Brake compliance calibration with an electrohydraulic brake

Abstract

An EH braking system includes a brake valve operably connected to a brake and a brake pressure sensor. For a calibration event of the EH braking system, wherein the compliance calibration time is measured from when the brake valve is operated under full activation until the brake pressure sensor detects that pressure begins to build in the brake circuit. The compliance calibration time is the time taken to fill the compliance volume of the brake. The compliance calibration fill time is used during a normal braking event, wherein during the duration of the compliance calibration time, the brake valve is operated to the full activation state. After the calibrated fill time has elapsed, the brake valve will be operated with the desired operator control of the brake pedal. This results in a shorter fill time for the brake and improved response of the braking system.

Description

Technical Field

[0001] The present disclosure relates to an EH brake and, more particularly, to determining a compliance calibration fill time for operating a brake valve to a fully activated state during a duration of a compliance calibration time during a normal braking event, after which the brake valve will operate under the operator control of a desired brake pedal. Background Art

[0002] A common problem with service brake performance consistency in hydraulic applications is brake compliance. The sizing of the brake valve depends on filling the brake valve within a reasonable amount of time. Due to manufacturing tolerances, brake compliance can vary from brake to brake. This compliance variation makes it difficult to design a consistent braking system between machines. Compliance causes a delay in the time from when the operator depresses the pedal until the brake can provide a decelerating force for the machine travel, due to the time required to fill the brake.

[0003] Conventional braking systems use a pedal that is mechanically linked to a hydraulic brake valve. The flow through the valve is proportional to the amount of displacement of the pedal and the hydraulic brake valve. The greater the distance or amount the operator depresses the pedal or the amount the pedal is engaged, the more the hydraulic brake valve opens and the greater the flow discharged through the hydraulic brake valve. As such, at lower brake pedal control, the response can be delayed due to the time to fill the brake.

[0004] Accordingly, there is a need to improve the compliance fill time of the brake. Summary of the Invention

[0005] Aspects for improving brake compliance fill time are disclosed. One aspect includes a method that includes: initiating a calibration event for an electrohydraulic braking system that includes a brake valve and a controller, the brake valve being operably connected to a brake and a brake pressure sensor, the controller being operably connected to the electrohydraulic braking system; operating the brake valve to a fully activated state; measuring a compliance calibration time for the brake valve in response to the operation of the brake valve being in the fully activated state; determining a pressure event associated with the brake pressure sensor; and terminating the measurement of the compliance calibration time in response to the occurrence of the pressure event.

[0006] In one form, the electro - hydraulic braking system includes a second brake valve operatively connected to a second brake and a second brake pressure sensor; wherein the method further includes: operating the second brake valve to a fully activated state; in response to the operation of the second brake valve being in the fully activated state, measuring a compliance calibration time for the second brake valve; determining a pressure event associated with the second brake pressure sensor; and terminating the measurement of the compliance calibration time in response to the occurrence of the pressure event.

[0007] In another form, the electro - hydraulic braking system includes a second brake valve operatively connected to the first brake and the first brake pressure sensor; wherein the method further includes: operating the first brake valve and the second brake valve simultaneously to a fully activated state; in response to the operation of the first brake valve and the second brake valve being simultaneously in the fully activated state, measuring a compliance calibration time for the electro - hydraulic braking system; determining a pressure event associated with the first brake pressure sensor; and terminating the measurement of the compliance calibration time in response to the occurrence of the pressure event.

[0008] In yet another form, the method further includes: detecting a normal braking event of the electro - hydraulic braking system; and in response to the normal braking event, operating the first brake valve to a fully activated state within the duration of the compliance calibration time. In an improvement of the method, it further includes: in response to reaching the duration of the compliance calibration time, operating the first brake valve in a braking state input by the operator. In another improvement of the method, the electro - hydraulic braking system includes a brake pedal connected to a position sensor configured to measure the brake pedal position, and detecting the normal braking event includes measuring the brake pedal position in response to a braking demand input by the operator. In yet another improvement of the method, it further includes: if the operator releases the brake pedal before reaching the compliance calibration time, canceling the fully activated state of the first brake valve, and instead, the control of the first brake valve will again follow the brake pedal demand.

[0009] In another form of the method, the electro - hydraulic braking system includes a hydraulic pump for pumping hydraulic fluid from a hydraulic fluid reservoir to the first brake valve.

[0010] In yet another form of the method, the calibration event is initiated by a controller connected to the electrohydraulic braking system in response to one of the following conditions being met: (i) a calibration request initiated by an operator via a vehicle monitor; (ii) calibration automatically initiated by vehicle software upon machine startup; or (iii) calibration automatically initiated by vehicle software when the parking brake is applied.

[0011] In yet another form of the method, the controller is configured to initiate the calibration event upon one or more of the following preconditions being met: (i) the hydraulic oil temperature is within a predetermined range; (ii) the engine speed is within a predetermined range; (iii) the parking brake is engaged; (iv) the brake pedal control is within a predetermined range; (v) a service time interval has been reached; or (vi) the brake pressure is within a predetermined range.

[0012] In a second aspect, an apparatus includes: an electrohydraulic braking system including a first brake valve operably connected to a first brake and a first brake pressure sensor; and a controller operably connected to the electrohydraulic braking system, wherein the controller is configured to:

[0013] initiate a calibration event associated with the electrohydraulic braking system; operate the first brake valve to a fully activated state; measure a compliance calibration time for the first brake valve in response to the operation of the first brake valve being in the fully activated state; determine a pressure event associated with the first brake pressure sensor; and terminate the measurement of the compliance calibration time in response to the pressure event.

[0014] In one form, the electrohydraulic braking system includes a second brake valve operably connected to the first brake and the first brake pressure sensor; wherein the controller is configured to operate the second brake valve to a fully activated state; wherein the controller is configured to measure a second compliance calibration time for the second brake valve in response to the operation of the second brake valve being in the fully activated state; and wherein the controller is configured to terminate the measurement of the second compliance calibration time in response to the pressure event.

[0015] In another form, the electro - hydraulic braking system includes a second brake valve operably connected to a second brake and a second brake pressure sensor; wherein the controller is configured to: operate the second brake valve to a fully - activated state; in response to the operation of the second brake valve being in the fully - activated state, measure a compliance calibration time for the second brake valve; determine a pressure event associated with the second brake pressure sensor; and terminate the measurement of the compliance calibration time in response to the pressure event.

[0016] In yet another form of the device, the controller is configured to detect a normal braking event during the driving movement of a vehicle including the electro - hydraulic braking system; and the controller is configured to operate the first brake valve to the fully - activated state in response to the normal braking event within a time period of the compliance calibration time. In an improvement of the device, the controller is configured to operate the first brake valve in response to a braking demand input by an operator upon reaching the time period of the compliance calibration time. In another improvement of the device, the electro - hydraulic braking system includes a brake pedal connected to a position sensor configured to measure the brake pedal position, and the detection of the normal braking event includes measuring the brake pedal position in response to a braking demand input by an operator.

[0017] In yet another form of the device, the electro - hydraulic braking system includes a hydraulic pump configured to pump hydraulic fluid from the hydraulic fluid reservoir to the first brake valve.

[0018] In yet another form of the device, the controller is configured to initiate the calibration event in response to one of the following conditions being met: (i) a calibration request initiated by an operator through a vehicle monitor; (ii) a calibration automatically initiated by vehicle software upon machine startup; or (iii) a calibration automatically initiated by vehicle software when the parking brake is applied. In yet another form of the device, one or more of the following pre - conditions are met before the calibration event is initiated: (i) the hydraulic oil temperature is within a predetermined range; (ii) the engine speed is within a predetermined range; (iii) the parking brake is engaged; (iv) the brake pedal control is within a predetermined range; (v) a service time interval is reached; or (vi) the brake pressure is within a predetermined range.

[0019] In another form of the device, it further includes: a battery operably connected to the controller.

[0020] The present invention content is provided to introduce some concepts that will be further described in the following specific embodiments. The present invention content is neither intended to identify the key features or essential features of the claimed subject matter nor to be used to assist in determining the scope of the claimed subject matter. Other embodiments, forms, objects, features, advantages, aspects, and benefits will become apparent from the following description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] By referring to the following description of the embodiments of the present disclosure in conjunction with the accompanying drawings, the above aspects of the present disclosure and the manner of obtaining them will become more apparent, and the present disclosure itself can be better understood.

[0022] Figure 1 is a schematic block diagram of a single brake valve circuit.

[0023] Figure 2 is Figure 1 a hydraulic schematic diagram of an embodiment.

[0024] Figure 3 is a schematic block diagram of a multi-brake valve circuit according to an embodiment.

[0025] Figure 4 is Figure 3 a hydraulic schematic diagram of an embodiment.

[0026] Figure 5 is a schematic block diagram of a multi-brake valve circuit according to a second embodiment.

[0027] Figure 6 is Figure 5 a hydraulic schematic diagram of an embodiment.

[0028] Figure 7 is for managing Figures 1 to 6 a schematic flowchart of a calibration process for the braking operation of an embodiment.

[0029] Figure 8 is for Figures 1 to 7 a schematic flowchart of a normal braking process.

[0030] In several of the drawings, corresponding reference numerals are used to indicate corresponding components. DETAILED DESCRIPTION

[0031] To facilitate an understanding of the principles of the present invention, reference will now be made to the embodiments shown in the accompanying drawings, and specific language will be used to describe them. However, it will be understood that this is not intended to limit the scope of the present invention, and any changes and further modifications to the illustrated embodiments, as well as any further applications of the principles of the present invention as illustrated herein, as would typically be contemplated by those skilled in the art to which the present invention pertains, are envisioned herein.

[0032] Reference Figure 1 and Figure 2 which is a first example of a single brake valve system 10 for a vehicle (not shown). Some examples of vehicles that may include the brake system 10 include wheel loaders, 4WD loaders, tractors, trucks, and motor graders, to name a few. The brake system 10 is an electro-hydraulic brake system that has an electronic brake pedal 12 operably connected to a position sensor 14. As shown, the electronic brake pedal 12 is not mechanically linked to the brake valve. The position sensor 14 measures the brake position of the brake pedal 12, which corresponds to the brake demand input by the operator. The position sensor 14 measures the position of the brake pedal 12 along its stroke path.

[0033] The controller 16 is operably connected to the position sensor 14, and the position sensor 14 is operably connected to the brake pedal 12 to use the position sensor 14 to read the pedal position of the brake pedal 12 and determine the electrical signal to be sent to the electro-hydraulically operated hydraulic brake valve 18. In some forms, there are multiple sensors measuring the brake pedal position to achieve redundancy. Since the brake pedal 12 is not mechanically linked to the brake valve 18, the controller 16 can be utilized to vary the control of the brake valve 18. For example, if the brake pedal 12 is only slightly depressed, the controller 16 can over-command the brake valve 18 to full activation when filling the brake 26. Then, when the brake 26 is fully filled, the control of the brake valve 18 can be reduced by the operator to the desired brake control. Implementing this process allows for a faster filling of the brake 26, resulting in a faster response of the brake system 10. One consideration is the amount of time the controller 16 controls the brake valve 18 to full activation before matching the desired brake control. Due to differences in brake compliance, the amount of time required between different types of brakes 26 may vary. Additionally, the present application relates to the amount of time of over-controlling the brake valve 18 to achieve a fast brake compliance fill time.

[0034] The braking system 10 includes an electrohydraulically operated hydraulic brake valve 18 that is fluidly connected via a hydraulic line 21 to a hydraulic pump 20 and fluidly connected via a second hydraulic line 23 to a hydraulic reservoir 22. In other embodiments, the braking system 10 may further include additional hydraulic pumps 20 and hydraulic fluid reservoirs 22. The hydraulic reservoir 22 is fluidly connected via a third hydraulic line 25 to the hydraulic pump 20. The hydraulic pump 20 operates to supply or pump pressurized hydraulic fluid from the hydraulic fluid reservoir 22 through the third hydraulic line 25 to the hydraulic pump 20 and then through the hydraulic line 21 to the brake valve 18. Optionally, an accumulator may be assembled with the braking system 10 for storing pressurized hydraulic fluid. After the braking event has ended, the hydraulic fluid returns from the hydraulic brake valve 18 through the second hydraulic line 23 to the hydraulic fluid reservoir 22. It is further contemplated and understood that the braking system 10 may include one or more actuators and may include multiple hydraulic lines in any number of configurations, as is known to those skilled in the art.

[0035] The braking system 10 includes a brake pressure sensor 24 that is fluidly connected to the hydraulic brake valve 18 and communicates with the controller 16. The brake pressure sensor 24 may generally be mounted to a fourth hydraulic line 30 or directly to the brake valve 18 or the brake assembly and measures the hydraulic fluid pressure through the fourth hydraulic line 30 between the brake valve 18 and the brake 26. In one form, the brake pressure sensor 24 may be a displacement sensor. An example of a displacement sensor may be a volume sensor for measuring the volume of hydraulic fluid leaving and entering the brake 26.

[0036] The braking system 10 further includes a wheel or other type of brake 26 that is fluidly connected to the brake pressure sensor 24 and the hydraulic brake valve 18. The brake pressure sensor 24 is configured to measure the pressure output of the hydraulic fluid from the hydraulic brake valve 18 to the brake 26. The brake 26 is configured to apply a desired braking force to the vehicle.

[0037] In some forms, the braking system 10 may further include multiple sensors that may communicate with the controller 16. These sensors may be located anywhere on the vehicle and may measure the deceleration of the vehicle, as is known to those skilled in the art.

[0038] The controller 16 may include a computer-based processor (e.g., a microprocessor) and a computer-readable and writable storage medium. Non-limiting examples of the controller 16 may include an arithmetic unit that executes algorithms and logical operations, an electronic control unit that extracts, decodes, and executes instructions from a memory, and an array unit that utilizes an array of multiple parallel computing elements. Other examples of the controller 16 may include an engine control module and an application-specific integrated circuit. It is further contemplated and understood that the controller 16 may include redundant controllers, and / or the system may include other redundancies to improve the reliability of the braking system 10. Optionally, the controller 16 may be electrically connected to a battery 34 or other power source for supplying power to the controller 16. In one form, there are multiple controllers on the vehicle, such as a first controller operably connected to a front brake valve and a second controller operably connected to a rear brake valve. In this form, an operator depresses or engages a brake pedal to initiate a braking or decelerating motion of the vehicle, and the controller 16 controls the first brake valve and the second brake valve.

[0039] Referring to Figure 3 and Figure 4 , which is a first example of a multi-brake valve system 200 for a vehicle (not shown). The multi-brake valve system 200 includes two or more EH brake valves that separately and independently control individual brakes. The multiple EH brake valves may be implemented on a machine to achieve redundancy. In this embodiment, each of the EH brake valves is on a separate circuit having its own dedicated brake, and thus, each brake circuit will have to be calibrated separately. Unless otherwise noted, the multi-brake valve system 200 is similar to the single-brake valve system 10 described above.

[0040] The braking system 200 is an electronically controlled hydraulic braking system that has an electronic brake pedal 212 operably connected to a position sensor 214. As shown, the electronic brake pedal 212 is not mechanically linked to the brake valve. The position sensor 214 measures the braking position of the brake pedal 212, which corresponds to the braking demand input by the operator. The position sensor 214 measures the position of the brake pedal 212 along its stroke path.

[0041] The controller 216 is operably connected to the position sensor 214, and the position sensor 214 is connected to the brake pedal 212 to read the pedal position of the brake pedal 212 and determine a first electrical signal to be sent to the first electro-hydraulically operated hydraulic brake valve 218 and a second electrical signal to be sent to the second electro-hydraulically operated hydraulic brake valve 248. In one form, there may be multiple sensors to measure the brake pedal position for redundancy. Since the brake pedal 212 is not mechanically linked to either the first brake valve 218 or the second brake valve 248, the controller 216 can be utilized to vary the control of the first brake valve 218 and the second brake valve 248. For example, if the brake pedal 212 is only slightly depressed, the controller 216 can override either the first brake valve 218 or the second brake valve 248 to full activation when filling the first brake 226 or the second brake 256, respectively. Then, when either the first brake 226 or the second brake 256 is fully filled, the control of the corresponding first brake valve 218 or second brake valve 248 can be reduced by the operator to the desired brake control. Implementing this process allows for faster filling of the first brake 226 or the second brake 256, resulting in a faster response of the brake system 200. One consideration is the amount of time the controller 216 controls the first brake valve 218 or the second brake valve 218 to full activation before matching the desired brake control. Due to differences in brake compliance, the amount of time required for different types of brakes may vary. Additionally, the present application relates to the amount of time to override the first brake valve 218 or the second brake valve 248 to achieve a fast brake compliance fill time.

[0042] The brake system 200 includes a first EH brake valve 218 that is fluidly connected to a hydraulic pump 220 via a hydraulic line 221 and is fluidly connected to a hydraulic reservoir 222 via a second hydraulic line 223. In other embodiments, the brake system 200 may also include additional hydraulic pumps 220 and hydraulic fluid reservoirs 222. The hydraulic reservoir 222 is fluidly connected to the hydraulic pump 220 via a third hydraulic line 225. The hydraulic pump 220 operates to supply or pump pressurized hydraulic fluid from the hydraulic fluid reservoir 222 through the third hydraulic line 225 to the hydraulic pump 220 and then through the hydraulic line 221 to the first brake valve 218. Optionally, an accumulator may be assembled with the brake system 200 for storing pressurized hydraulic fluid. After a braking event, the hydraulic fluid returns from the first brake valve 218 through the second hydraulic line 223 to the hydraulic fluid reservoir 222. It is further contemplated and understood that the brake system 200 may include one or more actuators and may include multiple hydraulic lines in any number of configurations, as known to those skilled in the art.

[0043] The braking system 200 includes a second EH brake valve 248 that is fluidly connected via a hydraulic line 251 to a hydraulic pump 220 and via a second hydraulic line 253 to a hydraulic reservoir 222. The hydraulic pump 220 operates to supply or pump pressurized hydraulic fluid from the hydraulic fluid reservoir 222 through a third hydraulic line 225 to the hydraulic pump 220 and then through the hydraulic line 251 to the second brake valve 248. After the braking event ends, the hydraulic fluid returns from the second brake valve 248 through the second hydraulic line 253 to the hydraulic fluid reservoir 222.

[0044] The braking system 200 includes a first brake pressure sensor 224 that is fluidly connected to the first brake valve 218 and communicates with the controller 216. The first brake pressure sensor 224 can typically be mounted to a fourth hydraulic line 230, directly to the first brake valve 218, or to the brake assembly, and measures the hydraulic fluid pressure through the fourth hydraulic line 230 between the first brake valve 218 and the first brake 226. In one form, the first brake pressure sensor 224 can be a displacement sensor or a volume sensor for measuring the volume of hydraulic fluid leaving and entering the first brake 226.

[0045] The braking system 200 also includes a wheel or other type of first brake 226 that is fluidly connected to the first brake pressure sensor 224 and the first brake valve 218. The first brake pressure sensor 224 is configured to measure the pressure output of the hydraulic fluid from the first brake valve 218 to the first brake 226. The first brake 226 is configured to apply a desired braking force to the vehicle.

[0046] The braking system 200 includes a second brake pressure sensor 254 that is fluidly connected to the second brake valve 248 and communicates with the controller 216. The second brake pressure sensor 254 can typically be mounted to a fourth hydraulic line 260, the second brake valve 248, or to the brake assembly, and measures the hydraulic fluid pressure through the fourth hydraulic line 260 between the second brake valve 248 and the second brake 256. In one form, the second brake pressure sensor 254 can be a displacement sensor or a volume sensor for measuring the volume of hydraulic fluid leaving and entering the second brake 256.

[0047] The brake system 200 also includes a wheel or other type of second brake 256 that is fluidly connected to a second brake pressure sensor 254 and a second brake valve 248. The second brake pressure sensor 254 is configured to measure the pressure output of the hydraulic fluid from the second brake valve 248 to the second brake 256. The second brake 256 is configured to apply a desired braking force to the vehicle.

[0048] Referring Figure 5 and Figure 6 FIG. is a second example of a multi-brake valve system 300 for a vehicle (not shown). The multi-brake valve system 300 includes two or more EH brake valves that control individual brakes. In this embodiment, the EH brake valves are located on the same circuit that controls the same brake, and the circuits will be calibrated together by measuring the time between activating the plurality of brake valves to full activation and when brake circuit pressure begins to form. Since there are two brake valves that control a single brake 326, the calibration of the two brake valves must be done together. Unless otherwise stated, the multi-brake valve system 300 is similar to the multi-brake valve system 200 described above.

[0049] The brake system 300 is an electro-hydraulic brake system that has an electronic brake pedal 312 operably connected to a position sensor 314. As shown, the electronic brake pedal 312 is not mechanically linked to the brake valve. The position sensor 314 measures the braking position of the brake pedal 312, which corresponds to the braking demand input by the operator. The position sensor 314 measures the position of the brake pedal 312 along its travel path.

[0050] The controller 316 is operably connected to a position sensor 314, which is operably connected to the brake pedal 312 to utilize the position sensor 314 to read the pedal position of the brake pedal 312 and determine a first electrical signal to be sent to the first electro-hydraulically operated hydraulic brake valve 318 and a second electrical signal to be sent to the second electro-hydraulically operated hydraulic brake valve 348. Since the brake pedal 312 is not mechanically linked to either the first brake valve 318 or the second brake valve 348, the control of the first brake valve 318 and the second brake valve 348 can be varied using the controller 316. For example, if the brake pedal 312 is only slightly depressed, the controller 316 can override either the first brake valve 318 or the second brake valve 348 to full activation when filling the brake 326. Then, when the brake 326 is fully filled, the control of either the first brake valve 318 or the second brake valve 348 can be reduced by the operator to the desired brake control. Implementing this process allows the brake 326 to be filled more quickly, resulting in a faster response of the braking system 300. One consideration is the amount of time the controller 316 controls the brake valve 318 to full activation before matching the desired brake control. Due to differences in brake compliance, the amount of time required for different types of brakes may vary. Additionally, the present application relates to the amount of time to override the first brake valve 318 to achieve a fast brake compliance fill time.

[0051] The braking system 300 includes a first EH brake valve 318 that is fluidly connected to a hydraulic pump 320 via a hydraulic line 321 and is fluidly connected to a hydraulic reservoir 322 via a second hydraulic line 323. In other embodiments, the braking system 300 may also include additional hydraulic pumps 320 and hydraulic fluid storage 322. The hydraulic storage 322 is fluidly connected to the hydraulic pump 320 via a third hydraulic line 325. The hydraulic pump 320 operates to supply or pump pressurized hydraulic fluid from the hydraulic fluid reservoir 322 through the third hydraulic line 325 to the hydraulic pump 320 and then through the hydraulic line 321 to the first brake valve 318. Optionally, an accumulator can be assembled with the braking system 300 and the hydraulic pump 320 for storing pressurized hydraulic fluid. After the braking event ends, the hydraulic fluid returns from the first brake valve 318 through the second hydraulic line 323 to the hydraulic fluid reservoir 322. It is further contemplated and understood that the braking system 300 can include one or more actuators and can include multiple hydraulic lines in any number of configurations, as known to those skilled in the art.

[0052] The braking system 300 includes a second EH brake valve 348 that is fluidly connected via a hydraulic line 351 to a hydraulic pump 320 and via a second hydraulic line 353 to a hydraulic reservoir 322. The hydraulic pump 320 operates to supply or pump pressurized hydraulic fluid from the hydraulic fluid reservoir 322 through a third hydraulic line 325 to the hydraulic pump 320 and then through the hydraulic line 351 to the second brake valve 348. After the braking event ends, the hydraulic fluid returns from the second brake valve 348 through the second hydraulic line 353 to the hydraulic fluid reservoir 322.

[0053] The braking system 300 includes a brake pressure sensor 324 that is fluidly connected to the first brake valve 318 and the second brake valve 348 and communicates with the controller 316. The brake pressure sensor 324 can typically be mounted to a fourth hydraulic line 330 and a fifth hydraulic line 360, or directly to the brake 326. The brake pressure sensor 324 measures the hydraulic fluid pressure between the first brake valve 318 and the brake 326 through the fourth hydraulic line 330 and measures the hydraulic fluid pressure between the second brake valve 348 and the brake 326 through the fifth hydraulic line 360. In one form, the brake pressure sensor 324 can be a displacement sensor or a volume sensor for measuring the volume of hydraulic fluid leaving and entering the brake 226.

[0054] The braking system 300 further includes a wheel or other type of brake 326 that is fluidly connected to the brake pressure sensor 324, the first brake valve 318, and the second brake valve 348. The brake pressure sensor 224 is configured to measure the pressure output of the hydraulic fluid from the first brake valve 318 and the second brake valve 348 to the brake 326. The brake 326 is configured to apply a desired braking force to the vehicle.

[0055] Now refer to Figure 7, which shows a process 400 for operating an embodiment of the braking system described herein. Process 400 begins at operation 401, where the controller 16 (216 or 316) is configured to initiate a calibration event associated with the corresponding EH braking system 10, 200, or 300. The calibration event is initiated in response to one or more conditions being met. The conditions that are met include: a calibration request initiated by the operator through the vehicle monitor; a calibration automatically initiated by the vehicle software when the machine is started; or a calibration automatically initiated by the vehicle software when the parking brake is applied. In addition, in order to initiate a calibration event, one or more of the following preconditions may be required: (i) the hydraulic oil temperature is within a predetermined range; (ii) the engine speed is within a predetermined range; (iii) the parking brake is engaged; (iv) the brake pedal control is within a predetermined range; (v) the service time interval is reached; (vi) the brake pressure is within a predetermined range; it can be understood that reaching the service time requirement is a consideration of the wear of machine parts, so recalibration may be required over time.

[0056] At operation 402, the controller 16 (216, 316) determines whether there are multiple brake valves in the corresponding EH braking system. If there are multiple brake valves, then at operation 404, the controller 216 or 316 determines whether the brake valves are on separate circuits, i.e., associated with separate brakes or the same brake. If the multiple brake valves are on separate circuits, then at operation 406, the uncalibrated brake valves are operated in a fully activated state. From operation 402, if there is a single brake valve, then process 400 proceeds to operation 406. From operation 404, if the brake valves are on the same circuit or operably connected to the same brake, then process 400 continues to operation 408, where all brake valves are operated to a fully activated state.

[0057] At operation 406, the corresponding controller is configured to operate the uncalibrated brake valves to a fully activated state. At operation 410, the controller is configured to measure the compliance calibration fill time of the brake valves in response to the operation of the brake valves being in a fully activated state. The compliance fill time depends on the compliance volume of the brake, which may vary between components due to manufacturing tolerances. This application takes into account this difference between components to improve the consistency of braking performance between machines. As described above, this compliance fill time can be measured at the factory when the machine is assembled or in the field after the machine is used. In order to determine the amount of time over which the brake valves are controlled to achieve a fast brake compliance fill time and to account for differences in brake compliance, calibration can be performed. To calibrate the compliance fill time, the operator can select a screen on the machine monitor to perform compliance calibration.

[0058] At operation 412, the controller is configured to determine a pressure event associated with the brake pressure sensor. At operation 412, if a pressure event occurs, then at operation 414, the controller terminates the measurement of the compliance calibration time in response to the pressure event. At operation 412, if no pressure event occurs, the controller continues at operation 410.

[0059] At operation 416, the controller is configured to determine whether all brake valves have been calibrated. If so, process 400 ends at operation 418. If not all brake valves have been calibrated, the process returns to operation 402 and repeats until all brake valves have been calibrated.

[0060] In an alternative embodiment, instead of relying on calibration of the brake valves, the controller can be configured to always control full activation of the brake valves until pressure begins to rise and then reduce control to the operator's demand. In this embodiment, this operation would eliminate the need for calibration and because wear of the brake system will self-regulate over time.

[0061] Now refer to Figure 8 , which illustrates process 500 for operating an embodiment of the brake system described herein. If brake compliance calibration is not active, process 500 will be followed. Process 500 begins at operation 504 to detect whether a normal braking event has occurred. A normal braking event is when the pedal position sensor measures that the operator has engaged the brake pedal.

[0062] If a normal braking event occurs, the process proceeds to operation 506 to operate the brake valve to a fully activated state in response to the normal braking event. At operation 508, the brake valve is operated to the fully activated state for the duration of the compliance calibration time determined at operation 414. At operation 508, the controller determines whether the compliance calibration time has ended. Optionally, a deviation value in the measured compliance calibration time can be considered to subtract the deviation value from the measured compliance calibration time. When the controller finds the measured compliance calibration time at operation 508, the controller can subtract the deviation value from the time. This deviation value will ensure that the brake valve does not remain at full current for too long. Keeping the brake valve at full current for a long time when the operator is not controlling the brake valve may result in a full braking moment. In normal braking operation, the time the brake valve remains at full current can be based on the hydraulic oil temperature. For example, the brake valve is kept at full current for a longer time at a lower hydraulic oil temperature because at a lower temperature the brake valve may flow less oil, resulting in a longer time to fill the brake compliance volume. For normal braking, the time the brake valve is at full current may also depend on the brake pressure before the pedal is depressed. For example, if the waiting time between brake applications is not sufficient to drain the oil, there may be oil remaining in the brake circuit, which will reduce the brake compliance volume. To address this issue, the time the brake valve remains at full current may vary with the change in pressure in the brake before the brake application. In another embodiment, if the pressure in the brake before the application is higher than a threshold, do not over-control the brake valve because the compliance may already be filled, so the time will change based on the pressure in the brake before the brake application.

[0063] If the compliance calibration time has ended, the process proceeds to operation 510, and the controller operates the brake valve in the brake state input by the operator in response to reaching the duration of the compliance calibration time. If the compliance calibration time has not ended, the process returns to operation 506.

[0064] Although the present disclosure has been described with respect to at least one embodiment, the present disclosure can be further modified within the spirit and scope of the present disclosure. Accordingly, this application is intended to cover any variations, uses, or adaptations of the present disclosure using its general principles. Additionally, this application is intended to cover departures from the present disclosure within the known or customary practice in the field to which the present disclosure pertains.

Claims

1. A method for calibrating brake compliance, the method comprising: Initiating a calibration event for an electronically controlled hydraulic braking system, the electronically controlled hydraulic braking system including a first brake valve operably connected to a first brake and a first brake pressure sensor; Operating the first brake valve to a fully activated state; In response to the operation of the first brake valve being in the fully activated state, measuring a compliance calibration time for the first brake valve; Determining a pressure event associated with the first brake pressure sensor; And Terminating the measurement of the compliance calibration time in response to the occurrence of the pressure event.

2. The method according to claim 1, Among them, The electronically controlled hydraulic braking system includes a second brake valve operably connected to a second brake and a second brake pressure sensor; Wherein, the method further comprises: Operating the second brake valve to a fully activated state; In response to the operation of the second brake valve being in the fully activated state, measuring a compliance calibration time for the second brake valve; Determining a pressure event associated with the second brake pressure sensor; and Terminating the measurement of the compliance calibration time in response to the occurrence of the pressure event.

3. The method according to claim 1, Among them, The electronically controlled hydraulic braking system includes a second brake valve operably connected to the first brake and the first brake pressure sensor; Wherein, the method further comprises: Operating the first brake valve and the second brake valve to a fully activated state simultaneously; In response to the operation of the first brake valve and the second brake valve being in the fully activated state simultaneously, measuring a compliance calibration time for the electronically controlled hydraulic braking system; Determining a pressure event associated with the first brake pressure sensor; and Terminating the measurement of the compliance calibration time in response to the occurrence of the pressure event.

4. The method according to claim 1, further comprising: Detecting a normal braking event of the electronically controlled hydraulic braking system; And In response to the normal braking event, operating the first brake valve to a fully activated state during the duration of the compliance calibration time.

5. The method according to claim 4, further comprising: In response to reaching the duration of the compliance calibration time, operating the first brake valve in a brake state input by an operator.

6. The method according to claim 4, wherein The electronically controlled hydraulic braking system includes a brake pedal connected to a position sensor configured to measure a brake pedal position, and detecting the normal braking event includes measuring the brake pedal position in response to a braking demand input by an operator.

7. The method according to claim 6, further comprising: If the operator releases the brake pedal before reaching the compliance calibration time, canceling the fully activated state of the first brake valve, and instead, the control of the first brake valve will again follow the brake pedal demand.

8. The method according to claim 1, wherein The electronically controlled hydraulic braking system includes a hydraulic pump for pumping hydraulic fluid from a hydraulic fluid reservoir to the first brake valve.

9. The method according to claim 1, wherein The calibration event is initiated by a controller operably connected to the electrohydraulic braking system in response to one of the following conditions being met: (i) A calibration request initiated by an operator via a vehicle monitor; (ii) Calibration automatically initiated by vehicle software upon machine startup; or (iii) Calibration automatically initiated by vehicle software when the parking brake is applied.

10. The method according to claim 9, wherein, The controller is configured to initiate the calibration event upon one or more of the following preconditions being met: (i) The hydraulic oil temperature is within a predetermined range; (ii) The engine speed is within a predetermined range; (iii) The parking brake is engaged; (iv) The brake pedal control is within a predetermined range; (v) A service time interval is reached; Or (vi) The brake pressure is within a predetermined range.

11. A brake compliance calibration device, comprising: An electrohydraulic braking system including a first brake valve operably connected to a first brake and a first brake pressure sensor; A controller operably connected to the electrohydraulic braking system, wherein the controller is configured to: Initiate a calibration event associated with the electrohydraulic braking system; Operate the first brake valve to a fully activated state; Measure a compliance calibration time for the first brake valve in response to the operation of the first brake valve being in the fully activated state; Determine a pressure event associated with the first brake pressure sensor; and And Terminate the measurement of the compliance calibration time in response to the pressure event.

12. The device according to claim 11, Among them, The electrohydraulic braking system includes a second brake valve operably connected to a second brake and a second brake pressure sensor; Wherein the controller is configured to: Operate the second brake valve to a fully activated state; Measure a compliance calibration time for the second brake valve in response to the operation of the second brake valve being in the fully activated state; Determine a pressure event associated with the second brake pressure sensor; and Terminate the measurement of the compliance calibration time in response to the pressure event.

13. The device according to claim 11, Among them, The electrohydraulic braking system includes a second brake valve operably connected to the first brake and the first brake pressure sensor; Wherein the controller is configured to operate the second brake valve to a fully activated state; Wherein the controller is configured to measure a second compliance calibration time for the second brake valve in response to the operation of the second brake valve being in the fully activated state; and Wherein the controller is configured to terminate the measurement of the second compliance calibration time in response to the pressure event.

14. The device according to claim 11, wherein, The controller is configured to detect normal braking events during the driving movement of a vehicle including the electrohydraulic braking system; and The controller is configured to operate the first brake valve to the fully activated state during a period of the compliance calibration time in response to the normal braking event.

15. The apparatus according to claim 14, wherein the controller is configured to operate the first brake valve under a braking demand input by an operator in response to reaching the period of the compliance calibration time.

16. The apparatus according to claim 14, wherein, The electrohydraulic braking system includes a brake pedal, the brake pedal is connected to a position sensor, the position sensor is configured to measure the brake pedal position, and the detection of the normal braking event includes measuring the brake pedal position in response to the braking demand input by the operator.

17. The device according to claim 11, wherein, The electrohydraulic braking system includes a hydraulic pump, the hydraulic pump is configured to pump hydraulic fluid from a hydraulic fluid reservoir to the first brake valve.

18. The device according to claim 11, wherein, The controller is configured to initiate the calibration event in response to one of the following conditions being met: (i) a calibration request initiated by an operator through a vehicle monitor; (ii) calibration automatically initiated by vehicle software when the machine is started; or (iii) calibration automatically initiated by vehicle software when the parking brake is applied.

19. The device according to claim 18, wherein, One or more of the following prerequisite conditions are met before the calibration event is initiated: (i) The hydraulic oil temperature is within a predetermined range; (ii) The engine speed is within a predetermined range; (iii) The parking brake is engaged; (iv) The brake pedal control is within a predetermined range; (v) A service time interval is reached; or (vi) The brake pressure is within a predetermined range.

20. The apparatus according to claim 11, further comprising: a battery, the battery is operably connected to the controller.

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