Dump truck brake system and dump truck braking method

Abstract

The application discloses a dump truck braking system and a dump truck braking method. The dump truck braking system is characterized in that the oil inlet P1 of a front wheel mechanical brake valve, the oil inlet P2 of a rear wheel mechanical brake valve and the oil inlet P3 of an electric auxiliary brake valve are all communicated with an oil pump. The oil return port T1 of the front wheel mechanical brake valve, the oil return port T2 of the rear wheel mechanical brake valve and the oil return port T3 of the electric auxiliary brake valve are all communicated with an oil tank. The oil outlet A2 of the rear wheel mechanical brake valve is communicated with the hydraulic input end of a rear wheel brake. An electric brake pedal, a rear wheel driving motor, a control switch and the electric auxiliary brake valve are all electrically connected with a controller. The controller applies electric current to the electric auxiliary brake valve according to the opening and closing state of the control switch and the rotation angle of the electric brake pedal. The oil outlet A1 of the front wheel mechanical brake valve and the oil outlet A3 of the electric auxiliary brake valve are both communicated with the hydraulic input end of a front wheel brake. The application has high braking precision, good braking performance and can prolong the service life of the front wheel brake and the rear wheel brake.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dump trucks, in particular to a dump truck braking system and a dump truck braking method. BACKGROUND

[0002] Currently, there are two kinds of driving braking modes for dump trucks: electric braking and mechanical braking, which are two relatively independent braking systems. The electric braking is to convert the driving motor into a generator when braking, so that the mechanical energy of the vehicle is converted into electrical energy through the driving motor, and the electrical energy is stored or consumed. The mechanical braking is to make the vehicle decelerate by locking the brakes installed on the front and rear axles, wherein the brakes of the mechanical braking are controlled by hydraulic oil, so it is also called hydraulic braking.

[0003] When the electric wheel dump truck brakes the vehicle by the electric braking mode, if the vehicle is running on a flat road, the vehicle braking can be well realized. However, if the vehicle is running on a muddy and slippery road, the center of gravity of the vehicle will move forward, resulting in a decrease in the load of the rear axle, and at the same time, the adhesion ability of the rear wheel to the ground will also decrease, thereby causing poor braking effect and poor driving safety of the electric braking. SUMMARY

[0004] The purpose of the present application is to provide a dump truck braking system and a dump truck braking method to solve the above-mentioned problems in the prior art when the vehicle is braked by the electric braking mode.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] The dump truck braking system comprises a mechanical braking system, an electric braking pedal, a rear wheel driving motor and a controller; the mechanical braking system comprises a front wheel brake, a rear wheel brake, a front wheel mechanical braking valve, a rear wheel mechanical braking valve and a mechanical braking pedal; the valve core of the front wheel mechanical braking valve and the valve core of the rear wheel mechanical braking valve are in transmission connection with the mechanical braking pedal; the oil inlet P1 of the front wheel mechanical braking valve and the oil inlet P2 of the rear wheel mechanical braking valve are in communication with an oil pump; the oil return T1 of the front wheel mechanical braking valve and the oil return T2 of the rear wheel mechanical braking valve are in communication with an oil tank; the oil outlet A2 of the rear wheel mechanical braking valve is in communication with the hydraulic input end of the rear wheel brake; the electric braking pedal and the rear wheel driving motor are electrically connected with the controller; and the dump truck braking system further comprises:

[0007] a control switch, which is electrically connected with the controller;

[0008] an electric auxiliary braking valve, which is electrically connected with the controller; the controller applies current to the electric auxiliary braking valve according to the on-off state of the control switch and the rotation angle of the electric braking pedal;

[0009] The oil inlet P3 of the electric auxiliary brake valve is communicated with the oil pump; the oil return T3 of the electric auxiliary brake valve is communicated with the oil tank; the oil outlet A1 of the front wheel mechanical brake valve and the oil outlet A3 of the electric auxiliary brake valve are both communicated with the hydraulic input end of the front wheel brake.

[0010] As a preferred solution of the above-mentioned dump truck brake system, the electric auxiliary brake valve is a three-position three-way electro-hydraulic proportional valve.

[0011] As a preferred solution of the above-mentioned dump truck brake system, the dump truck brake system further comprises a selector valve, the oil outlet A1 of the front wheel mechanical brake valve and the oil outlet A3 of the electric auxiliary brake valve are both communicated with two input ends of the selector valve, and the output end of the selector valve is communicated with the hydraulic input end of the front wheel brake; the two input ends of the selector valve can selectively communicate one of them with the output end of the selector valve.

[0012] As a preferred solution of the above-mentioned dump truck brake system, the selector valve is a shuttle valve.

[0013] A dump truck brake method for implementing the above-mentioned dump truck brake system, the dump truck brake method comprises:

[0014] Judging whether the road surface muddy and slippery degree of the current section is greater than or equal to the set muddy and slippery degree;

[0015] Judging whether the current vehicle speed is greater than or equal to the set vehicle speed;

[0016] If the road surface muddy and slippery degree of the current section is greater than or equal to the set muddy and slippery degree, and the current vehicle speed is greater than or equal to the set vehicle speed, then the control switch is controlled to be opened, the electric brake pedal is stepped on, and the controller applies current to the electric auxiliary brake valve.

[0017] As a preferred solution of the above-mentioned dump truck brake method, if the road surface muddy and slippery degree of the current section is less than the set muddy and slippery degree, and the current vehicle speed is less than the set vehicle speed, then the mechanical brake pedal is stepped on;

[0018] If the road surface muddy and slippery degree of the current section is greater than or equal to the set muddy and slippery degree, and the current vehicle speed is less than the set vehicle speed, then the mechanical brake pedal is stepped on;

[0019] If the road surface muddy and slippery degree of the current section is less than the set muddy and slippery degree, and the current vehicle speed is greater than or equal to the set vehicle speed, then the electric brake pedal is stepped on.

[0020] As a preferred solution of the above-mentioned dump truck brake method, the specific steps of the controller applying current to the electric auxiliary brake valve comprise:

[0021] When the duration of the step on the electric brake pedal is greater than or equal to the first set duration, the controller applies current to the electric auxiliary brake valve according to the actual demand brake oil pressure of the front wheels;

[0022] Or, when the constant C is greater than or equal to the set value, the controller applies current to the electric auxiliary brake valve according to the actual demand brake oil pressure of the front wheels; wherein the constant C = (the change value of the voltage output by the electric brake pedal / the rotation angle of the electric brake pedal) / 2.

[0023] As a preferred solution of the above-mentioned dump truck braking method, after the current is applied to the electric auxiliary brake valve, the controller applies current to the electric auxiliary brake valve according to the actual demand brake oil pressure of the front wheels again after the second set duration.

[0024] As a preferred solution of the above-mentioned dump truck braking method, the specific steps in which the controller applies current to the electric auxiliary brake valve according to the actual demand brake oil pressure of the front wheels include:

[0025] Calculating the actual demand braking torque of the front wheels according to the current rotation speed of the rear wheel drive motor;

[0026] Calculating the actual demand brake oil pressure of the front wheels according to the actual demand braking torque of the front wheels;

[0027] According to the actual demand brake oil pressure of the front wheels, the current value required to be applied to the electric auxiliary brake valve is obtained from the first MAP; the first MAP is formed by the actual demand braking torque of the front wheels and the current value required to be applied to the electric auxiliary brake valve;

[0028] The controller applies current to the electric auxiliary brake valve.

[0029] As a preferred solution of the above-mentioned dump truck braking method, the first set duration is equal to the second set duration.

[0030] The beneficial effects of the present application are:

[0031] The application provides a dump truck braking system and a dump truck braking method. The dump truck braking system comprises a mechanical braking system, an electric braking pedal, a rear wheel driving motor and a controller. The dump truck braking system further comprises a control switch and an electric auxiliary braking valve. The mechanical braking system comprises a front wheel brake, a rear wheel brake, a front wheel mechanical braking valve, a rear wheel mechanical braking valve and a mechanical braking pedal. The valve core of the front wheel mechanical braking valve and the valve core of the rear wheel mechanical braking valve are in transmission connection with the mechanical braking pedal. The oil inlet P1 of the front wheel mechanical braking valve and the oil inlet P2 of the rear wheel mechanical braking valve are in communication with an oil pump. The oil return T1 of the front wheel mechanical braking valve and the oil return T2 of the rear wheel mechanical braking valve are in communication with an oil tank. The oil outlet A2 of the rear wheel mechanical braking valve is in communication with the hydraulic input end of the rear wheel brake. The electric braking pedal and the rear wheel driving motor are electrically connected with the controller. The control switch is electrically connected with the controller. The electric auxiliary braking valve is electrically connected with the controller. The controller applies current to the electric auxiliary braking valve according to the opening and closing state of the control switch and the rotation angle of the electric braking pedal. The oil inlet P3 of the electric auxiliary braking valve is in communication with the oil pump. The oil return T3 of the electric auxiliary braking valve is in communication with the oil tank. The oil outlet A1 of the front wheel mechanical braking valve and the oil outlet A3 of the electric auxiliary braking valve are in communication with the hydraulic input end of the front wheel brake.

[0032] When the dump truck needs to be mechanically braked, the mechanical braking pedal is stepped on, the mechanical braking pedal drives the valve core of the front wheel mechanical braking valve to act, the oil inlet P1 of the front wheel mechanical braking valve and the oil outlet A1 of the front wheel mechanical braking valve are communicated, the hydraulic oil is delivered to the front wheel brake, the oil inlet P2 of the rear wheel mechanical braking valve and the oil outlet A2 of the rear wheel mechanical braking valve are communicated, the hydraulic oil is delivered to the rear wheel brake, and the front wheel and the rear wheel of the dump truck can be simultaneously braked.

[0033] When the dump truck needs to be electrically braked, the electric braking pedal is stepped on, the controller controls the rear wheel driving motor to brake the rear wheel as a generator according to the rotation angle of the electric braking pedal, and energy is recycled.

[0034] When the dump truck needs to be electrically braked and the road surface of the road section currently traveled by the dump truck is muddy and slippery, the adhesion of the dump truck to the ground is poor. At this time, the control switch is turned on and the electric braking pedal is stepped on. After the controller receives the electric signal of the control switch being turned on and the electric signal of the electric braking pedal being stepped on, it is indicated that auxiliary braking is needed when the dump truck is electrically braked. Then the controller applies current to the electric auxiliary braking valve, the oil inlet P3 of the electric auxiliary braking valve and the oil outlet A3 of the electric auxiliary braking valve are communicated, the hydraulic oil is delivered to the front wheel brake, the rear wheel of the dump truck can be electrically braked, and the front wheel of the dump truck can be mechanically braked. Thus, the problem that the braking effect is poor when the dump truck currently travels on a muddy and slippery road section and adopts the electric braking mode to brake the vehicle in the prior art can be effectively avoided.

[0035] Therefore, the self-unloading vehicle brake system can effectively improve the braking performance of the self-unloading vehicle, avoid the self-unloading vehicle from fishtailing and drifting, and effectively improve the driving safety of the self-unloading vehicle. In addition, when driving on a muddy and slippery road surface, the rear wheel brake can be effectively prevented from being worn compared with mechanical braking, thereby effectively improving the service life of the rear wheel brake. In addition, when driving on a muddy and slippery road surface, the size of the current applied to the electric auxiliary brake valve can be adjusted in real time according to the actual required braking force of the front wheel, thereby effectively improving the braking accuracy and effectively reducing the wear of the front wheel brake, thereby also effectively improving the service life of the front wheel brake. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic diagram of the self-unloading vehicle brake system provided by the specific embodiment of the present application.

[0037] In the drawings:

[0038] 1, electric brake pedal;

[0039] 2, rear wheel drive motor;

[0040] 3, controller;

[0041] 41, front wheel brake; 42, rear wheel brake; 43, front wheel mechanical brake valve; 44, rear wheel mechanical brake valve; 45, mechanical brake pedal; 46, push rod; 47, one-way valve; 48, first pipeline; 49, second pipeline;

[0042] 5, control switch;

[0043] 6, electric auxiliary brake valve;

[0044] 7, selection valve;

[0045] 8, traction converter. DETAILED DESCRIPTION

[0046] The present application will be further described in detail below in conjunction with the drawings and examples. It can be understood that the specific embodiments described herein are only used to explain the present application, and not to limit the present application. In addition, it should be noted that, in order to facilitate description, only the parts related to the present application are shown in the drawings, not all structures.

[0047] In the description of the application, unless otherwise clearly specified and limited, the terms "connected", "connected", "fixed" 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. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0048] In the present application, unless otherwise clearly specified and limited, "on" or "under" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "above" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. "Below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0049] In the description of the present embodiment, the terms "up", "down", "right", and other orientation or position relationships are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply 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 a limitation on the application. In addition, the terms "first", "second" are only used to distinguish in the description, and have no special meaning.

[0050] As Figure 1As shown, the present application provides a dump truck braking system, which comprises a mechanical braking system, an electric brake pedal 1, a rear wheel driving motor 2 and a controller 3. The dump truck braking system further comprises a control switch 5 and an electric auxiliary brake valve 6. The mechanical braking system comprises a front wheel brake 41, a rear wheel brake 42, a front wheel mechanical brake valve 43, a rear wheel mechanical brake valve 44 and a mechanical brake pedal 45. The spool of the front wheel mechanical brake valve 43 and the spool of the rear wheel mechanical brake valve 44 are both in transmission connection with the mechanical brake pedal 45. The inlet port P1 of the front wheel mechanical brake valve 43 and the inlet port P2 of the rear wheel mechanical brake valve 44 are both in communication with an oil pump. The return port T1 of the front wheel mechanical brake valve 43 and the return port T2 of the rear wheel mechanical brake valve 44 are both in communication with an oil tank. The outlet port A2 of the rear wheel mechanical brake valve 44 is in communication with the hydraulic input end of the rear wheel brake 42. The electric brake pedal 1 and the rear wheel driving motor 2 are both in electrical connection with the controller 3. The control switch 5 is in electrical connection with the controller 3. The electric auxiliary brake valve 6 is in electrical connection with the controller 3. The controller 3 applies current to the electric auxiliary brake valve 6 according to the on-off state of the control switch 5 and the rotation angle of the electric brake pedal 1. The inlet port P3 of the electric auxiliary brake valve 6 is in communication with the oil pump. The return port T3 of the electric auxiliary brake valve 6 is in communication with the oil tank. The outlet port A1 of the front wheel mechanical brake valve 43 and the outlet port A3 of the electric auxiliary brake valve 6 are both in communication with the hydraulic input end of the front wheel brake 41.

[0051] When the dump truck needs to be mechanically braked, the mechanical brake pedal 45 is stepped on, the mechanical brake pedal 45 drives the spool of the front wheel mechanical brake valve 43 to act, so that the inlet port P1 of the front wheel mechanical brake valve 43 and the outlet port A1 of the front wheel mechanical brake valve 43 are communicated, the hydraulic oil is delivered to the front wheel brake 41. And the inlet port P2 of the rear wheel mechanical brake valve 44 and the outlet port A2 of the rear wheel mechanical brake valve 44 are communicated, the hydraulic oil is delivered to the rear wheel brake 42. So that the front wheel and the rear wheel of the dump truck can be braked at the same time.

[0052] When the dump truck needs to be electrically braked, the electric brake pedal 1 is stepped on, the controller 3 controls the rear wheel driving motor 2 to brake the rear wheel as a generator according to the rotation angle of the electric brake pedal 1, and energy is recovered.

[0053] When the dump truck needs to be braked by the electric brake, and the road surface of the current driving section of the dump truck is muddy and slippery, the adhesion of the dump truck to the ground is poor. At this time, the control switch 5 is opened and the electric brake pedal 1 is stepped on. After the controller 3 receives the electric signal of the opening of the control switch 5 and the electric signal of the stepping on of the electric brake pedal 1, it is indicated that auxiliary braking is needed when the dump truck is braked by the electric brake. Then the controller 3 applies current to the electric auxiliary brake valve 6, so that the oil inlet P3 of the electric auxiliary brake valve 6 and the oil outlet A3 of the electric auxiliary brake valve 6 are communicated, and the hydraulic oil is delivered to the front wheel brake 41. So that the rear wheels of the dump truck can be braked by the electric brake, and the front wheels of the dump truck can be braked by the mechanical brake. Thus, the problem that the braking effect is poor when the dump truck is braked by the electric brake on the muddy and slippery road surface of the current driving section of the dump truck can be effectively avoided.

[0054] Thus, by using the dump truck braking system, the braking performance of the dump truck can be effectively improved, the dump truck can be effectively prevented from fishtailing and drifting, and the driving safety of the dump truck can be effectively improved. Secondly, when driving on a muddy and slippery road surface, the rear wheel brake 42 can be effectively prevented from being worn relative to the use of a mechanical brake, so that the service life of the rear wheel brake 42 can be effectively improved. Secondly, when driving on a muddy and slippery road surface, the size of the current applied to the electric auxiliary brake valve 6 can be adjusted in real time according to the actual braking force required by the front wheels, so that the braking accuracy can be effectively improved, the wear of the front wheel brake 41 can be effectively reduced, and the service life of the front wheel brake 41 can also be effectively improved.

[0055] Specifically, when the control switch 5 is in the closed state, whether the electric brake pedal 1 is stepped on or not, the controller 3 does not apply current to the electric auxiliary brake valve 6.

[0056] Specifically, the dump truck braking system further comprises a traction converter 8. The controller 3 is electrically connected with the traction converter 8. The traction converter 8 is electrically connected with the rear wheel driving motor 2. When the electric brake pedal 1 is stepped on, the controller 3 sends an electric braking signal to the traction converter 8, and the traction converter 8 controls the rear wheel driving motor 2 to brake the rear wheels as a generator and perform energy recovery.

[0057] Specifically, in this embodiment, the number of rear wheel driving motors 2 is two, and the two rear wheel driving motors 2 are arranged in one-to-one correspondence with the two rear wheels of the dump truck. Among them, the specific structure of the rear wheel driving motor 2 and the rear wheel transmission connection belongs to the prior art, so it will not be repeated here. The specific structure of the rear wheel driving motor 2 as a generator to brake the rear wheels and perform energy recovery also belongs to the prior art, so it will not be repeated here.

[0058] Specifically, in this embodiment, the mechanical brake pedal 45 is drivenly connected to the valve core of the rear wheel mechanical brake valve 44, so as to drive the valve core of the rear wheel mechanical brake valve 44 to actuate. The specific structure of the drive connection between the mechanical brake pedal 45 and the valve core of the rear wheel mechanical brake valve 44 is prior art and will not be described further here.

[0059] Specifically, in this embodiment, the valve core of the rear wheel mechanical brake valve 44 is further connected to a push rod 46, which is located between the valve core of the rear wheel mechanical brake valve 44 and the valve core of the front wheel mechanical brake valve 43. The push rod 46 can abut against the valve core of the front wheel mechanical brake valve 43, so that when the valve core of the rear wheel mechanical brake valve 44 moves and contacts the valve core of the front wheel mechanical brake valve 43, it can drive the valve core of the front wheel mechanical brake valve 43 to move synchronously.

[0060] Among them, the front wheel mechanical brake valve 43 and the rear wheel mechanical brake valve 44 are both three-position three-way mechanical valves.

[0061] like Figure 1 As shown, along Figure 1 In the up-down direction, when the mechanical brake pedal 45 is not depressed, the valve core of the front wheel mechanical brake valve 43 is in the middle position, and the oil inlet P1, oil outlet A1, and oil return T1 of the front wheel mechanical brake valve 43 are not connected to each other. The valve core of the rear wheel mechanical brake valve 44 is in the middle position, and the oil inlet P2, oil outlet A2, and oil return T2 of the rear wheel mechanical brake valve 44 are not connected to each other.

[0062] like Figure 1 As shown, along Figure 1 In the vertical direction, when the mechanical brake pedal 45 is pressed, the valve core of the rear wheel mechanical brake valve 44 moves to its uppermost position, connecting the oil inlet P2 and the oil outlet A2 of the rear wheel mechanical brake valve 44. The push rod 46 then drives the valve core of the front wheel mechanical brake valve 43 to its uppermost position, connecting the oil inlet P1 and the oil outlet A1 of the front wheel mechanical brake valve 43. This drives the front wheel brake 41 and the rear wheel brake 42 to brake.

[0063] It is understood that the oil pressure of the hydraulic oil output by the front wheel mechanical brake valve 43 is in a positive proportional relationship with the degree of depression of the mechanical brake pedal 45. That is, the oil pressure of the hydraulic oil output by the front wheel mechanical brake valve 43 is in a positive proportional relationship with the rotation angle of the mechanical brake pedal 45. The greater the rotation angle of the mechanical brake pedal 45, the greater the oil pressure of the hydraulic oil output by the front wheel mechanical brake valve 43. The oil pressure of the hydraulic oil output by the rear wheel mechanical brake valve 44 is also in a positive proportional relationship with the degree of depression of the mechanical brake pedal 45. That is, the oil pressure of the hydraulic oil output by the rear wheel mechanical brake valve 44 is also in a positive proportional relationship with the rotation angle of the mechanical brake pedal 45. The greater the rotation angle of the mechanical brake pedal 45, the greater the oil pressure of the hydraulic oil output by the rear wheel mechanical brake valve 44.

[0064] As shown in FIG. 4, along the up-down direction of the vehicle, when the mechanical brake pedal 45 is released, under the action of the internal control oil passage of the rear wheel mechanical brake valve 44, the spool of the rear wheel mechanical brake valve 44 moves to the lowermost position, and the oil outlet A2 of the rear wheel mechanical brake valve 44 and the oil return port T2 of the front wheel mechanical brake valve 43 are communicated. The rear wheel brake 42 is bled to stop braking. When the rear wheel brake 42 is bled, the spool of the rear wheel mechanical brake valve 44 is in the middle position. Under the action of the internal control oil passage of the front wheel mechanical brake valve 43, the spool of the front wheel mechanical brake valve 43 moves to the lowermost position, and the oil outlet A1 of the front wheel mechanical brake valve 43 and the oil return port T1 of the front wheel mechanical brake valve 43 are communicated. The front wheel brake 41 is bled to stop braking. When the front wheel brake 41 is bled, the spool of the front wheel mechanical brake valve 43 is in the middle position.

[0065] The electric auxiliary brake valve 6 is a three-position three-way electro-hydraulic proportional valve.

[0066] As shown in FIG. 4, along the up-down direction of the vehicle, when the mechanical brake pedal 45 is released, under the action of the internal control oil passage of the rear wheel mechanical brake valve 44, the spool of the rear wheel mechanical brake valve 44 moves to the lowermost position, and the oil outlet A2 of the rear wheel mechanical brake valve 44 and the oil return port T2 of the front wheel mechanical brake valve 43 are communicated. The rear wheel brake 42 is bled to stop braking. When the rear wheel brake 42 is bled, the spool of the rear wheel mechanical brake valve 44 is in the middle position. Under the action of the internal control oil passage of the front wheel mechanical brake valve 43, the spool of the front wheel mechanical brake valve 43 moves to the lowermost position, and the oil outlet A1 of the front wheel mechanical brake valve 43 and the oil return port T1 of the front wheel mechanical brake valve 43 are communicated. The front wheel brake 41 is bled to stop braking. When the front wheel brake 41 is bled, the spool of the front wheel mechanical brake valve 43 is in the middle position. Figure 1 Figure 1 As shown in FIG. 4, along the up-down direction of the vehicle, when the mechanical brake pedal 45 is released, under the action of the internal control oil passage of the rear wheel mechanical brake valve 44, the spool of the rear wheel mechanical brake valve 44 moves to the lowermost position, and the oil outlet A2 of the rear wheel mechanical brake valve 44 and the oil return port T2 of the front wheel mechanical brake valve 43 are communicated. The rear wheel brake 42 is bled to stop braking. When the rear wheel brake 42 is bled, the spool of the rear wheel mechanical brake valve 44 is in the middle position. Under the action of the internal control oil passage of the front wheel mechanical brake valve 43, the spool of the front wheel mechanical brake valve 43 moves to the lowermost position, and the oil outlet A1 of the front wheel mechanical brake valve 43 and the oil return port T1 of the front wheel mechanical brake valve 43 are communicated. The front wheel brake 41 is bled to stop braking. When the front wheel brake 41 is bled, the spool of the front wheel mechanical brake valve 43 is in the middle position.

[0067] When the controller 3 does not apply current to the electric auxiliary brake valve 6, the spool of the electric auxiliary brake valve 6 is in the middle position, and the oil inlet P3 of the electric auxiliary brake valve 6, the oil outlet A3 of the electric auxiliary brake valve 6, and the oil return port T3 of the electric auxiliary brake valve 6 are not communicated. When the controller 3 applies current to the electric auxiliary brake valve 6, the spool of the electric auxiliary brake valve 6 moves to the lowermost position, and the oil inlet P3 of the electric auxiliary brake valve 6 and the oil outlet A3 of the electric auxiliary brake valve 6 are communicated. This enables auxiliary braking of the electric brake front wheel. When the electric brake pedal 1 is released, the controller 3 stops applying current to the electric auxiliary brake valve 6, and under the action of the internal control oil passage of the electric auxiliary brake valve 6, the spool of the electric auxiliary brake valve 6 moves to the uppermost position, and the oil outlet A3 of the electric auxiliary brake valve 6 and the oil return port T3 of the electric auxiliary brake valve 6 are communicated. The front wheel brake 41 is bled to stop braking. When the front wheel brake 41 is bled, the spool of the front electric auxiliary brake valve 6 is in the middle position.​​

[0067] If the mechanical brake pedal 45 is stepped at the same time when the front wheel is assisted braking in the process of electric braking, the front wheel mechanical brake valve 43 and the electric auxiliary brake valve 6 will deliver hydraulic oil to the front wheel brake 41 at the same time. There will be a risk of damaging the front wheel brake 41 and / or the front wheel mechanical brake valve 43 and / or the electric auxiliary brake valve 6.

[0068] Therefore, it is preferred that the unloading vehicle braking system further comprises a selector valve 7. The oil outlet A1 of the front wheel mechanical brake valve 43 and the oil outlet A3 of the electric auxiliary brake valve 6 are respectively communicated with two input ends of the selector valve 7, and the output end of the selector valve 7 is communicated with the hydraulic input end of the front wheel brake 41. The two input ends of the selector valve 7 can selectively communicate one of them with the output end of the selector valve 7. In this way, if the mechanical brake pedal 45 is stepped at the same time when the front wheel is assisted braking in the process of electric braking, the two input ends of the selector valve 7 selectively communicate one of them with the output end of the selector valve 7. So that it can effectively keep assisting braking the front wheel continuously, and effectively avoid the problem of damaging the front wheel brake 41 and / or the front wheel mechanical brake valve 43 and / or the electric auxiliary brake valve 6 caused by the front wheel mechanical brake valve 43 and the electric auxiliary brake valve 6 delivering hydraulic oil to the front wheel brake 41 at the same time.

[0069] Specifically, in this embodiment, the selector valve 7 is a shuttle valve. If the mechanical brake pedal 45 is stepped at the same time when the front wheel is assisted braking in the process of electric braking, the one with higher pressure between the hydraulic oil delivered by the front wheel mechanical brake valve 43 to the shuttle valve and the hydraulic oil delivered by the electric auxiliary brake valve 6 to the shuttle valve is communicated with the front wheel brake 41 through the shuttle valve and delivers hydraulic oil to the front wheel brake 41. So that it can effectively avoid the problem of damaging the front wheel brake 41 and / or the front wheel mechanical brake valve 43 and / or the electric auxiliary brake valve 6 caused by the front wheel mechanical brake valve 43 and the electric auxiliary brake valve 6 delivering hydraulic oil to the front wheel brake 41 at the same time. And it can avoid energy consumption.

[0070] It can be understood that the one with higher pressure between the hydraulic oil delivered by the front wheel mechanical brake valve 43 to the shuttle valve and the hydraulic oil delivered by the electric auxiliary brake valve 6 to the shuttle valve is communicated with the front wheel brake 41 through the shuttle valve to deliver hydraulic oil to the front wheel brake 41, which can also effectively ensure that the braking effect of the front wheel brake 41 is optimal.

[0071] In this embodiment, the mechanical brake system further comprises a one-way valve 47. The input end of the one-way valve 47 is communicated with the leakage gap between the valve body of the rear wheel mechanical brake valve 44 and the valve core of the rear wheel mechanical brake valve 44 through the first pipeline 48, and the output end of the one-way valve 47 is communicated with the oil tank through the first pipeline 48. So that it can recover the hydraulic oil leaked by the rear wheel mechanical brake valve 44 to the oil tank.

[0072] The mechanical brake system further comprises a second pipeline 49, one end of the second pipeline 49 is communicated with the leakage gap between the valve body of the front wheel mechanical brake valve 43 and the valve core of the front wheel mechanical brake valve 43, and the other end of the second pipeline 49 is communicated with the oil tank. So that the hydraulic oil leaked from the front wheel mechanical brake valve 43 can be recovered to the oil tank.

[0073] The application further provides a dump truck braking method for implementing the above-mentioned dump truck braking system. By adopting the dump truck braking method to control the above-mentioned dump truck braking system, the braking performance and braking accuracy of the dump truck can be effectively improved, the driving safety of the dump truck can be effectively improved, and the service life of the front wheel brake 41 and the rear wheel brake 42 can be effectively improved.

[0074] Specifically, the dump truck braking method comprises:

[0075] determining whether the road surface muddy and slippery degree of the current section is greater than or equal to the set muddy and slippery degree.

[0076] determining whether the current vehicle speed is greater than or equal to the set vehicle speed.

[0077] If the road surface muddy and slippery degree of the current section is less than the set muddy and slippery degree, and the current vehicle speed is less than the set vehicle speed, the mechanical brake pedal 45 is stepped on.

[0078] When the road surface muddy and slippery degree of the current section is less than the set muddy and slippery degree, the adhesion of the rear wheel of the dump truck to the ground is better. When the current vehicle speed is less than the set vehicle speed, the driving speed of the dump truck is slower. Therefore, it is preferred to step on the mechanical brake pedal 45 to brake the dump truck. So that the dump truck can be effectively braked, and the energy consumption caused by the electric brake can be avoided.

[0079] If the road surface muddy and slippery degree of the current section is greater than or equal to the set muddy and slippery degree, and the current vehicle speed is less than the set vehicle speed, the mechanical brake pedal 45 is stepped on.

[0080] When the current vehicle speed is less than the set vehicle speed, the driving speed of the dump truck is slower. Secondly, the mechanical brake is the front wheel brake 41 braking the front wheel, and the rear wheel brake 42 braking the rear wheel. So that the front wheel and the rear wheel of the dump truck can be well adhered to the ground. Therefore, even if the road surface muddy and slippery degree of the current section is greater than or equal to the set muddy and slippery degree, the dump truck can also be well braked, and the energy consumption caused by the electric brake can be avoided.

[0081] If the road surface muddy and slippery degree of the current section is less than the set muddy and slippery degree, and the current vehicle speed is greater than or equal to the set vehicle speed, the electric brake pedal 1 is stepped on.

[0082] When the road surface sludge and wet degree of the current road section is less than the set sludge and wet degree, the adhesion ability of the rear wheel of the dump truck to the ground is better. When the current speed is greater than the set speed, the running speed of the dump truck is faster. Therefore, it is preferred to step on the electric brake pedal 1 to brake the dump truck. This can effectively brake the dump truck and reduce the wear of the front wheel brake 41 and the rear wheel brake 42, thereby effectively improving the service life of the front wheel brake 41 and the rear wheel brake 42.

[0083] If the road surface sludge and wet degree of the current road section is greater than or equal to the set sludge and wet degree, and the current speed is greater than or equal to the set speed, the control switch 5 is controlled to be opened, the electric brake pedal 1 is stepped on, and the controller 3 applies current to the electric auxiliary brake valve 6. It can be understood that at this time, the front wheel mechanical brake and the rear wheel electric brake are simultaneously mixed.

[0084] When the road surface sludge and wet degree of the current road section is greater than or equal to the set sludge and wet degree, and the current speed is greater than or equal to the set speed, it indicates that the adhesion ability of the rear wheel of the dump truck to the ground is poor. The mixed braking mode of the front wheel mechanical brake and the rear wheel electric brake is adopted to brake the dump truck, which can effectively avoid the problem of poor braking effect in the prior art when the dump truck is currently running on a road section with sludge and wet road surface and adopts an electric brake mode to brake the vehicle. Secondly, the size of the current applied to the electric auxiliary brake valve 6 can be adjusted in real time according to the actual braking force required by the front wheel, thereby effectively improving the braking precision and further reducing the wear of the front wheel brake 41, thereby further improving the service life of the front wheel brake 41.

[0085] The set sludge and wet degree is an empirical value obtained from a large number of previous tests. Alternatively, the set sludge and wet degree is determined by the driver. The set speed is an empirical value obtained from a large number of previous tests.

[0086] In this embodiment, the set sludge and wet degree is determined by the driver. The control switch 5 is a two-position rocker switch. The control switch 5 is installed in the cab. The driver selects whether to open the control switch 5 according to the road surface sludge and wet degree of the front road section. It can be understood that when the control switch 5 is in the closed state, the controller 3 does not output current to the electric auxiliary brake valve 6. When the control switch 5 is in the open state, the controller 3 outputs a corresponding brake signal to the traction converter 8 according to the rotation angle of the electric brake pedal 1, and the traction converter 8 controls the rear wheel driving motor 2 to make the rear wheel driving motor 2 act as a generator and output a corresponding braking force.

[0087] In this embodiment, the set speed is set to 5Km / h.

[0088] Further, since the dump truck brake system is provided with the selector valve 7, when the dump truck is braked by the hybrid braking mode of simultaneous mechanical braking of the front wheels and electric braking of the rear wheels, the mechanical brake pedal 45 can be pressed adaptively according to the actual working condition requirement, so that the rear wheels can be braked doubly, and the hydraulic oil delivered to the shuttle valve by the front wheel mechanical brake valve 43 and the hydraulic oil delivered to the shuttle valve by the electric auxiliary brake valve 6 can be delivered to the front wheel brake 41 by the one with greater pressure, so that the braking effect of the dump truck can be further improved.

[0089] Preferably, in the embodiment, the specific step of applying current to the electric auxiliary brake valve 6 by the controller 3 includes:

[0090] When the pressing time of the electric brake pedal 1 is greater than or equal to the first set time, the controller 3 applies current to the electric auxiliary brake valve 6 according to the actual demand braking oil pressure of the front wheels, so as to ensure that the rear wheels are braked by the electric brake before the front wheels are braked by the mechanical brake, so as to reduce the damage to the front wheel brake 41 when the dump truck is braked by the hybrid braking mode of simultaneous mechanical braking of the front wheels and electric braking of the rear wheels, thereby further improving the service life of the front wheel brake 41.

[0091] As an alternative, when the constant C is greater than or equal to the set value, the controller 3 applies current to the electric auxiliary brake valve 6 according to the actual demand braking oil pressure of the front wheels, wherein the constant C = (voltage change value output by the electric brake pedal / rotation angle of the electric brake pedal) / 2. The constant C is the average voltage change value corresponding to the rotation of 0.5° of the electric brake pedal 1. It can also ensure that the rear wheels are braked by the electric brake before the front wheels are braked by the mechanical brake, and can also reduce the damage to the front wheel brake 41 when the dump truck is braked by the hybrid braking mode, thereby further improving the service life of the front wheel brake 41.

[0092] Further preferably, in the embodiment, the first set time is equal to the time corresponding to the rotation of 0.5° of the electric brake pedal 1.

[0093] Preferably, after applying current to the electric auxiliary brake valve 6, the controller 3 applies current to the electric auxiliary brake valve 6 again according to the actual demand braking oil pressure of the front wheels after the second set time. It can be understood that the second set time is the interval time for adjusting the current applied to the electric auxiliary brake valve 6 again. So as to adjust the size of the current applied to the electric auxiliary brake valve 6 in real time according to the speed of the rear wheel driving motor 2, thereby further improving the braking precision of the front wheels, further improving the braking effect and braking precision of the dump truck when braked by the hybrid braking mode, and also reducing the wear of the front wheel brake 41.

[0094] Further preferably, in the present embodiment, the first set time length is equal to the second set time length. To further improve the braking effect and braking accuracy of the dump truck when braking by the hybrid braking mode of the front wheel mechanical braking and the rear wheel electric braking. As an alternative, the second set time length can also be set to be greater than the first set time length.

[0095] Specifically, the specific steps of the controller 3 applying the current to the electric auxiliary brake valve 6 according to the actual demand braking oil pressure of the front wheel include:

[0096] According to the current rear wheel drive motor 2 speed, the actual demand braking torque of the front wheel is calculated.

[0097] According to the actual demand braking torque of the front wheel, the actual demand braking oil pressure of the front wheel is calculated.

[0098] According to the actual demand braking oil pressure of the front wheel, the current value required to be applied to the electric auxiliary brake valve 6 is obtained from the first MAP. The first MAP is formed by the actual demand braking torque of the front wheel and the current value required to be applied to the electric auxiliary brake valve 6.

[0099] The controller 3 applies the current to the electric auxiliary brake valve 6.

[0100] So that the electric auxiliary brake valve 6 can be accurately controlled according to the braking demand.

[0101] Specifically, the calculation process of the actual demand braking torque of the front wheel according to the current rear wheel drive motor 2 speed is as follows:

[0102] The braking torque T of the rear wheel drive motor q电 = The rear wheel drive motor torque T 电 × (100% - the electric brake pedal opening percentage). The electric brake pedal opening percentage = the rotation angle of the electric brake pedal / the maximum rotation angle of the electric brake pedal. The rear wheel drive motor torque T 电 is related to the rear wheel drive motor speed n and the vehicle speed. In the present embodiment, the rear wheel drive motor torque T 电 is obtained from the second MAP by the rear wheel drive motor speed n. The second MAP is formed by the rear wheel drive motor speed n and the rear wheel drive motor torque T 电 . As an alternative, the rear wheel drive motor torque T 电 is obtained from the third MAP by the vehicle speed. The third MAP is formed by the vehicle speed and the rear wheel drive motor torque T 电 . Among them, the second MAP is an empirical MAP obtained from a large number of previous tests. The third MAP is an empirical MAP obtained from a large number of previous tests.

[0103] The front wheel braking required theoretical braking torque

[0104] Required theoretical braking torque of rear wheel

[0105] Wherein: μ is the ground adhesion coefficient; rg is the rolling radius of the tire / m; m is the total weight of the dump truck under full load / kg; g is the acceleration constant, g takes m / s 2 ; α is the slope angle / °; L is the wheelbase of the vehicle / m; L1 is the horizontal distance from the front axle center to the center of mass of the dump truck / m; L2 is the horizontal distance from the rear axle center to the center of mass of the dump truck / m; h is the height of the center of mass of the dump truck from the ground under full load / m; a is the average deceleration during braking, m / s 2 In this embodiment, the example sets α = 5.14°.

[0106] For convenience of calculation, the deceleration process of the dump truck in t time is exemplarily set as an equal deceleration motion. That is, a = (v1-v0) / t.

[0107] Wherein: v0 is the initial speed during braking, m / s; v1 is the real-time speed after braking, m / s.

[0108] Front and rear wheel braking torque ratio q = T q1 / T q2 .

[0109] Maximum front wheel brake torque T q3 = N × T ql .

[0110] Wherein, N is the number of front wheel brakes. In this embodiment, the example sets N = 8.

[0111] Actual required front wheel braking torque T q4 = q × T q电 .

[0112] Actual required front wheel braking oil pressure p = T q4 / T q3 × p max

[0113] Wherein, p max is the maximum front wheel braking pressure.

[0114] In this way, the actual required front wheel braking oil pressure p can be accurately calculated.

[0115] Then, according to the actual required front wheel braking oil pressure p, the current value required to be applied to the electric auxiliary brake valve 6 is searched from the first MAP. The controller 3 applies current to the electric auxiliary brake valve 6. So that the electric auxiliary brake valve 6 can be accurately controlled according to the braking demand.

[0116] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the scope of the present application. It is not necessary or possible to enumerate all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A dump truck braking method, which is implemented in a dump truck braking system, the dump truck braking system comprising a mechanical braking system, an electric brake pedal (1), a rear wheel driving motor (2) and a controller (3); the mechanical braking system comprising a front wheel brake (41), a rear wheel brake (42), a front wheel mechanical brake valve (43), a rear wheel mechanical brake valve (44) and a mechanical brake pedal (45); a valve core of the front wheel mechanical brake valve (43) and a valve core of the rear wheel mechanical brake valve (44) are in driving connection with the mechanical brake pedal (45); an oil inlet P1 of the front wheel mechanical brake valve (43) and an oil inlet P2 of the rear wheel mechanical brake valve (44) are in communication with an oil pump; an oil return T1 of the front wheel mechanical brake valve (43) and an oil return T2 of the rear wheel mechanical brake valve (44) are in communication with an oil tank; an oil outlet A2 of the rear wheel mechanical brake valve (44) is in communication with a hydraulic input end of the rear wheel brake (42); the electric brake pedal (1) and the rear wheel driving motor (2) are in electrical connection with the controller (3); characterized in that: the dump truck braking system further comprises: a control switch (5) in electrical connection with the controller (3); an electric auxiliary brake valve (6) in electrical connection with the controller (3); the controller (3) applies an electric current to the electric auxiliary brake valve (6) according to an on-off state of the control switch (5) and a rotation angle of the electric brake pedal (1); an oil inlet P3 of the electric auxiliary brake valve (6) is in communication with the oil pump; an oil return T3 of the electric auxiliary brake valve (6) is in communication with the oil tank; an oil outlet A1 of the front wheel mechanical brake valve (43) and an oil outlet A3 of the electric auxiliary brake valve (6) are in communication with a hydraulic input end of the front wheel brake (41); the dump truck braking method comprising: judging whether a road surface muddy and slippery degree of a current road section is greater than or equal to a set muddy and slippery degree; judging whether a current vehicle speed is greater than or equal to a set vehicle speed; if the road surface muddy and slippery degree of the current road section is greater than or equal to the set muddy and slippery degree, and the current vehicle speed is greater than or equal to the set vehicle speed, then controlling to open the control switch (5), stepping on the electric brake pedal (1), and the controller (3) applying an electric current to the electric auxiliary brake valve (6).

2. The method of claim 1, wherein, The electric auxiliary brake valve (6) is a three-position three-way electro-hydraulic proportional valve.

3. The method of claim 1, wherein, The dump truck braking system further comprises a selector valve (7), the oil outlet A1 of the front wheel mechanical brake valve (43) and the oil outlet A3 of the electric auxiliary brake valve (6) are in communication with two input ends of the selector valve (7) respectively, and an output end of the selector valve (7) is in communication with the hydraulic input end of the front wheel brake (41); the two input ends of the selector valve (7) can selectively communicate one of them with the output end of the selector valve (7).

4. The method of claim 3, wherein, The selector valve (7) is a shuttle valve. 5.The dump truck braking method according to claim 1, characterized in that: If the road surface slippage degree of the current road section is less than the set slippage degree, and the current vehicle speed is less than the set vehicle speed, the mechanical brake pedal (45) is depressed; If the road surface slippage degree of the current road section is greater than or equal to the set slippage degree, and the current vehicle speed is less than the set vehicle speed, the mechanical brake pedal (45) is depressed; If the road surface slippage degree of the current road section is less than the set slippage degree, and the current vehicle speed is greater than or equal to the set vehicle speed, the electric brake pedal (1) is depressed.

6. The method of claim 1, wherein, The specific steps of the controller (3) applying current to the electric auxiliary brake valve (6) include: When the depression time of the electric brake pedal (1) is greater than or equal to the first set time, the controller (3) applies current to the electric auxiliary brake valve (6) according to the actual front wheel demand brake oil pressure; Or, when the constant C is greater than or equal to the set value, the controller (3) applies current to the electric auxiliary brake valve (6) according to the actual front wheel demand brake oil pressure; wherein the constant C=(voltage change value output by the electric brake pedal / rotation angle of the electric brake pedal) / 2.

7. The method of claim 6, wherein, After applying current to the electric auxiliary brake valve (6), the controller (3) applies current to the electric auxiliary brake valve (6) again according to the actual front wheel demand brake oil pressure after the second set time.

8. The method of claim 6-7, wherein, The specific steps of the controller (3) applying current to the electric auxiliary brake valve (6) according to the actual front wheel demand brake oil pressure include: Calculating the actual front wheel demand braking torque according to the current rear wheel drive motor (2) speed; Calculating the actual front wheel demand brake oil pressure according to the actual front wheel demand braking torque; According to the actual front wheel demand brake oil pressure, the current value required to be applied to the electric auxiliary brake valve (6) is obtained from the first MAP; the first MAP is formed by the actual front wheel demand braking torque and the current value required to be applied to the electric auxiliary brake valve (6); The controller (3) applies current to the electric auxiliary brake valve (6).

9. The method of claim 7, wherein, The first set time is equal to the second set time.

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