Wheel cylinder pressure estimation method and device

Abstract

The application provides a wheel cylinder pressure estimation method and device, and relates to the technical field of automobiles.The method comprises the following steps: obtaining a first pressure value of an electric master cylinder at a current moment and a second pressure value of a target wheel cylinder at a previous moment; the electric master cylinder is in communication with a volume chamber; the volume chamber is in communication with a plurality of wheel cylinders respectively; the plurality of wheel cylinders are in communication with an oil tank; and the plurality of wheel cylinders comprise the target wheel cylinder; obtaining a target flow of the target wheel cylinder at the current moment based on the first pressure value and the second pressure value; obtaining a first volume of the target wheel cylinder corresponding to the second pressure value according to a pre-acquired first mapping relationship; the first mapping relationship is used to represent the corresponding relationship between the volume of the wheel cylinder and the pressure value; calculating a second volume of the target wheel cylinder after a preset time period based on the target flow and the first volume; and obtaining a target pressure of the target wheel cylinder corresponding to the second volume based on the first mapping relationship. The wheel cylinder pressure estimation of Onebox can be realized by adopting the above steps, and the estimation accuracy is improved.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to a method and apparatus for estimating wheel cylinder pressure. Background Technology

[0002] The Onebox brake-by-wire system is a new generation of brake-by-wire system proposed in contrast to the traditional Twobox system. It has advantages such as fast response, high functional integration, excellent pedal feel, good braking linearity, effective integration with energy recovery and autonomous driving-related functions, small footprint, and low cost.

[0003] When testing the pressure of the electric master cylinder and wheel cylinders in the Onebox brake-by-wire system, to save costs, pressure sensors are only installed at the electric master cylinder, and generally not at the wheel cylinders. Therefore, it is necessary to estimate the pressure based on the electric master cylinder pressure and the opening degree and opening time of each valve in the Onebox brake-by-wire system. The current estimation method is to establish a complete simulation model from the electric master cylinder to the wheel cylinders, and then give the wheel cylinder pressure.

[0004] However, to address the model stability issue, a hydraulic resistance model is typically introduced into the volumetric cavity of the Onebox brake-by-wire system, and the hydraulic resistance coefficient is adjusted. A suitable hydraulic resistance coefficient can stabilize the system, but it significantly impacts the system response time, making it difficult to find a realistic balance between response time and system stability. Therefore, the method of calculating wheel cylinder pressure by establishing a simulation model from the electric master cylinder to the wheel cylinders has relatively low accuracy. Summary of the Invention

[0005] This application provides a wheel cylinder pressure estimation method and apparatus that can realize wheel cylinder pressure estimation for Onebox and improve the accuracy of wheel cylinder pressure calculation.

[0006] In a first aspect, embodiments of this application provide a method for estimating wheel cylinder pressure, the method comprising:

[0007] The first pressure value of the electric master cylinder at the current moment and the second pressure value of the target wheel cylinder at the previous moment are obtained. The electric master cylinder is connected to the volume chamber, the volume chamber is connected to multiple wheel cylinders, the multiple wheel cylinders are all connected to the oil storage tank, and the multiple wheel cylinders include the target wheel cylinder.

[0008] Based on the first pressure value and the second pressure value, the target flow rate of the target wheel cylinder at the current moment is obtained;

[0009] Based on the pre-acquired first mapping relationship, the first volume of the target wheel cylinder corresponding to the second pressure value is obtained, and the first mapping relationship is used to characterize the correspondence between the volume of the wheel cylinder and the pressure value;

[0010] Based on the target flow rate and the first volume, calculate the second volume of the target wheel cylinder after a preset time period;

[0011] Based on the first mapping relationship, the target pressure of the target wheel cylinder corresponding to the second volume is obtained.

[0012] Secondly, this application provides a wheel cylinder pressure estimation device, the device comprising:

[0013] The acquisition module is used to acquire the first pressure value of the electric master cylinder at the current moment and the second pressure value of the target wheel cylinder at the previous moment. The electric master cylinder is connected to the volume chamber, the volume chamber is connected to multiple wheel cylinders respectively, the multiple wheel cylinders are all connected to the oil storage tank, and the multiple wheel cylinders include the target wheel cylinder.

[0014] The first calculation module is used to obtain the target flow rate of the target wheel cylinder at the current moment based on the first pressure value and the second pressure value;

[0015] The first lookup module is used to obtain the first volume of the target wheel cylinder corresponding to the second pressure value according to the pre-acquired first mapping relationship, wherein the first mapping relationship is used to characterize the correspondence between the volume of the wheel cylinder and the pressure value;

[0016] The second calculation module is used to calculate the second volume of the target wheel cylinder after a preset time period based on the target flow rate and the first volume;

[0017] The second lookup module is used to obtain the target pressure of the target wheel cylinder corresponding to the second volume based on the first mapping relationship.

[0018] Thirdly, embodiments of this application provide an electronic device, which includes: a processor and a memory storing computer program instructions;

[0019] When the processor executes computer program instructions, it implements the cylinder pressure estimation method as described in any of the embodiments of the first aspect.

[0020] Fourthly, embodiments of this application provide a computer storage medium storing computer program instructions, which, when executed by a processor, implement the cylinder pressure estimation method as described in any of the embodiments of the first aspect.

[0021] Fifthly, embodiments of this application provide a computer program product in which instructions, when executed by a processor of an electronic device, cause the electronic device to perform the wheel cylinder pressure estimation method as described in any of the embodiments of the first aspect above.

[0022] The wheel cylinder pressure estimation method and apparatus of this application embodiment include: obtaining a third pressure value of the volumetric cavity in the linear control system based on a pre-acquired first pressure value, a second pressure value, and a first parameter of a first valve; obtaining the total flow rate of the wheel cylinder under test at the current moment based on the second pressure value, the third pressure value, and a pre-acquired second parameter of a second valve, wherein the second valve includes a pressure reducing valve disposed between the wheel cylinder under test and an oil storage tank; obtaining a first volume of the wheel cylinder under test corresponding to the total flow rate at the current moment; obtaining a second volume of the wheel cylinder under test at the next moment based on the first volume, the total flow rate, and a step size, wherein the step size is the time interval between the current moment and the next moment; and obtaining the target wheel cylinder pressure corresponding to the second volume at the next moment based on a pre-acquired mapping relationship between volume and pressure. By iteratively calculating the wheel cylinder pressure and utilizing the valve's switching characteristics and the liquid's orifice throttling characteristics to calculate the pressure difference and flow rate of each valve, wheel cylinder pressure estimation is achieved, and the calculation is simple, fast, and highly accurate. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the Onebox brake-by-wire system provided in one embodiment of this application;

[0025] Figure 2 This is a schematic flowchart of a wheel cylinder pressure estimation method provided in one embodiment of this application;

[0026] Figure 3 This is a schematic diagram of the structure of a wheel cylinder pressure estimation device provided in an embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0028] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0029] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0031] To address the problems of the prior art, this application provides a method and apparatus for estimating wheel cylinder pressure. The wheel cylinder pressure estimation method provided in this application will be described first.

[0032] To facilitate understanding of the technical solutions provided in the embodiments of the present invention, the Onebox brake-by-wire system will be introduced first. Figure 1 A schematic diagram of the Onebox brake-by-wire system is shown. The Onebox brake-by-wire system includes a manual master cylinder 110 and an electric master cylinder 101. The manual master cylinder 110 is responsible for generating and adjusting the pedal feel, while the electric master cylinder 101 is responsible for pressure build-up. When the Onebox system is operating, the isolation valve is closed, isolating the two cylinders. The electric master cylinder 101 is the pressure source for the entire hydraulic circuit, with a piston driven by a motor for pressure increase and decrease. Its pressure can be measured in real time by a pressure sensor installed at the electric master cylinder 101. The pressure transmission is divided into two symmetrical paths, selectable by a hydraulic circuit selection valve 103. Each wheel cylinder is equipped with a pressure boosting valve and a pressure reducing valve to achieve pressure increase and decrease operations.

[0033] An electric master cylinder 101 is connected to a volumetric cavity 102, which is connected to multiple wheel cylinders. Each wheel cylinder is connected to an oil storage tank, and the multiple wheel cylinders include the target wheel cylinder. An oil circuit selection valve 103 is provided between the electric master cylinder 101 and the volumetric cavity 102. A pressure boosting valve is provided between the volumetric cavity 102 and each wheel cylinder. Each wheel cylinder includes a first wheel cylinder 105 and a second wheel cylinder 107. A first pressure boosting valve 104 is provided between the volumetric cavity 102 and the first wheel cylinder 105, and a second pressure boosting valve 109 is provided between the volumetric cavity 102 and the second wheel cylinder 107. A first pressure reducing valve 106 is provided between the first wheel cylinder 105 and the oil storage tank, and a second pressure reducing valve 108 is provided between the second wheel cylinder 107 and the oil storage tank. Figure 1The isolation valve is a solenoid valve that isolates the manual master cylinder and the electric master cylinder 101. The oil circuit selection valve 103 is a solenoid valve that selects the direction of pressure transmission. The booster valve is a solenoid valve located upstream of the wheel cylinder; when opened, it allows brake fluid from the electric master cylinder 101 to flow into the wheel cylinder, achieving the purpose of boosting pressure. The pressure reducing valve is a solenoid valve located downstream of the wheel cylinder; when opened, it allows brake fluid to flow out of the wheel cylinder, achieving the purpose of pressure reducing pressure. The volume chamber 102 is the oil circuit space between the oil circuit selection valve 103 and the two booster valves.

[0034] Figure 2 A schematic flowchart of a wheel cylinder pressure estimation method according to an embodiment of this application is shown. Figure 2 As shown, the method may specifically include the following steps:

[0035] Step 101: Obtain the first pressure value of the electric master cylinder 101 at the current moment and the second pressure value of the target wheel cylinder at the previous moment;

[0036] The first pressure value can be measured by a pressure sensor located at the electric master cylinder 101.

[0037] The pressure transmission path in the Onebox linear control system includes two paths. This embodiment uses one path as an example. The pressure transmission path is as follows: from the electric master cylinder 101 to the oil circuit selection valve 103, from the oil circuit selection valve 103 to the volume chamber 102, then to the first booster valve 104, then from the first booster valve 104 to the first wheel cylinder 105, then to the first pressure reducing valve 106, and finally to the oil reservoir. Additionally, while transmitting pressure from the volume chamber 102 to the first booster valve 104, it also transmits pressure through the volume chamber 102 to the second booster valve 109, then to the second wheel cylinder 107, then to the second pressure reducing valve 108, and finally to the oil reservoir. The target wheel cylinder is the one requiring pressure estimation; it can be either the first wheel cylinder 105 or the second wheel cylinder 107.

[0038] Since the second pressure value of the target wheel cylinder needs to be estimated, the second pressure value of the target wheel cylinder at the previous moment is the pressure value obtained in the previous estimation. It should be noted that when the initial estimation is performed, the second pressure value of the target wheel cylinder at the previous moment is the initial pressure, i.e., atmospheric pressure.

[0039] Step 102: Based on the first pressure value and the second pressure value, obtain the target flow rate of the target wheel cylinder at the current moment;

[0040] The target flow rate can be calculated by taking the first pressure value and the second pressure value, obtaining the pressure value of the volumetric cavity 102, and finally obtaining the final flow rate based on the pressure value of the volumetric cavity 102. The specific deduction process is as follows:

[0041] As the brake fluid flows through the linear control system, pressure and flow are generated at the electric wheel cylinder, volume chamber 102, first wheel cylinder 105, and second wheel cylinder 107, respectively, creating pressure differences across each valve. Furthermore, the brake fluid has a high elastic modulus and the volume chamber 102 is very small; therefore, the volume of brake fluid within the volume chamber 102 is almost incompressible, and the flow rate flowing into and out of the volume chamber 102 is always equal. Thus, in this embodiment, the flow rate out of the volume chamber 102 is the sum of the flow rate flowing into the first wheel cylinder 105 and the flow rate flowing into the second wheel cylinder 107; that is, flow rate is conserved, expressed by the calculation formula:

[0042]

[0043] in, To select the flow rate through the oil circuit selector valve 103, The flow rate through the first booster valve 104, The flow rate through the second booster valve 109.

[0044] The flow rate of each valve All satisfy the simplified orifice throttling formula:

[0045]

[0046] in, It is the flow constant. Let x be the pressure difference across the valve, and let x be the degree of valve opening.

[0047] Based on the calculation expression of flow conservation and the orifice throttling formula, we can obtain:

[0048]

[0049] in, It refers to the opening degree of the oil circuit selector valve 103. It is the flow coefficient of the oil circuit selector valve 103. The degree of opening of the first pressure boosting valve 104, The flow coefficient of the first booster valve 104 is... The degree of opening of the second pressure boosting valve 109. The flow coefficient of the second booster valve 109, The first pressure value, This is the second pressure value.

[0050] Therefore, it can be seen that the target flow rate of the target wheel cylinder can be further obtained by calculating the pressure value of the volume chamber 102.

[0051] Step 103: Based on the pre-acquired first mapping relationship, obtain the first volume of the target wheel cylinder corresponding to the second pressure value. The first mapping relationship is used to characterize the correspondence between the volume of the wheel cylinder and the pressure value.

[0052] The first mapping relationship can be a mapping table characterizing the correspondence between the volume and pressure value of a wheel cylinder, recording the pressure values ​​corresponding to different wheel cylinder volumes. The wheel cylinder volume refers to the volume of brake fluid within the wheel cylinder when it flows in. In this embodiment, the first volume of the target wheel cylinder corresponding to the second pressure value can be found in the mapping table, enabling a fast and accurate lookup of the wheel cylinder volume.

[0053] Step 104: Based on the target flow rate and the first volume, calculate the second volume of the target wheel cylinder after a preset time period;

[0054] Due to the viscosity of brake fluid, the change in flow rate in the target wheel cylinder has a certain response time. The time step for calculating the pressure in the target wheel cylinder needs to be small enough (<1ms). Therefore, the flow rate is constant within this very small time step.

[0055] In this embodiment, the preset time period can be one step or multiple steps. When calculating the second volume, it can be obtained by calculating the sum of the volume that the target cylinder will increase within the preset time period and the first volume at the current moment. The expression for calculating the second volume is:

[0056]

[0057] in, For the first volume, For a preset time period, For target traffic.

[0058] Step 105: Based on the first mapping relationship, obtain the target pressure of the target cylinder corresponding to the second volume.

[0059] The first mapping relationship is the correspondence between the wheel cylinder and the pressure value mentioned above. After obtaining the second volume cycle, the target pressure of the target wheel cylinder can be obtained directly from the table based on the mapping relationship between the wheel cylinder and the pressure value.

[0060] In this embodiment, the wheel cylinder pressure estimation method includes: obtaining a third pressure value of the volume chamber 102 in the linear control system based on a pre-acquired first pressure value, a second pressure value, and a first parameter of a first valve; obtaining the total flow rate of the wheel cylinder under test at the current moment based on the second pressure value, the third pressure value, and a pre-acquired second parameter of a second valve, wherein the second valve includes a pressure reducing valve disposed between the wheel cylinder under test and the oil storage tank; obtaining a first volume of the wheel cylinder under test corresponding to the total flow rate at the current moment; obtaining a second volume of the wheel cylinder under test at the next moment based on the first volume, the total flow rate, and a step size, wherein the step size is the time interval between the current moment and the next moment; and obtaining the target wheel cylinder pressure corresponding to the second volume at the next moment based on a pre-acquired mapping relationship between volume and pressure. By iteratively calculating the wheel cylinder pressure and utilizing the valve's switching characteristics and the liquid's orifice throttling characteristics to calculate the pressure difference and flow rate of each valve, wheel cylinder pressure estimation is achieved, and the calculation is simple, fast, and highly accurate.

[0061] In one embodiment of this application, the step of obtaining the target flow rate of the target wheel cylinder at the current moment based on the first pressure value and the second pressure value includes:

[0062] The pressure value of the volume chamber 102 is obtained based on the first pressure value, the second pressure value, the opening degree and flow coefficient of the oil circuit selection valve 103, the opening degree and flow coefficient of the first pressure boosting valve 104, and the opening degree and flow coefficient of the second pressure boosting valve 109.

[0063] Based on the pressure value of the volume chamber 102, the second pressure value, the opening degree and flow coefficient of the target booster valve, and the opening degree and flow coefficient of the target pressure reducing valve, the first flow rate of the target wheel cylinder is obtained. The target booster valve is one of the first booster valve 104 and the second booster valve 109, and the target pressure reducing valve is one of the first pressure reducing valve 106 and the second pressure reducing valve 108. The first booster valve 104, the first pressure reducing valve 106 and the first wheel cylinder 105 correspond to each other, and the second booster valve 109, the second pressure reducing valve 108 and the second wheel cylinder 107 correspond to each other.

[0064] In this embodiment, based on the above-mentioned orifice throttling formula, when calculating the pressure value of the volume chamber 102, in addition to the first pressure value and the second pressure value, it is also necessary to determine the pressure value based on the opening degree and flow coefficient of the oil circuit selection valve 103, the opening degree and flow coefficient of the first pressure boosting valve 104, and the opening degree and flow coefficient of the second pressure boosting valve 109.

[0065] It should be noted that the oil circuit selection valve 103, the first pressure boosting valve 104, and the second pressure boosting valve 109 are all solenoid valves. Their opening degrees are related to the pressure difference on either side. Therefore, the opening degrees of the oil circuit selection valve 103, the first pressure boosting valve 104, and the second pressure boosting valve 109 can be determined according to the pre-calibrated valve characteristic tables corresponding to the three valves. The valve characteristic tables record the solenoid valve current. and pressure difference With valve opening degree A two-dimensional table of relationships, where each row represents the same current. Below, the opening degree corresponding to different pressure differentials; the value in each column represents the same pressure differential. The opening degree corresponds to different currents. The pressure difference on both sides of the oil circuit selection valve 103 is the pressure difference between the electric master cylinder 101 and the volume chamber 102, the pressure difference on both sides of the first booster valve 104 is the pressure difference between the volume chamber 102 and the target wheel cylinder, and the pressure difference on both sides of the second booster valve 109 is the pressure difference between the volume chamber 102 and the target wheel cylinder.

[0066] In addition, the calibration process for the three valves is as follows: First, divide the current gradient and pressure differential gradient to obtain different currents and pressure differentials that need to be calibrated (for example, take a calibration value for the current every 100mA and a calibration value for the pressure differential every 5bar). During calibration, first apply a current that needs to be calibrated to the solenoid valve. Then adjust the flow. This ensures that the pressure difference across the valve reaches the required calibrated pressure difference. Record the traffic at this time. .Will and Substituting into the above orifice throttling formula, the degree of opening at this time can be calculated. For different and By performing the above operations, you can obtain the valve characteristic table.

[0067] The calibration process for the flow coefficient is as follows: A valve characteristic calibration bench is constructed. This bench has the function of stabilizing the flow rate and can measure the flow rate through the valve body and the pressure difference across the valve. During calibration, the valve port is fully opened (i.e., the opening degree is set to 1). The bench is controlled to deliver brake fluid at different flow rates. Flow through the valve body, while measuring each Pressure difference . and Proportional, flow coefficient Its proportionality coefficient. Using different groups and This can be obtained through least squares fitting. The values ​​can be obtained through the above process. The flow coefficients of oil circuit selection valve 103, first pressure boosting valve 104, second pressure boosting valve 109, first pressure reducing valve 106, and second pressure reducing valve 108 can be obtained.

[0068] When calculating the pressure value of the volume chamber 102, a calculation expression for the pressure value of the volume chamber 102 can be established based on the flow conservation between the oil circuit selection valve 103, the first booster valve 104, and the second booster valve 109. Then, the pressure value of the volume chamber 102 is calculated according to the valve characteristic table mentioned above. When calculating the target pressure value of the target wheel cylinder, a calculation expression for the target flow rate of the target wheel cylinder can be established based on the flow conservation between the target booster valve and the target pressure reducing valve. Then, the target flow rate is calculated according to the valve characteristic table mentioned above.

[0069] Specifically, the pressure value of volumetric cavity 102 The calculation expression is:

[0070]

[0071] in, It refers to the opening degree of the oil circuit selector valve 103. It is the flow coefficient of the oil circuit selector valve 103. The degree of opening of the first pressure boosting valve 104, The flow coefficient of the first booster valve 104 is... The degree of opening of the second pressure boosting valve 109. The flow coefficient of the second booster valve 109, The first pressure value, This is the second pressure value.

[0072] Target traffic The calculation expression is:

[0073]

[0074] in, To determine the opening degree of the target booster valve. The flow coefficient of the target booster valve, This represents the pressure value of volumetric cavity 102. This is the second pressure value. To determine the opening degree of the target pressure reducing valve. The flow coefficient of the target pressure reducing valve. This refers to the pre-acquired pressure of the oil storage tank. The oil storage tank pressure can be atmospheric pressure.

[0075] In this application, by simplifying and applying the orifice throttling formula, the pressure of the volume chamber 102 is accurately obtained, which simplifies the entire calculation process and further improves the calculation efficiency of the pressure of the volume chamber 102.

[0076] In one embodiment of this application, the process for determining the opening degree of the oil circuit selection valve 103 is as follows:

[0077] Based on the first preset current value flowing through the oil circuit selection valve 103, a plurality of first opening degrees corresponding to the first preset current value are obtained, and a first pressure difference of the oil circuit selection valve 103 corresponding to each first opening degree is obtained.

[0078] A target first opening degree is determined from the plurality of first opening degrees, such that the flow rate of the oil circuit selection valve 103 corresponding to the target first opening degree is equal to the sum of the flow rate of the first pressure boosting valve 104 and the flow rate of the second pressure boosting valve 109, and the flow rate of the oil circuit selection valve 103 is calculated based on the first pressure difference corresponding to the target first opening degree.

[0079] The process for determining the opening degree of the first pressure boosting valve 104 is as follows:

[0080] Based on the second preset current value flowing through the first pressure boosting valve 104, a plurality of second opening degrees corresponding to the second preset current value are obtained, and a second pressure difference of the first pressure boosting valve 104 corresponding to each second opening degree is obtained;

[0081] A target second opening degree is determined from the plurality of second opening degrees, such that the flow rate of the first booster valve 104 corresponding to the target second opening degree is equal to the difference between the flow rate of the oil circuit selection valve 103 and the flow rate of the second booster valve 109, and the flow rate of the first booster valve 104 is calculated based on the second pressure difference corresponding to the target second opening degree.

[0082] The process for determining the opening degree of the second pressure boosting valve 109 is as follows:

[0083] Based on the third preset current value flowing through the second pressure boosting valve 109, a plurality of third opening degrees corresponding to the third preset current value are obtained, and a third pressure difference of the second pressure boosting valve 109 corresponding to each third opening degree is obtained.

[0084] A target third opening degree is determined from the plurality of third opening degrees, such that the flow rate of the second booster valve 109 corresponding to the target third opening degree is equal to the difference between the flow rate of the oil circuit selection valve 103 and the flow rate of the first booster valve 104. The flow rate of the second booster valve 109 is calculated based on the third pressure difference corresponding to the target third opening degree.

[0085] In this embodiment, the first preset current value, the second preset current value, and the third preset current value can be the same or different values; this application does not impose any restrictions on these values. When determining the opening degree of the oil circuit selection valve 103, the target first opening degree and target first pressure difference corresponding to the first preset current can be found based on the first preset current value flowing through the oil circuit selection valve 103 and the valve characteristic table involved in the above embodiment, so that the flow rate through the oil circuit selection valve 103 is equal to the sum of the flow rates through the first booster valve 104 and the second booster valve 109. The pressure value in the volume chamber 102... In the calculation expression This indicates the flow rate through the oil selection valve 103. This represents the flow rate passing through the first booster valve 104. This represents the flow rate through the second booster valve 109. Similarly, the opening degree of the first booster valve 104 and the second booster valve 109 can be determined. Finally, the first pressure value, the second pressure value, the opening degree and flow coefficient of the oil circuit selection valve 103, the opening degree and flow coefficient of the first booster valve 104, and the opening degree and flow coefficient of the third booster valve are substituted into the above-mentioned calculation expression for the pressure value of the volume chamber 102 to determine the pressure value of the volume chamber 102.

[0086] In this embodiment, the pressure value of the volume chamber 102 can be calculated by determining the opening degree of the oil circuit selection valve 103, the first pressure boosting valve 104, and the second pressure boosting valve 109.

[0087] In one embodiment of this application, after the step of obtaining the target pressure of the target wheel cylinder corresponding to the second volume based on the first mapping relationship, the method further includes:

[0088] When the piston of the electric master cylinder 101 is in the initial position and both the first pressure valve 104 and the second pressure valve 109 are fully open, the second pressure value is set to the initial pressure.

[0089] Because the wheel cylinder pressure estimation algorithm in this application may accumulate errors after long-term operation, it needs to be initialized periodically. Therefore, when the linear control system does not execute any braking request, that is, when the piston of the electric master cylinder 101 has returned to the initial position and all pressure boosting valves are fully open, the wheel cylinder pressure can be reset by periodically and briefly opening the pressure reducing valve connected to the wheel cylinder. To ensure that the wheel cylinder pressure is consistent with the external atmospheric pressure, the accuracy of the wheel cylinder pressure iterative estimation is improved.

[0090] The wheel cylinder pressure estimation method provided in this application has the following beneficial effects:

[0091] 1. Improve the accuracy of wheel cylinder pressure estimation.

[0092] By establishing the flow conservation expression between the electric master cylinder, the volumetric chamber, and the wheel cylinder, the wheel cylinder pressure at the next moment can be accurately estimated. There is no need to establish a complete simulation model from the electric master cylinder to the wheel cylinder, and the calculation can be completed without introducing a hydraulic resistance model, thus avoiding the problem of low accuracy caused by incorrect selection of the hydraulic resistance coefficient.

[0093] 2. The calculation method is simple and effectively improves calculation efficiency.

[0094] In this application, it is only necessary to establish the flow conservation calculation expression between the electric master cylinder and the wheel cylinder to further estimate the wheel cylinder pressure. The calculation complexity is low, which can effectively improve the calculation efficiency and reduce the calculation cost.

[0095] Figure 4 A schematic diagram of a wheel cylinder pressure estimation device provided in one embodiment of this application is shown. For ease of explanation, only the parts related to the embodiment of this application are shown.

[0096] Reference Figure 4 The wheel cylinder pressure estimation device 300 may include:

[0097] The acquisition module 301 is used to acquire the first pressure value of the electric master cylinder at the current moment and the second pressure value of the target wheel cylinder at the previous moment. The electric master cylinder is connected to the volume chamber, the volume chamber is connected to multiple wheel cylinders respectively, the multiple wheel cylinders are all connected to the oil storage tank, and the multiple wheel cylinders include the target wheel cylinder.

[0098] The first calculation module 302 is used to obtain the target flow rate of the target wheel cylinder at the current moment based on the first pressure value and the second pressure value;

[0099] The first lookup module 303 is used to obtain the first volume of the target wheel cylinder corresponding to the second pressure value according to the pre-acquired first mapping relationship, wherein the first mapping relationship is used to characterize the correspondence between the volume of the wheel cylinder and the pressure value;

[0100] The second calculation module 304 is used to calculate the second volume of the target wheel cylinder after a preset time period based on the target flow rate and the first volume;

[0101] The second lookup module 305 is used to obtain the target pressure of the target wheel cylinder corresponding to the second volume based on the first mapping relationship.

[0102] Optionally, the first computing module 302 includes:

[0103] The first calculation submodule is used to obtain the pressure value of the volumetric cavity based on the first pressure value, the second pressure value, the opening degree and flow coefficient of the oil circuit selection valve, the opening degree and flow coefficient of the first pressure boosting valve, and the opening degree and flow coefficient of the second pressure boosting valve.

[0104] The second calculation submodule is used to obtain the target flow rate of the target wheel cylinder based on the pressure value of the volume chamber, the second pressure value, the opening degree and flow coefficient of the target boosting valve, and the opening degree and flow coefficient of the target depressurizing valve. The target boosting valve is one of the first boosting valve and the second boosting valve, and the target depressurizing valve is one of the first depressurizing valve and the second depressurizing valve. The first boosting valve, the first depressurizing valve and the first wheel cylinder correspond to each other, and the second boosting valve, the second depressurizing valve and the second wheel cylinder correspond to each other.

[0105] Optionally, the wheel cylinder pressure estimation device 300 further includes:

[0106] The first determining module is used to obtain a plurality of first opening degrees corresponding to the first preset current value and a first pressure difference of the oil circuit selection valve corresponding to each first opening degree based on the first preset current value flowing through the oil circuit selection valve.

[0107] A target first opening degree is determined from the plurality of first opening degrees, such that the flow rate of the oil circuit selection valve corresponding to the target first opening degree is equal to the sum of the flow rate of the first booster valve and the flow rate of the second booster valve, and the flow rate of the oil circuit selection valve is calculated based on the first pressure difference corresponding to the target first opening degree.

[0108] The second determining module is used to obtain a plurality of second opening degrees corresponding to the second preset current value and a second pressure difference of the first pressure valve corresponding to each second opening degree based on the second preset current value flowing through the first pressure valve.

[0109] A target second opening degree is determined from the plurality of second opening degrees, such that the flow rate of the first booster valve corresponding to the target second opening degree is equal to the difference between the flow rate of the oil circuit selection valve and the flow rate of the second booster valve, and the flow rate of the first booster valve is calculated based on the second pressure difference corresponding to the target second opening degree.

[0110] The third determining module is used to obtain multiple third opening degrees corresponding to the third preset current value and the third pressure difference of the second pressure valve corresponding to each third opening degree based on the third preset current value flowing through the second pressure valve.

[0111] A target third opening degree is determined from the plurality of third opening degrees, such that the flow rate of the second booster valve corresponding to the target third opening degree is equal to the difference between the flow rate of the oil circuit selection valve and the flow rate of the first booster valve, and the flow rate of the second booster valve is calculated based on the third pressure difference corresponding to the target third opening degree.

[0112] Optionally, the wheel cylinder pressure estimation device 300 further includes:

[0113] An initialization module is used to set the second pressure value to an initial pressure when the piston of the electric master cylinder is in the initial position and both the first pressure valve and the second pressure valve are fully open.

[0114] The cylinder pressure estimation device 300 provided in this application embodiment can realize the various processes implemented in the aforementioned method embodiment, and will not be described again here to avoid repetition.

[0115] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0116] Figure 4 A schematic diagram of the hardware structure of the electronic device provided in an embodiment of this application is shown.

[0117] The device may include a processor 401 and a memory 402 storing program instructions.

[0118] When processor 401 executes the program, it implements the steps in any of the above method embodiments.

[0119] For example, the program can be divided into one or more modules / units, one or more of which are stored in memory 402 and executed by processor 401 to complete this application. The one or more modules / units can be a series of program instruction segments capable of performing a specific function, which describe the execution process of the program in the device.

[0120] Specifically, the processor 401 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0121] Memory 402 may include mass storage for data or instructions. For example, and not limitingly, memory 402 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 402 may include removable or non-removable (or fixed) media. Where appropriate, memory 402 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 402 is non-volatile solid-state memory.

[0122] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0123] The processor 401 implements any of the methods described above by reading and executing program instructions stored in the memory 402.

[0124] In one example, the electronic device may also include a communication interface 403 and a bus 410. The processor 401, memory 402, and communication interface 403 are connected via the bus 410 and communicate with each other.

[0125] The communication interface 403 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0126] Bus 410 includes hardware, software, or both, that couples components of an online data traffic metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 410 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, this application contemplates any suitable bus or interconnect.

[0127] Furthermore, in conjunction with the methods in the above embodiments, this application embodiment can provide a storage medium for implementation. This storage medium stores program instructions; when these program instructions are executed by a processor, they implement any of the methods in the above embodiments.

[0128] This application also provides a chip, which includes a processor and a communication interface. The communication interface and the processor are coupled. The processor is used to run programs or instructions to implement the various processes of the above method embodiments and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0129] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0130] This application provides a computer program product, which is stored in a storage medium and executed by at least one processor to implement the various processes of the above method embodiments and achieve the same technical effects. To avoid repetition, it will not be described again here.

[0131] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0132] The functional modules shown in the above block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on machine-readable media or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable media" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer grids such as the Internet, intranets, etc.

[0133] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0134] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to create a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0135] The above are merely specific embodiments of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for estimating wheel cylinder pressure, characterized in that, The method includes: The first pressure value of the electric master cylinder at the current moment and the second pressure value of the target wheel cylinder at the previous moment are obtained. The electric master cylinder is connected to the volume chamber, the volume chamber is connected to multiple wheel cylinders, the multiple wheel cylinders are all connected to the oil storage tank, and the multiple wheel cylinders include the target wheel cylinder. Based on the first pressure value and the second pressure value, the target flow rate of the target wheel cylinder at the current moment is obtained; Based on the pre-acquired first mapping relationship, the first volume of the target wheel cylinder corresponding to the second pressure value is obtained, and the first mapping relationship is used to characterize the correspondence between the volume of the wheel cylinder and the pressure value; Based on the target flow rate and the first volume, calculate the second volume of the target wheel cylinder after a preset time period; Based on the first mapping relationship, the target pressure of the target wheel cylinder corresponding to the second volume is obtained; An oil circuit selection valve is provided between the electric master cylinder and the volume chamber, and a pressure boosting valve is provided between the volume chamber and each wheel cylinder. The wheel cylinder includes a first wheel cylinder and a second wheel cylinder. A first pressure boosting valve is provided between the volume chamber and the first wheel cylinder, and a second pressure boosting valve is provided between the volume chamber and the second wheel cylinder. A first pressure reducing valve is provided between the first wheel cylinder and the oil storage tank, and a second pressure reducing valve is provided between the second wheel cylinder and the oil storage tank. The step of obtaining the target flow rate of the target wheel cylinder at the current moment based on the first pressure value and the second pressure value includes: obtaining the pressure value of the volumetric cavity based on the first pressure value, the second pressure value, the opening degree and flow coefficient of the oil circuit selection valve, the opening degree and flow coefficient of the first booster valve, and the opening degree and flow coefficient of the second booster valve; obtaining the target flow rate of the target wheel cylinder based on the pressure value of the volumetric cavity, the second pressure value, the opening degree and flow coefficient of the target booster valve, and the opening degree and flow coefficient of the target pressure reducing valve, wherein the target booster valve is one of the first booster valve and the second booster valve, and the target pressure reducing valve is one of the first pressure reducing valve and the second pressure reducing valve, wherein the first booster valve, the first pressure reducing valve, and the first wheel cylinder correspond to each other, and the second booster valve, the second pressure reducing valve, and the second wheel cylinder correspond to each other.

2. The wheel cylinder pressure estimation method as described in claim 1, characterized in that, The pressure value of the volume chamber The calculation expression is: in, It refers to the opening degree of the oil circuit selector valve. It is the flow coefficient of the oil circuit selection valve. This refers to the opening degree of the first pressure boosting valve. The flow coefficient of the first booster valve. This refers to the opening degree of the second pressure boosting valve. The flow coefficient of the second booster valve. The first pressure value, This is the second pressure value.

3. The wheel cylinder pressure estimation method as described in claim 2, characterized in that, The process for determining the opening degree of the oil circuit selection valve is as follows: Based on the first preset current value flowing through the oil circuit selection valve, a plurality of first opening degrees corresponding to the first preset current value are obtained, and a first pressure difference of the oil circuit selection valve corresponding to each first opening degree is obtained. A target first opening degree is determined from the plurality of first opening degrees, such that the flow rate of the oil circuit selection valve corresponding to the target first opening degree is equal to the sum of the flow rate of the first booster valve and the flow rate of the second booster valve, and the flow rate of the oil circuit selection valve is calculated based on the first pressure difference corresponding to the target first opening degree.

4. The wheel cylinder pressure estimation method as described in claim 2, characterized in that, The process for determining the opening degree of the first pressure boosting valve is as follows: Based on the second preset current value flowing through the first booster valve, a plurality of second opening degrees corresponding to the second preset current value are obtained, and a second pressure difference of the first booster valve corresponding to each second opening degree is obtained; A target second opening degree is determined from the plurality of second opening degrees, such that the flow rate of the first booster valve corresponding to the target second opening degree is equal to the difference between the flow rate of the oil circuit selection valve and the flow rate of the second booster valve, and the flow rate of the first booster valve is calculated based on the second pressure difference corresponding to the target second opening degree.

5. The wheel cylinder pressure estimation method as described in claim 2, characterized in that, The process for determining the opening degree of the second pressure boosting valve is as follows: Based on the third preset current value flowing through the second pressure booster valve, a plurality of third opening degrees corresponding to the third preset current value are obtained, and a third pressure difference of the second pressure booster valve corresponding to each third opening degree is obtained. A target third opening degree is determined from the plurality of third opening degrees, such that the flow rate of the second booster valve corresponding to the target third opening degree is equal to the difference between the flow rate of the oil circuit selection valve and the flow rate of the first booster valve, and the flow rate of the second booster valve is calculated based on the third pressure difference corresponding to the target third opening degree.

6. The wheel cylinder pressure estimation method as described in claim 1, characterized in that, The target traffic The calculation expression is: in, To determine the opening degree of the target booster valve. The flow coefficient of the target booster valve, This represents the pressure value of the volumetric cavity. This is the second pressure value. To determine the opening degree of the target pressure reducing valve. The flow coefficient of the target pressure reducing valve. The pressure of the oil storage tank to be obtained.

7. The wheel cylinder pressure estimation method as described in claim 1, characterized in that, The second volume The calculation expression is: in, For the first volume, For a preset time period, For target traffic.

8. The wheel cylinder pressure estimation method as described in claim 1, characterized in that, After the step of obtaining the target pressure of the target wheel cylinder corresponding to the second volume based on the first mapping relationship, the method further includes: With the piston of the electric master cylinder in the initial position and both the first and second pressure valves fully open, the second pressure value is set to the initial pressure.

9. A wheel cylinder pressure estimation device, characterized in that, include: The acquisition module is used to acquire the first pressure value of the electric master cylinder at the current moment and the second pressure value of the target wheel cylinder at the previous moment. The electric master cylinder is connected to the volume chamber, the volume chamber is connected to multiple wheel cylinders respectively, the multiple wheel cylinders are all connected to the oil storage tank, and the multiple wheel cylinders include the target wheel cylinder. The first calculation module is used to obtain the target flow rate of the target wheel cylinder at the current moment based on the first pressure value and the second pressure value; The first lookup module is used to obtain the first volume of the target wheel cylinder corresponding to the second pressure value according to the pre-acquired first mapping relationship, wherein the first mapping relationship is used to characterize the correspondence between the volume of the wheel cylinder and the pressure value; The second calculation module is used to calculate the second volume of the target wheel cylinder after a preset time period based on the target flow rate and the first volume; The second lookup module is used to obtain the target pressure of the target wheel cylinder corresponding to the second volume based on the first mapping relationship; An oil circuit selection valve is provided between the electric master cylinder and the volume chamber, and a pressure boosting valve is provided between the volume chamber and each wheel cylinder. The wheel cylinder includes a first wheel cylinder and a second wheel cylinder. A first pressure boosting valve is provided between the volume chamber and the first wheel cylinder, and a second pressure boosting valve is provided between the volume chamber and the second wheel cylinder. A first pressure reducing valve is provided between the first wheel cylinder and the oil storage tank, and a second pressure reducing valve is provided between the second wheel cylinder and the oil storage tank. The first calculation module includes: a first calculation submodule, used to obtain the pressure value of the volumetric cavity based on the first pressure value, the second pressure value, the opening degree and flow coefficient of the oil circuit selection valve, the opening degree and flow coefficient of the first pressure boosting valve, and the opening degree and flow coefficient of the second pressure boosting valve; The second calculation submodule is used to obtain the target flow rate of the target wheel cylinder based on the pressure value of the volume chamber, the second pressure value, the opening degree and flow coefficient of the target boosting valve, and the opening degree and flow coefficient of the target depressurizing valve. The target boosting valve is one of the first boosting valve and the second boosting valve, and the target depressurizing valve is one of the first depressurizing valve and the second depressurizing valve. The first boosting valve, the first depressurizing valve and the first wheel cylinder correspond to each other, and the second boosting valve, the second depressurizing valve and the second wheel cylinder correspond to each other.

Images