Parking brake hydraulic control system and fork truck

Abstract

The application discloses a parking brake hydraulic control system and a forklift truck, and the parking brake hydraulic control system is applied to a vehicle and comprises a parking brake, an oil port P1, a parking brake hydraulic oil path, a first electromagnetic switching valve and a flow control valve. The parking brake hydraulic oil path is connected with the oil port P1 and is used for supplying hydraulic oil to the parking brake or making the parking brake release pressure. The first electromagnetic switching valve is arranged in the parking brake hydraulic oil path and is used for switching the oil flow direction of the parking brake hydraulic oil path. The flow control valve is arranged in the parking brake hydraulic oil path and is located between the first electromagnetic switching valve and the parking brake, and is used for adjusting the pressure release flow of the parking brake when the vehicle is suddenly stopped. When the vehicle is suddenly stopped, the opening size of the flow control valve can be controlled before the first electromagnetic switching valve is switched, the flow control valve has a proper flow, the first electromagnetic switching valve is switched again, the parking brake is slowly released and reset, the parking brake is prevented from being directly locked after the vehicle is suddenly stopped, smooth parking is realized, and vehicle impact is avoided.

Description

Technical Field

[0001] This invention relates to the field of parking brake control technology, and more specifically, to a parking brake hydraulic control system. Furthermore, this invention also relates to a forklift truck including the aforementioned parking brake hydraulic control system. Background Technology

[0002] When vehicles such as high-lift forklifts are in motion, in case of an emergency, the driver will press the emergency stop button to shut down the vehicle's engine. At this time, all hydraulic pumps will stop supplying oil, which will cause the vehicle's parking brake to quickly reset and lock up when the vehicle is traveling at high speed, resulting in a large impact or even rollover of the vehicle, posing a significant safety hazard.

[0003] In the prior art, in order to avoid large impacts or rollovers during emergency braking, a check valve is added before the oil inlet line of the solenoid directional valve in the parking brake hydraulic circuit. In this way, when the hydraulic pump stops supplying oil, the check valve can be used to maintain pressure for a period of time. After the vehicle decelerates, the parking brake can be reset by switching the solenoid directional valve to release pressure.

[0004] However, by adding a check valve before the oil inlet line of the solenoid directional valve, although the delayed switching of the solenoid directional valve can effectively maintain a certain parking pressure and prevent the parking brake from locking up directly after pressing the emergency stop, it is still difficult to avoid vehicle impact at the moment of pressure relief after the solenoid directional valve switches.

[0005] In summary, how to avoid impact during emergency braking and at the moment of depressurization is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a parking brake hydraulic control system that can avoid impact during emergency braking of the vehicle and at the moment of depressurization.

[0007] Another objective of this invention is to provide a forklift truck that includes the above-mentioned parking brake hydraulic control system, which can ensure smooth parking during emergency stops and avoid vehicle impact.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A parking brake hydraulic control system, applied to a vehicle, includes:

[0010] Parking brake, which includes oil port P1;

[0011] The parking brake hydraulic circuit is connected to the oil port P1 and is used to supply hydraulic oil to the parking brake or to release pressure from the parking brake.

[0012] The first electromagnetic reversing valve is located in the parking brake hydraulic circuit and is used to switch the flow direction of the hydraulic fluid in the parking brake hydraulic circuit.

[0013] A flow control valve is provided in the parking brake hydraulic circuit and located between the first solenoid directional valve and the parking brake, and is used to adjust the pressure relief flow of the parking brake when the vehicle stops suddenly.

[0014] Optionally, it also includes a second solenoid directional valve, which is connected in parallel with the flow control valve, wherein the second solenoid directional valve is normally open and the flow control valve is normally closed.

[0015] Optionally, a pressure sensor is also included for real-time monitoring of the pressure at the oil port P1.

[0016] Optionally, the pressure sensor is connected to a controller, which is also connected to the flow control valve and a speed sensor. The speed sensor is used to detect the vehicle's travel speed, and the controller is used to control and adjust the opening of the flow control valve according to the vehicle's travel speed and the pressure at the oil port P1 when the vehicle stops suddenly.

[0017] Optionally, when the vehicle stops suddenly, after the first solenoid directional valve switches positions and the second solenoid directional valve closes, the controller delays for a preset time and then controls and adjusts the opening of the flow control valve.

[0018] Optionally, the flow control valve includes an electro-proportional flow valve or a servo valve.

[0019] Optionally, the first solenoid directional valve includes a switching valve, a proportional valve, or a servo valve; and / or, the second solenoid directional valve includes a switching valve, a proportional valve, or a servo valve.

[0020] Optionally, the parking brake hydraulic circuit includes:

[0021] A hydraulic pump used to provide a hydraulic power source is connected to a prime mover;

[0022] The oil inlet circuit has one end connected to the outlet of the hydraulic pump and the other end connected to the oil inlet P of the first solenoid directional valve.

[0023] The return oil circuit has one end connected to the hydraulic oil tank and the other end connected to the return oil port T of the first solenoid directional valve.

[0024] A connecting oil circuit is provided between the working oil port A of the first electromagnetic directional valve and the oil port P1, and the flow control valve is located in the connecting oil circuit.

[0025] Optionally, an overflow valve is connected between the outlet of the hydraulic pump and the hydraulic oil tank.

[0026] A forklift truck, including any of the above-mentioned parking brake hydraulic control systems.

[0027] The parking brake hydraulic control system provided by this invention, during normal vehicle operation, when the driver applies an emergency stop and the vehicle engine shuts off, can adjust the opening of the flow control valve to ensure a suitable flow rate before the first solenoid directional valve switches positions. Then, the first solenoid directional valve switches, allowing the parking brake hydraulic circuit to release pressure from the parking brake. This allows the parking brake to slowly release pressure and reset, preventing it from locking up immediately after an emergency stop, thus achieving smooth parking and avoiding vehicle-wide impact. In other words, even at the moment of pressure release after the first solenoid directional valve switches, vehicle impact can be avoided. Therefore, this parking brake hydraulic control system can prevent impact during emergency braking and also prevents impact at the moment of pressure release.

[0028] The forklift provided by the present invention includes the above-mentioned parking brake hydraulic control system, which has the above-mentioned beneficial effects, and can ensure smooth parking during emergency stops and avoid vehicle impact. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 The control principle diagram of the parking brake hydraulic control system provided in a specific embodiment of the present invention is shown.

[0031] Figure 1 The accompanying figure labels are as follows:

[0032] 1 is the parking brake, 2 is the first solenoid directional valve, 3 is the flow control valve, 4 is the second solenoid directional valve, 5 is the pressure sensor, 6 is the hydraulic pump, 7 is the prime mover, 8 is the oil inlet circuit, 9 is the oil return circuit, 10 is the hydraulic oil tank, 11 is the connecting oil circuit, 12 is the relief valve, and 13 is the preset drive oil circuit. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The core of this invention is to provide a parking brake hydraulic control system that can prevent impacts during emergency braking and at the moment of pressure release. Another core aspect of this invention is to provide a forklift truck including the aforementioned parking brake hydraulic control system, which can ensure smooth parking during emergency stops and prevent vehicle impacts.

[0035] Please refer to Figure 1 This is a control principle diagram of the parking brake hydraulic control system provided in a specific embodiment of the present invention.

[0036] This invention provides a parking brake hydraulic control system for use in vehicles. The system includes a parking brake 1, a parking brake hydraulic circuit, a first electromagnetic directional valve 2, and a flow control valve 3. The parking brake 1 includes an oil port P1. The parking brake hydraulic circuit is connected to the oil port P1 and is used to supply hydraulic oil to the parking brake 1 or to release pressure from the parking brake 1. The first electromagnetic directional valve 2 is located in the parking brake hydraulic circuit and is used to switch the flow direction of the hydraulic fluid in the parking brake circuit. The flow control valve 3 is located in the parking brake hydraulic circuit and between the first electromagnetic directional valve 2 and the parking brake 1, and is used to adjust the pressure release flow of the parking brake 1 when the vehicle stops suddenly.

[0037] Understandably, when the vehicle is moving normally, the hydraulic oil in the parking brake hydraulic circuit supplies hydraulic oil to the oil port P1 of the parking brake 1 through the first solenoid directional valve 2 and the flow control valve 3. Under the action of the hydraulic oil, the parking brake 1 is in an unlocked state to meet the requirements for normal vehicle movement. It should be noted that under this operating condition, the flow control valve 3 can be controlled to the maximum flow rate so that the hydraulic oil supplied by the parking brake hydraulic circuit can flow quickly into the oil port P1 of the parking brake 1, ensuring that the parking brake 1 is quickly unlocked when the vehicle begins to move.

[0038] During normal vehicle operation, when the driver applies an emergency stop to shut off the engine, the opening of the flow control valve 3 can be adjusted to provide a suitable flow rate before the first solenoid directional valve 2 switches positions. Then, the first solenoid directional valve 2 switches, allowing the parking brake hydraulic circuit to release pressure from the parking brake 1. This allows the parking brake 1 to slowly depressurize and reset, preventing it from locking up immediately after the emergency stop and ensuring smooth parking. This avoids a vehicle-wide impact, meaning that even at the moment of pressure release after the first solenoid directional valve 2 switches, a vehicle impact can be avoided. Therefore, this parking brake hydraulic control system can prevent impact during emergency braking and also prevents impact at the moment of pressure release.

[0039] Additionally, it is understandable that during normal vehicle movement, when the vehicle comes to a normal stop, the first solenoid directional valve 2 switches positions, causing the hydraulic oil in the parking brake 1 to be depressurized through the parking brake hydraulic circuit. At this time, under the action of the spring in the parking brake 1, the parking brake function is achieved. It should be noted that under this operating condition, the flow control valve 3 can be controlled to be at its maximum flow rate to allow the hydraulic oil in the parking brake 1 to be depressurized quickly, achieving rapid parking braking during normal parking.

[0040] It should be noted that in order to enable the parking brake 1 to unlock quickly when the vehicle starts to move and to achieve rapid parking braking when the vehicle is parked normally, it is necessary to ensure that the flow control valve 3 has a sufficiently large flow capacity when it is at its maximum flow rate.

[0041] Furthermore, for ease of control, in some embodiments, a second solenoid directional valve 4 is also included. The second solenoid directional valve 4 is connected in parallel with the flow control valve 3. The second solenoid directional valve 4 is normally open, and the flow control valve 3 is normally closed.

[0042] It is understandable that normal vehicle movement and parking are the norm, while emergency stops are relatively infrequent. Therefore, this embodiment adds a second solenoid directional valve 4, which is normally open while the flow control valve 3 is normally closed. This ensures that during normal vehicle movement and parking, the oil circuit between the first solenoid directional valve 2 and the oil port P1 is connected via the second solenoid directional valve 4. In other words, regardless of whether the vehicle is in normal driving or parking conditions, the second solenoid directional valve 4 is always open, and the flow control valve 3 is always closed and does not operate. This avoids the need to adjust the flow control valve 3 during normal vehicle movement and parking, facilitating control. Simultaneously, it enables rapid unlocking of the parking brake 1 and rapid parking braking, meeting the normal usage requirements of the vehicle. When the driver applies the emergency stop button, the second solenoid directional valve 4 closes and the flow control valve 3 opens. The oil circuit between the first solenoid directional valve 2 and the oil port P1 is connected through the flow control valve 3. When the vehicle stops suddenly, the pressure relief flow of the parking brake 1 is adjusted by regulating the opening of the flow control valve 3, so that the oil port P1 of the parking brake 1 is slowly depressurized, thereby achieving smooth parking when applying the emergency stop button.

[0043] Specifically, when the vehicle is moving normally, the first solenoid directional valve 2 is open and the second solenoid directional valve 4 is in the open state. The hydraulic oil in the parking brake hydraulic circuit is supplied to the oil port P1 of the parking brake 1 through the first solenoid directional valve 2 and the second solenoid directional valve 4. Under the action of the hydraulic oil, the parking brake 1 is in the unlocked state to meet the requirements of normal vehicle movement.

[0044] When the vehicle stops normally, the first solenoid directional valve 2 switches positions, while the second solenoid directional valve 4 remains open. The hydraulic oil in the parking brake 1 flows out from the oil port P1 and is depressurized through the parking brake hydraulic oil circuit. During the depressurization process, the hydraulic oil passes through the second solenoid directional valve 4 and the first solenoid directional valve 2 in sequence. At this time, the parking brake function is realized under the action of the spring in the parking brake 1.

[0045] When the driver applies the emergency stop button and shuts off the vehicle's engine, the first solenoid directional valve 2 switches positions, and the second solenoid directional valve 4 closes. At this time, because the flow control valve 3 is in the closed state, the oil port P1 of the parking brake 1 can maintain pressure, preventing the parking brake 1 from locking up directly at high speeds. Then, by controlling and adjusting the opening of the flow control valve 3, a suitable flow rate can be achieved, allowing the oil port P1 of the parking brake 1 to slowly release pressure, thus achieving smooth parking during an emergency stop and preventing vehicle impact and rollover.

[0046] In addition, in order to monitor the pressure of the oil port P1 of the parking brake 1 in real time, in some embodiments, the parking brake hydraulic control system further includes a pressure sensor 5 for monitoring the pressure of the oil port P1 in real time. That is, this embodiment adds a pressure sensor 5 to monitor the pressure of the oil port P1 of the parking brake 1 in real time, so as to adjust the opening of the flow control valve 3 according to the pressure of the oil port P1 of the parking brake 1.

[0047] Furthermore, in some embodiments, the pressure sensor 5 is connected to a controller, which is also connected to the flow control valve 3 and the speed sensor. The speed sensor is used to detect the vehicle's travel speed, and the controller is used to control and adjust the opening of the flow control valve 3 according to the vehicle's travel speed and the pressure at the oil port P1 when the vehicle stops suddenly.

[0048] During operation, pressure sensor 5 collects and monitors the pressure of port P1 of parking brake 1 and sends the pressure of port P1 of parking brake 1 to the controller; speed sensor collects and monitors the vehicle's travel speed and sends the vehicle's travel speed to the controller; after receiving the pressure of port P1 and the vehicle's travel speed, the controller sends a control signal to the flow control valve 3 according to the pressure of port P1 and the vehicle's travel speed, and controls the real-time adjustment of the opening of the flow control valve 3, so that the pressure of port P1 of parking brake 1 is slowly released, so as to achieve smooth parking when emergency stops are made at different vehicle speeds.

[0049] Furthermore, in some embodiments, when the vehicle comes to an emergency stop, after the first solenoid directional valve 2 switches positions and the second solenoid directional valve 4 closes, the controller delays for a preset time before controlling the opening of the flow control valve 3. That is, when the first solenoid directional valve 2 switches positions and the second solenoid directional valve 4 closes, the flow control valve 3 is normally closed. The parking brake hydraulic control system maintains pressure for a preset time to prevent the parking brake 1 from locking up directly at high speeds. After the parking brake hydraulic control system maintains pressure for the preset time, the controller then controls the flow control valve 3 to open to a certain degree, allowing the oil port P1 of the parking brake 1 to slowly release pressure, achieving smooth parking and preventing vehicle impact and rollover.

[0050] It should be noted that this embodiment does not specifically limit the value of the preset delay time. In some embodiments, the preset time is 1 to 5 seconds. That is, when the first electromagnetic reversing valve 2 switches positions and the second electromagnetic reversing valve 4 closes, the controller delays for 1 to 5 seconds before controlling the opening of the flow control valve 3.

[0051] It should be noted that in the above embodiments, the type of flow control valve 3 is not specifically limited, as long as it can achieve flow regulation.

[0052] In some embodiments, the flow control valve 3 includes an electro-proportional flow valve or a servo valve.

[0053] Furthermore, in the above embodiments, the types of the first electromagnetic reversing valve 2 and / or the second electromagnetic reversing valve 4 are not specifically limited, as long as they can achieve the corresponding functions of the first electromagnetic reversing valve 2 and the second electromagnetic reversing valve 4.

[0054] In some embodiments, the first electromagnetic directional valve 2 includes a switching valve, a proportional valve, or a servo valve.

[0055] In some embodiments, the second electromagnetic directional valve 4 includes a switching valve, a proportional valve, or a servo valve.

[0056] In addition, the first solenoid directional valve 2 can be a two-position valve or a three-position valve; it can also be a three-way valve or a four-way valve. The second solenoid directional valve 4 can be a two-position valve or a three-position valve.

[0057] It should be noted that the above embodiments do not limit the specific composition of the parking brake hydraulic circuit, as long as the parking brake hydraulic circuit can provide hydraulic oil with stable pressure and return oil.

[0058] In some embodiments, the parking brake hydraulic circuit includes a hydraulic pump 6, a prime mover 7, an oil inlet circuit 8, an oil return circuit 9, and a connecting circuit 11. The hydraulic pump 6 provides a hydraulic power source and is connected to the prime mover 7. One end of the oil inlet circuit 8 is connected to the outlet of the hydraulic pump 6, and the other end is connected to the oil inlet P of the first solenoid directional valve 2. One end of the oil return circuit 9 is connected to the hydraulic oil tank 10, and the other end is connected to the oil return T of the first solenoid directional valve 2. The connecting circuit 11 is connected between the working oil port A and the oil port P1 of the first solenoid directional valve 2, and the flow control valve 3 is located in the connecting circuit 11.

[0059] It should be noted that this embodiment does not limit the type of hydraulic pump 6. For example, hydraulic pump 6 can be a fixed displacement pump or a variable displacement pump.

[0060] In some embodiments, the outlet of the hydraulic pump 6 is also connected to a preset drive oil circuit 13, which is used to supply oil to preset actuators. That is, the hydraulic pump 6 can supply hydraulic oil not only to the parking brake hydraulic circuit, but also to other preset actuators.

[0061] In some embodiments, an overflow valve 12 is connected between the outlet of the hydraulic pump 6 and the hydraulic oil tank 10. The overflow valve 12 can adjust the maximum pressure output by the hydraulic pump 6 to the parking brake hydraulic circuit to ensure the safety of the parking brake hydraulic control system.

[0062] In addition to the parking brake hydraulic control system described above, the present invention also provides a forklift truck including the parking brake hydraulic control system disclosed in the above embodiments. The structure of other parts of the forklift truck is described in the prior art and will not be repeated here.

[0063] It should also be noted that, in this specification, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0064] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0065] The parking brake hydraulic control system and forklift provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A parking brake hydraulic control system, applied to a vehicle, characterized in that, include: Parking brake (1), which includes oil port P1; The parking brake hydraulic circuit is connected to the oil port P1 and is used to supply hydraulic oil to the parking brake (1) or to depressurize the parking brake (1). The first electromagnetic reversing valve (2) is located in the parking brake hydraulic circuit and is used to switch the flow direction of the hydraulic fluid in the parking brake hydraulic circuit; the first electromagnetic reversing valve (2) includes a switching valve, a proportional valve or a servo valve. A flow control valve (3) is provided in the parking brake hydraulic circuit and located between the first electromagnetic reversing valve (2) and the parking brake (1), and is used to adjust the pressure relief flow of the parking brake (1) when the vehicle stops suddenly. It also includes a second electromagnetic reversing valve (4), which is connected in parallel with the flow control valve (3). The second electromagnetic reversing valve (4) is normally open, and the flow control valve (3) is normally closed. It also includes a pressure sensor (5) for real-time monitoring of the pressure at the oil port P1; The pressure sensor (5) is connected to a controller, which is also connected to the flow control valve (3) and a speed sensor. The speed sensor is used to detect the vehicle's travel speed, and the controller is used to control and adjust the opening of the flow control valve (3) according to the vehicle's travel speed and the pressure of the oil port P1 when the vehicle stops suddenly.

2. The parking brake hydraulic control system according to claim 1, characterized in that, When the vehicle comes to an emergency stop, after the first electromagnetic reversing valve (2) switches positions and the second electromagnetic reversing valve (4) closes, the controller delays for a preset time and then controls and adjusts the opening of the flow control valve (3).

3. The parking brake hydraulic control system according to claim 1 or 2, characterized in that, The flow control valve (3) includes an electro-proportional flow valve or a servo valve.

4. The parking brake hydraulic control system according to claim 1 or 2, characterized in that, The second electromagnetic directional valve (4) includes a switching valve, a proportional valve, or a servo valve.

5. The parking brake hydraulic control system according to claim 1 or 2, characterized in that, The parking brake hydraulic circuit includes: A hydraulic pump (6) is used to provide a hydraulic power source, and a prime mover (7) is connected to it. The oil inlet (8) is connected at one end to the outlet of the hydraulic pump (6) and at the other end to the oil inlet P of the first solenoid directional valve (2). The return oil circuit (9) has one end connected to the hydraulic oil tank (10) and the other end connected to the return oil port T of the first solenoid directional valve (2); The connecting oil circuit (11) is connected between the working oil port A of the first electromagnetic reversing valve (2) and the oil port P1, and the flow control valve (3) is located in the connecting oil circuit (11).

6. The parking brake hydraulic control system according to claim 5, characterized in that, An overflow valve (12) is connected between the outlet of the hydraulic pump (6) and the hydraulic oil tank (10).

7. A forklift truck, characterized in that, The parking brake hydraulic control system as described in any one of claims 1-6.

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