model without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.
Claims
1. A pilot braking hydraulic system, comprising a tank (10) and an accumulator (20), characterized in that, Also includes: Oil pump (30), which is installed on the main circuit between oil tank (10) and accumulator (20); A pilot control branch, which forms a control loop between the main circuit and the oil tank (10) for controlling the operation of the working device; and The braking branch is located on the main circuit on the side of the pilot control branch away from the oil tank (10). The braking branch includes a parking brake (610), a service brake (620), and a braking circuit located between the two and forming between the main circuit and the oil tank (10) for braking the parking brake (610) and / or the service brake (620).
2. The pilot braking hydraulic system according to claim 1, characterized in that, The main circuit includes a first four-way pipe (410), an overflow valve (420), a one-way valve (430), a first three-way pipe (440), and a second four-way pipe (450). The first port of the first four-way pipe is connected to the oil outlet of the oil pump (30), the third port of the first four-way pipe (410) is connected to the oil inlet of the overflow valve (420), the oil outlet of the overflow valve is connected to the oil tank (10), the fourth port of the first four-way pipe is connected to the inlet of the one-way valve (430), the outlet of the one-way valve is connected to the first port of the second four-way pipe (450) through the first three-way pipe (440), and the third port of the second four-way pipe is connected to the accumulator (20).
3. The pilot braking hydraulic system according to claim 1, characterized in that, The pilot control branch is located on the main circuit on the side of the oil pump (30) away from the oil tank (10).
4. The pilot braking hydraulic system according to claim 2, characterized in that, The pilot control branch includes a first solenoid valve (510), a third four-way pipe (520), a pilot control valve (530), and a second solenoid valve (540). The second port of the first four-way pipe (410) is connected to the oil inlet P1 of the first solenoid valve (510). The oil return port T1 of the first solenoid valve is connected to the oil tank through the first port of the third four-way pipe (520). The outlet of the one-way valve (430) is also connected to the oil inlet P2 of the second solenoid valve (540) through the first three-way pipe (440). The working port A2 of the second solenoid valve is connected to the oil inlet P5 of the pilot control valve (530). The oil return port T2 of the second solenoid valve is connected to the oil tank (10) through the second port of the third four-way pipe (520). The oil return port T5 of the pilot control valve is connected to the oil tank (10) through the third port of the third four-way pipe.
5. The pilot braking hydraulic system according to claim 4, characterized in that, The first solenoid valve (510) is a two-position two-way solenoid valve, and the second solenoid valve (540) is a two-position three-way solenoid valve.
6. The pilot braking hydraulic system according to claim 4, characterized in that, The braking branch also includes a third solenoid valve (630) and a service brake valve (640). The second port of the second four-way pipe (450) is connected to the oil inlet P3 of the third solenoid valve (630). The fourth port of the second four-way pipe is connected to the oil inlet P4 of the service brake valve (640). The working port of the service brake valve is connected to the service brake (620). The working port A3 of the third solenoid valve (630) is connected to the parking brake (610). The return port T3 of the third solenoid valve is connected to the oil tank (10) through the second port of the third four-way pipe (520).
7. The pilot braking hydraulic system according to claim 6, characterized in that, The third solenoid valve (630) is a two-position three-way solenoid valve.
8. The pilot braking hydraulic system according to claim 1, characterized in that, The pilot braking hydraulic system also includes a low-pressure alarm switch (70) and a system unloading switch (80).
9. A forklift, characterized in that, The forklift includes the pilot braking hydraulic system as described in any one of claims 1-8.