JP5530740B2 - Brake control device - Google Patents

Description

  The present invention relates to a brake control device that applies braking force to wheels.

  2. Description of the Related Art Conventionally, there has been known a brake device that applies a braking force by generating a hydraulic pressure in a hydraulic circuit according to an operation amount of a brake pedal and supplying the hydraulic pressure to a wheel cylinder of each wheel. The hydraulic pressure of the wheel cylinder is adjusted by supplying and discharging brake fluid by a pump and an electromagnetic control valve provided in the hydraulic pressure circuit.

  Patent Document 1 discloses that in a brake booster negative pressure control device, a large booster negative pressure is applied to a negative pressure chamber of a brake booster only at a low temperature.

JP 11-348765 A

  The viscosity of the brake fluid changes according to the temperature of the brake fluid, and the responsiveness of transmitting hydraulic pressure to the wheel cylinder can change. Therefore, it is desired to acquire the temperature of the brake fluid in order to cope with the change in the response of the hydraulic pressure transmission. In the technical idea described in Patent Document 1, in order to determine whether or not the brake oil is at a low temperature, a separate temperature sensor for detecting the temperature of the brake oil is necessary, which increases costs.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a brake control device capable of reducing the cost and calculating the temperature of the brake fluid.

In order to solve the above-described problems, a brake control device according to an aspect of the present invention supplies a brake fluid to a wheel cylinder by driving a motor, pressurizes the wheel cylinder pressure, and discharges the brake fluid in the wheel cylinder. Control valve to control, hydraulic pressure sensor to detect wheel cylinder pressure, pump and control valve to control the target cylinder pressure of wheel cylinder pressure and pressure loss by control valve based on wheel cylinder pressure detected by hydraulic pressure sensor Control means for calculating the amount and estimating and calculating the temperature of the brake fluid based on the pressure loss amount and the discharge flow rate of the pump.

According to this aspect, the temperature of the brake fluid can be calculated without providing a temperature sensor that directly detects the temperature of the brake fluid. Further, the temperature of the brake fluid can be estimated based on the pressure loss amount and the discharge flow rate.

  The control means may determine a control gain for energizing the control valve according to the temperature of the brake fluid. Thereby, the energization control of the control valve can be executed in response to the change in the viscosity of the brake fluid according to the temperature of the brake fluid.

  The control means selects one of the brake fluid temperatures estimated by an evaluation function based on the pump discharge flow rate and the orifice diameter of the control valve, and determines the brake fluid temperature based on the selected brake fluid temperature. May be. Thereby, it is possible to evaluate which of the brake fluid temperatures estimated for each wheel is reliable.

  If the difference between the temperatures of the two brake fluids selected by the evaluation function is equal to or greater than a predetermined temperature, the control means brakes either of the temperatures of the two selected brake fluids based on the temperature of the brake fluid that was not selected. The temperature of fluid may be determined. Thereby, the temperature of the brake fluid can be calculated with higher accuracy.

  The control means may determine the temperature of the brake fluid using a temperature excluding the maximum temperature and the minimum temperature among the estimated temperatures of the plurality of brake fluids. As a result, the temperature of the brake fluid can be accurately calculated except for the estimated temperature of the brake fluid that may have been greatly affected by the disturbance.

  The control means may calculate the temperature of the brake fluid based on the discharge flow rate of the pump obtained by driving the motor at a motor rotational speed of a predetermined value or more and the wheel cylinder pressure detected by the hydraulic pressure sensor. Thereby, the wheel cylinder pressure for calculating the pressure loss amount in a state where the discharge flow rate of the pump is increased can be acquired.

  The control means may gradually increase the motor rotation speed until the motor rotation speed reaches a predetermined value. Thereby, it can suppress that braking force generate | occur | produces suddenly by pressure loss.

  When calculating the temperature of the brake fluid, the control means may stop the driving of the motor when the motor being driven reaches an upper limit number of rotations corresponding to the outside air temperature. Thereby, it can suppress that a motor rotation speed becomes large too much, and can reduce the braking force generated by pressure loss.

  The control means may stop the driving of the motor when a predetermined time has elapsed for driving the motor when calculating the temperature of the brake fluid. Thereby, it can prevent that the process which calculates the temperature of brake fluid takes excessive time.

  The motor may be driven in response to an operation on the brake pedal, and the control unit may start calculating the brake fluid temperature when the operation on the brake pedal is switched from on to off. Thereby, after the driver executes the braking control, the temperature of the brake fluid can be calculated as it is, and the braking force generated by the operating noise and the pressure loss generated during the calculation can be made inconspicuous.

  The control means may set the motor rotational speed set at the start of the calculation of the brake fluid temperature to be larger than the motor rotational speed set at the start of the previous calculation of the brake fluid temperature. As a result, for example, when a desired pressure loss amount cannot be obtained due to limitations such as time, there is a high possibility that the desired pressure loss amount will be obtained when calculating the temperature of the next brake fluid.

  According to the present invention, the brake control device can reduce the cost and calculate the temperature of the brake fluid.

It is a schematic structure figure of a brake control device concerning an embodiment. It is a figure which shows the pressure loss amount in the hydraulic pressure control valve which concerns on embodiment. It is a figure explaining the relationship between the pump discharge flow volume which concerns on embodiment, the amount of pressure loss, and the temperature of brake fluid. It is a figure explaining the relationship between the control gain of energization control of the hydraulic pressure control valve which concerns on embodiment, target hydraulic pressure, and the temperature of brake fluid. It is a flowchart which shows the temperature estimation process of the brake fluid which concerns on embodiment.

  FIG. 1 is a schematic configuration diagram of a brake control device 100 according to the embodiment. In this figure, an example in which the brake control device 100 according to the embodiment is applied to a vehicle constituting a hydraulic circuit of X piping provided with piping systems of right front wheel-left rear wheel and left front wheel-right rear wheel will be described. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  As shown in FIG. 1, the brake control apparatus 100 includes a brake pedal 1, a stroke sensor 2, a master cylinder 3, a stroke control valve 30, a stroke simulator 4, a brake fluid pressure control actuator 5, a wheel cylinder 6FL, 6FR, 6RL, 6RR (hereinafter referred to as “wheel cylinder 6” unless otherwise specified). In addition, the brake control device 100 includes a brake ECU 200 as a control unit that controls the operation of each unit of the brake control device 100. The brake control device 100 supplies hydraulic pressure (referred to as “wheel cylinder pressure”) to the wheel cylinder 6 by supplying brake fluid to the wheel cylinder 6 via a hydraulic circuit, and applies braking force to the wheel by the hydraulic pressure. To do. Each wheel cylinder 6 may be built in a brake disc (not shown) and a brake caliper (not shown), and includes a wheel cylinder, a brake disc, and a brake caliper, and is called a disc brake unit.

  When the brake pedal 1 is depressed by the driver, a pedal stroke as an operation amount of the brake pedal 1 is input to the stroke sensor 2, and a detection signal corresponding to the pedal stroke is output from the stroke sensor 2. This detection signal is input to the brake ECU 200, and the brake ECU 200 detects the pedal stroke of the brake pedal 1. Here, the stroke sensor 2 is taken as an example of the operation amount sensor for detecting the operation amount of the brake operation member, but a pedal force sensor for detecting the pedal force applied to the brake pedal 1 may be used.

  The brake pedal 1 is connected to a push rod that transmits the pedal stroke to the master cylinder 3, and when the push rod is pushed, the master chamber 3a and the secondary chamber 3b provided in the master cylinder 3 are mastered. Cylinder pressure is generated.

  The master cylinder 3 is provided with a primary piston 3c and a secondary piston 3d that constitute a primary chamber 3a and a secondary chamber 3b. The primary piston 3c and the secondary piston 3d are configured to receive the elastic force of the spring 3e so that when the brake pedal 1 is not depressed, the pistons 3c and 3d are pressed to return the brake pedal 1 to the initial position side. ing.

  The primary chamber 3a and the secondary chamber 3b of the master cylinder 3 are connected to a pipeline B and a pipeline A that extend toward the brake fluid pressure control actuator 5, respectively.

  The master cylinder 3 is provided with a reservoir tank 3f. The reservoir tank 3f is connected to each of the primary chamber 3a and the secondary chamber 3b via a passage (not shown) when the brake pedal 1 is in the initial position, and supplies the brake fluid into the master cylinder 3 or the master tank 3f. Excess brake fluid in the cylinder 3 is stored. A pipeline C and a pipeline D extending toward the brake fluid pressure control actuator 5 are connected to the reservoir tank 3f.

  The stroke simulator 4 is connected to a pipeline E connected to the pipeline A, and plays a role of accommodating brake fluid in the secondary chamber 3b. The pipe E is provided with a stroke control valve 30 constituted by a normally-closed two-position valve capable of controlling the communication / cut-off state of the pipe E. The stroke control valve 30 allows the brake fluid to be supplied to the stroke simulator 4. It is configured so that the flow can be controlled.

  The brake fluid pressure control actuator 5 is provided with a pipe line F connected to the pipe line A so as to connect the secondary chamber 3b of the master cylinder 3 and the wheel cylinder 6FR corresponding to the front wheel FR. The pipe F is provided with a shutoff valve 36. The shutoff valve 36 is a two-position valve that is open (communication state) when not energized, and is closed (shutoff state) when energized. The shutoff valve 36 controls the communication / shutoff state of the pipe F. The supply of brake fluid to the wheel cylinder 6FR via the paths A and F is controlled.

  Further, the brake fluid pressure control actuator 5 is provided with a pipeline G connected to the pipeline B so as to connect the primary chamber 3a of the master cylinder 3 and the wheel cylinder 6FL corresponding to the front wheel FL. The pipe line G is provided with a shut-off valve 37. The shut-off valve 37 is a two-position valve that is opened when not energized and closed when energized. The shut-off valve 37 controls the communication / shut-off state of the pipeline G, whereby the wheel via the pipelines B and G is controlled. Brake fluid supply to the cylinder 6FL is controlled.

  Further, the brake fluid pressure control actuator 5 is provided with a pipeline H connected to the pipeline C extending from the reservoir tank 3f and a pipeline I connected to the pipeline D. The pipe H is branched into two pipes H1 and H2, and is connected to the wheel cylinders 6FR and 6RL, respectively. Further, the pipeline I branches into two pipelines I3 and I4 and is connected to the wheel cylinders 6FL and 6RR, respectively. The wheel cylinder 6RL and the wheel cylinder 6RR correspond to the rear wheel RL and the rear wheel RR, respectively.

  Each of the pipelines H1, H2, I3, and I4 is provided with one pump 7, 8, 9, and 10, respectively. Each pump 7-10 is comprised, for example by the trochoid pump excellent in silence. Of the pumps 7 to 10, the two pumps 7 and the pump 8 are driven by the first motor 11, and the two pumps 9 and the pump 10 are driven by the second motor 12. The first motor 11 and the second motor 12 are driven in response to an operation on the brake pedal 1. The first motor 11 and the second motor 12 (hereinafter simply referred to as a motor if they are not particularly distinguished) supply brake fluid to each wheel cylinder 6 via each pump 7 to 10 according to driving. In the embodiment, the four pumps 7 to 10 function as hydraulic pressure sources. Each pump 7-10 is provided in a hydraulic circuit, and supplies a brake fluid to a wheel cylinder according to the rotation speed of the connected 1st motor 11 or the 2nd motor 12. FIG. That is, two pumps are operated by driving one motor, and one wheel cylinder is connected to each of the two pumps. The batteries that supply power to the first motor 11 and the second motor 12 may be common. The pumps 7 to 10 supply brake fluid to the wheel cylinder 6 by driving the motors 11 and 12 to increase the wheel cylinder pressure.

  Each of the pumps 7 to 10 is provided with pipelines J1, J2, J3, and J4 in parallel. A pipe J1 connected in parallel to the pump 7 is provided with a communication valve 38 and a hydraulic pressure adjusting valve 32 connected in series. The communication valve 38 and the hydraulic pressure adjustment valve 32 are arranged such that the communication valve 38 is on the suction port side of the pump 7 (downstream side in the flow direction of the brake fluid in the pipeline J1) and the hydraulic pressure adjustment valve 32 is on the discharge port side of the pump 7 (pipe). It arrange | positions so that it may each be located in the brake fluid flow direction in the path | route J1. That is, the communication valve 38 can control the communication / blocking between the reservoir tank 3f and the hydraulic pressure adjustment valve 32. The communication valve 38 is a two-position valve that is closed when not energized and opened when energized, and the hydraulic pressure adjusting valve 32 is open when de-energized and closed when energized. It is a normally open linear valve that is adjusted.

  Here, the following force acts on the hydraulic pressure adjusting valve 32. The electromagnetic driving force according to the energization current to the linear solenoid of the hydraulic pressure adjusting valve 32 is F1, the spring biasing force is F2, and the differential pressure acting force according to the differential pressure between the inlet and outlet of the hydraulic pressure adjusting valve 32 is F3. Assuming that the frictional force F4 with respect to the sliding of the solenoid is satisfied, the relationship of F1 = F2 + F3 + F4 is established, and the opening of the hydraulic pressure adjusting valve 32 depends on the value of {(F2 + F3 + F4) −F1}. That is, as the electromagnetic driving force F1 increases, the valve opening decreases.

  Next, the hydraulic pressure adjusting valve 32 has the following valve closing current characteristics. The valve closing current refers to the value of the energization current to the valve when the valve is closed from the opened state. The valve closing current characteristic refers to a characteristic indicating the relationship between the valve closing current and the wheel cylinder pressure. The valve closing current characteristic is a linear function in which the valve closing current is linearly proportional to the wheel cylinder pressure. The hydraulic fluid of the hydraulic pressure adjustment valve 32 is discharged from the wheel cylinder 6FR toward the communication valve 38 on the downstream side. In a normally open type linear valve, the opening degree of the valve decreases as the energizing current of the hydraulic pressure adjusting valve 32 increases, and the flow rate of the hydraulic pressure adjusting valve 32 decreases. When the energization current reaches the valve closing current, the hydraulic pressure adjustment valve 32 is closed, and the flow rate of the hydraulic pressure adjustment valve 32 becomes zero.

  A hydraulic pressure adjustment valve 33 is provided in the pipe line J2 connected in parallel to the pump 8. The hydraulic pressure adjustment valve 33 is a linear valve, like the hydraulic pressure adjustment valve 32. The hydraulic pressure adjustment valves 33 to 35 that are normally open linear valves also function in the same manner as the hydraulic pressure adjustment valve 32. In the following, when the hydraulic pressure adjustment valves 32 to 35 are not particularly distinguished, they may be simply referred to as “hydraulic pressure adjustment valves”, and when the communication valve 38 and the communication valve 39 are not particularly distinguished, they may be simply referred to as “communication valves”. is there.

  A pipe J3 connected in parallel to the pump 9 is provided with a communication valve 39 and a hydraulic pressure adjusting valve 35 connected in series. As for the communication valve 39 and the hydraulic pressure adjusting valve 35, the communicating valve 39 is on the suction port side of the pump 9 (downstream in the flow direction of the brake fluid in the pipe J3), and the hydraulic pressure adjusting valve 35 is on the discharge port side of the pump 9 (pipe). It arrange | positions so that it may each be located in the brake fluid flow direction in the path J3. That is, the communication valve 39 can control the communication / blockage between the reservoir tank 3 f and the hydraulic pressure adjustment valve 35. The communication valve 39 is a two-position valve that is closed when not energized and opened when energized, and the hydraulic pressure adjusting valve 35 is open when de-energized and closed when energized. A linear valve to be adjusted. The hydraulic pressure adjusting valve 35 adjusts the brake fluid amount of the wheel cylinder 6FL by adjusting the opening degree by energization control. The hydraulic pressure adjusting valve and the communication valve control the discharge of the brake fluid in the wheel cylinder 6 by energization control.

  A hydraulic pressure adjusting valve 34 is provided in the pipe line J4 connected in parallel to the pump 10. The hydraulic pressure adjustment valve 34 is a linear valve, like the hydraulic pressure adjustment valve 35.

  And hydraulic pressure sensors 13, 14, 15, and 16 are arranged between each pump 7-10 in each of pipelines J1-J4 and each wheel cylinder 6FR, 6FL, 6RR, 6RL, and each wheel cylinder 6FR. , 6FL, 6RR, 6RL can be detected. Further, fluid pressure sensors 17 and 18 are also arranged upstream of the shutoff valves 36 and 37 (on the master cylinder 3 side) in the pipelines F and G, and are generated in the primary chamber 3a and the secondary chamber 3b of the master cylinder 3. The master cylinder pressure can be detected.

  Furthermore, check valves 20 and 21 are provided in the discharge port of the pump 7 for pressurizing the wheel cylinder 6FR and the discharge port of the pump 9 for pressurizing the wheel cylinder 6FL, respectively. The check valves 20 and 21 are provided to inhibit the flow of brake fluid from the wheel cylinders 6FR and 6FL to the pumps 7 and 9, respectively. With such a structure, the brake fluid pressure control actuator 5 is configured.

  In the brake control device 100 having the above-described configuration, a circuit that connects the reservoir tank 3f and the wheel cylinders 6FR and 6RL through the pipe C, the pipe H, the pipe H1, and the pipe H2 and the pumps 7 and 8 are connected in parallel. The hydraulic circuit including the connected pipelines J1 and J2 and the hydraulic circuit connecting the secondary chamber 3b and the wheel cylinder 6FR through the pipeline A and the pipeline F constitute the first piping system. .

  A circuit connecting the reservoir tank 3f and the wheel cylinders 6FL and 6RR through the pipe D, the pipe I, the pipe I3, and the pipe I4, and circuits of the pipes J3 and J4 connected in parallel to the pumps 9 and 10 And a hydraulic circuit that connects the primary chamber 3a and the wheel cylinder 6FL through the pipeline B and the pipeline G constitutes a second piping system.

  Then, the detection signals of the stroke sensor 2 and the hydraulic pressure sensors 13 to 18 are input to the brake ECU 200, and the stroke control valve 30 is based on the pedal stroke, the hydraulic pressure of the wheel cylinder, and the master cylinder pressure obtained from these detection signals. The brake ECU 200 outputs control signals for driving the shutoff valves 36 and 37, the communication valves 38 and 39, the hydraulic pressure adjusting valves 32 to 35, and the first motor 11 and the second motor 12. Yes.

  In normal times, when the brake pedal 1 is depressed and the detection signals of the stroke sensor 2 and the hydraulic pressure sensors 17 and 18 are input to the brake ECU 200, the brake ECU 200 sets the electromagnetic control valves 30, 32 to 39 and the first motor 11 to each other. Then, the second motor 12 is controlled to be in the following state. That is, energization of both the shutoff valve 36 and the shutoff valve 37 is turned on, and energization of the communication valve 38 and the communication valve 39 is both turned on. Thus, the shutoff valve 36 and the shutoff valve 37 are shut off, and the communication valve 38 and the communication valve 39 are put in a communication state.

  Moreover, the opening degree of the hydraulic pressure adjusting valves 32 to 35 is adjusted according to the energization current value. The stroke control valve 30 is energized. For this reason, even if each piston 3c, 3d moves when the stroke simulator 4 will be in communication with the secondary chamber 3b through the pipe lines A and E and the brake pedal 1 is depressed, the brake fluid in the secondary chamber 3b Will move to the stroke simulator 4. Therefore, when the master cylinder pressure becomes high, the brake pedal 1 can be stepped on without causing a feeling of stepping on a hard plate against the brake pedal 1.

  Further, energization of both the first motor 11 and the second motor 12 is turned on, and the brake fluid is discharged from the pumps 7 to 10 to the wheel cylinder 6 without passing through the electromagnetic control valve. That is, when the pump operation by the pumps 7 to 10 is performed, the brake fluid is supplied to each wheel cylinder 6.

  The brake ECU 200 controls the motor rotation speeds of the first motor 11 and the second motor 12 to control the amount of brake fluid supplied to the wheel cylinder 6. At this time, since the shut-off valve 36 and the shut-off valve 37 are in the shut-off state, the hydraulic pressure downstream of the pumps 7 to 10, that is, the amount of brake fluid supplied to each wheel cylinder 6 increases. Since the communication valve 38 and the communication valve 39 are in a communication state and the opening degrees of the hydraulic pressure adjustment valves 32 to 35 are controlled, the brake fluid is discharged according to the opening degree, and each wheel cylinder 6 The hydraulic pressure is adjusted.

  The brake ECU 200 monitors the hydraulic pressure supplied to each wheel cylinder 6 based on the detection signals of the respective hydraulic pressure sensors 13 to 16 and controls the energization current value to the hydraulic pressure adjusting valves 32 to 35. The hydraulic pressure of each wheel cylinder 6 is set to a desired value. Thereby, the braking force according to the pedal stroke of the brake pedal 1 is generated. As described above, the brake control of the brake control device 100 of the embodiment is performed.

  The brake control device 100 according to the embodiment, during braking, drives the pumps 7 to 10 to supply the brake fluid, and adjusts the valve opening while discharging the brake fluid while opening the hydraulic pressure adjustment valve. Perform leakage control. That is, in the leakage control during braking, the brake fluid is continuously supplied and discharged.

  This brake fluid has a characteristic that the viscosity changes according to the temperature of the brake fluid. If the viscosity of the brake fluid changes, the responsiveness of transmitting hydraulic pressure to the wheel cylinder 6 can change. Therefore, the brake ECU 200 according to the embodiment determines a control gain for energizing the control valve according to the temperature of the brake fluid. Thereby, it is possible to cope with a change in hydraulic pressure transmission according to the temperature of the brake fluid.

  Providing a separate temperature sensor for measuring the temperature of the brake fluid is expensive. Therefore, the brake ECU 200 according to the embodiment calculates the temperature of the brake fluid based on the wheel cylinder pressure detected by the hydraulic pressure sensor and the discharge flow rate of the pump, in addition to the control of the pump and the control valve. Thereby, the temperature of the brake fluid can be calculated without using a temperature sensor.

  FIG. 2 is a diagram illustrating a pressure loss amount in the hydraulic pressure control valve according to the embodiment. In this figure, the vertical axis represents wheel cylinder pressure, and the horizontal axis represents time. In addition, a one-dot chain line in the figure indicates the target hydraulic pressure 81, and a solid line indicates the wheel cylinder pressure 80 controlled to the target hydraulic pressure.

  The wheel cylinder pressure 80 is controlled so as to approach the target hydraulic pressure 81, but does not approach any more when it approaches the target hydraulic pressure 81 to some extent. This is due to the pressure loss caused by the orifice of the hydraulic pressure adjusting valve and the communication valve (hereinafter, the hydraulic pressure adjusting valve and the communication valve may be simply referred to as “control valve”). Because it remains.

  Therefore, the pressure loss caused by the orifice of the control valve is the difference 82 between the wheel cylinder pressure 80 and the target hydraulic pressure 81. It should be noted that the wheel cylinder pressure 80 when calculating the pressure loss amount is preferably in a constant state after several seconds since the target hydraulic pressure 81 is set.

  The control valve shuts off or communicates the flow of the brake fluid when the valve element is seated on or separated from the valve seat, and the orifice of the control valve is a hole provided in the valve seat and the valve seat. Further, two control valves are provided on the front wheel side, respectively, and the orifice of the front wheel control valve is the sum of the orifice of the hydraulic pressure adjusting valve and the orifice of the communication valve. Further, the pressure loss is also caused by the inner wall of the pipe, but the pressure loss amount is very small compared with the pressure loss amount at the orifice of the control valve.

  FIG. 3 is a diagram illustrating a relationship among a pump discharge flow rate, a pressure loss amount, and a brake fluid temperature according to the embodiment. In the figure, the vertical axis represents the pressure loss amount, and the horizontal axis represents the pump discharge flow rate. The pump discharge flow rate is a value determined according to the motor rotation speed.

  Characteristics 83 to 85 shown in the figure indicate the relationship between the pump flow rate and the pressure loss when the temperature of the brake fluid is constant. The temperature of the brake fluid increases in the order of characteristic 83, characteristic 84, and characteristic 85.

  As shown in the figure, the amount of pressure loss due to the control valve increases as the pump discharge flow rate increases. Moreover, if the pressure loss amount by a control valve is large, since the viscosity of brake fluid is high, the temperature of brake fluid is low. If the pump discharge flow rate is increased, the difference in the amount of pressure loss caused by the control valve in accordance with the brake fluid temperature increases, and the temperature of the brake fluid can be calculated with high accuracy.

  Although shown two-dimensionally in this figure, the brake ECU 200 may hold a three-dimensional map indicating the relationship among the pump discharge flow rate, the pressure loss amount, and the temperature of the brake fluid. Using this map, the brake ECU 200 calculates the temperature of the brake fluid based on the pump discharge flow rate and the pressure loss amount.

  Specifically, the brake ECU 200 calculates a pressure loss amount and a pump discharge flow rate by the control valve for each wheel. The pressure loss amount by the control valve is calculated as a difference obtained by subtracting the target hydraulic pressure from the wheel cylinder pressure detected by the hydraulic pressure sensors 13 to 16. When the wheel cylinder pressure is detected by the hydraulic pressure sensors 13 to 16, it is preferable that the control valve is in a fully opened state. The pump discharge flow rate is calculated according to the motor rotation speed.

  The brake ECU 200 calculates the temperature of the brake fluid based on the discharge flow rate of the pump obtained by driving the motor at a motor rotation speed equal to or greater than a predetermined value and the wheel cylinder pressure detected by the hydraulic pressure sensor. This is because, as shown in FIG. 3, if the pump discharge flow rate is large, the difference in pressure loss is large compared to the case where the pump discharge flow rate is small, so that the temperature of the brake fluid can be calculated with high accuracy. Thereby, the pump discharge flow rate necessary for calculating the pressure loss amount can be ensured. Further, the brake ECU 200 controls the motor rotational speed to gradually increase until the motor rotational speed reaches a predetermined value. As a result, compared with the case where the motor is driven at a motor rotation speed of a predetermined value or more from the beginning, it is possible to suppress sudden generation of unnecessary braking force due to pressure loss, and to improve the driver's brake feeling. .

  Further, the brake ECU 200 may limit the motor rotation speed when a pressure loss amount equal to or greater than a predetermined amount is detected. The predetermined amount is an amount suitable for use in calculating the temperature, and is set by an experiment or the like. Thereby, it can suppress driving a motor unnecessarily.

  The brake ECU 200 estimates the brake fluid temperature with reference to the map from the calculated pressure loss amount by the control valve and the pump discharge flow rate. The estimated temperature of the brake fluid is sometimes referred to as an estimated temperature. Four estimated temperatures are calculated using the pressure loss amount of each wheel.

  Here, the estimated temperature calculated for each wheel may be affected by disturbance such as electrical noise superimposed on the outputs of the hydraulic pressure sensors 13 to 16 in the estimation process. For this reason, the estimated temperature may deviate from the actual temperature.

  Therefore, the brake ECU 200 according to the embodiment calculates the temperature of the brake fluid based on any relatively large pressure loss amount among the four pressure loss amounts calculated for the plurality of control valves. Specifically, the brake ECU 200 selects two relatively large pressure loss amounts from the four calculated pressure loss amounts, and determines the average value of the selected brake fluid temperatures as the brake fluid temperature. Thereby, the temperature of the brake fluid can be calculated with high accuracy.

  Further, the brake ECU 200 uses two temperatures excluding the maximum temperature and the minimum temperature among the temperatures of the plurality of brake fluids estimated based on the pressure loss amounts by the plurality of control valves, and the average value of the two temperatures. May be determined as the temperature of the brake fluid. As a result, the estimated temperature that may have been greatly affected by the disturbance can be removed, and the temperature of the brake fluid can be calculated with high accuracy.

  Further, the brake ECU 200 may select which estimated temperature to use depending on whether or not the evaluation is high, using an evaluation function for evaluating the calculated pressure loss amount. Specifically, the brake ECU 200 may select one of the estimated temperatures based on an evaluation function based on the discharge flow rate of the pump and the orifice diameter of the control valve, and determine the brake fluid temperature based on the selected estimated temperature. . Here, the orifice diameter of the control valve of the front wheel is the sum of the orifice diameter of the hydraulic pressure adjusting valve and the orifice diameter of the communication valve. The evaluation function of the orifice diameter of the rear wheel control valve is higher than the orifice diameter of the front wheel control valve. Further, if the pump discharge flow rate is large, the evaluation function is highly evaluated. By using the evaluation function, the temperature of the brake fluid can be calculated with high accuracy.

  Furthermore, if the difference between the temperatures of the two brake fluids selected by the evaluation function is equal to or greater than a predetermined temperature, the brake ECU 200 brakes either of the selected brake fluid temperatures based on the temperature of the brake fluid that was not selected. Determine fluid temperature. Specifically, the brake ECU 200 selects two estimated temperatures based on the evaluation function, and if the difference between the selected two estimated temperatures is equal to or higher than a predetermined temperature, the brake ECU 200 was not selected from the two selected estimated temperatures. The one closer to the average estimated temperature is determined as the brake fluid temperature. For example, there is a possibility that the selected estimated temperature is greatly affected by disturbance, and if the difference between two selected estimated temperatures is equal to or higher than a predetermined temperature, one of them indicates an inaccurate brake fluid temperature. Sometimes. Therefore, the brake fluid temperature can be accurately calculated by determining which brake fluid temperature is accurate by using the brake fluid temperature not selected by the evaluation function.

  FIG. 4 is a diagram for explaining a relationship among a control gain of energization control of the hydraulic pressure regulating valve, a target hydraulic pressure, and a brake fluid temperature according to the embodiment. In this figure, the vertical axis represents the control gain, and the horizontal axis represents the target hydraulic pressure. A characteristic 87 and a characteristic 88 indicate the relationship between the control gain and the target hydraulic pressure at a constant temperature, respectively.

  Although shown two-dimensionally in the figure, the brake ECU 200 may hold a three-dimensional map showing the relationship between the control gain, the target hydraulic pressure, and the brake fluid temperature. Using this map, the brake ECU 200 determines a control gain.

  As shown in this figure, as the target hydraulic pressure increases, the differential pressure applied to the hydraulic pressure adjustment valve increases, so the control gain increases. The characteristic 88 is at a lower temperature than the characteristic 87, and the control gain of the characteristic 88 is smaller than that of the relatively high temperature characteristic 87. Accordingly, by reducing the control gain of the hydraulic pressure adjusting valve with respect to the reduced transmission response, the valve can be prevented from being opened much during braking, and the hydraulic pressure is left in the wheel cylinder 6 for safe braking. Can control. In another aspect, by increasing the control gain of the hydraulic pressure adjustment valve with respect to the decrease in transmission response, the valve can be quickly closed during braking, and safe brake control can be performed.

  FIG. 5 is a flowchart showing a brake fluid temperature estimation process according to the embodiment. First, the brake ECU 200 determines whether the driver has boarded the vehicle (S10). For example, if the ignition switch is on, the brake ECU 200 determines that the driver has boarded the vehicle. The brake ECU 200 may determine whether the driver has boarded the vehicle based on the output of the driver's seat sensor or the driver's door switch. Thus, by first calculating the temperature of the brake fluid immediately after boarding the vehicle, the control gain of the control valve can be determined before the vehicle starts.

  If the driver is not on board (N in S10), the brake ECU 200 repeats the boarding determination. If the driver gets on (Y in S10), the brake ECU 200 calculates the temperature of the brake fluid (S12).

  Here, the brake ECU 200 gradually increases the motor rotation speed until a predetermined pressure loss amount can be acquired. However, when the motor being driven reaches the upper limit rotation speed according to the outside air temperature, the driving of the motor is stopped. May be. Thereby, it can suppress that motor rotation speed becomes large too much. The outside air temperature has a certain relationship with the temperature of the brake fluid, and if the outside air temperature is low, the viscosity of the brake fluid may be high. If the viscosity of the brake fluid is high, it is possible to obtain a pressure loss amount of a magnitude necessary for temperature calculation without increasing the motor speed. Further, it is possible to reduce the braking force generated by the pressure loss during the temperature calculation. The upper limit rotational speed is set to increase as the outside air temperature increases. If an abnormality occurs in the outside air temperature detection sensor, the subsequent temperature calculation may be stopped.

  Further, the brake ECU 200 may stop driving the motor when a predetermined time has elapsed for driving the motor when calculating the temperature of the brake fluid. Thereby, when the motor rotation speed is gradually increased, it is possible to prevent the temperature calculation from taking too much time.

  The brake ECU 200 determines whether the temperature of the brake fluid has been calculated (S14). If the brake fluid temperature cannot be calculated (N in S14), the brake ECU 200 calculates the brake fluid temperature again (S12). For example, when the motor rotation speed reaches the upper limit rotation speed or when the motor drive time exceeds a predetermined time, the temperature calculation may not be performed, and the temperature calculation is executed again.

  The brake ECU 200 may set the motor rotational speed set at the start of the calculation of the brake fluid temperature to be larger than the motor rotational speed set at the start of the previous calculation of the brake fluid temperature. As a result, for example, when the temperature cannot be calculated without obtaining a desired pressure loss amount due to the motor driving time exceeding a predetermined time, it is possible to obtain the desired pressure loss amount during the retry. Can be increased. The brake ECU 200 stores the motor rotational speed at the start of the previous temperature calculation, and adds a predetermined rotational speed to the stored motor rotational speed. As another aspect, the brake ECU 200 may store the motor rotation speed at the end of the previous temperature calculation, and subtract the predetermined rotation speed from the stored motor rotation speed. In any case, the current temperature calculation is executed at a motor speed higher than the previous motor speed.

  If the brake fluid temperature has been calculated (Y in S14), the brake ECU 200 determines the control gain of the control valve based on the calculated brake fluid temperature (S16). Then, the brake ECU 200 determines whether or not the calculated temperature of the brake fluid is higher than a predetermined temperature (S18). If the calculated temperature of the brake fluid is higher than the predetermined temperature (Y in S18), the brake ECU 200 ends this process. This is because, for example, if the predetermined temperature is set to 10 ° C. and the temperature is 10 ° C. or higher, the viscosity of the brake fluid is not so high, and thus this processing may be finished.

  If the calculated brake fluid temperature is not higher than the predetermined temperature (N in S18), the brake ECU 200 determines whether or not a predetermined restart condition is satisfied (S20). The predetermined restart condition may include whether one hour has elapsed since the previous temperature calculation and whether the vehicle speed is equal to or lower than a predetermined speed. For example, by setting the predetermined speed to 20 km / h, the temperature can be calculated at a low speed with little influence on the brake feeling. In a vehicle that executes regenerative braking, whether or not the engine is driven may be added to a predetermined restart condition. Thereby, compared with the case where temperature calculation is performed when the engine is stopped, the operation sound of the motor due to temperature calculation can be made inconspicuous. Further, when the vehicle is driven, heat can be transmitted from the engine or the like to the brake fluid, and the temperature of the brake fluid can be changed.

  Further, the predetermined resumption condition may include whether or not the operation on the brake pedal 1 is switched from on to off. That is, the brake ECU 200 calculates the temperature of the brake fluid when the operation on the brake pedal 1 is switched from on to off. Thereby, for example, after the driver executes the braking control, the temperature calculation can be executed without stopping the driving of the motor. As a result, it is not necessary to newly drive the motor, and the braking force generated by the operating noise and pressure loss due to temperature calculation can be made inconspicuous. In particular, when the brake ECU 200 executes a temperature calculation that gradually increases the motor rotation speed, the operation sound of the motor changes, and the operation sound may be conspicuous to the driver. Even in such a case, if the temperature is calculated following the normal braking control, the motor operation noise can be reduced.

  If the predetermined restart condition is not satisfied (N in S20), the brake ECU 200 repeats the determination whether the predetermined restart condition is satisfied. If the predetermined resumption condition is satisfied (Y in S20), the brake ECU 200 calculates the temperature of the brake fluid again (S12). Thereafter, the above steps are repeated.

  As described above, the brake control device 100 according to the embodiment can calculate the temperature of the brake fluid according to the pressure loss amount by the control valve.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and such modifications have been added. Embodiments may also be included within the scope of the present invention.

  A, B, C, D, E, F, G, H, H1, H2, I, I3, I4, J1, J2, J3, J4, K, L, M, N pipeline, 1 brake pedal, 2 strokes Sensor, 3 master cylinder, 3a primary chamber, 3b secondary chamber, 3c primary piston, 3d secondary piston, 3e spring, 3f reservoir tank, 4 stroke simulator, 5 brake hydraulic pressure control actuator, 6FL, 6FR, 6RL, 6RR wheel cylinder 7, 8, 9, 10 Pump, 11 First motor, 12 Second motor, 13, 14, 15, 16, 17, 18 Hydraulic pressure sensor, 20, 21 Check valve, 30 Stroke control valve, 32, 33 , 34, 35 Hydraulic pressure regulating valve, 36, 37 shutoff valve, 38, 39 communication valve, 100 Brake control device, 200 Brake ECU.

Claims (11)

A pump for supplying brake fluid to the wheel cylinder by driving the motor and pressurizing the wheel cylinder pressure;
A control valve that controls the discharge of brake fluid in the wheel cylinder;
A hydraulic pressure sensor for detecting wheel cylinder pressure;
The pump and the control valve are controlled, a pressure loss amount by the control valve is calculated based on a target hydraulic pressure of the wheel cylinder pressure and a wheel cylinder pressure detected by the hydraulic pressure sensor , and the pressure loss amount and the discharge of the pump And a control means for estimating and calculating the temperature of the brake fluid based on the flow rate.   The brake control device according to claim 1, wherein the control means determines a control gain for energizing the control valve according to a temperature of the brake fluid. The control means selects one of a plurality of brake fluid temperatures estimated by an evaluation function based on the discharge flow rate of the pump and the orifice diameter of the control valve, and determines the brake fluid temperature based on the selected brake fluid temperature. The brake control device according to claim 1 or 2 , wherein a temperature is determined. If the difference between the temperatures of the two brake fluids selected by the evaluation function is equal to or greater than a predetermined temperature, the control means selects one of the temperatures of the two selected brake fluids based on the temperature of the brake fluid that was not selected. The brake control device according to claim 3 , wherein the temperature of the brake fluid is determined. Wherein, in any one of claims 1 to 4, characterized in that to determine the temperature of brake fluid with a temperature excluding the maximum temperature and the minimum temperature among the temperatures of the plurality of brake fluid estimated The brake control device described. The control means calculates the temperature of the brake fluid based on the discharge flow rate of the pump obtained by driving the motor at a motor rotation speed equal to or greater than a predetermined value and the wheel cylinder pressure detected by the hydraulic pressure sensor. The brake control device according to any one of claims 1 to 5 . The brake control device according to claim 6 , wherein the control unit gradually increases the motor rotation speed until the motor rotation speed reaches a predetermined value. 2. The control device according to claim 1, wherein when the temperature of the brake fluid is calculated, the motor stops driving when the motor being driven reaches an upper limit number of rotations corresponding to an outside air temperature. The brake control device according to any one of to 7 . The said control means stops the drive of the said motor, if the time which drives the said motor when calculating the temperature of brake fluid passes predetermined time, The motor of any one of Claims 1-8 characterized by the above-mentioned. Brake control device. The motor is driven in response to an operation on the brake pedal,
The brake control device according to any one of claims 1 to 9 , wherein the control means starts calculating the temperature of the brake fluid when the operation on the brake pedal is switched from on to off. The control means sets the motor rotational speed set at the start of the calculation of the brake fluid temperature to be larger than the motor rotational speed set at the start of the previous calculation of the brake fluid temperature. The brake control device according to any one of 1 to 10 .

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