WO2024021065A1

WO2024021065A1 - Pressure volume measurement system and method, storage medium, and pressure volume measurement device

Info

Publication number: WO2024021065A1
Application number: PCT/CN2022/109106
Authority: WO
Inventors: 张浩然; 周勇有; 马文涛; 王广义
Original assignee: 华为技术有限公司
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2024-02-01
Also published as: CN117897595A

Abstract

A pressure volume measurement system and method, a storage medium, and a pressure volume measurement device. A brake fluid supply mechanism (3) in the measurement system can supply a brake fluid to a piston cylinder (1) or recycle a brake fluid in the piston cylinder (1), and can also be connected to an exhaust port (220) of a brake system (200). A piston (11) is driven by means of a driving device (2) to move in the piston cylinder (1), so as to push the brake fluid. A pressure measurement device (4), a temperature measurement device (5) and a displacement amount measurement device (6) respectively measure the pressure and temperature of the brake fluid in the piston cylinder (1) and the displacement of the piston (11), and accordingly measure PV characteristics of the brake system (200). A flow rate measurement device (7) can measure the volume of the recycled brake fluid, so as to accurately control the volume of air supplemented to the brake system (200), such that the brake system (200) continuously measures the PV characteristics when different air volumes are provided. It is not necessary to change the system and a loop structure, thereby making operations more convenient and faster.

Description

Pressure volume measurement system, measurement method, storage medium and measurement device

Technical field

This application relates to the field of hydraulic braking technology, and in particular to a pressure volume measurement system, measurement method, storage medium and measurement device.

Background technique

The automobile braking system is designed to slow down or stop the vehicle while driving. At present, most passenger cars use electronic hydraulic braking systems. The driver presses the brake pedal to push the master cylinder or electric cylinder to pressurize the brake fluid. It flows through the brake pipeline to the four brake calipers and pushes the four caliper pistons. Moving forward, the friction pads and brake discs come into close contact to generate braking force, causing the vehicle to slow down or stop.

Pressure Volume (PV for short) refers to the amount of brake fluid generated during braking due to the deformation of brake calipers, friction pads, brake pipes, brake hoses and other components, as well as the compression of the brake fluid itself. During the process of establishing the pressure of the braking system, corresponding volumes of brake fluid need to be added to the braking system under different pressures. This relationship between pressure and volume reflects the stiffness and response characteristics of the entire brake hydraulic system. Therefore, accurate measurement of the pressure volume of the braking system is critical.

The existing technology usually vents the system before measuring the pressure volume until the brake fluid fills the brake circuit, and then performs the PV measurement. However, after the vehicle leaves the factory, air will still enter the brake circuit, causing the PV characteristics of the system to be different from those when the vehicle leaves the factory. There is a difference, which makes the PV characteristics of the system softer. Existing measurement devices cannot quantitatively measure the PV characteristics of the braking system at different air contents.

Contents of the invention

The purpose of this application is to provide a pressure volume measurement system, measurement method, storage medium and measurement device to solve the above-mentioned problem in the prior art that the measurement device cannot quantitatively measure the PV characteristics of the braking system at different air contents.

A first aspect of the present application provides a pressure volume measurement system, which includes:

A piston cylinder, the piston cylinder includes a liquid inlet and a liquid outlet, and the liquid outlet is used to be connected to the liquid inlet of the braking system;

A piston is arranged in the piston cylinder;

A driving device, connected to the piston, used to drive the piston to move within the piston cylinder;

Brake fluid supply mechanism, the first end of the brake fluid supply mechanism is connected to the liquid inlet of the piston cylinder, used to supply brake fluid to the piston cylinder or recover brake fluid in the piston cylinder ;The second end of the brake fluid supply mechanism is used to be connected to the exhaust port of the brake system;

A pressure detection device is provided on the piston cylinder and used to detect the pressure of the brake fluid in the piston cylinder;

A temperature detection device is provided on the piston cylinder and used to detect the temperature of the brake fluid in the piston cylinder;

A displacement detection device used to detect the displacement of the piston;

A flow detection device for detecting the flow rate of brake fluid flowing back from the piston cylinder to the brake fluid supply mechanism;

A first solenoid valve connected in series between the second end of the brake fluid supply mechanism and the exhaust port of the brake system;

A controller is respectively connected to the driving device, the pressure detection device, the displacement detection device, the flow detection device and the first solenoid valve.

The pressure volume measurement system provided by this application can make the brake fluid in the piston cylinder flow back to the brake system through its inlet through the flow detection device when it is necessary to measure the PV characteristics of the brake system in the presence of a certain volume of air. The dynamic fluid supply mechanism and flow detection device can accurately detect the volume of backflow brake fluid. When the brake fluid returns, the pressure in the brake system decreases, and air can be replenished into the brake system. That is to say, the volume of brake fluid return is equal to the volume of replenished air, thus passing through the flow detection device. By detecting the volume of brake fluid return, the volume of air added to the braking system can be obtained. By controlling the volume of brake fluid return, the volume of air added to the braking system can be accurately controlled, thereby achieving Measurement of PV characteristics with a set volume of air in the braking system. Of course, after measuring the PV characteristics of the braking system with a certain amount of air, the brake fluid in the piston cylinder can continue to flow back to the brake fluid supply mechanism, and the volume of the return flow can be controlled through the flow detection device. The next air replenishment in the braking system can change the volume of air in the braking system, enabling continuous PV characteristics measurement of the braking system with different air volumes without changing the system and circuit. The structure makes the operation more convenient and faster, and the control of the flow detection device can ensure the accuracy of the volume of supplementary air in the braking system, ensuring the accuracy of the measurement results of the PV characteristics of the braking system.

Each time the PV characteristics are measured, the temperature of the brake fluid in the piston cylinder can be detected through the temperature detection device, and the temperature of the braking system can be further obtained to obtain the PV characteristics under the current braking system temperature conditions, so as to be able to comprehensively And accurately reflect the PV characteristics of the braking system under different conditions.

In addition, the pressure volume measurement system provided by this application can connect multiple identical detection circuits to the piston cylinder. For example, each detection circuit includes a pipeline connected to the piston cylinder and the brake fluid supply mechanism, and a first solenoid valve. and other components, each detection circuit can be connected to a brake caliper, so that the PV characteristics of multiple brake calipers can be measured, the operation is simple and fast, and the measurement efficiency is high.

In a possible implementation, the flow detection device is connected to the liquid inlet of the piston cylinder. The liquid inlet of the piston cylinder is connected to the brake fluid supply mechanism. The space between the liquid inlet of the piston cylinder and the brake fluid supply mechanism is always filled with brake fluid without air. Connect the flow detection device to the piston cylinder. The liquid inlet can ensure that the flow detection device can only detect the flow rate of the returning pure brake fluid without being affected by the air, thus ensuring the detection accuracy of the brake fluid return flow rate.

In a possible implementation, the brake fluid supply mechanism includes a liquid storage container and an actuating device, and the actuating device is respectively connected to the liquid storage container and the liquid inlet of the piston cylinder for The brake fluid in the fluid storage container is pumped into the piston cylinder through the liquid inlet of the piston cylinder. The actuating device is respectively connected to the liquid inlet of the liquid storage container and the piston cylinder, and is used to pump the brake fluid in the liquid storage container into the piston cylinder through the liquid inlet of the piston cylinder. The fluid storage container is used to store brake fluid, and the actuating device can provide power for pumping the brake fluid in the fluid storage container into the piston cylinder. The actuating device may specifically include a hydraulic pump, which may provide power to pump the brake fluid in the fluid storage container into the piston cylinder.

In a possible implementation, the brake fluid supply mechanism further includes a stationary container, one end of the stationary container is connected to the liquid storage container through the actuating device, and the other end of the stationary container is connected to the fluid storage container through the actuating device. One end is connected to the exhaust port of the braking system through a pipeline. The static container can be used to store part of the brake fluid that flows back from the piston cylinder, and is also used to store the brake fluid that flows out from the exhaust port of the brake system when the air in the brake system is exhausted. The brake fluid stored in the static container can be returned to the liquid storage container through the actuating device to facilitate the next cycle. In addition, when the static container recovers the brake fluid mixed with air, the brake fluid mixed with air can be allowed to stand in the static container to separate the air and brake fluid, thereby allowing the pure brake fluid to return to the storage tank. liquid container.

In a possible implementation, the pipeline includes a first pipe and a second pipe; one end of the first pipe is connected to the first port of the first solenoid valve, and the other end of the first pipe Used to connect the exhaust port of the braking system; the second pipe is a transparent hose, one end of the second pipe is connected to the second port of the first solenoid valve, and the other end of the second pipe is One end is connected to the resting container.

The first tube is a hard tube that will not expand or deform, such as a metal brake tube, a hard plastic tube, etc. The second tube is a transparent hose. One end of the second tube is connected to the second port of the first solenoid valve. The other end of the second tube is inserted into the static container. The port is above the liquid level to ensure communication with the atmosphere. When exhausting the brake system, the brake fluid in the piston cylinder enters the brake system through the outlet port of the piston cylinder and the inlet port of the brake system. When the brake fluid fills the brake system, The brake fluid can flow out from the exhaust port of the brake system, and can enter the second pipe through the first pipe and the first solenoid valve in sequence. Since the second pipe is a transparent hose, the operator can intuitively observe what is inside the second pipe. Whether the brake fluid enters, if pure brake fluid enters the second tube (no air bubbles are mixed in the brake fluid), it can be accurately judged that the air in the brake system has been completely discharged, and at this time it can be controlled by the controller The first solenoid valve is closed, and the circuit between the first solenoid valve, the braking system, and the piston cylinder is filled with brake fluid and has no air, so that the PV characteristics of the braking system in the air-free state can be measured.

In a possible implementation, a second solenoid valve is further included, and the second solenoid valve is connected in series between the liquid outlet and the liquid inlet of the braking system; the second solenoid valve and The controller signal connection. The second solenoid valve can be opened or closed under the control of the controller, thereby enabling automatic conduction or disconnection of the flow path between the liquid outlet of the piston cylinder and the liquid inlet of the braking system.

In a possible implementation, a third solenoid valve is further included, and the third solenoid valve is connected in series between the liquid inlet of the piston cylinder and the flow detection device; the third solenoid valve is connected to the flow detection device; Describe the controller signal connections. The third solenoid valve can be opened or closed under the control of the controller, thereby enabling automatic conduction or disconnection of the flow path between the liquid inlet of the piston cylinder and the brake fluid supply mechanism.

In a possible implementation, the driving device includes a motor and a driving screw, the driving screw is drivingly connected to the motor, and one end of the driving screw is connected to the piston. The forward and reverse rotation of the motor can drive the transmission screw to move in the opposite direction, so that the piston can be controlled to move forward or backward through the transmission screw, which facilitates operation control.

In a possible implementation, the displacement detection device is a displacement sensor, and the displacement sensor is provided on the transmission screw; the displacement sensor sends out a displacement signal, and the controller obtains the displacement signal based on the displacement signal. The displacement of the piston. The displacement sensor can send out a displacement signal, and the controller obtains the displacement of the piston based on the displacement signal. When the transmission screw moves, the displacement sensor can detect the axial displacement of the transmission screw, that is, the displacement of the piston. Based on the displacement and the stored cross-sectional area of the piston, the controller can calculate the change in volume caused by the movement of the piston. , which is the change in brake fluid volume. Among them, the cross-sectional area of the piston is the cross-sectional area orthogonal to the direction of piston movement.

In a possible implementation, the displacement detection device is a rotational speed position sensor, and the rotational speed position sensor is provided on the motor; the rotational speed position sensor sends out a rotational position signal, and the controller determines the rotational position according to the rotational position. The displacement of the piston is calculated from the signal and the transmission ratio between the motor and the transmission screw. The speed position sensor can obtain the rotation angle of the motor. The controller can calculate the displacement of the transmission screw based on the rotation angle and the stored transmission ratio between the motor and the transmission screw, which is the displacement of the piston. The controller can calculate the displacement of the piston based on the rotation angle and the stored transmission ratio between the motor and the transmission screw. The change in volume caused by the movement of the piston can be calculated by using the amount and stored cross-sectional area of the piston, which is the change in brake fluid volume. Among them, the cross-sectional area of the piston is the cross-sectional area orthogonal to the direction of piston movement.

In a possible implementation, the piston cylinder is provided with a through hole, the piston is provided with a limiter, the transmission screw passes through the through hole and is connected to the limiter, and the limiter The component is used to adjust the position of the piston on the drive screw. The limiter can drive the piston to move and be fixed on the transmission screw. When the transmission screw is in the initial position, the piston can be adjusted by the limiter to a position that matches the braking system to be measured, so that the pressure volume measurement system can be It has applicability to different master cylinder or electric cylinder volumetric braking systems, broadening the application range of this pressure volume measurement system.

In a possible implementation, the transmission screw is provided with a threaded segment, and the limiting member is provided with a threaded hole. The limiting member is sleeved on the threaded hole and the threaded segment through the cooperation. The transmission screw; the limiter is provided with a scale for calibrating the inner volume of the piston cylinder. When it is necessary to adjust the position of the piston on the drive screw, the stopper can be rotated. The stopper can undergo slight axial displacement by cooperating with the thread of the drive screw, thereby driving the piston to achieve position adjustment. The stopper on the stopper can The scale can provide an intuitive reference for the operator to ensure the accuracy of adjustment.

A second aspect of the application also provides a pressure volume measurement method, wherein the pressure volume measurement system provided by the first aspect of the application is used, and the method includes:

Add brake fluid to the braking system to be tested and discharge the air in the braking system to be tested;

Measuring the pressure-volume curve of the braking system under test in the first state;

Recover a set volume of brake fluid from the braking system to be tested so that the braking system to be tested is filled with the set volume of air;

Obtain the temperature of the braking system to be tested;

Measure the pressure volume curve of the braking system under test in the second state and under different temperature conditions.

In a possible implementation, after a set volume of brake fluid is recovered from the braking system to be tested so that the set volume of air is filled into the braking system to be tested, the The above methods also include:

Thoroughly mix the air and brake fluid in the brake system to be tested.

In a possible implementation, adding brake fluid to the braking system to be tested and discharging the air in the braking system to be tested specifically includes:

Control the first solenoid valve, the second solenoid valve and the third solenoid valve to open, and start the actuating device so that the brake fluid in the liquid storage container is injected into the piston cylinder and the braking system to be tested;

Determine whether pure brake fluid flows from the second pipe;

If pure brake fluid flows out, the actuating device is stopped and the first solenoid valve and the third solenoid valve are controlled to close.

In a possible implementation, the measurement of the pressure volume curve of the braking system under test in an airless state specifically includes;

Start the drive to control the piston to push the brake fluid;

Obtain the displacement corresponding to the piston movement to different positions, the pressure value of the brake fluid in the piston cylinder, and the temperature value of the brake fluid in the piston cylinder;

The change amount of the brake fluid volume in the piston cylinder is obtained based on the displacement amount and the cross-sectional area of the piston, and the pressure volume curve is obtained based on the change amount of the brake fluid volume and the pressure value. The temperature value obtains the temperature of the braking system under test.

In a possible implementation, recovering a set volume of brake fluid from the braking system to be tested so that the braking system to be tested is filled with the set volume of air, specifically includes:

Control the first solenoid valve, the second solenoid valve and the third solenoid valve to open, and start the actuating device to draw part of the brake fluid in the piston cylinder back to the rest container;

Obtain the volume of the withdrawn brake fluid through the flow detection device and send out a flow signal;

The controller determines whether the volume of the withdrawn brake fluid reaches a preset volume based on the flow signal;

If so, the first solenoid valve and the third solenoid valve are controlled to close, and the second solenoid valve is kept open.

A third aspect of the present application also provides a storage medium, wherein the storage medium includes a stored application program, and the application program executes the pressure volume measurement method provided by the second aspect of the present application.

A fourth aspect of the application also provides a measuring device, wherein the measuring device includes:

The first control module is used to send a first signal, the first signal is to add brake fluid to the braking system to be tested and discharge the air in the braking system to be tested;

The second control module is used to send a second signal. The second signal is to recover a set volume of brake fluid from the braking system to be tested, so that the braking system to be tested is filled with the brake fluid. Set volume of air;

The first measurement module is used to measure the pressure volume curve of the braking system to be tested in a state without air; the measurement module is also used to measure the pressure volume curve of the braking system to be tested in a state with the set volume of air. pressure volume curve;

The second measurement module is used to measure the temperature of the braking system to be tested.

It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application.

Description of drawings

Figure 1 is a schematic structural diagram of a pressure volume measurement system provided by an embodiment of the present application;

Figure 2 is a schematic structural diagram of a pressure volume measurement system provided by another embodiment of the present application;

Figure 3 is a schematic structural diagram of a pressure volume measurement system provided by another embodiment of the present application;

Figure 4 is a schematic diagram of PV curves with different air contents;

Figure 5 is a status diagram of the limiter in application;

Figure 6 is a flow chart (1) of the pressure volume measurement method provided by the embodiment of the present application;

Figure 7 is a flow chart (2) of the pressure volume measurement method provided by the embodiment of the present application;

Figure 8 is a flow chart (3) of the pressure volume measurement method provided by the embodiment of the present application;

Figure 9 is a flow chart (4) of the pressure volume measurement method provided by the embodiment of the present application.

Reference signs:

100-wheel; 200-braking system; 210-liquid inlet; 220-exhaust port; 230-bleeding bolt; 1-piston cylinder; 1a-liquid inlet; 1b-liquid outlet; 11-piston; 111 -limiting member; 111a-scale; 12-second solenoid; 13-third solenoid valve; 2-driving device; 21-motor; 22-transmission screw; 221-threaded section; 3-brake fluid supply mechanism; 31 -First solenoid valve; 32-Pipeline; 321-First pipe; 322-Second pipe; 33-Actuating device; 34-Liquid storage container; 35-Standing container; 36-Valve; 4-Pressure detection device ; 5-Temperature detection device; 6-Displacement detection device; 7-Flow detection device; 8-Controller.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

In the description of this application, unless otherwise expressly stipulated and limited, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; unless otherwise specified or stated , the term "multiple" refers to two or more; the terms "connection", "fixed", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection. Connection, or electrical connection; may be direct or indirect through an intermediary. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present application are described from the perspective shown in the drawings and should not be understood as a reference to the embodiments of the present application. limited. Additionally, it should be understood in this context that when an element is referred to as being connected "on" or "under" another element, it can not only be directly connected "on" or "under" the other element, but also can be directly connected "on" or "under" the other element. Indirectly connected "on" or "below" another element through an intermediate element.

The main function of a car braking system is to slow down or even stop a moving car, keep the speed of a car traveling downhill stable, and keep a stopped car motionless. At present, most passenger cars use electronic hydraulic braking systems. The driver presses the brake pedal to push the master cylinder or electric cylinder to pressurize the brake fluid. It flows through the brake pipeline to the four brake calipers and pushes the four caliper pistons. Moving forward, the friction pads and brake discs come into close contact to generate braking force, causing the vehicle to slow down or stop.

However, during the braking process, due to the deformation of brake calipers, friction plates, brake pipes, brake hoses and other components, as well as the compression of the brake fluid itself, the pressure of the braking system is different during the establishment process. Different volumes of brake fluid need to be added to the brake system under pressure. If the stiffness of the brake hydraulic system is low and more brake fluid is required to build up pressure, the vehicle's braking system will respond more slowly. The above relationship between pressure and volume reflects the stiffness and response characteristics of the entire brake hydraulic system. Therefore, it is very necessary to detect the pressure volume (PV) characteristics of the vehicle braking system.

The existing technology usually exhausts the system before PV measurement until the brake fluid fills the brake circuit, and then performs PV measurement. However, after the vehicle leaves the factory, air will still enter the brake circuit, causing the PV characteristics of the system to be different from those when leaving the factory. The difference makes the PV characteristics of the system softer. At the same time, the existing measuring device has a large volume and mass and is complicated to operate. It can only measure the PV characteristics of the braking system when there is no air, but cannot measure the PV characteristics when there are different air contents in the braking system.

This application provides a pressure volume measurement system that can test the PV characteristics of the braking system before or after the vehicle leaves the factory. It can measure the PV characteristics of the braking system in an airless state and can also measure The PV characteristics of the braking system when it has a set volume of air, and the overall volume of the measurement system is small, easy to operate, and easy to carry and use in vehicles.

Specifically, as shown in FIG. 1 , the pressure volume measurement system includes a piston cylinder 1 , a piston 11 , a driving device 2 and a brake fluid supply mechanism 3 . Among them, the piston 11 is arranged in the piston cylinder 1 and can move in the piston cylinder 1 by driving the driving device 2 to change the volume of the space in the piston cylinder 1 used to store brake fluid. The piston cylinder 1 includes a liquid inlet 1a and a liquid outlet 1b. The liquid outlet 1b is used to be connected to the liquid inlet 210 of the brake system 200. The movement of the piston 11 can pass the brake fluid through the liquid inlet of the brake system 200. 210 is pushed into the caliper assembly (brake caliper) of the braking system 200 on the wheel 100 . The first end of the brake fluid supply mechanism 3 is connected to the liquid inlet 1a of the piston cylinder 1 and is used to supply brake fluid to the piston cylinder 1 or recover brake fluid in the piston cylinder 1. The third end of the brake fluid supply mechanism 3 The two ends are used to be connected to the exhaust port 220 of the braking system 200. The gas exhausted from the braking system 200 can be recovered by the brake fluid supply mechanism 3, and the brake fluid flowing out from the exhaust port 220 can also be recovered by the brake fluid. Supply organization 3 recycling. Therefore, when it is necessary to measure the PV characteristics of the vehicle's braking system 200, the fluid inlet 210 of the braking system 200 is connected to the fluid outlet 1b of the piston cylinder 1, and the exhaust port 220 of the braking system 200 is connected to The second end of the brake fluid supply mechanism 3 is sufficient, and the operation is simple.

Among them, as shown in Figure 1, the piston cylinder 1 is connected to a pressure detection device 4 and a temperature detection device 5. The pressure detection device 4 is used to detect the pressure of the brake fluid in the piston cylinder 1, and the braking system 200 is connected to the pressure volume. After measuring the system, a closed brake fluid circuit is formed between the pressure volume measurement system and the braking system 200 . The pressure of the brake fluid in the piston cylinder 1 can directly reflect the pressure of the braking system 200 . Therefore, the pressure of the braking system 200 can be obtained simply and effectively by detecting the pressure of the brake fluid in the piston cylinder 1 through the pressure detection device 4 .

In addition, the temperature detection device 5 is used to detect the temperature of the brake fluid in the piston cylinder 1 . During the actual braking operation of the vehicle, the temperature of the braking system 200 is not constant and is easily affected by the driving conditions and ambient temperature. The temperature of the braking system 200 also affects the PV characteristics of the braking system 200 . When measuring the PV characteristics of the braking system 200, the temperature of the braking system 200 is also an important factor that needs to be considered. In this application, the temperature detection device 5 can be used to detect the temperature of the brake fluid in the piston cylinder 1. After obtaining the temperature of the brake fluid in the piston cylinder 1, the braking system can be estimated through the temperature estimation model in the software. The temperature of 200 is input as the current temperature condition, and the PV characteristics are further measured under this temperature condition. The above software can be configured in the vehicle's driving computer.

Wherein, the pressure detection device 4 and the temperature detection device 5 may be a pressure sensor and a temperature sensor respectively.

As shown in FIG. 1 , the pressure volume measurement system also includes a displacement detection device 6 for detecting the displacement of the piston 11 . The displacement detection device 6 may be disposed on the driving device 2 , or may be disposed at another position capable of detecting the displacement of the piston 11 . The piston 11 can be displaced in the piston cylinder 1 by the driving device 2. The displacement detection device 6 can obtain the displacement value of the piston 11, so that the piston can be obtained through the displacement value and the cross-sectional area of the piston 11 in the radial direction of the piston cylinder 1. 11 The change in space volume caused by movement is the change in brake fluid volume.

As shown in FIG. 1 , the pressure volume measurement system also includes a flow detection device 7 , which is used to detect the flow rate of brake fluid flowing back from the piston cylinder 1 to the brake fluid supply mechanism 3 . When measuring the PV characteristics of the braking system 200 , the entire circuit may be filled with brake fluid and the air in the circuit may be exhausted to measure the PV characteristics of the braking system 200 in an airless state. When it is necessary to measure the PV characteristics of the brake system 200 in the presence of a certain volume of air, the brake fluid in the piston cylinder 1 can be returned to the brake fluid supply mechanism 3 through its liquid inlet 1a and the flow detection device 7 , the flow detection device 7 can accurately detect the volume of the backflow brake fluid. When the brake fluid returns, the pressure in the brake system 200 decreases, and air can be replenished into the brake system 200 at this time. That is to say, the volume of the brake fluid return is equal to the volume of the replenished air, so that through the flow The detection device 7 detects the volume of brake fluid return, and can obtain the volume of air added to the brake system 200. By controlling the volume of brake fluid return, the volume of air added to the brake system 200 can be accurately controlled. The size of the brake system 200 enables the measurement of the PV characteristics when there is a set volume of air in the brake system 200 . Of course, after measuring the PV characteristics of the braking system 200 with a certain amount of air at one time, the brake fluid in the piston cylinder 1 can continue to flow back into the brake fluid supply mechanism 3, and the backflow can be controlled through the flow detection device 7 volume to replenish the air in the braking system 200 for the next time, so that the volume of air in the braking system 200 can be changed, and the braking system 200 can continuously perform PV characteristics with different volumes of air. The measurement does not need to change the system and circuit structure, making the operation more convenient and faster, and the control of the flow detection device 7 can ensure the accuracy of the volume of supplementary air in the braking system 200, ensuring the accuracy of the PV characteristic measurement results of the braking system 200 .

It should be noted that each time the PV characteristics are measured, the temperature of the brake fluid in the piston cylinder 1 can be detected by the temperature detection device 5, and the temperature of the brake system 200 can be further obtained to obtain the current temperature of the brake system 200. The PV characteristics under temperature conditions can comprehensively and accurately reflect the PV characteristics of the braking system 200 under different conditions.

In addition, the exhaust port 220 on the existing brake caliper has a bleed bolt 230, and the bleed bolt 230 can be manually tightened or loosened to close or open the exhaust port 220. In one embodiment, as shown in FIG. 2 , the above-mentioned manual method can be used to exhaust the exhaust port 220 . The manual operation method can reduce the use of components between the brake caliper and the pressure volume measurement system. , reduce the size. However, frequent tightening or loosening of the bleed bolt 230 will increase the wear of the bleed bolt 230 , and may even lead to slipping problems, thereby reducing the service life of the bleed bolt 230 . In a preferred embodiment of the present application, as shown in Figure 1, a first solenoid valve 31 is connected in series between the second end of the brake fluid supply mechanism 3 and the exhaust port 220 of the braking system 200. The first solenoid valve 31 can automatically connect or disconnect the flow path between the second end of the brake fluid supply mechanism 3 and the exhaust port 220 of the braking system 200 through the control of the controller 8 . When it is necessary to fill the circuit with brake fluid to discharge the air in the brake system 200, the controller 8 controls the first solenoid valve 31 to open, so that the second end of the brake fluid supply mechanism 3 is connected with the exhaust port of the brake system 200. The flow path between 220 is connected, thus realizing the rapid automatic exhaust of the measurement system. When performing the PV test, the controller 8 controls the first solenoid valve 31 to close to disconnect the flow path between the second end of the brake fluid supply mechanism 3 and the exhaust port 220 of the brake system 200 to avoid braking. Liquid flows out from the exhaust port 220.

The controller 8 is also connected to the driving device 2, the pressure detection device 4, the displacement detection device 6 and the flow detection device 7 respectively. The driving device 2 can drive the movement of the piston 11 under the control of the controller 8. The controller 8 can also control the pressure detection device 4 to measure the pressure, control the displacement detection device 6 to detect the displacement of the piston 11, and control the flow detection device 7 to detect the flow of backflow. The volume of fluid.

It should be noted that existing ordinary passenger cars generally have four wheels, and the hydraulic circuit arrangement may be H-shaped or X-shaped. Among the four wheels, the two wheels located at the front of the car may have brake calipers, or they may have brake calipers. The two wheels located at the rear of the vehicle have brake calipers, or the two wheels located at opposite corners of the vehicle have brake calipers. However, in each of the above cases, when measuring the PV characteristics of the brake calipers of multiple wheels, multiple sets of independent measurement devices are required, or only one measurement device can be used to measure the brake calipers of each wheel in sequence. , long measurement time and low efficiency.

As shown in Figure 3, the pressure volume measurement system provided by this application can connect multiple identical detection circuits to the piston cylinder 1. For example, each detection circuit includes a circuit connected to the piston cylinder 1 and the brake fluid supply mechanism 3. Pipes, first solenoid valve 31 and other components, each detection circuit can be connected to a brake caliper, so that the PV characteristics of multiple brake calipers can be measured, the operation is simple and fast, and the measurement efficiency is high.

Specifically, as shown in FIG. 1 , the flow detection device 7 can be connected to the liquid inlet 1a of the piston cylinder 1 . The liquid inlet 1a of the piston cylinder 1 is connected to the brake fluid supply mechanism 3. The space between the liquid inlet 1a of the piston cylinder 1 and the brake fluid supply mechanism 3 is always filled with brake fluid, and there will be no air. The flow rate is detected The device 7 is connected to the liquid inlet 1a of the piston cylinder 1, which can ensure that the flow detection device 7 can only detect the flow rate of the returning pure brake fluid without being affected by the air, thus ensuring the detection of the return flow rate of the brake fluid. Accuracy.

Of course, the flow detection device 7 can also be disposed at other locations where the brake fluid return flow can be detected, and this embodiment is not limited to this.

Specifically, as shown in Figure 1, the brake fluid supply mechanism 3 includes a liquid storage container 34 and an actuating device 33. The actuating device 33 is connected to the liquid storage container 34 and the liquid inlet 1a of the piston cylinder 1 respectively, and is used to The brake fluid in the fluid storage container 34 is pumped into the piston cylinder 1 through the liquid inlet 1 a of the piston cylinder 1 . The liquid storage container 34 is used to store brake fluid, and the actuating device 33 can provide power for pumping the brake fluid in the liquid storage container 34 into the piston cylinder 1 . The actuating device 33 may specifically include a hydraulic pump, and the hydraulic pump may provide power to pump the brake fluid in the fluid storage container 34 into the piston cylinder 1 .

Specifically, as shown in Figure 1, the brake fluid supply mechanism 3 also includes a static container 35. One end of the static container 35 is connected to the liquid storage container 34 through the actuator 33, and the other end of the static container 35 is connected through a pipeline. 32 is connected to the exhaust port 220 of the braking system 200 . The static container 35 can be used to store part of the brake fluid that flows back from the piston cylinder 1 , and is also used to store the brake fluid that flows out from the exhaust port 220 of the brake system 200 when the air in the brake system 200 is discharged. The brake fluid stored in the static container 35 can flow back to the liquid storage container 34 through the actuating device 33 to facilitate the next cycle. In addition, when the static container 35 recovers the brake fluid mixed with air, the brake fluid mixed with air can be allowed to stand in the static container 35 to separate the air and brake fluid, thereby allowing the pure brake fluid to return. into the liquid storage container 34. Among them, an active separation device can be provided in the static container 35, which can speed up the separation of brake fluid and air and improve separation and testing efficiency.

In a specific embodiment, the actuating device 33 may also include a pump, which may provide power to pump the brake fluid in the static container 35 back into the fluid storage container 34 . As shown in Figure 1, the actuating device 33 may also include a valve 36 in another specific embodiment. The valve 36 may be connected in series between the static container 35 and the liquid storage container 34. The static container 35 The height can be higher than the height of the liquid storage container 34, so that the brake fluid in the static container 35 has a tendency to flow back into the liquid storage container 34 through its own gravity. The valve 36 can be automatically controlled by the controller 8. Open or close to realize the conduction or disconnection of the flow path between the static container 35 and the liquid storage container 34. When the valve 36 is opened, the brake fluid in the static container 35 can be realized to flow back to the storage container through gravity. in the liquid container 34.

Among them, the static container 35 is provided with a vent for communicating with the atmosphere. The brake fluid in the static container 35 is always in a non-filled state, that is, there is a certain space above the brake fluid in the static container 35 It is used to accommodate air. This space is connected to the atmosphere through the vent. When part of the brake fluid in the piston cylinder 1 returns to the brake fluid supply mechanism 3, the air in the static container 35 can pass through the pipeline 32 and the brake fluid. The exhaust port 220 of the system 200 supplements the braking system 200 .

Specifically, as shown in FIG. 1 , the pipeline 32 between the exhaust port 220 of the braking system 200 and the rest container 35 may include a first pipe 321 and a second pipe 322 , one end of the first pipe 321 is connected to the A first port of the solenoid valve 31 and the other end of the first pipe 321 are used to connect to the exhaust port 220 of the braking system 200 . The first pipe 321 is a hard pipe, such as a metal brake pipe, a hard plastic pipe, etc. The second tube 322 is a transparent hose, one end of the second tube 322 is connected to the second port of the first solenoid valve 31, and the other end of the second tube 322 is connected to the resting container 35. When the brake system 200 is exhausted, the brake fluid in the piston cylinder 1 enters the brake system 200 through the liquid outlet 1b of the piston cylinder 1 and the liquid inlet 210 of the brake system 200. When the brake system 200 is filled with fluid, the brake fluid can flow out from the exhaust port 220 of the brake system 200 and can enter the second tube 322 through the first tube 321 and the first solenoid valve 31 in sequence. Since the second tube 322 is The transparent hose allows the operator to intuitively observe whether brake fluid has entered the second tube 322. If pure brake fluid is discharged from the second tube 322, it can be accurately determined that the air in the brake system 200 has been completely discharged. , at this time, the controller 8 can be used to control the first solenoid valve 31 to close. The circuit between the first solenoid valve 31, the braking system 200, and the piston cylinder 1 is filled with brake fluid and has no air, so that the measurement of no air can be started. PV characteristics of the braking system 200 in the air state. The brake fluid that enters the second pipe 322 can flow into the resting container 35 for recovery. After the measurement is completed, it can further flow back to the liquid storage container 34 through the actuating device 33 . It should be noted that whether the air in the brake system 200 has been completely discharged can be determined by directly observing the state of the brake fluid in the second tube 322. The brake fluid begins to enter the second tube 322. When the brake fluid is mixed with air, it is a gas-liquid mixture. Obvious bubbles can be observed in the brake fluid. When the brake fluid entering the second pipe 322 is not mixed with bubbles, it means that it enters the second pipe 322. The brake fluid in the second pipe 322 is pure brake fluid, and the air in the brake system 200 has been completely exhausted at this time.

As a specific implementation, as shown in Figure 1, the pressure volume measurement system also includes a second solenoid valve 12. The second solenoid valve 12 is connected in series between the liquid outlet 1b and the liquid inlet 210 of the braking system 200. During this time, the second solenoid valve 12 is connected to the controller 8 via a signal. The second solenoid valve 12 can be opened or closed under the control of the controller 8, thereby enabling automatic conduction or disconnection of the flow path between the liquid outlet 1b of the piston cylinder 1 and the liquid inlet 210 of the braking system 200. . Before exhausting the brake system 200, both the first solenoid valve 31 and the second solenoid valve 12 can be opened through the controller 8, and brake fluid is pumped into the piston cylinder 1 through the brake fluid supply mechanism 3. The brake fluid in 1 can sequentially pass through the fluid outlet 1b, the second solenoid valve 12, and the fluid inlet 210 of the brake system 200 and then enter the brake system 200 until the brake fluid can be observed in the second pipe 322. , the first solenoid valve 31 can be closed through the controller 8, and the brake fluid supply mechanism 3 can be stopped at the same time, and then the PV measurement can be performed without air.

As a specific implementation, as shown in Figure 1, the pressure volume measurement system also includes a third solenoid valve 13. The third solenoid valve 13 is connected in series between the liquid inlet 1a of the piston cylinder 1 and the flow detection device 7. , the third solenoid valve 13 is connected with the controller 8 via a signal. The third solenoid valve 13 can be opened or closed under the control of the controller 8, thereby enabling automatic conduction or disconnection of the flow path between the liquid inlet 1a of the piston cylinder 1 and the brake fluid supply mechanism 3. Before exhausting the brake system 200 , the first solenoid valve 31 , the second solenoid valve 12 and the third solenoid valve 13 can all be opened through the controller 8 , and the brake fluid is pumped into the piston cylinder 1 through the brake fluid supply mechanism 3 brake fluid to bleed the air. After the air in the braking system 200 is exhausted, the first solenoid valve 31 and the third solenoid valve 13 can be closed, and the second solenoid valve 12 can be kept open. At this time, the braking system 200PV can be realized through the movement of the driving piston 11 Measurement. Specifically, when the driving device 2 pushes the piston 11 to move forward, the piston 11 squeezes the brake fluid, causing the pressure of the braking system 200 to increase. The real-time pressure value can be obtained through the pressure detection device 4, and the movement of the piston 11 brings The resulting volume change can be indirectly obtained through calculation through the displacement of the piston 11 measured by the displacement detection device, so that the PV characteristic curve of the braking system 200 in the absence of air can be obtained based on the PV values corresponding to different positions of the piston 11 movement. ,As shown in Figure 4. In Figure 4, the horizontal axis represents the pressure P of the braking system 200, and the vertical axis represents the volume V of brake fluid required in the braking system 200. Curves 1 to 3 are distributed from bottom to top, and curves 1 to 3 respectively represent The volume of air mixed into the braking system 200 increases successively. It can be seen from Figure 4 that as the volume of mixed air increases, under the condition of establishing the same pressure P0, the volume of brake fluid required by the braking system 200 will be larger, that is, V1>V2>V3.

When it is necessary to measure the PV characteristic curve with a certain amount of air, the piston 11 can be controlled to return to the initial position through the driving device 2, and the first solenoid valve 31, the second solenoid valve 12 and the third solenoid valve can be controlled through the controller 8. The valves 13 are all opened, and the actuating device 33 is started. The actuating device 33 can withdraw part of the brake fluid in the piston cylinder 1 to the rest container 35. During the withdrawal process, the withdrawal can be controlled by the flow detection device 7 The volume of the air supplied to the brake system 200 is controlled. When the air replenishment is completed, the first solenoid valve 31 and the third solenoid valve 13 are closed, the second solenoid valve 12 is kept open, the driving device 2 is started, and the piston 11 is controlled by the driving device 2 to reciprocate rapidly at a certain high frequency for a certain period. time to allow the brake fluid and air to fully mix and become a gas-liquid mixture. Then, the driving device 2 can be used to control the piston 11 to advance slowly, push the brake fluid, and record the PV values corresponding to different positions of the piston 11 movement to obtain the PV characteristic curve of the braking system 200 with a constant amount of air.

If it is necessary to further increase the volume of air in the braking system 200, the above-mentioned operation of supplementing the air can be repeated, which will not be described again.

Therefore, through the cooperation of the first solenoid valve 31, the second solenoid valve 12 and the third solenoid valve 13, the automatic control of the pressure volume measurement system can be realized, which facilitates the operation, shortens the measurement time, and improves the accuracy of the operation. .

As a specific implementation, for the driving device 2 , the driving device 2 may include a motor 21 and a driving screw 22 . The driving screw 22 is drivingly connected to the motor 21 , and one end of the driving screw 22 is connected to the piston 11 . The forward and reverse rotation of the motor 21 can drive the transmission screw 22 to move in opposite directions, so that the piston 11 can be controlled to move forward or backward through the transmission screw 22 to facilitate operation control.

In a specific embodiment, the displacement detection device 6 may be a displacement sensor, and the displacement sensor is provided on the transmission screw 22 . The displacement sensor can send out a displacement signal, and the controller 8 obtains the displacement of the piston 11 based on the displacement signal. When the transmission screw 22 moves, the displacement sensor can detect the axial displacement of the transmission screw 22, that is, the displacement of the piston 11. The controller 8 can calculate the axial displacement of the piston 11 based on the displacement and the stored cross-sectional area of the piston 11. The change in volume is the change in brake fluid volume. The cross-sectional area of the piston 11 is the cross-sectional area orthogonal to the movement direction of the piston 11 .

In another specific embodiment, the displacement detection device 6 may be a rotational speed position sensor, and the rotational speed position sensor is provided on the motor 21 . The rotational speed position sensor can obtain the rotation angle of the motor 21. The controller 8 can calculate the displacement of the transmission screw 22 based on the rotation angle and the stored transmission ratio between the motor 21 and the transmission screw 22, which is the displacement of the piston 11. , the controller 8 can calculate the change in volume caused by the movement of the piston 11 based on the displacement and the stored cross-sectional area of the piston 11, which is the change in the brake fluid volume. The cross-sectional area of the piston 11 is the cross-sectional area orthogonal to the movement direction of the piston 11 .

As a specific implementation, as shown in Figures 1 and 5, the piston cylinder 1 is provided with a through hole, the piston 11 is provided with a limiter 111, and the transmission screw 22 passes through the through hole and is connected to the limiter 111. The position piece 111 is used to adjust the position of the piston 11 on the drive screw 22 . It should be noted that different braking systems 200 have different requirements for the volume of brake fluid stored in the piston cylinder 1. Therefore, before using the pressure volume measurement system, it is necessary to adjust the piston cylinder according to the braking system 200 to be tested. 1 space used to store brake fluid for matching calibration. In this embodiment, the limiter 111 can be fixed to the piston 11 and can drive the piston 11 to move and be fixed on the transmission screw 22. When the transmission screw 22 is in the initial position, the piston 11 can be adjusted by the limiter 111. The position matches the braking system 200 to be measured, so that the pressure volume measurement system can be adapted to different braking systems 200 and broadens the application range of the pressure volume measurement system.

Specifically, as shown in FIG. 5 , the transmission screw 22 is provided with a threaded segment 221 , and the limiting member 111 is provided with a threaded hole. The limiting member 111 is sleeved on the driving screw 22 through the cooperation of the threaded hole and the threaded segment 221 . The position piece 111 is provided with a scale 111a for calibrating the internal volume of the piston cylinder 1 . When it is necessary to adjust the position of the piston 11 on the drive screw 22, the stopper 111 can be rotated. The stopper 111 can undergo slight axial displacement by cooperating with the thread of the drive screw 22, thereby driving the piston 11 to achieve position adjustment. The scale 111a on the limiter 111 can provide an intuitive reference for the operator to ensure the accuracy of adjustment.

The embodiment of the present application also provides a pressure volume measurement method, as shown in Figure 6. This method uses the pressure volume measurement system provided by any embodiment of the present application. The method includes:

Step S1: Add brake fluid to the braking system 200 to be tested, and discharge the air in the braking system 200 to be tested.

Specifically, when it is necessary to measure the pressure volume of the braking system, the braking system 200 to be measured can first be connected to the pressure volume measurement system. Then, the brake fluid can be replenished into the piston cylinder 1 through the brake fluid supply mechanism 3, and the brake fluid in the piston cylinder 1 can flow into the braking system 200 to be tested. When the brake fluid is filled with the braking system 200 to be tested, During the test, the air in the braking system 200 to be tested is completely exhausted.

Step S2: Measure the pressure volume curve of the braking system 200 under test in the first state.

Specifically, in this embodiment, the first state is an airless state, and the driving device 2 can control the piston 11 to advance slowly. When the piston 11 pushes the brake fluid, the pressure of the brake fluid in the piston cylinder 1 changes, and at the same time, the piston 11 The movement of can bring about changes in the volume of the brake fluid. According to the pressure values and volume changes of the brake fluid in the piston cylinder 1 at different positions of the piston 11, the PV curve of the brake system 200 in the airless state can be obtained.

Step S3: Recover a set volume of brake fluid from the braking system 200 to be tested, so that a set volume of air is added to the braking system 200 to be tested.

After measuring the PV curve of the braking system 200 without air, further measurement of the PV characteristics with a certain amount of air may be performed. Specifically, part of the brake fluid in the piston cylinder 1 can be withdrawn into the brake fluid supply mechanism 3, and the volume of the withdrawn brake fluid can be controlled by the flow detection device 7. The brake fluid in the piston cylinder 1 When the fluid is extracted, the brake fluid pressure decreases. At this time, air can be replenished into the brake system 200 through the exhaust port 220 of the brake system 200, and the volume of the replenished air is equal to the volume of the extracted brake fluid. , thereby by controlling the volume of brake fluid extracted, the volume of supplemented air can be precisely controlled, thereby achieving quantitative supplementation of air to the brake system 200 .

Step S4: Obtain the temperature of the braking system 200 to be tested.

During the actual braking operation of the vehicle, the temperature of the braking system 200 is not constant, and the temperature of the braking system 200 also affects the PV characteristics of the braking system 200 . When measuring the PV characteristics of the braking system 200, the temperature of the braking system 200 is also an important factor that needs to be considered. In this application, the temperature detection device 5 can be used to detect the temperature of the brake fluid in the piston cylinder 1. After obtaining the temperature of the brake fluid in the piston cylinder 1, the braking system can be estimated through the temperature estimation model in the software. The temperature of 200 is input as the current temperature condition, and the PV characteristics are further measured under this temperature condition. The above software can be configured in the vehicle's driving computer.

Step S5: Measure the pressure volume curve of the braking system 200 under test in the second state and under different temperature conditions. In this embodiment, the second state is a state with a set volume of air.

The pressure volume measurement method provided by this application enables the brake system 200 to continuously measure the PV characteristics without air and with different air volumes without changing the system and circuit structure, making the operation more convenient and faster, and through The control of the flow detection device 7 can ensure the accuracy of the volume of supplementary air in the braking system 200 and the accuracy of the PV characteristic measurement results of the braking system 200. By detecting the temperature of the braking system 200, the PV characteristics of the braking system 200 under the current temperature conditions can be obtained, thereby comprehensively and accurately reflecting the PV characteristics of the braking system 200 under different conditions.

It should be noted that after step S6 completes a measurement of the pressure-volume curve in a state with a set volume of air, steps S4 to S6 can be further repeated, so that the braking system 200 can have different air volumes. PV characteristics. Therefore, this method can realize continuous PV characteristic measurement of the braking system 200 with different volumes of air and different temperatures of the braking system 200,

Specifically, after step S3, the method also includes:

Step S31, mix the air and brake fluid in the braking system 200 to be tested.

When the air replenishment is completed, the driving device 2 can be started, and the driving device 2 controls the piston 11 to reciprocate rapidly at a certain high frequency for a certain time, so that the brake fluid and air are fully mixed and become a gas-liquid mixed state. Then, the driving device 2 can be used to control the piston 11 to advance slowly, push the brake fluid, and record the PV values corresponding to different positions of the piston 11 movement to obtain the PV characteristic curve of the braking system 200 with a constant amount of air.

Specifically, as shown in Figure 7, step S1 specifically includes:

Step S11, control the first solenoid valve 31, the second solenoid valve 12 and the third solenoid valve 13 to open, and start the actuating device 33 so that the brake fluid in the liquid storage container 34 is injected into the piston cylinder 1 and the braking system to be tested. 200 in.

Step S12, determine whether pure brake fluid flows out from the second pipe 322; if so, proceed to step S13.

Step S13, stop the actuating device 33, and control the first solenoid valve 31 and the third solenoid valve 13 to close.

When the brake system 200 is exhausted, the brake fluid in the piston cylinder 1 enters the brake system 200 through the liquid outlet 1b of the piston cylinder 1 and the liquid inlet 210 of the brake system 200. When the brake fluid is filled with the brake system 200, the brake fluid can flow out from the exhaust port 220 of the brake system 200, and can enter the second tube 322 through the first tube 321 and the first solenoid valve 31 in sequence. 322 is a transparent hose. The operator can intuitively observe whether the brake fluid has entered the second tube 322. If the brake fluid has entered the second tube 322, it can be accurately judged that the air in the brake system 200 has been Completely discharged, at this time, the controller 8 can be used to control the first solenoid valve 31 and the third solenoid valve 13 to close, so that the circuit between the first solenoid valve 31, the braking system 200, and the piston cylinder 1 is filled with brake fluid, and There is no air, so that the measurement of the PV characteristics of the braking system 200 in the air-free state can be started. The brake fluid entering the second pipe 322 can flow into the rest container 35 for recovery, and can further flow back to the liquid storage container 34 through the actuating device 33 .

Specifically, as shown in Figure 8, step S2 specifically includes:

In step S21, the driving device 2 is started to control the movement of the piston 11 to push the brake fluid.

Step S22: Obtain the displacement amount corresponding to the movement of the piston 11 to different positions, the pressure value of the brake fluid in the piston cylinder 1, and the temperature value of the brake fluid in the piston cylinder 1.

Among them, the displacement of the piston 11 can be obtained through the displacement detection device, the pressure of the brake fluid in the piston cylinder 1 can be obtained through the pressure detection device 4, and the temperature of the brake fluid in the piston cylinder 1 can be obtained through the temperature detection device 5.

Step S23, obtain the change amount of the brake fluid volume in the piston cylinder 1 according to the displacement amount and the cross-sectional area of the piston 11, and obtain the pressure-volume curve according to the change amount of the brake fluid volume and the pressure value, and obtain the pressure-volume curve according to the temperature value in the piston cylinder 1 Obtain the temperature of the braking system 200 under test. Among them, the cross-sectional area of the piston 11 is the cross-sectional area orthogonal to the movement direction of the piston 11.

Specifically, as shown in Figure 9, step S3 specifically includes:

In step S3a, the first solenoid valve 31, the second solenoid valve 12 and the third solenoid valve 13 are controlled to open, and the actuating device 33 is started to draw part of the brake fluid in the piston cylinder 1 back into the resting container 35.

In step S3b, the volume of the withdrawn brake fluid is obtained through the flow detection device 7 and a flow signal is sent.

In step S3c, the controller 8 determines whether the volume of the withdrawn brake fluid reaches a preset volume based on the flow signal.

Step S3d, if yes, control the first solenoid valve 31 and the third solenoid valve 13 to close, and keep the second solenoid valve 12 open.

During the process of withdrawing brake fluid, the flow detection device 7 can measure the volume of brake fluid return in real time and send out a flow signal. The controller 8 can analyze the flow signal to determine whether it reaches the preset value. If so, , then the first solenoid valve 31 and the third solenoid valve 13 are controlled to close. At this time, the operation of supplementing air to the braking system 200 is completed.

Embodiments of the present application also provide a storage medium that includes a stored application program that executes the pressure volume measurement method provided by any embodiment of the present application.

An embodiment of the present application also provides a measurement device, which includes a first control module, a second control module, a first measurement module and a second measurement module.

Wherein, the first control module is used to send a first signal, and the first signal is to add brake fluid to the braking system to be tested and to discharge the air in the braking system to be tested.

The second control module is used to send a second signal. The second signal is to recover a set volume of brake fluid from the braking system to be tested, so that a set volume of air is added to the braking system to be tested.

The first measurement module is used to measure the pressure-volume curve of the brake system to be tested in a state without air; the measurement module is also used to measure the pressure-volume curve of the brake system to be tested in a state with a set volume of air.

The above descriptions are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the protection scope of this application.

Claims

A pressure volume measurement system, characterized by including:

A piston cylinder, the piston cylinder includes a liquid inlet and a liquid outlet, and the liquid outlet is used to be connected to the liquid inlet of the braking system;

A piston is arranged in the piston cylinder;

A driving device, connected to the piston, used to drive the piston to move within the piston cylinder;

Brake fluid supply mechanism, the first end of the brake fluid supply mechanism is connected to the liquid inlet of the piston cylinder, used to supply brake fluid to the piston cylinder or recover brake fluid in the piston cylinder ;The second end of the brake fluid supply mechanism is used to be connected to the exhaust port of the brake system;

A pressure detection device is provided on the piston cylinder and used to detect the pressure of the brake fluid in the piston cylinder;

A temperature detection device is provided on the piston cylinder and used to detect the temperature of the brake fluid in the piston cylinder;

A displacement detection device used to detect the displacement of the piston;

a flow detection device for detecting the flow rate of brake fluid flowing back from the piston cylinder to the brake fluid supply mechanism;

A first solenoid valve connected in series between the second end of the brake fluid supply mechanism and the exhaust port of the brake system;

A controller is respectively connected to the driving device, the pressure detection device, the displacement detection device, the flow detection device and the first solenoid valve.
The pressure volume measurement system according to claim 1, wherein the flow detection device is connected to the liquid inlet of the piston cylinder.
The pressure volume measurement system according to claim 1, characterized in that the brake fluid supply mechanism includes a liquid storage container and an actuating device, and the actuating device is connected to the liquid storage container and the piston cylinder respectively. The fluid inlet is connected and used for pumping the brake fluid in the fluid storage container into the piston cylinder through the fluid inlet of the piston cylinder.
The pressure volume measurement system according to claim 3, wherein the brake fluid supply mechanism further includes a static container, one end of the static container is connected to the liquid storage container through the actuating device, The other end of the static container is connected to the exhaust port of the braking system through a pipeline.
The pressure volume measurement system according to claim 4, characterized in that the static container is provided with a vent for communicating with the atmosphere.
The pressure volume measurement system according to claim 4, wherein the pipeline includes a first tube and a second tube;

One end of the first pipe is connected to the first port of the first solenoid valve, and the other end of the first pipe is used to connect to the exhaust port of the braking system;

The second tube is a transparent hose, one end of the second tube is connected to the second port of the first solenoid valve, and the other end of the second tube is connected to the resting container.
The pressure volume measurement system according to any one of claims 1 to 6, further comprising a second solenoid valve connected in series to the liquid outlet and the inlet of the braking system. between liquid ports;

The second solenoid valve is signally connected to the controller.
The pressure volume measurement system according to any one of claims 1 to 7, further comprising a third solenoid valve connected in series to the liquid inlet of the piston cylinder and the flow detection between devices;

The third solenoid valve is signally connected to the controller.
The pressure volume measurement system according to any one of claims 1 to 8, characterized in that the driving device includes a motor and a transmission screw, the transmission screw is connected to the motor, and one end of the transmission screw is connected to the motor. The pistons are connected.
The pressure volume measurement system according to claim 9, characterized in that the displacement detection device is a displacement sensor, and the displacement sensor is arranged on the transmission screw;

The displacement sensor sends out a displacement signal, and the controller obtains the displacement of the piston based on the displacement signal.
The pressure volume measurement system according to claim 9, wherein the displacement detection device is a rotational speed position sensor, and the rotational speed position sensor is provided on the motor;

The rotational speed position sensor emits a rotational position signal indicating the rotational angle of the motor, and the controller calculates the rotation angle of the piston based on the rotational position signal and the transmission ratio between the motor and the transmission screw. Displacement amount.
The pressure volume measurement system according to claim 9, characterized in that a through hole is provided on the piston cylinder, a limiter is provided on the piston, and the transmission screw passes through the through hole and is connected to the limiter. The positioning member is used to adjust the position of the piston on the transmission screw.
The pressure volume measurement system according to claim 12, characterized in that the transmission screw is provided with a threaded section, the limiting member is provided with a threaded hole, and the limiting member passes through the threaded hole and the The threaded section is fitted and sleeved on the transmission screw;

The limiter is provided with a scale for calibrating the internal volume of the piston cylinder.
A pressure volume measurement method, characterized in that the pressure volume measurement system according to any one of claims 1 to 13 is used, and the method includes:

Add brake fluid to the braking system to be tested and discharge the air in the braking system to be tested;

Measuring the pressure-volume curve of the braking system under test in the first state;

Recover a set volume of brake fluid from the braking system to be tested so that the braking system to be tested is filled with the set volume of air;

Obtain the temperature of the braking system to be tested;

Measure the pressure volume curve of the braking system under test in the second state and under different temperature conditions.
The pressure volume measurement method according to claim 14, characterized in that a set volume of brake fluid is recovered from the braking system to be tested, so that the device is added to the braking system to be tested. After setting the volume of air, the method further includes:

Mix the air and brake fluid in the brake system to be tested.
The pressure volume measurement method according to claim 14, wherein the step of adding brake fluid to the braking system to be tested and discharging the air in the braking system to be tested specifically includes:

Control the first solenoid valve, the second solenoid valve and the third solenoid valve to open, and start the actuating device so that the brake fluid in the liquid storage container is injected into the piston cylinder and the braking system to be tested;

Determine whether pure brake fluid flows from the second pipe;

If so, the actuating device is stopped and the first solenoid valve and the third solenoid valve are controlled to close.
The pressure volume measurement method according to claim 14, characterized in that measuring the pressure volume curve of the brake system to be tested in an airless state specifically includes;

Start the drive to control the piston to push the brake fluid;

Obtain the displacement corresponding to the piston movement to different positions, the pressure value of the brake fluid in the piston cylinder, and the temperature value of the brake fluid in the piston cylinder;

The change amount of the brake fluid volume in the piston cylinder is obtained based on the displacement amount and the cross-sectional area of the piston, and the pressure volume curve is obtained based on the change amount of the brake fluid volume and the pressure value. The temperature value obtains the temperature of the braking system under test.
The pressure volume measurement method according to claim 14, characterized in that the set volume of brake fluid is recovered from the braking system to be tested, so that the braking system to be tested is filled with the brake fluid. Set volume of air, including:

Control the first solenoid valve, the second solenoid valve and the third solenoid valve to open, and start the actuating device to draw part of the brake fluid in the piston cylinder back to the rest container;

Obtain the volume of the withdrawn brake fluid through the flow detection device and send out a flow signal;

The controller determines whether the volume of the withdrawn brake fluid reaches a preset volume based on the flow signal;

If so, the first solenoid valve and the third solenoid valve are controlled to close, and the second solenoid valve is kept open.
A storage medium, characterized in that the storage medium includes a stored application program, and the application program executes the pressure volume measurement method according to any one of claims 14 to 18.
A measuring device, characterized in that the measuring device includes:

The first control module is used to send a first signal, the first signal is to add brake fluid to the braking system to be tested and discharge the air in the braking system to be tested;

The second control module is used to send a second signal. The second signal is to recover a set volume of brake fluid from the braking system to be tested, so that the braking system to be tested is filled with the brake fluid. Set volume of air;

The first measurement module is used to measure the pressure volume curve of the braking system to be tested in a state without air; the measurement module is also used to measure the pressure volume curve of the braking system to be tested in a state with the set volume of air. pressure volume curve;

The second measurement module is used to measure the temperature of the braking system to be tested.