CN113650596B - Service braking system, control method and electric loader - Google Patents

Abstract

The invention relates to a service braking system, in order to solve the problem of the service braking of an electric loader, it provides a service braking system, a control method and an electric loader, wherein the service braking system comprises an electronic brake pedal, a service brake valve, Pressure sensor; the service brake valve includes a two-position three-way electric proportional pressure reducing valve and a two-position three-way solenoid valve; the oil inlet of the service brake valve is connected to the brake pressure oil source, the oil outlet is connected to the brake, and the return port is connected to the brake. The oil port is communicated with the hydraulic oil tank, and the electric proportional pressure reducing valve in the service brake valve and the solenoid coil of the two-position three-way solenoid valve are connected with the controller; the controller is based on the control current sent to the electric proportional pressure reducing valve. And the detection value of the pressure sensor controls the working position of the two-position three-way solenoid valve. In the present invention, by detecting the brake pressure behind the valve of the service brake valve, it is estimated whether there is a fault in the electric proportional pressure reducing valve, and if there is a fault, the two-position three-way solenoid valve is controlled to make the second oil port and the third oil port Conduction to achieve emergency braking.

Description

Service braking system, control method and electric loader

technical field

The present invention relates to a service braking system, and more particularly, to a service braking system, a control method and an electric loader.

Background technique

The braking system is one of the most important systems in a loader. The existing loader braking system mainly includes full hydraulic braking system and air-top oil hydraulic system. In the full hydraulic brake system and the air-cap oil hydraulic system, the brake valve is usually directly connected with the brake pedal, the opening of the brake valve is directly related to the pedal stroke, and the opening of the brake valve is directly related to the brake pedal. power related.

In an electric loader, the loader is driven by an electric motor, and the travel motor of the loader is connected to the drive axle of the loader through a gearbox and a transmission shaft. The traveling motor of the loader has the function of reverse dragging power generation braking and recovering energy, that is, when braking, the drive axle rotates through the transmission shaft and the reverse drag motor of the gearbox to realize the motor power generation, thereby converting the kinetic energy of the loader into electric energy, realizing purpose of energy recovery. Therefore, in the electric loader, the depression stroke of the brake pedal does not coincide with the opening degree of the brake valve. Braking systems on existing loaders do not work well on electric loaders.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a service braking system, a control method and an electric loader for the problem of service braking of an electric loader.

The technical scheme of the present invention to achieve its purpose is as follows: a service braking system is provided for an electric loader, which includes a brake pressure oil source for providing hydraulic oil for braking, a brake, and a hydraulic oil tank, characterized in that It also includes a controller, an electronic brake pedal connected with the controller for braking operation, a service brake valve, and a pressure sensor connected with the controller for detecting the brake pressure behind the service brake valve;

The service brake valve is characterized in that it has an oil inlet, an oil outlet and an oil return port, and includes a two-position three-way electric proportional pressure reducing valve and a two-position three-way solenoid valve; the electric proportional pressure reducing valve The first oil port is connected with the oil inlet, the second oil port is connected with the first oil port of the two-position three-way solenoid valve, and the third oil port is connected with the oil return port; the second oil port of the two-position three-way solenoid valve is connected with the oil return port. The oil port is communicated with the oil outlet, and the third oil port is communicated with the oil inlet;

The oil inlet of the service brake valve is connected with the brake pressure oil source, the oil outlet is connected with the brake, the oil return port is connected with the hydraulic oil tank, the electric proportional pressure reducing valve in the service brake valve and the two The solenoid coil of the three-way solenoid valve is connected with the controller;

The controller controls the working position of the two-position three-way solenoid valve according to the control current sent to the electric proportional pressure reducing valve and the detection value of the pressure sensor.

In the present invention, the service brake valve is an electronically controlled valve, controlled by the controller, the valve opening of the electric proportional pressure reducing valve has a corresponding relationship with the control current, and the rear brake pressure has a corresponding relationship with the valve opening. In the present invention, by detecting the brake pressure behind the valve of the service brake valve and comparing whether there is a corresponding relationship between the brake pressure behind the valve and the control current, it is judged whether the electric proportional pressure reducing valve is working normally. When there is no corresponding relationship between the brake pressure behind the valve and the control current, it is presumed that the electric proportional pressure reducing valve is faulty, and the controller controls the two-position three-way solenoid valve to make the second oil port and the third oil port conduct to realize emergency braking. verb: move.

In the above-mentioned service braking system, a pressure reducing valve is provided on the communication oil circuit between the third oil port of the two-position three-way solenoid valve and the oil inlet, which is used for emergency braking and makes the two-position three-way electromagnetic valve. When the second oil port of the valve is connected with the third oil port, the brake bears the output pressure of the set pressure reducing valve.

In the above-mentioned service braking system, a damping hole connected in series with the pressure reducing valve is provided on the communication oil circuit between the third oil port of the two-position three-way solenoid valve and the oil inlet, and the damping hole avoids two The hydraulic shock when the second oil port and the third oil port of the three-way solenoid valve are connected.

The technical solution of the present invention to achieve its purpose is as follows: a service brake control method is provided, which is characterized in that it is used for the control of the service brake valve in the aforementioned service brake system, and the control method is as follows:

The controller controls the two-position three-way solenoid valve to make the first oil port and the second oil port conduct;

The controller outputs the corresponding control current to the electric proportional pressure reducing valve according to the electric signal of the electronic brake pedal and the working parameters of the motor;

Detect the rear brake pressure of the service brake valve; when the rear brake pressure of the service brake valve does not correspond to the current control current of the electric proportional pressure reducing valve, the controller controls the two-position three-way solenoid valve to make the second oil port and The third oil port is turned on.

In the present invention, by detecting the brake pressure behind the service brake valve, it is estimated whether there is a fault in the electric proportional pressure reducing valve, and if there is a fault, the two-position three-way solenoid valve is controlled to make the second oil port and the third oil port Conduction to achieve emergency braking.

In the above-mentioned driving brake control method, the controller also obtains the feedback current of the electric proportional pressure reducing valve, and when the feedback current does not correspond to the current control current of the electric proportional pressure reducing valve, the controller controls the two-position three-way solenoid valve to make it second. The oil port is connected to the third oil port.

In the above-mentioned service braking control method, when the first oil port and the second oil port of the two-position three-way solenoid valve are connected, the electromagnetic coil is in an energized state, and when the second oil port and the third oil port are connected, the electromagnetic coil is in a state of conduction. Power off state.

The technical solution of the present invention to achieve its purpose is as follows: an electric loader is provided, which is characterized by having the aforementioned service braking system.

Compared with the prior art, in the present invention, by detecting the brake pressure behind the valve of the service brake valve, it is estimated whether there is a fault in the electric proportional pressure reducing valve, and if there is a fault, the two-position three-way solenoid valve is controlled to make it The second oil port is connected with the third oil port to realize emergency braking.

Description of drawings

FIG. 1 is a schematic diagram of the service brake valve of the present invention.

Fig. 2 is a schematic diagram of the loader braking system of the present invention.

Fig. 3 is a control block diagram of the loader braking system of the present invention.

Part names and serial numbers in the picture:

Service brake valve 10, electric proportional pressure reducing valve 11, two-position three-way solenoid valve 12, pressure reducing valve 13, orifice 14, pressure sensor 20, hydraulic oil tank 21, variable pump 22, oil filter 23, filling valve 24. Front axle brake 25, rear axle brake 26, working or steering system 27, parking brake system 28, accumulator 29, controller 31, electronic brake pedal 32, whole machine controller 33.

Detailed ways

Specific embodiments are described below with reference to the accompanying drawings.

FIG. 1 shows the principle diagram of the service brake valve of the present invention. In this embodiment, the service brake valve 10 has an oil inlet A, an oil outlet B and an oil return port T, and includes a two-position three-way electrical Proportional pressure reducing valve 11 , two-position three-way solenoid valve 12 , pressure reducing valve 13 and orifice 14 . The first oil port a of the electric proportional pressure reducing valve 11 is connected with the oil inlet port A, the second oil port b is connected with the first oil port d of the two-position three-way solenoid valve 12, and the third oil port c is connected with the oil return port T. Connected.

The second oil port e of the two-position three-way solenoid valve 12 is communicated with the oil outlet port B, and the third oil port f is communicated with the oil inlet port A. The orifice 14 and the pressure reducing valve 13 are arranged between the third oil port f of the two-position three-way solenoid valve 12 and the oil inlet A, and the orifice 14 and the pressure reducing valve 13 are connected in series. The function of the pressure reducing valve 13 is when the controller judges that the braking system is faulty or the driver actively pulls up the emergency stop mushroom head (handle), that is, the second oil port e and the third oil port f of the two-position three-way solenoid valve 12. When turned on, the front and rear axle brakes are subjected to the output pressure of the pressure reducing valve 13 to realize emergency braking. The damping hole 14 avoids the hydraulic shock when the second oil port and the third oil port of the two-position three-way solenoid valve are connected. In the service brake valve, the normal state of the two-position three-way solenoid valve 12 (electromagnetic coil de-energized state) is that the second oil port e and the third oil port f are connected.

Fig. 2 shows a schematic diagram of the hydraulic oil circuit part of the service brake system in the electric loader. In this embodiment, the service brake system includes a brake pressure oil source for providing brake hydraulic oil, a front axle brake 25, a rear axle brake 26, a hydraulic oil tank 21, a controller 31, and a The electronic brake pedal 32 for braking operation, the pressure sensor 20 connected to the controller, the service brake valve 10, and the like.

As shown in FIG. 2 , the brake pressure oil source includes a variable pump 22 , an oil filter 23 , a charging valve 24 , and an accumulator 29 . The oil suction port of the variable pump 22 is connected to the hydraulic oil tank 21, the oil inlet of the charging valve 24 is connected to the pump port of the variable pump 22 through the oil filter 23, and the oil outlet of the charging valve 24 is connected to the parking brake system 28 and the storage valve. The accumulator 29 is in communication for supplying oil to the accumulator 29 and the stop brake system 28 .

The oil inlet of the service brake valve 10 is communicated with the oil outlet of the charging valve 24, and the oil outlet of the service brake valve 10 is connected with the front axle brake 25 and the rear axle brake 26 at the same time, and the pressure sensor 20 is arranged on the service brake. After the valve of the valve 10, it is used to detect the brake pressure of the front and rear axle brakes.

The pressure feedback port of the filling valve 24 is connected to the LS port of the variable pump 22, and the LS port of the variable pump 22 is also connected to the load feedback port of the working hydraulic system of the loader or the steering hydraulic system 27, so as to realize the pressure control according to the load feedback. displacement.

FIG. 3 shows a block diagram of the electric loader service brake valve control in the present invention. The controller 31 controls the service brake valve 10 according to the electric signal of the electronic brake pedal 32, and the details are as follows:

The controller 31 controls the two-position three-way solenoid valve 12 to make the first oil port and the second oil port conduct, that is, the controller 31 energizes the electromagnetic coil of the two-position three-way solenoid valve 12 to make it work in the left position.

The controller 31 calculates and determines the expected braking torque according to the electric signal of the electronic brake pedal 32, and at the same time obtains the working parameters of the loader traveling motor through the whole machine controller 33, and obtains the electric brake pedal 32 when the traveling motor is stepped on. The resulting motor braking torque. When the electronic brake pedal 32 is stepped on, the whole machine controller of the loader sends a control command to the travel motor controller according to the electrical signal of the electronic automatic pedal, the speed of the whole machine and related parameters, so that the travel motor is in a state of generating electricity and absorbs the loader. The walking kinetic energy of the motor generates the braking torque of the motor.

When the braking torque of the motor is greater than or equal to the desired braking torque, the controller 31 does not send control current to the electric proportional pressure reducing valve 11, the electric proportional pressure reducing valve 11 works in the right position, and the hydraulic oil in the accumulator 29 cannot pass through the vehicle. The brake valve 10 is transmitted to the front axle brake 25 and the rear axle brake 26, so the front axle brake 25 and the rear axle brake 26 do not brake, and the braking of the loader is completely realized by the motor braking torque generated by the anti-drag power generation of the traveling motor. .

When the motor braking torque is less than the desired braking torque, the controller 31 determines the control current value according to the difference between the motor braking torque and the desired braking torque, and sends the control current of this value to the electric proportional pressure reducing valve 11, so that the electric The proportional pressure reducing valve 11 is reversed, so that the electric proportional pressure reducing valve 11 outputs the brake pressure oil corresponding to the pressure of the front and rear axle brakes, so that the front and rear axle brakes generate braking action. The sum of the braking torque generated by the front and rear axle brakes and the braking torque of the motor is equal to the desired braking torque.

Under normal circumstances, the braking pressure output by the service brake valve 10 and the current output by the controller 31 to the electric proportional pressure reducing valve 11 have a corresponding relationship, that is, the control current and the valve opening of the electric proportional pressure reducing valve have a corresponding relationship. There is a corresponding relationship, and the opening of the valve port has a corresponding relationship with the brake pressure behind the valve. If the electric proportional pressure reducing valve 11 fails, for example, the electromagnetic coil or the connecting wire is disconnected, in this case, although the controller 31 outputs the corresponding control current, the electric proportional pressure reducing valve 11 does not respond accordingly due to the fault. action, the service brake valve 10 does not output the corresponding brake pressure, so it may lead to the problem of brake failure. In order to avoid the problem of brake failure caused by the failure of the electric proportional pressure reducing valve 10, the controller 31 detects the brake pressure behind the valve of the service brake valve through the pressure sensor, and compares whether there is a corresponding relationship between the brake pressure behind the valve and the control current, If there is no corresponding relationship, it is presumed that the electric proportional pressure reducing valve 11 is faulty. At this time, the controller 31 stops the power supply to the two-position three-way solenoid valve 12, so that the two-position three-way solenoid valve 12 is powered off and works in the right position. The pressure oil in the accumulator 29 enters the front and rear axle brakes through the pressure reducing valve 13, the damping hole 14, the third oil port and the second oil port of the two-position three-way solenoid valve 12, and realizes the emergency braking action and avoids braking. motion failure problem. In case of emergency braking, the controller 31 can also prompt the operator of the fault through an alarm or a meter, and conduct inspection and maintenance as soon as possible.

The control current of the electric proportional pressure reducing valve also has a corresponding relationship with the feedback current. Therefore, after the controller 31 sends the control current to the electric proportional pressure reducing valve, it can also detect the feedback current of the electric proportional pressure reducing valve 11 to determine whether the electric proportional valve is normal. , if the feedback current does not have a corresponding relationship with the control current currently delivered by the controller 31 to the electric proportional pressure reducing valve 11, it is presumed that the electric proportional pressure reducing valve 11 is faulty, and the controller 31 stops sending the two-position three-way solenoid The valve 12 is powered, so that the two-position three-way solenoid valve 12 is powered off and works in the right position. The pressure oil in the accumulator 29 passes through the pressure reducing valve 13, the damping hole 14, and the third oil of the two-position three-way solenoid valve 12 valve. The port and the second oil port enter the front and rear axle brakes to realize emergency braking action and avoid the problem of brake failure.

Claims (7)

1. a service brake system is used for an electric loader, which comprises a brake pressure oil source that provides hydraulic oil for braking, a brake, a hydraulic oil tank, and is characterized in that also comprising a controller, a controller connected with the controller for Electronic brake pedal for braking operation, service brake valve, and a pressure sensor connected to the controller for detecting the brake pressure behind the service brake valve; The service brake valve has an oil inlet, an oil outlet and an oil return port, and includes a two-position three-way electric proportional pressure reducing valve and a two-position three-way solenoid valve; The first oil port of the electric proportional pressure reducing valve is connected with the oil inlet, the second oil port of the electric proportional pressure reducing valve is connected with the first oil port of the two-position three-way solenoid valve, and the third oil port of the electric proportional pressure reducing valve is connected with the first oil port of the two-position three-way solenoid valve. The oil port is communicated with the oil return port, and the second oil port of the electric proportional pressure reducing valve can be selected to be connected with the first oil port of the electric proportional pressure reducing valve or with the third oil port of the electric proportional pressure reducing valve; The second oil port of the two-position three-way solenoid valve communicates with the oil outlet, the third oil port of the two-position three-way solenoid valve communicates with the oil inlet, and the second oil port of the two-position three-way solenoid valve communicates with the oil inlet. The port can be selected from the first oil port of the one- and two-position three-way solenoid valve or connected with the third oil port of the two-position three-way solenoid valve; The oil inlet of the service brake valve is connected with the brake pressure oil source, the oil outlet is connected with the brake, the oil return port is connected with the hydraulic oil tank, the electric proportional pressure reducing valve in the service brake valve and the two The solenoid coil of the three-way solenoid valve is connected with the controller; The controller controls the working position of the two-position three-way solenoid valve according to the control current sent to the electric proportional pressure reducing valve and the detection value of the pressure sensor. 2 . The service braking system according to claim 1 , wherein a pressure reducing valve is provided on the communication oil path between the third oil port of the two-position three-way solenoid valve and the oil inlet port. 3 . 3 . The service braking system according to claim 2 , wherein the communication oil path between the third oil port of the two-position three-way solenoid valve and the oil inlet port is provided with the pressure reducing valve. 4 . Orifices connected in series. 4. A service brake control method, characterized in that it is used for the control of a service brake valve in the service brake system described in any one of claims 1 to 3, and its control method is as follows: The controller controls the two-position three-way solenoid valve to make the first oil port and the second oil port conduct; The controller outputs the corresponding control current to the electric proportional pressure reducing valve according to the electric signal of the electronic brake pedal and the working parameters of the motor; Detect the rear brake pressure of the service brake valve; when the rear brake pressure of the service brake valve does not correspond to the current control current of the electric proportional pressure reducing valve, the controller controls the two-position three-way solenoid valve to make the second oil port and The third oil port is turned on. 5. The service braking control method according to claim 4, wherein the controller also obtains the feedback current of the electric proportional pressure reducing valve, and when the feedback current does not correspond to the current control current of the electric proportional pressure reducing valve, the controller controls The two-position three-way solenoid valve connects the second oil port with the third oil port. 6. The service braking control method according to claim 4 or 5, characterized in that when the first oil port and the second oil port of the two-position three-way solenoid valve are connected, its solenoid coil is in an energized state, and its second oil port is in an electrified state. When the port and the third oil port are connected, the electromagnetic coil is in a power-off state. 7. An electric loader characterized by having the service braking system according to any one of claims 1 to 3.

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