Electronic emergency braking system for tractors

Abstract

The present application relates to a kind of tractor electronic emergency braking systems, belong to tractor field.It includes: proportional pressure reducing valve, first reversing valve, parking brake cylinder and finger switch, the first reversing valve, the proportional pressure reducing valve and the parking brake cylinder are sequentially communicated, the finger switch is connected with the proportional pressure reducing valve, and its pressing stroke and the electromagnetic valve current size of the proportional pressure reducing valve are linear relationship.The present application adopts electronic emergency braking, and proportional pressure reducing valve is used to realize controllable braking force, avoid brake lock phenomenon occurs, improve safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tractors, in particular to a tractor electronic emergency braking system. BACKGROUND

[0002] At present, the auxiliary emergency braking on the tractor is mostly hand brake braking, that is to say, if the service brake (i.e. foot brake) of the tractor is invalid or fails, the tractor can be slowed down by slowly pulling up the hand brake.

[0003] However, the operation of the hand brake needs to be very cautious, and needs to avoid the tractor from skidding and overturning due to the instant locking of the wheels caused by the hand brake being pulled up too quickly. However, the actual operation process of the hand brake is often not ideal, and the operation of the hand brake by the tractor driver is often not stable. In addition, when the service brake of the tractor is invalid or fails, the tractor driver is prone to nervousness, and is more likely to pull up the hand brake too quickly. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a tractor electronic emergency braking system, which adopts electronic emergency braking, realizes controllable braking force through a proportional pressure reducing valve, avoids the occurrence of brake locking phenomenon, and improves safety.

[0005] The technical scheme for solving the above technical problem is as follows: a tractor electronic emergency braking system, comprising: a proportional pressure reducing valve, a first reversing valve, a parking brake oil cylinder and a finger switch, the first reversing valve, the proportional pressure reducing valve and the parking brake oil cylinder are sequentially communicated, the finger switch is connected with the proportional pressure reducing valve, and the pressing stroke of the finger switch is in linear relationship with the electromagnetic valve current size of the proportional pressure reducing valve.

[0006] The beneficial effects of the present application are as follows: the finger switch is connected with the proportional pressure reducing valve, and the pressing stroke of the finger switch is in linear relationship with the electromagnetic valve current size of the proportional pressure reducing valve, which is conducive to adjusting the electromagnetic force of the proportional pressure reducing valve through the pressing stroke of the finger switch, thereby adjusting the valve core position of the proportional pressure reducing valve, and further adjusting the speed of the hydraulic oil backflow in the parking brake oil cylinder, so as to brake and adjust the tractor when the service brake of the tractor is invalid or fails during driving, avoid the occurrence of brake locking phenomenon, and improve safety.

[0007] On the basis of the above technical scheme, the present application can also be improved as follows.

[0008] Further, the first oil port of the proportional pressure reducing valve is communicated with the parking brake oil cylinder, and the first oil port of the proportional pressure reducing valve is communicated with the first valve cavity of the proportional pressure reducing valve through an oil path, the second oil port of the proportional pressure reducing valve is communicated with the first oil port of the first reversing valve, and the third oil port of the proportional pressure reducing valve is communicated with an oil tank;

[0009] Pressing the finger switch causes the valve core of the proportional pressure reducing valve to switch to a flow rate that gradually increases in the communication channel between the first and third ports of the proportional pressure reducing valve, and the flow rate that gradually decreases in the communication channel between the first and second ports of the proportional pressure reducing valve, under the combined force of the electromagnetic force F13 generated by the finger switch, the hydraulic pressure F11 generated by the oil filling the first valve chamber of the proportional pressure reducing valve, and the spring force F12 of the proportional pressure reducing valve. Alternatively, releasing the finger switch causes the valve core of the proportional pressure reducing valve to switch to a flow rate that gradually decreases in the communication channel between the first and third ports of the proportional pressure reducing valve, and the flow rate that gradually increases in the communication channel between the first and second ports of the proportional pressure reducing valve, under the combined force of the electromagnetic force F13 generated by the finger switch, the hydraulic pressure F11 generated by the oil filling the first valve chamber of the proportional pressure reducing valve, and the spring force F12 of the proportional pressure reducing valve.

[0010] The beneficial effects of adopting the above-mentioned further solution are: it helps to adjust the braking force of the tractor through the electromagnetic force F13 generated by the finger switch, avoids brake lock-up, and improves safety.

[0011] Furthermore, the first port of the first directional valve is connected to the second port of the proportional pressure reducing valve, the second port of the first directional valve is connected to the oil source, and the third port of the first directional valve is connected to the oil tank. The first directional valve can be switched to have its first port connected to its third port, or its first port connected to its second port.

[0012] The beneficial effect of adopting the above-mentioned further solution is that it is beneficial to regulate the energization and de-energization of the first directional valve through the tractor's electronic control unit, thereby regulating the flow of hydraulic oil into the proportional pressure reducing valve.

[0013] Furthermore, a filter and a third check valve are provided in the oil line between the oil source and the first directional valve to allow hydraulic oil to flow unidirectionally from the oil source to the first directional valve.

[0014] The beneficial effects of adopting the above-mentioned further solution are: the oil source facilitates the flow of hydraulic oil from the tractor hydraulic system into the electronic emergency braking system of this application, and the third check valve helps to prevent the hydraulic oil in the electronic emergency braking system of this application from flowing back into other hydraulic functional structures of the tractor hydraulic system.

[0015] Further, the hydraulic system further comprises an overflow valve and a first accumulator, the first accumulator is communicated with an oil passage between the third check valve and the filter, the first accumulator is communicated with the overflow valve, an oil passage between the oil source and the third check valve is communicated with a load sensing oil passage and a load sensing interface of a variable plunger pump, an inlet end of the overflow valve is communicated with the load sensing oil passage, and an outlet end of the overflow valve is communicated with the oil tank, and a throttle valve is arranged on the load sensing oil passage.

[0016] The beneficial effect of the above further scheme is that the position of the first accumulator is beneficial to avoid the influence of the first accumulator on the pressure F23 generated by the load sensing oil passage, the first accumulator is communicated with the overflow valve, and the first accumulator is beneficial to generate the accumulator pressure F21; the overflow valve is beneficial to ensure the stable energy storage of the first accumulator, and the first accumulator is beneficial to provide hydraulic pressure for the parking brake cylinder.

[0017] Further, the sum of the accumulator pressure F21 generated by the first accumulator and the pressure F23 generated by the load sensing oil passage is greater than or less than the spring force F22 of the overflow valve, so that the overflow valve is opened or closed.

[0018] The beneficial effect of the above further scheme is that the overflow valve is beneficial to realize the stable energy storage of the first accumulator by being continuously opened or closed, and ensure the stability of the first accumulator during work.

[0019] Further, the first accumulator is connected with a pressure sensor for detecting the pressure value of the first accumulator.

[0020] The beneficial effect of the above further scheme is that the pressure sensor is beneficial to provide a signal for the driver to monitor the pressure value of the first accumulator in real time.

[0021] Further, the hydraulic system further comprises a service brake assembly, the service brake assembly comprises a service brake valve, a service brake cylinder and a second accumulator, the oil source, the third check valve, the service brake valve and the service brake cylinder are communicated in sequence, an oil passage between the third check valve and the service brake valve is provided with a second check valve for allowing hydraulic oil to flow from the third check valve to the service brake valve in one direction, and the second accumulator is arranged on an oil passage between the second check valve and the service brake valve.

[0022] The beneficial effect of the above further scheme is that the cooperation of the second accumulator, the service brake valve and the service brake cylinder is beneficial to realize service braking during driving.

[0023] Further, the vehicle braking assembly further comprises a service brake assembly, the service brake assembly comprises a service brake valve and a second accumulator, the oil source, the third check valve and the service brake valve are sequentially communicated, a second check valve allowing hydraulic oil to flow from the third check valve to the service brake valve in one direction is arranged on an oil passage between the third check valve and the service brake valve, the second accumulator is arranged on an oil passage between the second check valve and the service brake valve, and the service brake valve is communicated with the parking brake cylinder.

[0024] The beneficial effect of the further scheme is that the cooperation of the second accumulator, the service brake valve and the parking brake cylinder is conducive to realizing service braking during driving.

[0025] Further, the vehicle braking assembly further comprises a second switching valve, a first oil port of the second switching valve is communicated with the proportional pressure reducing valve, a second oil port of the second switching valve is communicated with the first oil port of the first switching valve, the second switching valve can be switched to allow the first switching valve to be unidirectionally or bidirectionally communicated with the proportional pressure reducing valve, the first oil port of the second switching valve is further communicated with the parking brake cylinder through an oil passage, and a first check valve allowing hydraulic oil to flow from the parking brake cylinder to the first oil port of the second switching valve in one direction is arranged on an oil passage between the first oil port of the second switching valve and the parking brake cylinder.

[0026] The beneficial effect of the further scheme is that the second switching valve is conducive to realizing vehicle braking when the proportional pressure reducing valve fails or is invalid. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A hydraulic principle diagram provided for the embodiment one of the present application;

[0028] Figure 2 A hydraulic principle diagram provided for the embodiment two of the present application.

[0029] In the drawings, the components represented by the respective reference numerals are listed as follows:

[0030] 1, oil source; 2, oil tank; 3, second switching valve; 4, first check valve; 5, pressure sensor; 6, third check valve; 11, proportional pressure reducing valve; 12, first switching valve; 13, parking brake cylinder; 14, finger switch; 15, filter; 21, service brake valve; 22, service brake cylinder; 23, second accumulator; 24, second check valve; 31, overflow valve; 32, first accumulator; 33, variable plunger pump. DETAILED DESCRIPTION

[0031] The principles and features of the present application are described below, and the examples are only used to explain the present application, and are not used to limit the scope of the present application.

[0032] Embodiment one.

[0033] As Figure 1 shown, the embodiment provides a tractor electronic emergency braking system, comprising: a proportional pressure reducing valve 11, a first reversing valve 12, a parking brake oil cylinder 13 and a finger switch 14, the first reversing valve 12, the proportional pressure reducing valve 11 and the parking brake oil cylinder 13 are communicated in sequence, the finger switch 14 is connected with the proportional pressure reducing valve 11, and the pressing stroke of the finger switch 14 is in linear relationship with the electromagnetic valve current size of the proportional pressure reducing valve 11.

[0034] It should be noted that: in the embodiment, an electronic control unit (ECU) of the tractor is also included, the electronic control unit of the tractor is electrically connected with the first reversing valve 12 and the second reversing valve 3, and controls the power-on or power-off of the first reversing valve 12 and the second reversing valve 3;

[0035] The finger switch 14 is provided with a displacement sensor for detecting the pressing stroke of the finger switch 14, and the pressing stroke of the finger switch 14 is set to be proportional to the voltage in the electronic control unit of the tractor. The displacement sensor transmits the detected signal to the electronic control unit of the tractor, and the electronic control unit of the tractor outputs corresponding current to the electromagnetic valve of the proportional pressure reducing valve 11, so that the pressing stroke of the finger switch 14 is in proportional linear relationship with the electromagnetic valve current size of the proportional pressure reducing valve 11. This technology belongs to the prior art.

[0036] The beneficial effects of the embodiment are: the finger switch is connected with the proportional pressure reducing valve, and the pressing stroke of the finger switch is in linear relationship with the electromagnetic valve current size of the proportional pressure reducing valve, which is conducive to adjusting the electromagnetic force of the proportional pressure reducing valve through the pressing stroke of the finger switch, thereby adjusting the valve core position of the proportional pressure reducing valve, and further adjusting the speed of the hydraulic oil backflow in the parking brake oil cylinder, so as to brake and adjust the tractor when the service brake fails or fails during the driving process of the tractor, avoid brake lock phenomenon, and improve safety.

[0037] In fact, if the service brake of the tractor does not fail or fail during the driving process, the finger switch 14 in the electronic emergency braking system of the present application can also realize the brake adjustment of the tractor.

[0038] As Figure 1 shown, the first oil port of the proportional pressure reducing valve 11 is communicated with the parking brake oil cylinder 13, and the first oil port of the proportional pressure reducing valve 11 is communicated with the first valve cavity of the proportional pressure reducing valve 11 through an oil path, the second oil port of the proportional pressure reducing valve 11 is communicated with the first oil port of the first reversing valve 12, and the third oil port of the proportional pressure reducing valve 11 is communicated with the oil tank 2;

[0039] When the finger switch 14 is pressed, the spool of the proportional pressure reducing valve 11 switches to a flow gradually increasing in the communication passage between the first oil port and the third oil port of the proportional pressure reducing valve 11 and a flow gradually decreasing in the communication passage between the first oil port and the second oil port of the proportional pressure reducing valve 11 under the combined action of the electromagnetic force F13 generated by the finger switch 14, the hydraulic pressure F11 generated by the first valve cavity of the proportional pressure reducing valve 11 being filled with oil, and the spring force F12 of the proportional pressure reducing valve 11, or when the finger switch 14 is released, the spool of the proportional pressure reducing valve 11 switches to a flow gradually decreasing in the communication passage between the first oil port and the third oil port of the proportional pressure reducing valve 11 and a flow gradually increasing in the communication passage between the first oil port and the second oil port of the proportional pressure reducing valve 11 under the combined action of the electromagnetic force F13 generated by the finger switch 14, the hydraulic pressure F11 generated by the first valve cavity of the proportional pressure reducing valve 11 being filled with oil, and the spring force F12 of the proportional pressure reducing valve 11.

[0040] It should be noted that, in the present embodiment, as shown in Figure 1 The first valve cavity of the proportional pressure reducing valve 11 is located at one end of the spool of the proportional pressure reducing valve 11, i.e., at the end of the proportional pressure reducing valve 11 close to the finger switch 14, and the second valve cavity of the proportional pressure reducing valve 11 is located at the other end of the spool of the proportional pressure reducing valve 11, i.e., at the end of the proportional pressure reducing valve 11 close to the spring generating the spring force F12.

[0041] The first reversing valve 12 is powered to switch its spool from the first valve position to the second valve position, and the hydraulic oil flows through the second valve position of the first reversing valve 12 to the second valve position of the proportional pressure reducing valve 11 in the initial state, and then flows out of the second valve position of the proportional pressure reducing valve 11 to the parking brake oil cylinder 13 and to the first valve cavity of the proportional pressure reducing valve 11. The first valve cavity of the proportional pressure reducing valve 11 is filled with hydraulic oil to generate hydraulic pressure, that is, the hydraulic pressure F11 generated by the first valve cavity of the proportional pressure reducing valve 11 gradually increases from 0 to equal the spring force F12 of the proportional pressure reducing valve 11. In this process, the proportional pressure reducing valve 11 gradually switches from the second valve position to the first valve position, but does not completely switch to the first valve position, but allows hydraulic oil to enter the first valve position and the second valve position of the proportional pressure reducing valve 11 at the same time, and the flow rate of the hydraulic oil entering the second valve position of the proportional pressure reducing valve 11 gradually decreases. However, since the hydraulic oil entering the first valve position of the proportional pressure reducing valve 11 is blocked, the hydraulic oil cannot enter the first valve position of the proportional pressure reducing valve 11 from the first reversing valve 12, but instead the hydraulic oil in the parking brake oil cylinder 13 flows back through the first valve position of the proportional pressure reducing valve 11 and flows to the oil tank 2. Therefore, as F11 gradually increases, the hydraulic oil flowing through the second valve position of the proportional pressure reducing valve 11 to the parking brake oil cylinder 13 and the hydraulic oil flowing through the first valve position of the proportional pressure reducing valve 11 to the oil tank 2 are relatively balanced, and a balanced state is maintained when F11 is equal to F12, so that the proportional pressure reducing valve 11 maintains a stable pressure. As for the parking brake oil cylinder 13, the brake piston rod continuously compresses the brake spring to a stable state (i.e., the piston hydraulic pressure of the parking brake oil cylinder 13 is equal to the spring force) during the process of gradually filling the hydraulic oil to a stable hydraulic pressure, and the brake piston rod is retracted to release the parking brake, so that the tractor can start normally.

[0042] Pressing the finger switch 14 will generate electromagnetic force F13, and as the pressing stroke of the finger switch 14 gradually increases, the electromagnetic force F13 also gradually increases, and under the balance condition that F11 is equal to F12, the gradual increase of F13 will destroy this balance state, so that the proportional pressure reducing valve 11 is further switched to the first valve position, that is, the hydraulic oil flowing through the second valve position of the proportional pressure reducing valve 11 and then flowing to the parking brake oil cylinder 13 is further reduced, and the hydraulic oil flowing through the first valve position of the proportional pressure reducing valve 11 and then flowing to the oil tank 2 is further increased, so that in this process, the hydraulic oil in the parking brake oil cylinder 13 gradually decreases, and the brake piston rod inside it is gradually pushed out to achieve braking, that is, braking during driving is achieved by pressing the finger switch 14, and according to different pressing strokes of the finger switch 14, different braking deceleration can be achieved. When the finger switch 14 is pressed to the maximum stroke, the proportional pressure reducing valve 11 is completely switched to the first valve position, and the hydraulic oil no longer enters the parking brake oil cylinder 13 through the proportional pressure reducing valve 11, but the hydraulic oil in the parking brake oil cylinder 13 completely returns to the oil tank 2 through the first valve position of the proportional pressure reducing valve 11, and the brake piston rod inside the parking brake oil cylinder 13 is completely pushed out to achieve braking;

[0043] Before pressing the finger switch 14, F11 has gradually increased from 0 to equal F12;

[0044] At this moment when the finger switch 14 is pressed, the sum of F13 and F11 is greater than F12;

[0045] During the pressing process of the finger switch 14, F13 gradually increases, F12 also increases due to the compression of the spring of the proportional pressure reducing valve 11, and F11 gradually decreases due to the continuous return of the hydraulic oil in the parking brake oil cylinder 13 and the valve cavity of the proportional pressure reducing valve 11, but the sum of F13 and F11 is still greater than F12, so that under the action of the resultant force of F13, F11 and F12, the flow rate in the communication passage between the first oil port and the third oil port of the proportional pressure reducing valve 11 gradually increases, and the flow rate in the communication passage between the first oil port and the second oil port of the proportional pressure reducing valve 11 gradually decreases, that is, the above-mentioned "the proportional pressure reducing valve 11 is further switched to the first valve position, that is, the hydraulic oil flowing through the second valve position of the proportional pressure reducing valve 11 and then flowing to the parking brake oil cylinder 13 is further reduced, and the hydraulic oil flowing through the first valve position of the proportional pressure reducing valve 11 and then flowing to the oil tank 2 is further increased";

[0046] When the finger switch 14 is pressed and kept in a stable stroke, F13 increases to a constant value, F11 decreases to a constant value due to the increase of the hydraulic oil return flow in the parking brake cylinder 13 and the valve cavity of the proportional pressure reducing valve 11, and F12 also increases to a constant value due to the stable compression of the spring of the proportional pressure reducing valve 11, so that the sum of F13 and F11 is equal to F12 again, and the balance state is reached again;

[0047] If the finger switch 14 is pressed to the maximum stroke, F13 reaches the maximum value, F12 reaches the maximum value due to the maximum compression of the spring of the proportional pressure reducing valve 11, and F11 is almost 0 due to the complete return of the hydraulic oil in the parking brake cylinder 13 and the valve cavity of the proportional pressure reducing valve 11;

[0048] After the finger switch 14 is released, F13 gradually decreases from the maximum value to 0, F12 gradually decreases from the maximum value, and F11 gradually increases from 0, until the balance state is reached again, i.e. F13 is 0 and F11 is equal to F12, so that the proportional pressure reducing valve 11 is switched to the state that the flow in the communication passage between the first oil port and the third oil port of the proportional pressure reducing valve 11 gradually decreases, and the flow in the communication passage between the first oil port and the second oil port of the proportional pressure reducing valve 11 gradually increases, that is, the hydraulic oil flowing through the second valve position of the proportional pressure reducing valve 11 and then flowing to the parking brake cylinder 13 is further increased, and the hydraulic oil flowing through the first valve position of the proportional pressure reducing valve 11 and then flowing to the tank 2 is further reduced;

[0049] In addition, in order to avoid vehicle braking caused by accidental touch or jolt, the finger switch 14 has an idle stroke, that is, pressing the finger switch 14 will not generate electromagnetic force F13 in the idle stroke.

[0050] The electromagnetic force F13 generated by the finger switch is beneficial to adjust the braking force of the tractor, avoid brake lock phenomenon, and improve safety.

[0051] As shown in Figure 1 The first oil port of the first directional valve 12 is in communication with the second oil port of the proportional pressure reducing valve 11, the second oil port of the first directional valve 12 is in communication with the oil source 1, and the third oil port of the first directional valve 12 is in communication with the tank 2. The first directional valve 12 can be switched to the state that the first oil port is in communication with the third oil port, or the first oil port is in communication with the second oil port.

[0052] The power-on and power-off of the first directional valve are beneficial to be controlled by the electronic control unit of the tractor, so as to adjust the hydraulic oil on-off of the proportional pressure reducing valve.

[0053] As shown in Figure 1As shown, a filter 15 and a third one-way valve 6 are arranged on the oil path between the oil source 1 and the first reversing valve 12, and hydraulic oil flows from the oil source 1 to the first reversing valve 12 in one direction.

[0054] The oil source is beneficial to make hydraulic oil in the tractor hydraulic system flow into the electronic emergency brake system of the application, and the third one-way valve is beneficial to avoid the backflow of hydraulic oil in the electronic emergency brake system of the application into other hydraulic functional structures of the tractor hydraulic system.

[0055] As shown in the figure, Figure 1 The first accumulator 32 is in communication with the oil path between the third one-way valve 6 and the filter 15, and the first accumulator 32 is in communication with the overflow valve 31. The oil path between the oil source 1 and the third one-way valve 6 is in communication with the load sensing oil path and the load sensing interface (LS) of the variable piston pump 33. The inlet end of the overflow valve 31 is in communication with the load sensing oil path, and the outlet end is in communication with the oil tank 2.

[0056] It should be noted that the first accumulator 32 is in communication with the oil path between the third one-way valve 6 and the filter 15, which means that the first accumulator 32 is in communication with the second oil port of the first reversing valve 12, so that the hydraulic oil in the first accumulator 32 can flow to the proportional pressure reducing valve 11 and the parking brake oil cylinder 13 through the second valve position of the first reversing valve 12 after the electric reversing.

[0057] The load sensing interface (LS) of the variable piston pump 33 can automatically adjust the hydraulic oil pressure input by the oil source 1 by sensing the pressure of the load sensing oil path.

[0058] The position of the first accumulator is beneficial to avoid the influence of the first accumulator on the pressure F23 generated by the load sensing oil path. The first accumulator is in communication with the overflow valve, which is beneficial to generate the accumulator pressure F21. The overflow valve is beneficial to ensure the stable energy storage of the first accumulator, and the first accumulator is beneficial to provide hydraulic pressure for the parking brake oil cylinder.

[0059] As shown in the figure, Figure 1 The sum of the accumulator pressure F21 generated by the first accumulator 32 and the pressure F23 generated by the load sensing oil path is greater than or less than the spring force F22 of the overflow valve 31, so that the overflow valve 31 is opened or closed.

[0060] It should be noted that in the present embodiment, hydraulic oil continuously flows from the oil source 1 to the first accumulator 32 and the load sensing oil circuit, and the accumulator pressure F21 generated by the first accumulator 32 and the pressure F23 generated by the load sensing oil circuit are continuously increased until the sum of F21 and F23 is greater than the spring force F22 of the overflow valve 31, at which time the overflow valve 31 is opened, and hydraulic oil flows through the overflow valve 31 to the oil tank 2. When the load sensing oil circuit is in communication with the oil tank 2, the pressure F23 generated by the load sensing oil circuit is reduced, and the sum of F21 and F23 is less than F22, so the overflow valve 31 is closed. Subsequently, as hydraulic oil continuously flows from the oil source 1 into the first accumulator 32 and the load sensing oil circuit, the accumulator pressure F21 generated by the first accumulator 32 continues to increase, and the pressure F23 generated by the load sensing oil circuit gradually increases again until the sum of F21 and F23 is greater than the spring force F22 of the overflow valve 31 again. The above process is continuously repeated until the accumulator pressure F21 generated by the first accumulator 32 reaches a preset target value (i.e., greater than or equal to the spring force F22 of the overflow valve 31), at which time the pressure F23 generated by the load sensing oil circuit is approximately 0, and the overflow valve 31 is opened;

[0061] In the working process, if the first accumulator 32 leaks or a brake is applied, the accumulator pressure F21 generated by the first accumulator 32 decreases, and the overflow valve 31 is closed. Subsequently, the pressure F23 generated by the load sensing oil circuit and the accumulator pressure F21 generated by the first accumulator 32 increase due to the continuous input of hydraulic oil from the oil source 1 until the sum of F21 and F23 is greater than F22 again, at which time the overflow valve 31 is opened, and hydraulic oil flows through the overflow valve 31 to the oil tank 2. When the load sensing oil circuit is in communication with the oil tank 2, the pressure F23 generated by the load sensing oil circuit is reduced, and the overflow valve 31 is closed. Subsequently, as hydraulic oil continuously flows from the oil source 1 into the first accumulator 32 and the load sensing oil circuit, the accumulator pressure F21 generated by the first accumulator 32 continues to increase, and the pressure F23 generated by the load sensing oil circuit gradually increases again until the sum of F21 and F23 is greater than the spring force F22 of the overflow valve 31 again. The above process is continuously repeated until the accumulator pressure F21 generated by the first accumulator 32 reaches a preset target value (i.e., greater than or equal to the spring force F22 of the overflow valve 31) again, at which time the pressure F23 generated by the load sensing oil circuit is approximately 0, and the overflow valve 31 is opened;

[0062] The throttle valve is arranged on the load-sensitive oil passage, and is beneficial to avoiding that the hydraulic oil input from the oil source 1 flows into the oil tank 2 through the load-sensitive oil passage in a large amount when the first accumulator 32 needs to be punched, so that the accumulator pressure F21 generated by the first accumulator 32 quickly reaches the preset target value.

[0063] The overflow valve is beneficial to realizing stable charging of the first accumulator by being continuously opened or closed, and ensuring stability of the first accumulator during operation.

[0064] As shown in Figure 1 The first accumulator 32 is connected with a pressure sensor 5 for detecting the pressure value of the first accumulator 32.

[0065] The pressure sensor is beneficial to providing a signal for the driver to monitor the pressure value of the first accumulator in real time.

[0066] As shown in Figure 1 The vehicle braking assembly comprises a vehicle braking valve 21, a vehicle braking oil cylinder 22 and a second accumulator 23. The oil source 1, the third one-way valve 6, the vehicle braking valve 21 and the vehicle braking oil cylinder 22 are sequentially communicated. A second one-way valve 24 is arranged on an oil passage between the third one-way valve 6 and the vehicle braking valve 21, and is beneficial to allowing hydraulic oil to flow from the third one-way valve 6 to the vehicle braking valve 21 in a one-way manner. The second accumulator 23 is arranged on an oil passage between the second one-way valve 24 and the vehicle braking valve 21.

[0067] It should be noted that, in the embodiment, the vehicle braking valve 21 cooperates with the vehicle braking oil cylinder 22 and the second accumulator 23 to realize vehicle braking, which belongs to the prior art, and thus the specific structure of the vehicle braking valve 21 is not shown, and the vehicle braking principle is not described.

[0068] The cooperation of the second accumulator, the vehicle braking valve and the vehicle braking oil cylinder is beneficial to realizing vehicle braking during driving.

[0069] As shown in Figure 1 The second reversing valve 3 is beneficial to allowing the first reversing valve 12 to be unidirectionally or bidirectionally guided to the proportional pressure-reducing valve 11. The first oil port of the second reversing valve 3 is also communicated with the parking brake oil cylinder 13 through an oil passage. A first one-way valve 4 is arranged on an oil passage between the first oil port of the second reversing valve 3 and the parking brake oil cylinder 13, and is beneficial to allowing hydraulic oil to flow from the parking brake oil cylinder 13 to the first oil port of the second reversing valve 3 in a one-way manner.

[0070] It should be noted that in the present embodiment, the first oil port of the second reversing valve 3 is in communication with the first oil port of the proportional pressure reducing valve 11, which is conducive to returning all the hydraulic oil in the valve cavity of the proportional pressure reducing valve 11 to the oil tank 2 through the second reversing valve 3.

[0071] When the proportional pressure reducing valve 11 fails or malfunctions, i.e. pressing the finger switch 14 still cannot achieve braking, the electronic control unit (ECU) of the tractor will intervene (the judgment condition is that the finger switch 14 reaches the maximum value of the stroke for a period of time, i.e. the displacement sensor for detecting the pressing stroke of the finger switch 14 detects that the pressing stroke of the finger switch 14 is the maximum value and continuously generates a signal for a period of time, still cannot achieve braking, and this period of time can be set according to the actual situation), controls the second reversing valve 3 to switch to the second valve position with power on, and the first reversing valve 12 to switch to the first valve position with power off. At this time, the external hydraulic oil is blocked in the first valve position of the first reversing valve 12, the hydraulic oil in the proportional pressure reducing valve 11 and the parking brake oil cylinder 13 all flow to the second valve position of the second reversing valve 3 through the first one-way valve 4, and then flow to the passage in the first valve position of the first reversing valve 12 (i.e. the passage when the first oil port of the first reversing valve 12 is in communication with the third oil port) along the passage in the second valve position of the second reversing valve 3. Finally, the hydraulic oil flows to the oil tank 2 after passing through the passage in the first valve position of the first reversing valve 12, realizing the return and pressure relief of the parking brake oil cylinder 13. Then the brake piston rod in the parking brake oil cylinder 13 is pushed out under the spring force rebounding action in the parking brake oil cylinder 13, realizing braking.

[0072] In the above technical solution, when the second reversing valve 3 switches to make the first reversing valve 12 to the proportional pressure reducing valve 11 one-way conductive, it is realized by the one-way valve in the first valve position of the second reversing valve 3, which can make the hydraulic oil one-way flow from the second valve position of the first reversing valve 12 to the proportional pressure reducing valve 11.

[0073] The second reversing valve is conducive to realizing vehicle braking when the proportional pressure reducing valve fails or malfunctions.

[0074] Embodiment two.

[0075] As shown in Figure 1 the present embodiment, except that the service brake assembly is different from embodiment one, the other structures are the same, which will not be described below.

[0076] The service brake assembly in the embodiment comprises a service brake valve 21 and a second accumulator 23, the oil source 1, the third one-way valve 6 and the service brake valve 21 are sequentially communicated, a second one-way valve 24 for allowing hydraulic oil to flow from the third one-way valve 6 to the service brake valve 21 in one direction is arranged on the oil path between the third one-way valve 6 and the service brake valve 21, the second accumulator 23 is arranged on the oil path between the second one-way valve 24 and the service brake valve 21, and the service brake valve 21 is communicated with the parking brake oil cylinder 13.

[0077] It should be noted that, in the embodiment, the service brake valve 21 cooperates with the service brake oil cylinder 22 and the second accumulator 23 to realize service braking, which belongs to the prior art, and therefore the specific structure of the service brake valve 21 is not shown, and the service braking principle is not described.

[0078] The service brake valve 21 is communicated with the chamber provided with a spring in the parking brake oil cylinder 13, the hydraulic oil in the service brake valve 21 enters the chamber provided with a spring in the parking brake oil cylinder 13, drives the brake piston rod to push out, and realizes braking.

[0079] The cooperation of the second accumulator, the service brake valve and the parking brake oil cylinder is conducive to realizing service braking during service.

[0080] In the above two embodiments, the second switching valve 3, the first one-way valve 4, the proportional pressure reducing valve 11, the first switching valve 12, the filter 15, the third one-way valve 6, the second one-way valve 24 and the overflow valve 31 can be integrated into one whole body and used as an “electronic emergency brake valve”, and the parking brake oil cylinder 13, the finger switch 14, the oil tank 2, the pressure sensor 5, the first accumulator 32, the second accumulator 23, the oil source 1 and the variable plunger pump 33 are communicated with the interfaces reserved on the “electronic emergency brake valve”.

[0081] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0082] In addition, the terms "first", "second", etc. are used only for the purpose of description and do not imply or imply relative importance or imply the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified.

[0083] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0084] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0085] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, those skilled in the art can combine and combine different embodiments or features of different embodiments or examples described in the present application without contradiction.

[0086] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A tractor electronic emergency braking system, characterized in that, The utility model relates to a kind of proportional pressure reducing valve, first reversing valve, parking brake cylinder and finger switch, the first reversing valve, the proportional pressure reducing valve and the parking brake cylinder are sequentially communicated, and the finger switch is connected with the proportional pressure reducing valve, and its pressing stroke is linearly related with the electromagnetic valve current size of the proportional pressure reducing valve. The first oil port of the proportional pressure reducing valve is communicated with the parking brake cylinder, and the first oil port of the proportional pressure reducing valve is communicated with the first valve cavity of the proportional pressure reducing valve by oil circuit, the second oil port of the proportional pressure reducing valve is communicated with the first oil port of the first reversing valve, and the third oil port of the proportional pressure reducing valve is communicated with oil tank (2). When the finger switch (14) is pressed, the spool of the proportional pressure reducing valve (11) is switched to the flow passage in which the first oil port and the third oil port of the proportional pressure reducing valve (11) are communicated under the action of the resultant force of the electromagnetic force F13 generated by the finger switch (14), the hydraulic pressure F11 generated by the first valve cavity of the proportional pressure reducing valve (11) being filled with oil, and the spring force F12 of the proportional pressure reducing valve (11), and the flow in the flow passage in which the first oil port and the second oil port of the proportional pressure reducing valve (11) are communicated gradually decreases, or when the finger switch (14) is released, the spool of the proportional pressure reducing valve (11) is switched to the flow passage in which the first oil port and the third oil port of the proportional pressure reducing valve (11) are communicated under the action of the resultant force of the electromagnetic force F13 generated by the finger switch (14), the hydraulic pressure F11 generated by the first valve cavity of the proportional pressure reducing valve (11) being filled with oil, and the spring force F12 of the proportional pressure reducing valve (11), and the flow in the flow passage in which the first oil port and the second oil port of the proportional pressure reducing valve (11) are communicated gradually increases. The first oil port of the first reversing valve is communicated with the second oil port of the proportional pressure reducing valve, the second oil port of the first reversing valve is communicated with oil source (1), the third oil port of the first reversing valve is communicated with the oil tank (2), and the first reversing valve can be switched to the state in which the first oil port and the third oil port are communicated or the state in which the first oil port and the second oil port are communicated. A filter (15) and a third one-way valve (6) for allowing hydraulic oil to flow from the oil source (1) to the first reversing valve (12) in one direction are arranged in the oil circuit between the oil source (1) and the first reversing valve (12). ​ The vehicle further comprises a service brake assembly, which comprises a service brake valve (21), a service brake cylinder (22) and a second accumulator (23), the oil source (1), the third one-way valve (6), the service brake valve (21) and the service brake cylinder (22) are sequentially communicated, a second one-way valve (24) is arranged on an oil passage between the third one-way valve (6) and the service brake valve (21), the second one-way valve (24) allows hydraulic oil to flow from the third one-way valve (6) to the service brake valve (21) in one direction, and the second accumulator (23) is arranged on an oil passage between the second one-way valve (24) and the service brake valve (21). The vehicle further comprises a second reversing valve (3), a first oil port of the second reversing valve (3) is communicated with the proportional pressure reducing valve (11), a second oil port of the second reversing valve (3) is communicated with a first oil port of the first reversing valve (12), the second reversing valve (3) can be switched to allow the first reversing valve (12) to be unidirectionally or bidirectionally communicated with the proportional pressure reducing valve (11), the first oil port of the second reversing valve (3) is further communicated with the parking brake cylinder (13) through an oil passage, and a first one-way valve (4) is arranged on an oil passage between the first oil port of the second reversing valve (3) and the parking brake cylinder (13), the first one-way valve (4) allows hydraulic oil to flow from the parking brake cylinder (13) to the first oil port of the second reversing valve (3) in one direction.

2. The electronic emergency braking system for a tractor as set forth in claim 1, wherein The vehicle further comprises an overflow valve (31) and a first accumulator (32), the first accumulator (32) is communicated with an oil passage between the third one-way valve (6) and the filter (15), the first accumulator (32) is communicated with the overflow valve (31), an oil passage between the oil source (1) and the third one-way valve (6) is communicated with a load-sensitive oil passage and a load-sensitive interface of a variable plunger pump (33), an inlet end of the overflow valve (31) is communicated with the load-sensitive oil passage, and an outlet end of the overflow valve (31) is communicated with the oil tank (2), and a throttle valve is arranged on the load-sensitive oil passage.

3. The electronic emergency braking system for a tractor as set forth in claim 2, wherein A sum of an accumulator pressure F21 generated by the first accumulator (32) and a pressure F23 generated by the load-sensitive oil passage is greater than or less than a spring force F22 of the overflow valve (31), so that the overflow valve (31) is opened or closed.

4. The electronic emergency braking system for a tractor as set forth in claim 2, wherein The first accumulator (32) is connected with a pressure sensor (5) for detecting a pressure value of the first accumulator (32).

5. The electronic emergency braking system for a tractor unit of claim 1, wherein, The vehicle further comprises a service brake assembly, which comprises a service brake valve (21) and a second accumulator (23), the oil source (1), the third one-way valve (6) and the service brake valve (21) are sequentially communicated, a second one-way valve (24) is arranged on an oil passage between the third one-way valve (6) and the service brake valve (21), the second one-way valve (24) allows hydraulic oil to flow from the third one-way valve (6) to the service brake valve (21) in one direction, the second accumulator (23) is arranged on the oil passage between the second one-way valve (24) and the service brake valve (21), and the service brake valve (21) is communicated with the parking brake cylinder (13).

Images