Control device and control method

Abstract

The present invention diagnoses the presence or absence of an abnormality in a sensor for detecting the fluid level position of brake fluid in a reservoir. A brake system 20 comprises: a first flow path group G1 connected to a master cylinder 42; and a second flow path group G2 connected to a wheel cylinder 44. A connection state of the brake system 20 can be switched between a first state in which the first flow path group G1 and the second flow path group G2 are disconnected and a second state in which the first flow path group G1 and the second flow path group G2 are connected. The brake system 20 comprises: a pressure generation unit 66 that controls the pressure of brake fluid in the wheel cylinder 44 in the first state; and a sensor that detects the fluid level position of the brake fluid in a reservoir 43 attached to the master cylinder 42. The control device comprises: a control unit that executes fluid level control to raise the fluid level by using the pressure generation unit 66; and a diagnosis unit that diagnoses the presence or absence of an abnormality in the sensor on the basis of a detection result from the sensor during execution of the fluid level control.

Description

[Document name] Statement

[0002] [Title of invention] Control device and control method

[0004] [Technical Field]

[0006]

. 0 0 1

[0008] The present invention relates to a control device and a control method.

[0010] [Background technology]

[0012]

. 0 0 2

[0014] Some vehicle brake systems include a hydraulic control unit for controlling the pressure of brake fluid in wheel cylinders. For example, as disclosed in Patent Document 1, a plurality of valves and pumps are provided in the flow path within the hydraulic control unit, and the pressure of the brake fluid in the wheel cylinders is adjusted by controlling the operation of these valves and pumps.

[0016] [Prior art documents]

[0018] [Patent documents]

[0020]

〇 0 0 3

[0022] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-052519

[0024] Summary of the Invention

[0026] [Problem to be solved by the invention]

[0028]

〇 0 0 4

[0030] In some brake systems that use brake fluid, the connection state of the brake system can be switched between a first state in which a first group of fluid passages connected to the master cylinder and a second group of fluid passages connected to the wheel cylinders are disconnected, and a second state in which the first group of fluid passages and the second group of fluid passages are connected. In such a system, in the first state, the master cylinder and the wheel cylinders are disconnected, but by driving a pressure generating unit, the pressure of the brake fluid in the wheel cylinders is controlled to a pressure corresponding to the amount of brake pedal operation.

[0032]

〇 0 0 5

[0034] In the first state, if the brake fluid level in the reservoir drops too low due to the pressure generating unit sucking the brake fluid from the reservoir, air may enter the brake fluid flow path from the reservoir. To avoid this situation, a sensor is provided to detect the brake fluid level in the reservoir. To appropriately avoid this situation, it is desirable to diagnose whether or not there is an abnormality in this sensor.

[0036]

〇 0 0 6

[0038] In view of the above, the present invention aims to provide a control device and a control method capable of diagnosing whether or not there is an abnormality in a sensor that detects the level of brake fluid in a reservoir.

[0040] [Means for solving the problem]

[0042]

〇 0 0 7

[0044] In order to solve the above problem, the control device is a control device for a vehicle brake system, the brake system comprising a first group of flow paths connected to a master cylinder and a second group of flow paths connected to a wheel cylinder, the connection state of the brake system being switchable between a first state in which the first group of flow paths and the second group of flow paths are blocked and a second state in which the first group of flow paths and the second group of flow paths are connected, the brake system comprising a pressure generating unit that controls the pressure of the brake fluid in the wheel cylinder in the first state, and a sensor that detects the liquid level of the brake fluid in a reservoir attached to the master cylinder, the control device comprising a control unit that performs liquid level control to raise the liquid level using the pressure generating unit, and a diagnosis unit that diagnoses whether or not there is an abnormality in the sensor based on the detection result of the sensor when the liquid level control is being performed.

[0046]

〇 0 0 8

[0048] In order to solve the above problem, a control method is provided for a vehicle brake system, wherein the brake system comprises a first group of flow paths connected to a master cylinder and a second group of flow paths connected to wheel cylinders, and the connection state of the brake system is switchable between a first state in which the first group of flow paths and the second group of flow paths are blocked and a second state in which the first group of flow paths and the second group of flow paths are connected, and the brake system comprises a pressure generating unit that controls the pressure of the brake fluid in the wheel cylinders in the first state, and a sensor that detects the level of the brake fluid in a reservoir attached to the master cylinder, and a control unit of the control device performs fluid level control to raise the fluid level using the pressure generating unit, and a diagnostic unit of the control device diagnoses whether or not there is an abnormality in the sensor based on the detection result of the sensor when the fluid level control is being performed.

[0050] [Effects of the Invention]

[0052] [ 0 0 0 9 ]

[0054] According to the present invention, it is possible to diagnose whether or not there is an abnormality in the sensor that detects the level of the brake fluid in the reservoir.

[0056] [Brief explanation of the drawings]

[0058] [ 0 0 1 0 ]

[0060] [Figure 1] Schematic diagram showing the general configuration of a vehicle relating to an embodiment of the present invention.

[0062] [Figure 2] A schematic diagram showing the general configuration of a brake system according to an embodiment of the present invention.

[0064] FIG. 3 is a schematic diagram showing a second state of the brake system according to the embodiment of the present invention.

[0066] [Figure 4] A schematic diagram showing an example of a reservoir liquid level sensor according to an embodiment of the present invention.

[0068] [Figure 5] A block diagram showing an example of the functional configuration of a control device according to an embodiment of the present invention. [Figure 6] A time chart showing an example of the progression of various state quantities when a diagnosis is made to determine whether or not there is an abnormality in a liquid level sensor according to an embodiment of the present invention.

[0070] [Figure ?] A schematic diagram showing the state of the brake system while fluid level control according to an embodiment of the present invention is being performed.

[0072] [Mode for carrying out the invention]

[0074] [ 0 0 1 1 ]

[0076] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values ​​shown in these embodiments are merely examples to facilitate understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0078] [ 0 0 1 2 ]

[0080] <Vehicle configuration>

[0082] The configuration of a vehicle 1 according to an embodiment of the present invention will be described.

[0084] [ 0 0 1 3 ]

[0086] Fig. 1 is a schematic diagram showing the general configuration of a vehicle 1. As shown in Fig. 1, the vehicle 1 includes a drive source 10, a brake system 20, and a control device 100.

[0088] [ 0 0 1 4 ]

[0090] The drive source 10 outputs a drive force that is transmitted to the drive wheels of the vehicle 1. Specifically, the vehicle 1 is equipped with a traction motor as the drive source 10. For example, the vehicle 1 may be equipped with an engine in addition to the traction motor as the drive source 10, or may be equipped with only the traction motor as the drive source 10. However, the vehicle 1 may also be equipped with only the engine as the drive source 10.

[0092] [ 0 0 1 5 ]

[0094] The brake system 20 includes a hydraulic pressure control unit 30. The hydraulic pressure control unit 30 controls the braking force of the vehicle 1. The hydraulic pressure control unit 30 controls the braking force applied to the wheels by controlling the wheel cylinder pressure, which is the pressure of the brake fluid in the wheel cylinder. Details of the brake system 20 will be described later.

[0096] [ 0 0 1 6 ]

[0098] The control device 100 controls the operation of the brake system 20. The control device 100 is provided, for example, inside the hydraulic control unit 30 (for example, inside the first hydraulic control unit 31 or the second hydraulic control unit 32 described below). The control device 100 includes a CPU (Central Processing Unit), which is an arithmetic processing device, a ROM (Read On 1 Memory), which is a memory element that stores programs used by the CPU, calculation parameters, etc., and a RAM (Random Access Memory), which is a memory element that temporarily stores parameters, etc. that change as appropriate during CPU execution. Details of the control device 100 will be described later.

[0100] [ 0 0 1 7 ]

[0102] FIG. 2 is a schematic diagram showing the overall configuration of a brake system 20. The brake system 20 is mounted on a vehicle 1 and is a system for controlling the braking force generated in the vehicle 1. As shown in FIG. 2, the brake system 20 includes a first hydraulic pressure control unit 31 and a second hydraulic pressure control unit 32 as a hydraulic pressure control unit 30. The brake system 20 also includes a brake pedal 41, a master cylinder 42, a reservoir 43, a wheel cylinder 44, and wheels 45.

[0104] [ 0 0 1 8 ]

[0106] The vehicle 1 has, for example, four wheels 45. The brake system 20 controls the braking force acting on each wheel 45 by controlling the pressure of the brake fluid in the wheel cylinder 44 (i.e., wheel cylinder pressure) provided in each of these wheels 45. When the wheel cylinder pressure increases, a brake pad (not shown) operates to press against a brake disc (not shown), thereby applying a braking force corresponding to the wheel cylinder pressure to the wheel 45.

[0108] [ 0 0 1 9 ]

[0110] Here, the connection state of the brake system 20 can be switched between a first state in which the first flow path group G1 (specifically, the first flow path 51 described below) connected to the master cylinder 42 and the second flow path group G2 (specifically, the second flow path 52 and the first flow path 11 described below) connected to the wheel cylinder 44 are blocked, and a second state in which the first flow path group G1 and the second flow path group G2 are connected. Figure 2 shows the brake system 20 in the first state.

[0112] [ 0 0 2 0 ]

[0114] The brake pedal 41 is used by the driver to apply the brakes. When applying the brakes, the driver presses down the brake pedal 41. The master cylinder 42 contains two pistons 42a (two pistons 42a arranged at a distance from each other on the left and right in Figure 2) that reciprocate in conjunction with the brake pedal 41. As the pistons 42a move in response to the brake application, the pressure in the two fluid chambers 42b separated by the pistons 42a in the master cylinder 42 (i.e., master cylinder pressure) is increased. The reservoir 43 is attached to the master cylinder 42 and stores brake fluid.

[0116] [ 0 0 2 1 ]

[0118] The brake system 20 is provided with a brake sensor 91 that detects the amount of operation of the brake pedal 41. The detection result of the brake sensor 91 is output to the control device 100.

[0120] [ 0 0 2 2 ]

[0122] The first hydraulic pressure control unit 31 is connected to the master cylinder 42 and the reservoir 43 via fluid pipes through which brake fluid flows. The first hydraulic pressure control unit 31 is also provided with a port P1 and a port P2. The port P1 is connected to a port P3 of the second hydraulic pressure control unit 32 via a fluid pipe through which brake fluid flows. The port P2 is connected to a port P4 of the second hydraulic pressure control unit 32 via a fluid pipe through which brake fluid flows.

[0124] [ 0 0 2 3 ]

[0126] The first hydraulic pressure control unit 31 is formed with a first flow path 51, a second flow path 52, a third flow path 53, a fourth flow path 54, and a fifth flow path 55 as flow paths for the brake fluid. The first hydraulic pressure control unit 31 is also provided with a first valve 61, a check valve 62, a second valve 63, a damping device 64, a third valve 65, a pressure generating unit 66, a motor 67, and a fourth valve 68 as components for controlling the flow of the brake fluid.

[0128] [ 0 0 2 4 ]

[0130] The first flow paths 51 are provided for each fluid chamber 42b in the master cylinder 42 and communicate with each fluid chamber 42b. In other words, a total of two first flow paths 51 are formed in the first hydraulic pressure control unit 31.

[0132] [ 0 0 2 5 ]

[0134] The second flow paths 52 are provided for the ports P1 and P2, respectively, and communicate with the ports P1 and P2. In other words, a total of two second flow paths 52 are formed in the first hydraulic pressure control unit 31. Each second flow path 52 branches into three flow paths within the first hydraulic pressure control unit 31.

[0136] [ 0 0 2 6 ]

[0138] The third flow path 53 communicates with the reservoir 43. The third flow path 53 branches into two flow paths within the first hydraulic pressure control unit 31.

[0140] [ 0 0 2 7 ]

[0142] Each second flow path 52 is connected to each first flow path 51 via a first valve 61. The first valve 61 is, for example, an electromagnetic valve that is open when de-energized and closed when energized.

[0144] [ 0 0 2 8 ]

[0146] In addition, each second flow path 52 is connected to a third flow path 53 via a check valve 62. The check valve 62 is a valve that prevents backflow of brake fluid from the second flow path 52 to the third flow path 53.

[0148] [ 0 0 2 9 ]

[0150] One of the two first flow paths 51 (the left first flow path 51 in FIG. 2) is connected to the third flow path 53 via a second valve 63 and a damping device 64. The second valve 63 is, for example, a solenoid valve that is closed when de-energized and open when energized. The damping device 64 is a device that damps pressure pulsations of the brake fluid. The second valve 63 and the damping device 64 are arranged in this order from the first flow path 51 side.

[0152] [ 0 0 3 0 ]

[0154] The fourth flow path 54 is connected to each second flow path 52 via a third valve 65. The third valve 65 is, for example, a solenoid valve that is closed when de-energized and open when energized.

[0156] [ 0 0 3 1 ]

[0158] The end of the fourth flow path 54 opposite to the third valve 65 is connected to a pressure generating unit 66. The pressure generating unit 66 is driven by a motor 67. The pressure generating unit 66 is, for example, a diaphragm pump. In this case, the motor 67 pressurizes a piston provided in a chamber of the pressure generating unit 66, thereby pressurizing and feeding the brake fluid.

[0160] [ 0 0 3 2 ]

[0162] The fifth flow path 55 connects the pressure generating unit 66 and the third flow path 53. Therefore, the pressure generating unit 66 is connected to the reservoir 43 via the fifth flow path 55 and the third flow path 53. In other words, the fifth flow path 55 corresponds to a flow path that connects the pressure generating unit 66 and the reservoir 43.

[0164] [ 0 0 3 3 ]

[0166] A fourth valve 68 is provided in the fifth flow path 55. The fourth valve 68 is, for example, a solenoid valve that is closed when de-energized and open when energized.

[0168] [ 0 0 3 4 ]

[0170] As described above, the ports P3 and P4 of the second hydraulic pressure control unit 32 are connected to the ports P1 and P2, respectively, of the first hydraulic pressure control unit 31. The second hydraulic pressure control unit 32 is also connected to each wheel cylinder 44 via fluid pipes through which brake fluid flows.

[0172] [ 0 0 3 5 ]

[0174] The second hydraulic pressure control unit 32 has a first flow path 71, a second flow path 72, and a third flow path 73 formed as flow paths for the brake fluid. The second hydraulic pressure control unit 32 also has a first valve 81, a second valve 82, a third valve 83, an accumulator 84, a pump 85, a motor 86, and a fourth valve 87 as components for controlling the flow of the brake fluid.

[0036]

[0176] Port P3 is connected to the wheel cylinders 44 of two wheels 45 (e.g., the left front wheel and the right rear wheel) via flow paths. Port P4 is connected to the wheel cylinders 44 of the other two wheels 45 (e.g., the right front wheel and the left rear wheel) via flow paths. In the second hydraulic control unit 32, the flow path communicating with port P3 (the left flow path in FIG. 2) has the same configuration as the flow path communicating with port P4 (the right flow path in FIG. 2).

[0178] [ 0 0 3 7 ]

[0180] A flow path consisting of a first flow path 71, a second flow path 72, and a third flow path 73 is connected to port P3. Similarly, a flow path consisting of a first flow path 71, a second flow path 72, and a third flow path 73 is connected to port P4. In other words, the second hydraulic pressure control unit 32 is provided with a total of two flow paths consisting of a first flow path 71, a second flow path 72, and a third flow path 73.

[0182] [ 0 0 3 8 ]

[0184] The first flow path 71 connects the port P3 or the port P4 (hereinafter also referred to as the ports P3 and P4) with the two wheel cylinders 44. The first flow path 71 allows the brake fluid sent to the ports P3 and P4 to flow to the wheel cylinders 44.

[0186] [ 0 0 3 9 ]

[0188] The first flow path 71 branches into two flow paths on the wheel cylinder 44 side. A first valve 81 is provided in each of these flow paths. The first valve 81 is, for example, a solenoid valve that is open when de-energized and closed when energized.

[0190] [ 0 0 4 0 ]

[0192] A second valve 82 is provided in the first flow path 71 on the side of ports P3 and P4 from the branching point. The second valve 82 is, for example, a solenoid valve that is open when de-energized and closed when energized.

[0194] [ 0 0 4 1 ]

[0196] The second flow path 72 connects the wheel cylinder 44 side of the first flow path 71 via the first valve 81, the wheel cylinder 44 side of the first flow path 71 via the second valve 82, and the ports P3 and P4 of the first valve 81. The second flow path 72 releases brake fluid from the wheel cylinder 44.

[0198] [ 0 0 4 2 ]

[0200] The second flow path 72 branches into two flow paths on the wheel cylinder 44 side. A third valve 83 is provided in each of these flow paths. The third valve 83 is, for example, a solenoid valve that is closed when de-energized and open when energized.

[0202] [ 0 0 4 3 ]

[0204] An accumulator 84 and a pump 85 are provided in the second flow path 72 on the side of ports P3 and P4 from the branching point, in that order from the branching point. The pump 85 is driven by a motor 86 and draws brake fluid from the wheel cylinder 44 side and discharges it to ports P3 and P4. The pump 85 is, for example, a reciprocating plunger pump. In this case, the plunger of the pump 85 is intermittently pressed by an eccentric cam provided on the output shaft of the motor 86, causing it to reciprocate, thereby pressurizing and feeding the brake fluid.

[0206] [ 0 0 4 4 ]

[0208] The third flow path 73 connects ports P3 and P4 of the second valve 82 in the first flow path 71 with the suction side of the pump 85 in the second flow path 72. The third flow path 73 supplies brake fluid sent to ports P3 and P4 to the second flow path 72.

[0210] [ 0 0 4 5 ]

[0212] A fourth valve 87 is provided in the third flow path 73. The fourth valve 87 is, for example, a solenoid valve that is closed when de-energized and open when energized.

[0214] [ 0 0 4 6 ]

[0216] As shown in FIG. 2, the first state of the brake system 20 is a state in which the first valve 61 is closed, the second valve 63 is open, the third valve 65 is open, and the fourth valve 68 is closed in the first hydraulic control unit 31.

[0218] [ 0 0 4 7 ]

[0220] In the first state, the first valve 61 is closed, blocking the first flow path group G1 (specifically, the first flow path 51) connected to the master cylinder 42 and the second flow path group G2 (specifically, the second flow path 52 and the first flow path 11) connected to the wheel cylinder 44. Also, in the first state, the second valve 63 is opened, connecting the first flow path 51 and the third flow path 53 via the damping device 64. Therefore, when the driver depresses the brake pedal 41, the pressure in the first flow path 51 increases as the master cylinder pressure increases, and then the increased pressure in the first flow path 51 is damped by the damping device 64.

[0222] [ 0 0 4 8 ]

[0224] In the first state, the third valve 65 is opened, thereby interconnecting the fourth flow path 54 with the second flow path 52 and the first flow path 71. As shown in Fig. 2, the second hydraulic control unit 32 is basically in a state where the first valve 81 is open, the second valve 82 is open, the third valve 83 is closed, and the fourth valve 87 is closed. Therefore, the pressure generating unit 66 and the wheel cylinder 44 are interconnected via the fourth flow path 54, the second flow path 52, and the first flow path 71. Therefore, by driving the pressure generating unit 66 with the motor 67, the wheel cylinder pressure can be increased and the wheels 45 can be braked.

[0226] [ 0 0 4 9 ]

[0228] In the first state, the control device 100 controls the wheel cylinder pressure to a pressure corresponding to the amount of operation of the brake pedal 41 by driving the pressure generating unit 66 in accordance with the amount of operation of the brake pedal 41. As a result, even though the master cylinder 42 and the wheel cylinder 44 are disconnected, the driver can brake the vehicle 1 by operating the brakes.

[0230] [ 0 0 5 0 ]

[0232] In addition, in both the first state and the second state described below, the control device 100 can also perform various controls by controlling the operation of each device in the second hydraulic control unit 32.

[0234] [ 0 0 5 1 ]

[0236] For example, in anti-lock brake control, which is a control to prevent the wheels 45 from locking, the control device 100 closes the first valve 81 and opens the third valve 83 from the state shown in FIG. 2. This stops the flow of brake fluid between the first flow path 71 and the wheel cylinder 44, allowing brake fluid to flow from the wheel cylinder 44 to the second flow path 72. Therefore, brake fluid flows from the wheel cylinder 44 to the accumulator 84, reducing the wheel cylinder pressure and the braking force applied to the wheels 45. The brake fluid that has flowed into the accumulator 84 is returned to the first flow path 71 via the second flow path 72 by driving the pump 85. This makes it possible to prevent the wheels 45 from locking.

[0238] [ 0 0 5 2 ]

[0240] Furthermore, for example, in control for automatically braking the vehicle 1 (e.g., automatic emergency braking, etc.) or control for automatically increasing the braking force of the vehicle 1 (e.g., attitude stabilization control for stabilizing the attitude of the vehicle 1, etc.), the control device 100 closes the first valve 81 and opens the fourth valve 87 from the state shown in FIG. 2 . This causes the pressure generating unit 66 and the wheel cylinder 44 to communicate with each other via the third flow path 73. In this state, the motor 86 drives the pump 85, thereby increasing the wheel cylinder pressure and generating or increasing the braking force that brakes the wheels 45.

[0242] [ 0 0 5 3 ]

[0244] FIG. 3 is a schematic diagram showing the second state of the brake system 20. As shown in FIG. 3, the second state of the brake system 20 is a state in which, in the first hydraulic pressure control unit 31, the first valve 61 is open, the second valve 63 is closed, the third valve 65 is closed, and the fourth valve 68 is closed.

[0054]

[0246] In the second state, the first valve 61 is opened, thereby connecting the first flow path group G1 (specifically, the first flow path 51) connected to the master cylinder 42 with the second flow path group G2 (specifically, the second flow path 52 and the first flow path 71) connected to the wheel cylinder 44. Therefore, in the second state, the master cylinder 42 and the wheel cylinder 44 are in communication with each other via the first flow path 51, the second flow path 52, and the first flow path 71. Therefore, the driver can increase the master cylinder pressure by depressing the brake pedal 41, thereby increasing the wheel cylinder pressure and braking the wheels 45.

[0248] [ 0 0 5 5 ]

[0250] As described above, the connection state of the brake system 20 can be switched between a first state (state in Figure 2) in which the first flow path group G1 connected to the master cylinder 42 and the second flow path group G2 connected to the wheel cylinder 44 are blocked, and a second state (state in Figure 3) in which the first flow path group G1 and the second flow path group G2 are connected.

[0252] [ 0 0 5 6 ]

[0254] Also, as described above, in the first state, although the master cylinder 42 and the wheel cylinder 44 are disconnected, the driver can brake the vehicle 1 by operating the brakes. However, in the first state, the wheel cylinder pressure is actually controlled by the control device 100. Therefore, in the first state, the control device 100 can, for example, generate part of the braking force corresponding to the amount of operation of the brake pedal 41 using the wheel cylinder pressure, and generate the other part using regenerative braking. Such a braking method is also called regenerative cooperative braking. Regenerative cooperative braking can improve the electric fuel efficiency of the vehicle 1.

[0256] [ 0 0 5 7 ]

[0258] Here, in the first state, the brake fluid level in the reservoir 43 may drop due to the pressure generating unit 66 sucking the brake fluid from the reservoir 43. For example, the brake fluid level in the reservoir 43 may drop due to brake fluid flowing from the third flow path 53 to the second flow path 52 through the check valve 62. If the brake fluid level in the reservoir 43 drops too much, air may enter the flow path in the hydraulic control unit 30 from the reservoir 43. If air enters the flow path in the hydraulic control unit 30, it may become difficult to operate the hydraulic control unit 30 normally. Therefore, to avoid such a situation, the control device 100 switches the connection state of the brake system 20 to the second state.

[0260] [ 0 0 5 8 ]

[0262] As described above, in the brake system 20, it is necessary to detect the level of the brake fluid in the reservoir 43 in order to prevent air from entering the flow path in the hydraulic control unit 30. Therefore, the brake system 20 is provided with a fluid level sensor that detects the position of the brake fluid level in the reservoir 43. The fluid level sensor will be described below with reference to Figure 4.

[0264] [ 0 0 5 9 ]

[0266] 4 is a schematic diagram showing an example of a fluid level sensor 92 for the reservoir 43. The fluid level sensor 92 detects the position of the fluid level F1 of the brake fluid L1 in the reservoir 43. The detection result of the fluid level sensor 92 is output to the control device 100. As shown in FIG. 4, the fluid level sensor 92 includes, for example, a float 92a, a permanent magnet 92b, a shaft 92c, and a magnetic field detection device 92d.

[0268] [ 0 0 6 0 ]

[0270] The float 92a floats on the liquid level F1 of the brake fluid L! in the reservoir 43 and moves up and down together with the liquid level F1 as the liquid level F! moves up and down. A permanent magnet 92b is embedded in the float 92a. A shaft 92c extends vertically and is fixed to the reservoir 43. The shaft 92c passes through the float 92a. The float 92a slides relative to the shaft 92c, allowing it to move up and down as the liquid level F1 moves up and down. Therefore, the permanent magnet 92b, which moves integrally with the float 92a, can also move up and down as the liquid level F1 moves up and down. The permanent magnet 9 2 b is located on the float 9 2 a on the magnetic field detector 9 2 d side with respect to the shaft 9 2 c.

[0272] [ 0 0 6 1 ]

[0274] The magnetic field detector 92d can detect the vertical position of the permanent magnet 92 by detecting the magnetic field. The magnetic field detector 92d is, for example, a device that converts the magnitude or change in the detected magnetic field into an electrical signal. As described above, the permanent magnet 92b moves up and down in accordance with the vertical movement of the liquid level F1. Here, the permanent magnet 92b is located at the center of the float 92a in the vertical direction. Therefore, the vertical position of the permanent magnet 92b detected by the magnetic field detector 92d can be considered to be the position of the liquid level F1 of the brake fluid L! in the reservoir 43.

[0276] [ 0 0 6 2 ]

[0278] In the example of Figure 4, the liquid level F1 of the brake fluid L1 in the reservoir 43 is higher than the minimum value TH. In this case, it can be determined that a situation will not occur in which air will be mixed from the reservoir 43 into the flow path in the hydraulic control unit 30. On the other hand, if the liquid level F1 of the brake fluid L1 in the reservoir 43 is lower than the minimum value TH, it can be determined that a situation will occur in which air will be mixed from the reservoir 43 into the flow path in the hydraulic control unit 30.

[0280] [ 0 0 6 3 ]

[0282] The fluid level sensor 92 only needs to have the function of detecting the position of the fluid level F1 of the brake fluid L1 in the reservoir 43, and the example of Figure 4 is merely one example of the fluid level sensor 92.

[0284] [ 0 0 6 4 ]

[0286] 5 is a block diagram showing an example of the functional configuration of the control device 100. Note that the control device 100 may be, for example, one device or may be divided into multiple devices. When the control device 100 is divided into multiple devices, the various functions described below may be shared among the multiple devices.

[0288] [ 0 0 6 5 ]

[0290] The control device 100 can acquire information from each device in the brake system 20 (specifically, the brake sensor 91 and the fluid level sensor 92). The control device 100 can also control the operation of each device in the brake system 20 (specifically, each component of the first hydraulic pressure control unit 31 and each component of the second hydraulic pressure control unit 32) by outputting operation commands to the devices. As shown in FIG. 5, the control device 100 includes, for example, a control unit 110 and a diagnosis unit 120.

[0292] [ 0 0 6 6 ]

[0294] The control unit 110 controls the operation of each device in the vehicle 1 (particularly in the brake system 20). For example, the control unit 110 controls the operation of each component in the first hydraulic pressure control unit 31 and each component in the second hydraulic pressure control unit 32.

[0296] [ 0 0 6 7 ]

[0298] Specifically, the control unit 110 switches the connection state of the brake system 20 between a first state and a second state by controlling the open / close state of each valve of the first hydraulic pressure control unit 31. In addition, in the first state, the control unit 110 controls the wheel cylinder pressure to a pressure corresponding to the amount of operation of the brake pedal 41 by driving the pressure generating unit 66 in accordance with the amount of operation of the brake pedal 41. In addition, the control unit 110 controls the operation of each device of the second hydraulic pressure control unit 32 to perform various controls such as antilock brake control, automatic emergency braking, and attitude stabilization control.

[0300] [ 0 0 6 8 ]

[0302] The diagnosis unit 120 diagnoses whether or not there is an abnormality in the liquid level sensor 92. Details of the processing by the diagnosis unit 120 will be described later.

[0304] [ 0 0 6 9 ]

[0306] <Control device operation>

[0308] The operation of the control device 1 XXX according to the embodiment of the present invention will be described.

[0310] [ 0 0 7 0 ]

[0312] As described above, the control unit 110 of the control device 100 switches the connection state of the brake system 20 between the first state and the second state. Also, as described above, the control unit 110 switches the connection state of the brake system 20 to the second state when the liquid level F1 of the brake fluid L! in the reservoir 43 drops and a situation may arise in which air is mixed from the reservoir 43 into the flow path in the hydraulic control unit 30.

[0314] [ 0 0 7 1 ]

[0316] Here, the control unit 110 determines whether or not a situation may occur in which air may enter the flow path in the hydraulic control unit 30 from the reservoir 43 based on the detection result of the fluid level sensor 92. For example, when the fluid level F1 of the brake fluid L1 in the reservoir 43 is lower than the minimum value TH, the control unit 110 determines that a situation may occur in which air may enter the flow path in the hydraulic control unit 30 from the reservoir 43, and switches the connection state of the brake system 20 to the second state. Note that in the second state, the wheel cylinder pressure changes in response to the brake operation by the driver, making it difficult to perform regenerative cooperative braking. Therefore, when the fluid level F1 of the brake fluid L1 in the reservoir 43 is lower than the minimum value TH, the control unit 110 preferably further prohibits regenerative braking of the vehicle 1.

[0318] [ 0 0 7 2 ]

[0320] As described above, when switching the connection state of the brake system 20, it is important to diagnose whether or not there is an abnormality in the liquid level sensor 92. Therefore, in this embodiment, by improving the processing performed by the control device 100, it becomes possible to diagnose whether or not there is an abnormality in the liquid level sensor 92. The processing related to diagnosing the liquid level sensor 92 will be described below.

[0322] [ 0 0 7 3 ]

[0324] Fig. 6 is a time chart showing an example of the transition of various state quantities when diagnosing whether or not there is an abnormality in the liquid level sensor 92. In Fig. 6, the horizontal axis T represents time, and the vertical axis represents the detection result DR_S of the liquid level sensor 92, the drive state ST_P of the pressure generating unit 66, the connection state 5T_S of the brake system 20, and the open / close state ST_V of the fourth valve 68, and the transition of the various state quantities is shown.

[0326] [ 0 0 7 4 ]

[0328] Regarding the detection result DR_S of the fluid level sensor 92, "low" in FIG. 6 indicates a determination result that the fluid level F1 of the brake fluid L1 in the reservoir 43 is lower than the minus value TH, and "high J" in FIG. 6 indicates a determination result that the fluid level F1 of the brake fluid L1 in the reservoir 43 is higher than the minus value TH.

[0330] [ 0 0 7 5 ]

[0332] Furthermore, with regard to the drive state ST_P of the pressure generating unit 66, "off" in Figure 6 indicates that the pressure generating unit 66 is stopped, and in cases other than "○ ff" in Figure 6, the line indicating the drive state ST indicates the drive amount of the pressure generating unit 66.

[0334] [ 0 0 7 6 ]

[0336] Furthermore, with regard to the connection state ST_S of the brake system 2 〇, "model" in Figure 6 indicates the first state, and "m 〇 de 2" in Figure 6 indicates the second state.

[0338] [ 0 0 7 7 ]

[0340] Furthermore, with regard to the open / closed state ST_V of the fourth valve 68, "open" in FIG. 6 indicates a state in which the fourth valve 68 is open, and "close" in FIG. 6 indicates a state in which the fourth valve 68 is closed.

[0342] [ 0 0 7 8 ]

[0344] In the example of Figure 6, the connection state ST_S is in the first state before time T1. Therefore, before time T1, the fourth valve 68 is closed and the pressure generating unit 66 is operating. Also, before time T1, the detection result of the liquid level sensor 92 is that the liquid level F1 is higher than the minimum value TH.

[0346] [ 0 0 7 9 ]

[0348] Then, at time T1, the detection result of the liquid level sensor 92 changes from a result indicating that the liquid level F1 is higher than the minimum value TH to a result indicating that the liquid level F1 is lower than the minimum value TH. Therefore, at time T1, the control unit 110 switches the connection state ST_S from the first state to the second state. Accordingly, at time T1, the pressure generating unit 66 stops.

[0080]

[0350] For example, as described above, when the detection result of the liquid level sensor 92 changes from a result that the liquid level F1 is higher than the min value TH to a result that the liquid level F1 is lower than the min value TH and the connection state ST_S changes to the second state, the control device 100 executes processing related to the diagnosis of the liquid level sensor 92 (specifically, processing performed after time T2 described below). In particular, when the connection state ST_S changes to the second state as a result of the liquid level sensor 92 detecting that the liquid level F! is lower than the min value TH, the control device 100 may execute processing related to the diagnosis of the liquid level sensor 92 only if a predetermined time has elapsed since the time when the processing related to the diagnosis of the liquid level sensor 92 was last executed.

[0352] [ 0 0 8 1 ]

[0354] Below, we will explain the processing related to the diagnosis of the liquid level sensor 92 that is performed after time T2.

[0356] [ 0 0 8 2 ]

[0358] At time T2 after time T1, the control unit 110 starts liquid level control to raise the liquid level F1 using the pressure generating unit 66. For example, in the liquid level control, the control unit 110 opens the fourth valve 68, which is closed when the liquid level control is not being executed, and drives the pressure generating unit 66 with the fourth valve 68 open.

[0360] [ 0 0 8 3 ]

[0362] FIG. 7 is a schematic diagram showing the state of the brake system 20 while fluid level control is being performed. As described above, when fluid level control is performed in the brake system 20 in the second state, the fourth valve 68 is opened. As a result, as shown in FIG. 7, the pressure generating unit 66 and the reservoir 43 are in communication with each other via the fifth flow path 55 and the third flow path 53. Then, during fluid level control, the pressure generating unit 66 is driven in this state. As a result, brake fluid is sent from the pressure generating unit 66 to the reservoir 43 via the fifth flow path 55 and the third flow path 53. Therefore, the fluid level F1 of the brake fluid L! in the reservoir 43 can be raised.

[0364] [ 0 0 8 4 ]

[0366] From time T2 in Figure 6 onwards, the liquid level control continues to be executed, the fourth valve 68 remains open, and the pressure generating unit 66 remains driven. Then, at time T3 after time T2, the detection result of the liquid level sensor 92 changes from the result that the liquid level F1 is lower than the minimum value TH to the result that the liquid level F1 is higher than the minimum value TH. Thereafter, the control unit 110 stops the pressure generating unit 66 and closes the fourth valve 68 at time T4. As a result, the liquid level control ends at time T4. When the fluid level control ends and the pressure generating unit 66 stops, the pressure in the reservoir 43, which had been increased by the pressure generating unit 66, decreases, causing the brake fluid L1 to gradually flow out of the reservoir 43 and the fluid level F1 to gradually drop. Then, at time T5 after time T4, the detection result of the fluid level sensor 92 changes from a result that the fluid level F1 is higher than the min value TH to a result that the fluid level F1 is lower than the min value TH.

[0368] [ 0 0 8 5 ]

[0370] In this embodiment, the diagnostic unit 12 〇 diagnoses whether or not there is an abnormality in the liquid level sensor 92 based on the detection results of the liquid level sensor 92 when liquid level control is being performed and the detection results of the liquid level sensor 92 when the liquid level F1 drops after liquid level control is performed.

[0372] [ 0 0 8 6 ]

[0374] For example, in the example of Figure 6, at time T3 when the liquid level control is being performed, the liquid level sensor 92 detects that the liquid level F1 is higher than the minimum value TH. When the liquid level control is performed, the pressure generating unit 66 forcibly raises the liquid level F1, so the above detection result by the liquid level sensor 92 indicates that the liquid level sensor 92 is normal.

[0376] [ 0 0 8 7 ]

[0378] Also, for example, in the example of Figure 6, at time T5 when the liquid level F1 is dropping after the liquid level control is executed, the liquid level sensor 92 detects that the liquid level F! is lower than the minimum value TH. As described above, the liquid level F1 gradually drops after the liquid level control is executed, so the above detection result by the liquid level sensor 92 is a result that can be assumed to indicate that the liquid level sensor 92 is normal.

[0380] [ 0 0 8 8 ]

[0382] The diagnostic unit 120 diagnoses that the liquid level sensor 92 is normal when both the first condition that the liquid level sensor 92 detects that the liquid level F1 is higher than the minimum value TH when the liquid level control is being performed and the second condition that the liquid level sensor 92 detects that the liquid level F! is lower than the minimum value TH when the liquid level F1 drops after the liquid level control is performed are satisfied, as in the example of Figure 6. In this example, the diagnostic unit 120 diagnoses that the liquid level sensor 92 is abnormal when, for example, only one of the first and second conditions is satisfied, or when neither the first nor second conditions is satisfied.

[0384] [ 0 0 8 9 ]

[0386] However, the diagnosis unit 120 may diagnose that the liquid level sensor 92 is normal if the first condition is satisfied, regardless of whether the second condition is satisfied.

[0388] If the diagnosis unit 120 diagnoses that the liquid level sensor 92 is abnormal, the control unit 110 can perform various processes.

[0390] [ 0 0 9 1 ]

[0392] For example, if the diagnosis unit 120 diagnoses that the fluid level sensor 92 is abnormal, the control unit 110 may switch the connection state of the brake system 20 to the second state. If the fluid level sensor 92 is abnormal, the fluid level sensor 92 detects that the fluid level F! is higher than the minimum value TH, but the fluid level F! of the brake fluid L! in the reservoir 43 may be excessively low. Therefore, by switching the connection state of the brake system 20 to the second state, it is possible to prevent air from entering the flow path in the hydraulic control unit 30 from the reservoir 43.

[0394] [ 0 0 9 2 ]

[0396] Furthermore, for example, when the diagnosing unit 120 diagnoses that the liquid level sensor 92 is abnormal, the control unit 110 may notify the driver of the vehicle 1. If the liquid level sensor 92 is abnormal, maintenance such as repair or replacement of the liquid level sensor 92 is necessary. Therefore, for example, by notifying the driver of the vehicle 1 that the liquid level sensor 92 is abnormal, the driver can be prompted to perform maintenance on the liquid level sensor 92. Note that the notification to the driver can be realized, for example, by using a display device or a sound output device provided in the vehicle 1.

[0398] [ 0 0 9 3 ]

[0400] <Effects of the control device>

[0402] The effects of the control device 1 XX according to the embodiment of the present invention will be described.

[0404] [ 0 0 9 4 ]

[0406] The brake system 20 comprises a first flow path group G1 connected to the master cylinder 42 and a second flow path group G2 connected to the wheel cylinder 44, and the connection state of the brake system 20 can be switched between a first state in which the first flow path group G1 and the second flow path group G2 are blocked, and a second state in which the first flow path group G1 and the second flow path group G2 are connected, and the brake system 20 comprises a pressure generating unit 66 that controls the pressure of the brake fluid in the wheel cylinder 44 in the first state, and a sensor (in the above example, a fluid level sensor 92) that detects the position of the fluid level F1 of the brake fluid L1 in a reservoir 43 attached to the master cylinder 42, and a control device 1. The liquid level control system 100 includes a control unit 110 that executes liquid level control to raise the liquid level F1 using a pressure generating unit 66, and a diagnosis unit 120 that diagnoses whether or not there is an abnormality in the sensor based on the detection result of the sensor when the liquid level control is executed. As a result, it is possible to diagnose whether or not there is an abnormality in the sensor by focusing on the detection result of the sensor when the liquid level F1 is forcibly raised.

[0408] [ 0 0 9 5 ]

[0410] Preferably, the brake system 20 includes a flow path (the fifth flow path 55 in the above example) connecting the pressure generating unit 66 and the reservoir 43, and a valve (the fourth valve 68 in the above example) that is provided in the flow path and is closed when the liquid level control is not being performed, and the control unit 110 drives the pressure generating unit 66 with the valve open to raise the liquid level F1 during the liquid level control. This allows the liquid level F1 to be forcibly raised appropriately by the liquid level control.

[0412] [ 0 0 9 6 ]

[0414] Preferably, in the control device 100, the diagnosis unit 120 diagnoses the presence or absence of a sensor abnormality based on the detection result of the sensor when the liquid level F1 drops after the liquid level control is executed, in addition to the detection result of the sensor (liquid level sensor 92 in the above example) when the liquid level control is executed. Thereby, by further focusing on the detection result of the sensor when the liquid level F1 gradually drops after the liquid level control is executed, the presence or absence of a sensor abnormality can be diagnosed with higher accuracy.

[0416] [ 0 0 9 7 ]

[0418] Preferably, in the control device 100, when the diagnosing unit 120 diagnoses that the sensor (in the above example, the liquid level sensor 92) is abnormal, the control unit 110 switches the connection state to the second state, thereby preventing air from entering the flow path in the hydraulic control unit 30 from the reservoir 43.

[0420] [ 0 0 9 8 ]

[0422] Preferably, in the control device 100, when the diagnosing unit 120 diagnoses that a sensor (in the above example, the liquid level sensor 92) is abnormal, the control unit 110 notifies the driver of the vehicle 1. This can prompt the driver to perform maintenance on the sensor.

[0424] [ 0 0 9 9 ]

[0426] Preferably, in the control device 100, when the control unit 110 determines based on the detection result of the sensor (in the above example, the liquid level sensor 92) that the liquid level F1 is lower than the minimum value TH, the control unit 110 switches the connection state to the second state, thereby preventing air from entering the flow path in the hydraulic control unit 30 from the reservoir 43.

[0428] [ 0 1 0 0 ]

[0430] Preferably, in the control device 100, when the control unit 110 determines that the fluid level F1 is lower than the minimum value TH based on the detection result of the sensor (fluid level sensor 92 in the above example), it switches the connection state to the second state and prohibits regenerative braking of the vehicle 1. This makes it possible to prohibit regenerative braking in situations where it is difficult to perform regenerative cooperative braking.

[0432] [ 0 1 0 1 ]

[0434] The above describes a preferred embodiment of the present invention with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

[0436] [ 0 1 0 2 ]

[0438] For example, the series of processes performed by the control device 100 described above may be realized using software, hardware, or a combination of software and hardware. The programs constituting the software are stored in advance in a storage medium provided inside or outside the information processing device, for example.

[0440] [Explanation of symbols]

[0442] [ 0 1 0 3 ]

[0444] 1 vehicle

[0446] 1. Power source

[0448] 2 Brake system

[0450] 3. Hydraulic control unit

[0452] 3 1 First hydraulic control unit

[0454] 3 2 Second hydraulic control unit

[0456] 4 1 Brake pedal

[0458] 4 2 Master cylinder

[0460] 4 3 Reservoir

[0462] 4 4 Wheel cylinder 4 5 Wheel

[0464] 5 1 First flow path

[0466] 5 2 Second flow path

[0468] 5 3 Third flow path

[0470] 5 4 4th channel

[0472] 5 5 5th channel (channel)

[0474] 6 1 First valve

[0476] 6 2 Check valve

[0478] 6 3 Second valve

[0480] 6 4 Damping device

[0482] 6 5 Third valve

[0484] 6 6 Pressure generating section

[0486] 6 7 Motor

[0488] 6 8 4th valve (valve) 7 1 1st flow path

[0490] 7 2 Second flow path

[0492] 7 3 Third channel

[0494] 8 1 First valve

[0496] 8 2 Second valve

[0498] 8 3 Third valve

[0500] 8 4 Accumulator

[0502] 8 5 Pump

[0504] 8 6 motor

[0506] 8 7 4th valve

[0508] 9 1 Brake sensor

[0510] 9 2 Liquid level sensor (sensor) 1 0 0 Control device

[0512] 1 1 0 Control section

[0514] 1 2 〇 Diagnostic Department

[0516] DR_S detection results

[0518] F 1 liquid level

[0520] G 1 First group of channels

[0522] G 2 Second flow channel group

[0524] L 1 Brake fluid

[0526] P1 port

[0528] P2 port

[0530] P3 port

[0532] P4 port

[0534] ST_P driving status

[0536] ST_S connection status

[0538] ST _V Open / Close status

[0540] TH Min value

Claims

[Document name] Scope of claims

1. A control device (100) for a brake system (20) of a vehicle (1), The brake system (20) includes a first flow path group (G1) connected to a master cylinder (42) and a second flow path group (G2) connected to a wheel cylinder (44), and the connection state of the brake system (20) is switchable between a first state in which the first flow path group (G1) and the second flow path group (G2) are disconnected and a second state in which the first flow path group (G1) and the second flow path group (G2) are connected, The brake system (20) comprises a pressure generating unit (66) that controls the pressure of the brake fluid in the wheel cylinder (44) in the first state, and a sensor (92) that detects the position of a fluid level (F1) of the brake fluid (L1) in a reservoir (43) attached to the master cylinder (42), The control device (100) a control unit (110) that executes liquid level control to raise the liquid level (F1) using the pressure generating unit (66); a diagnosis unit (120) that diagnoses whether or not there is an abnormality in the sensor (92) based on the detection result of the sensor (92) when the liquid level control is being performed; Equipped with Control device.

2. The brake system (20) comprises: a flow path (55) connecting the pressure generating unit (66) and the reservoir (43); and a valve (68) provided in the flow path (55) and closed when the liquid level control is not being performed. Equipped with The control device according to claim 1, wherein the control unit (110) raises the liquid level (F1) by driving the pressure generating unit (66) with the valve (68) open during the liquid level control.

3. The diagnosing unit (120) diagnoses whether or not there is an abnormality in the sensor (92) based on the detection result of the sensor (92) when the liquid level control is being performed, as well as the detection result of the sensor (92) when the liquid level (F1) is dropping after the liquid level control is performed. The control device according to claim 1.

4. When the diagnosis unit (120) diagnoses that the sensor (92) is abnormal, the control unit (110) switches the connection state to the second state. The control device according to claim 1.

5. When the diagnosing unit (120) diagnoses that the sensor (92) is abnormal, the control unit (110) notifies the driver of the vehicle (1). The control device according to claim 1.

6. The control device according to any one of claims 1 to 5, wherein the control unit (110) switches the connection state to the second state when it determines based on the detection result of the sensor (92) that the liquid level (F1) is lower than a threshold value (TH).

7. When the control unit (110) determines that the fluid level (F1) is lower than the threshold value (TH) based on the detection result of the sensor (92), it switches the connection state to the second state and prohibits regenerative braking of the vehicle (1). The control device according to claim 6.

8. A method for controlling a brake system (20) of a vehicle (1), comprising: The brake system (20) includes a first flow path group (G1) connected to a master cylinder (42) and a second flow path group (G2) connected to a wheel cylinder (44), and the connection state of the brake system (20) is switchable between a first state in which the first flow path group (G1) and the second flow path group (G2) are disconnected and a second state in which the first flow path group (G1) and the second flow path group (G2) are connected, The brake system (20) comprises a pressure generating unit (66) that controls the pressure of the brake fluid in the wheel cylinder (44) in the first state, and a sensor (92) that detects the position of a fluid level (F1) of the brake fluid (L1) in a reservoir (43) attached to the master cylinder (42), a control unit (110) of the control device (100) executes liquid level control to raise the liquid level (F1) using the pressure generating unit (66); A diagnostic unit (120) of the control device (100) diagnoses whether or not there is an abnormality in the sensor (92) based on the detection result of the sensor (92) when the liquid level control is being performed. Control method.

Images