JP4525301B2 - Brake device - Google Patents

Description

  The present invention relates to a vehicle brake device, and more particularly, to a brake device that brakes a vehicle by supplying hydraulic pressure to a wheel cylinder from a pressure accumulator that is a hydraulic pressure source different from a master cylinder pressure.

  There is known a brake control device that brakes a vehicle by supplying hydraulic pressure to a wheel cylinder from an accumulator that is a hydraulic pressure source different from the master cylinder pressure. In such a brake control device, the operation amount of the brake operation member by the driver is detected, and the hydraulic pressure from the pressure accumulator is controlled so that the wheel cylinder pressure according to the operation amount is obtained.

  The said brake control apparatus is comprised so that it may have the operation amount detection means which detects the operation amount of a brake operation member, and the control apparatus which controls wheel cylinder pressure. The control means sets the target wheel cylinder pressure based on the detection result of the operation amount detection means, and controls the supply current to the solenoid valve through which the working fluid passes so as to be the target wheel cylinder pressure. By the control, for example, a braking pressure proportional to the operation amount or a system pressure that provides a vehicle body deceleration proportional to the operation force is supplied to the wheel cylinder, and the rotation of the wheel is suppressed.

In such a brake control device, since the viscosity of the working fluid changes depending on the temperature or the like, the time from when the current is supplied to the solenoid valve until the wheel cylinder pressure reaches the target wheel cylinder pressure changes depending on the temperature of the working fluid. For this reason, an invention has been proposed in which the target wheel cylinder pressure is corrected by a predetermined amount at low temperatures to prevent a delay in the response of the wheel cylinder pressure due to an increase in viscosity (see, for example, Patent Document 1).
JP 2000-177567 A

  However, the conventional brake control device detects the hydraulic pressure of the accumulator with a pressure sensor and controls the hydraulic pressure of the accumulator based on the detected hydraulic pressure. There is an unsolved problem that there is a difference between the pressure detected by the pressure sensor and the pressure detected by the pressure sensor.

  FIG. 8 is a graph showing the actual pressure of the pressure accumulator and the pressure detected by the pressure sensor. In FIG. 8, the X axis represents time, and the Y axis represents the actual pressure P-ACC of the accumulator, the detected pressure M-ACC detected by the pressure sensor, and the wheel cylinder pressure PWC. When the brake operating member is operated at time t1, a current is supplied to the solenoid valve so as to reach a predetermined target wheel cylinder pressure, the wheel cylinder pressure PWC increases, and the detected pressure M-ACC starts to decrease. At time t2, the detected pressure M-ACC has decreased from a predetermined pressure (accumulation start pressure), so the hydraulic pump that generates the hydraulic pressure is turned on. At time t3, since the detected pressure M-ACC has increased to a predetermined pressure (accumulation stop pressure), the hydraulic pump is turned off. Thereafter, similar control is repeatedly performed.

  However, according to the actual pressure P-ACC of the pressure accumulator between times t1 and t3, the actual pressure of the pressure accumulator has not decreased to the pressure accumulation start pressure. That is, there is a large difference between the actual pressure P-ACC of the accumulator and the detected pressure M-ACC. The divergence is due to a decrease in the fluidity of the working fluid due to a low temperature. In particular, the divergence increases as the distance between the pressure accumulator and the pressure sensor increases.

  Although it is conceivable that the accumulator and the pressure sensor are close to each other, there are many cases where it is difficult to design the vehicle. Therefore, as shown in FIG. 8, when the control to turn on the hydraulic pump based on the detected pressure M-ACC is performed, the control of the hydraulic pump is repeated with a large deviation from the actual pressure P-ACC of the accumulator. This causes problems such as an increase in power consumption due to the increase in the load on the control relay.

  In view of the above problems, an object of the present invention is to provide a brake device in which the hydraulic pump that generates the hydraulic pressure of the accumulator is frequently turned on and off at low temperatures.

In view of the above problems, pressure accumulating means (accumulator) for accumulating hydraulic pressure generated by a hydraulic pressure generating means (hydraulic pump) for generating hydraulic pressure, and pressure accumulating detection means (accumulated pressure) for detecting the hydraulic pressure value of the pressure accumulating means Sensor) and the hydraulic pressure generating means is driven when the hydraulic pressure value detected by the accumulated pressure detecting means is equal to or lower than the accumulated pressure start pressure. Fluid pressure generation control means for stopping, in a brake device for supplying braking pressure from the pressure accumulation means to brake the vehicle, fluid temperature calculation means for estimating or detecting the temperature of the working fluid of the brake device; When the temperature of the working fluid estimated or detected by the fluid temperature calculation means is lower than a predetermined value, and when the pressure increase is detected by the pressure increase detection means case, the accumulator start And accumulator starting pressure correction means for reducing the force, if the pressure increase is detected by the increase of pressure detecting means, characterized by having a a accumulator stop pressure compensation means for decreasing the accumulator stop pressure.

  ADVANTAGE OF THE INVENTION According to this invention, it can reduce that the hydraulic pump which generate | occur | produces the hydraulic pressure of an accumulator repeats on / off frequently at low temperature.

In one embodiment of the present invention, in the state where the hydraulic pressure generation control means drives the hydraulic pressure generation means, when the pressure increase is detected by the pressure increase detection means, the pressure accumulation stop pressure correction means is When the accumulated pressure stop pressure is lowered and no increase is detected by the increased pressure detection means, the accumulated pressure stop pressure correcting means sets the accumulated pressure stop pressure to the same value as when the temperature of the working fluid is equal to or higher than a predetermined value. Features.

In one embodiment of the present invention, when the temperature of the working fluid estimated or detected by the fluid temperature calculation unit is lower than a predetermined value, and when no pressure increase is detected by the pressure increase detection unit, the pressure accumulation start pressure correction is performed. The means increases the pressure accumulation start pressure .

Moreover, in one form of this invention, the said pressure increase detection means is a brake operation detection means which detects operation of a brake operation member, It is characterized by the above-mentioned.

In one embodiment of the present invention, the pressure accumulation start pressure correcting means reduces the pressure accumulation start pressure only during a time that has elapsed since the time when pressure increase was detected by the pressure increase detection means for less than a predetermined time. It is characterized by.

ADVANTAGE OF THE INVENTION According to this invention, it can reduce that the hydraulic pump which generate | occur | produces the hydraulic pressure of an accumulator repeats on / off frequently. When the pressure increase is detected by the pressure increase detection means, the hydraulic pressure detected by the pressure accumulation detection means decreases. Therefore, in the present invention, the hydraulic pressure is generated for a predetermined time after the pressure increase is detected by the pressure increase detection means. Control is performed so that the hydraulic pressure is not generated by the means. In the present invention, it is only necessary to be able to detect that the brake operation has been performed. Therefore, the pressure increase detection signal is output to the electromagnetic valve that controls the fluid pressure or flow rate of the working fluid. May be replaced.
By reducing the accumulated pressure starting pressure, for example, at room temperature or immediately after the start of the brake operation, even if the hydraulic pressure value detected by the accumulated pressure detecting means temporarily decreases, the hydraulic pump is controlled to be turned on. Therefore, it is possible to reduce frequent repetition of on / off of the hydraulic pump that generates the hydraulic pressure of the accumulator.
According to the present invention, since the hydraulic pump is controlled to be turned on when the brake operation member is not operated, the hydraulic pump can be turned on in a state where the fluctuation of the detected pressure M-ACC is small. It is possible to reduce that the hydraulic pump 4 is frequently turned on or off.
Since the hydraulic pressure value filter processing means can delay the detection response of the hydraulic pressure value, even if the hydraulic pressure value temporarily decreases, the hydraulic pressure value is less likely to be detected, and the temporary hydraulic pressure value is reduced. Therefore, the hydraulic pump is controlled to be turned on.
According to the present invention, the hydraulic pressure filter processing means can switch the filter value used for the filter processing according to the estimated or detected temperature of the working fluid, so that the hydraulic pump can be switched according to the fluidity of the working fluid. Can be controlled.

  It is possible to provide a brake device in which the hydraulic pump that generates the hydraulic pressure of the pressure accumulator is frequently turned on and off at low temperatures.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a hydraulic circuit diagram of a brake device in which a braking pressure of a wheel cylinder is controlled based on an operation amount of a brake operation member (hereinafter referred to as a brake pedal) 2. The brake device according to the present embodiment is controlled by an electronic control unit (hereinafter referred to as a brake ECU) 30, and the hydraulic pressure of the accumulator is reduced even when the vehicle is placed in a low-temperature environment and the fluidity of the working fluid is reduced. Can be appropriately controlled.

  A master cylinder 1 having two hydraulic chambers 1a and 1b is connected to the brake pedal 2. A master cylinder pressure corresponding to the depression force of the brake pedal 2 is generated in the hydraulic chambers 1a and 1b. A reservoir tank 18 in which a working fluid is stored is provided at the upper part of the master cylinder 1. When the brake pedal 2 is not operated, that is, when the pressurizing piston is at the rear end position, the reservoir tank 18 and the hydraulic chambers 1a and 1b are communicated, and the brake pedal 2 is operated and the pressurizing piston is moved forward. Then, the reservoir tank 18 and the hydraulic chambers 1a and 1b are shut off.

  A first master passage 26a and a second master passage 26b communicate with the hydraulic chambers 1a and 1b of the master cylinder 1, respectively. The first master passage 26a is provided with an MC hydraulic sensor 5a that outputs a signal corresponding to the internal hydraulic pressure, that is, the master cylinder pressure generated in the hydraulic chamber 1a. Similarly, the MC pressure sensor 5b for outputting a signal corresponding to the internal hydraulic pressure, that is, the master cylinder pressure generated in the hydraulic pressure chamber 1b is disposed in the second master passage 26b.

  The first master passage 26a is connected to the wheel cylinder of the wheel FR via a master cut valve 24FR that allows / blocks the flow of the working fluid. Similarly, the second master passage 26b is connected to a wheel cylinder of the wheel FL via a master cut valve 24FL. The master cut valve 26a is in a normal state and the first master passage 26a and the mass cut valve 26b are in a normal state and the second master passage 26b is in a conducting state, and when the brake pedal 2 is depressed, these passages are shut off. This is an electromagnetic on-off valve.

  A stroke simulator 22 is connected to the first master passage 26 a via a simulator cut valve 23. The simulator cut valve 23 is a normally closed electromagnetic on-off valve that normally shuts off the first master passage 26a and the stroke simulator 22 and turns them on when the brake pedal 2 is depressed.

  When the control system described later is normal, when the brake pedal 2 is depressed, the ECU 30 closes the master cut valve 24FR and the master cut valve 24FL. In such a situation, when the simulator cut valve 23 is opened, an amount of working fluid corresponding to the master cylinder pressure flows into the stroke simulator 22 from the hydraulic chamber 1a. The stroke simulator 22 is configured to simulate the amount of oil consumed by depressing the brake pedal 2 and absorb and consume the amount of oil discharged from the master cylinder 1 to ensure the driver's brake pedal depression feeling. ing. FIG. 1 shows a case where the brake pedal 2 is depressed while the control system is in a normal state, and a thick line shows a hydraulic pressure passage.

  If any abnormality is detected in the control system, when the brake pedal 2 is depressed, the pressure control valves 24FR and 24FL are opened, the simulator cut valve 23 is closed, and the hydraulic chamber 1a of the master cylinder 1 is closed. From 1b, an amount of working fluid corresponding to the master cylinder pressure flows into the wheel cylinders of the wheels FR and FL. That is, even if some abnormality is detected in the control system, the braking pressure corresponding to the operation amount of the brake pedal 2 is supplied to the wheel cylinder, so that the vehicle is mechanically braked (backup braking).

  The reservoir tank 18 communicates with the input side of the hydraulic pump 4 via the return pipe 11. The pressure accumulator 3 is connected to the discharge side of the hydraulic pump 4, and when the motor of the hydraulic pump 4 is driven, a high-pressure working fluid is held in the accumulator 3.

  The discharge side of the pressure accumulator 3 communicates with the high pressure passage 8. In the high pressure passage 8, a pressure accumulation sensor 13 for detecting the internal fluid pressure is disposed in the high pressure passage 8 at a position away from the pressure accumulator 3 by a predetermined length (distance L in the drawing).

  The high pressure passage 8 is connected to the wheel cylinders of the wheels FR, FL, RL, and RR via linear pressure increasing valves 6FR, 6FL, 6RL, and 6RR. The high pressure passage 8 is connected to the low pressure return pipe 11 via the linear pressure increasing valves 6FR to RR and the linear pressure reducing valves 7FR, 7FL, 7RL and 7RR. Brake pressure sensors 9FR, 9FL, 9RL, and 9RR that detect the pressure of the wheel cylinder and output a brake pressure signal indicating the pressure are provided between the linear pressure increasing valves 6FR to 6RR and the wheel cylinders of the wheels FR to RR. It is arranged.

  The linear pressure increasing valves 6FR to RR and the linear pressure reducing valves 7FR to RR are configured as normally closed valves that are closed in a state where power is not supplied. When the brake pedal 2 is not operated, the linear pressure increasing valves 6FR to RR and the linear pressure reducing valves 7FR to RR are closed. When the brake pedal 2 is depressed, the linear pressure increasing valves 7FR to 7RR remain closed and the linear pressure increasing valves 6FR are closed. ˜RR adjusts the opening according to control signals V-FR˜V-RR. The braking pressure of the wheel cylinder is controlled in proportion to the control signals V-FR to V-RR that are current values input to the linear pressure increasing valves 6FR to 6RR, and each wheel cylinder is controlled to a desired braking pressure. Each wheel is braked.

  Further, when the depression amount of the brake pedal 2 is reduced (when the master cylinder pressure is reduced), the linear pressure increasing valves 6FR to 6RR are controlled so that the braking pressure is reduced according to the depression amount by adjusting the opening degree. 7FR-7RR is opened and the wheel cylinder communicates with the low pressure return pipe 11, so that the braking pressure in the wheel cylinder is relieved.

  The brake ECU 30 that controls the braking pressure in the hydraulic circuit described above includes a signal input unit 31 that includes a signal processing circuit that receives various signals and processes the signals, an arithmetic processing device 32 that performs arithmetic operations, and an accumulation start pressure. A storage device 33 composed of ROM and RAM for storing parameters and programs such as accumulator stop pressure and the like, and a control signal output unit 34 for outputting a calculation result by the arithmetic processing device 32 as a control signal by a drive circuit or the like. Composed.

  The signal input unit 31 is electrically connected to the pressure accumulation sensor 13, the MC hydraulic pressure sensors 5a and 5b, the braking pressure sensors 9FR to 9RR, and a vehicle speed detector that detects a traveling speed and outputs a vehicle speed signal. The detected pressure M-ACC detected by the pressure accumulation sensor 13 is an accumulator pressure signal, the master cylinder pressure detected by the MC hydraulic pressure sensors 5a and 5b is an MC hydraulic pressure signal, and the vehicle speed detected by the vehicle speed detector is a vehicle speed signal. The braking pressure PWC detected by the braking pressure sensors 9FR to 9RR is input to the signal input unit 31 as a braking pressure signal.

  The control signal output unit 34 is electrically connected to the hydraulic pump 4, the linear pressure increasing valves 6FR to RR, and the linear pressure reducing valves 7FR to RR, and the hydraulic pump 4 receives a hydraulic pump control signal for controlling on or off. Is output.

  The storage device 33 includes parameters such as a pressure accumulation start pressure (Pmot_on) 47, a pressure accumulation stop pressure (Pmot_off) 48, a filter value P [Hz] 49 for filtering the detected pressure M-ACC, and a temperature control MAP 50 described later. A program necessary for arithmetic processing of the arithmetic processing unit 32 is stored.

  Further, the brake ECU 30 functions as a functional block to drive the hydraulic pump 4 when the detected M-ACC detected by the pressure accumulation sensor 13 is equal to or lower than the pressure accumulation start pressure, and when the M-ACC is equal to or higher than the pressure accumulation stop pressure. 4, a fluid pressure generation control means 41 for estimating or detecting the temperature of the working fluid, a pressure accumulation start pressure correction means 42 for correcting the pressure accumulation start pressure, and a pressure accumulation stop pressure correction means 43 for correcting the pressure accumulation low pressure. , A pressure increase detecting means 43 for detecting an increase in the braking pressure PWC of the wheel cylinder, a brake operation detecting means 45 for detecting the operation of the brake pedal 2, and a liquid for performing a filtering process using the filter value P as the detected pressure M-ACC. The pressure value filter processing means 46 is configured.

  The operation of the hydraulic circuit controlled by the brake ECU 30 will be described. When the brake pedal 2 is depressed, the MC hydraulic pressure sensors 5a and 5b detect the master cylinder pressure and output an MC hydraulic pressure signal to the brake ECU 30. The brake ECU 30 calculates a target deceleration based on the master cylinder pressure, the speed of stepping on, and the like, and calculates a brake distribution for each wheel based on the target deceleration, the traveling state of the vehicle, and the like. When the target deceleration and the brake distribution of each wheel are calculated, the target wheel cylinder pressure that controls the braking pressure of each wheel is set.

  The brake ECU 30 generates control signals V-FR to V-RR having current values based on the set target wheel cylinder pressure, and outputs them to the linear pressure increasing valves 6FR to 6RR. The linear pressure increasing valves 6FR to 6RR adjust the opening according to the current value, control the pressure supplied from the pressure accumulator 3, and supply the braking pressure to the wheel cylinders of the wheels FR to RR.

  Next, the control procedure of the pressure of the pressure accumulator 3 by the brake ECU 30 will be described. The detected pressure M-ACC detected by the pressure accumulation sensor 13 is input to the brake ECU 30 as a detected pressure signal of the pressure accumulator 3. When the detected pressure M-ACC is equal to or lower than the accumulated pressure, the hydraulic pressure generation control means 40 outputs a hydraulic pump control signal for turning on the hydraulic pump 4 to increase the pressure accumulator 3, and the detected pressure M-ACC is accumulated. When the pressure is lower than the stop pressure, a hydraulic pump control signal for turning off the hydraulic pump 4 is output.

  FIG. 2 is an example of a flowchart showing a control procedure for controlling the hydraulic pressure of the pressure accumulator 3 at normal temperature. The brake ECU 30 executes the control of the hydraulic pump 4 as a timer interruption process every predetermined time (for example, 6 msec).

  The hydraulic pressure generation control means compares the detected pressure M-ACC input from the pressure accumulation sensor 13 with a constant Pmot_on stored in advance in the storage device 33 (S11). When the detected pressure M-ACC is not smaller than Pmot_on (No in step S11), it is determined that the pressure increase in the pressure accumulator 3 is not necessary, and the process ends. If the detected pressure M-ACC is smaller than Pmot_on (Yes in step S11), it is determined that the pressure in the pressure accumulator 3 has decreased, so the hydraulic pump 4 is controlled to be on (S12).

  Next, the hydraulic pressure generation control means monitors the detected pressure M-ACC and compares it with the detected pressure M-ACC and a constant Pmot_off stored in advance in the storage device 33 (S13). If the detected pressure M-ACC is not greater than Pmot_off (No in step S13), the determination in step S13 is repeated until the detected pressure M-ACC is greater than Pmot_off.

  When the detected pressure M-ACC is larger than Pmot_off (Yes in step S13), the hydraulic pressure generation control unit determines that the pressure increase in the accumulator 3 has been completed, and controls the hydraulic pump 4 to be turned off ( S14). Thus, the pressure control of the pressure accumulator 3 at normal temperature is completed.

  In the pressure control of the pressure accumulator 3 at room temperature, for example, by setting Pmot_on to A [MPa] and Pmot_off to B [MPa], the actual pressure P-MCC of the pressure accumulator 13 is also about A to B [Mpa]. Controlled (A <B).

  Then, the control procedure of the hydraulic pressure of the pressure accumulator 3 at the time of low temperature is demonstrated. In this embodiment, when the brake pedal 2 is depressed (when a braking operation is performed), the hydraulic pressure of the accumulator 3 is controlled so that the hydraulic pump 4 is not turned on.

  FIG. 3 is an example of a flowchart including a hydraulic pressure control procedure of the pressure accumulator 3 at a low temperature. The brake ECU 30 executes the control of the hydraulic pump 4 as a timer interruption process every predetermined time (for example, 6 msec). In this embodiment, in the control of the pressure accumulator 3 at normal temperature, A [MPa] (hereinafter referred to as normal temperature pressure start pressure) is set to Pmot_on, and B [MPa] (hereinafter referred to as normal pressure pressure stop pressure) is set to Pmot_off. (A <B).

  The fluid temperature calculation means 41 estimates or detects the temperature of the working fluid and determines whether or not to perform a control procedure at a low temperature (S21). If the result of the low temperature determination is normal temperature, the hydraulic pressure of the pressure accumulator 3 is controlled by the normal temperature control procedure of FIG. 2 (S10). If it is determined that the temperature is low, a control procedure at a low temperature after step S22 is performed.

[Low temperature judgment (S21)]
A method for determining the low temperature will be described. The low temperature determination is performed based on temperature information from an outside air temperature sensor or an intake air temperature sensor mounted on the vehicle, for example. The fluid temperature calculation means 41 compares the temperature of the detected temperature information with a temperature that is a reference whether or not the temperature is stored in advance in the storage device 33, and makes a low temperature determination.

  The low temperature determination may be performed by comparing the amount of change in the braking pressure PWC of the wheel cylinder and the amount of change in the detected pressure M-ACC of the pressure accumulation sensor 13. Since the viscosity of the working fluid increases at low temperatures and is difficult to flow, the flow rate of the working fluid that passes through the braking pressure sensors 9FR to 9RR that detects the braking pressure PWC of the wheel cylinder and the flow rate of the working fluid that passes through the pressure accumulation sensor 13 The divergence increases. At a low temperature, as shown in FIG. 8, the change amount of the detected pressure M-ACC is larger than the change amount of the braking pressure PWC of the wheel cylinder.

  Therefore, for example, the flow rate of the working fluid passing through the pressure accumulating sensor 13 estimated from the detected pressure M-ACC immediately before the start of the braking pressure increase of the wheel cylinder and the M-ACC after the pressure increase is ΔM-ACC, the pressure increase start By comparing ΔM-ACC and ΔPWC with the flow rate of the working fluid passing through the braking pressure sensors 9FR to 9RR estimated from the braking pressure PWC of the immediately preceding wheel cylinder and the braking pressure PWC of the wheel cylinder after being increased as ΔPWC, Low temperature determination can be performed. For example, the fluid temperature calculation means 41 determines that the temperature is low when ΔM−ACC> ΔPWC × α (α> 1). When the low temperature is determined from the flow rate of the working fluid, it is possible to easily detect a decrease in the fluidity of the working fluid due to the low temperature even when the outside air temperature and the temperature of the working fluid are different.

  If it is determined that the room temperature is normal as a result of the low temperature determination in step S21, pressure control at the normal temperature in FIG. 2 is performed.

  As a result of the low temperature determination in step S21, when it is determined that the temperature is low, the brake operation detection means determines whether or not the brake pedal 2 is turned on (S22). The brake pedal 2 being turned on means a case where the brake pedal 2 is depressed and a braking request is received from the driver. It is preferable to determine whether or not the brake pedal is on based on, for example, an increase in the master cylinder pressure. Even if the brake pedal 2 is depressed, it is not determined that the brake pedal is on in the state where the depression is being released.

  When it is determined that the brake pedal is on (Yes in step S22), the pressure accumulation start pressure correction unit 42 sets Pmot_on, which is a determination criterion for controlling the hydraulic pump 4 to on, from A → a1 (A> a1) ( S23). When it is determined that the brake pedal is off (No in step S22), the pressure accumulation start pressure correction unit 42 sets Pmot_on from A → a2 (a2> A) (S24).

  Therefore, in step S23, a value smaller than the room temperature pressure start pressure is set to Pmot_on, and in step S24, a value larger than the room temperature pressure start pressure is set to Pmot_on. As a result, when the brake pedal 2 is depressed, the value of Pmot_on is smaller than the normal pressure accumulation start pressure, so that the hydraulic pump 4 is less likely to be turned on when the brake pedal 2 is depressed. Further, when the brake pedal 2 is not depressed, a value higher than the normal pressure accumulation start pressure is set to Pmot_on. Therefore, when the brake pedal 2 is not depressed, the hydraulic pump 4 is controlled to be turned on. Will increase.

  Next, the hydraulic pressure generation control means 40 determines whether or not the detected pressure M-ACC is smaller than Pmot_on (S25). As a result of the determination, when the detected pressure M-ACC is not smaller (No in step S25), the present control procedure ends. When the detected pressure M-ACC is smaller (Yes in step S25), the hydraulic pump 4 is controlled to be on (S26).

  When the hydraulic pump 4 is controlled to be turned on, the brake operation detecting means determines whether or not the brake pedal 2 is turned on (S27). When the brake pedal 2 is on (Yes in step S27), the pressure accumulation stop pressure correcting means 43 sets Pmot_off from B → b1 (B> b1) (S28), and when the brake pedal 2 is not on (in step S27). No), the accumulated pressure stop pressure correcting means 43 sets Pmot_off to B (S29).

  Therefore, in step S28, a pressure smaller than the normal temperature accumulation stop pressure is set to Pmot_off, and in step S29, the same value as the normal temperature accumulation stop pressure is set to Pmot_off. As a result, when the brake pedal 2 is depressed, the value of Pmot_off becomes smaller than the normal temperature accumulator stop pressure, so that the hydraulic pump 4 is often controlled to be turned off when the brake pedal 2 is depressed. Further, when the brake pedal 2 is not depressed, the same value as the normal temperature accumulating stop pressure is set to Pmot_off, so that the hydraulic pump 4 continues to be controlled to be turned on to the same degree as the normal temperature.

  Next, the hydraulic pressure generation control unit 40 compares the detected pressure M-ACC and Pmot_off (S30). If the detected pressure M-ACC is not greater than Pmot_off (No in step S30), the determination of whether or not the brake pedal in step S27 is on is repeated and until the detected pressure M-ACC becomes greater than Pmot_off. Then, the hydraulic pump 4 is controlled to be turned on.

  If the detected pressure M-ACC is greater than Pmot_off (Yes in step S30), it is determined that the pressure increase in the pressure accumulator 3 has been completed, and the hydraulic pump 4 is controlled to be turned off (S31). Thus, the pressure control of the pressure accumulator 3 at normal temperature is completed.

  According to the present embodiment, when it is determined that the temperature is low, correction is performed so as to reduce the pressure accumulation start pressure. Therefore, even if the detected pressure M-ACC temporarily decreases due to a decrease in fluidity of the working fluid, the hydraulic pump 4 Is prevented from being turned on.

  In particular, in the case of the present embodiment, the control is performed so that the hydraulic pump 4 is turned on when the brake pedal 2 is not depressed by the driver. Further, when the brake pedal 2 is depressed while the hydraulic pump 4 is turned on, the hydraulic pump 4 is controlled to tend to be turned off. In a state where the brake pedal 2 is not depressed, the brake pressure is not supplied from the pressure accumulator 3 to the wheel cylinder, so that the decrease in the detected pressure M-ACC is assumed to be minimal. Therefore, the hydraulic pump 4 can be turned on while the detected pressure M-ACC is stable, and the hydraulic pump 4 is prevented from being frequently turned on or off.

  The set values of Pmot_on and Pmot_off are preferably set according to the viscosity characteristics of the working fluid with respect to the temperature and the distance L between the pressure accumulator 3 and the pressure accumulation sensor 13.

  In the present embodiment, a control procedure for controlling the pressure of the pressure accumulator 3 by filtering the detected value of the detected pressure M-ACC will be described. FIG. 4 is an example of a flowchart including a control procedure of the hydraulic pressure of the pressure accumulator 3 at a low temperature.

  The fluid temperature calculation means 41 estimates or calculates the temperature of the working fluid and determines whether or not to perform a control procedure at a low temperature (S21). If the result of the low temperature determination is normal temperature, the hydraulic pressure of the pressure accumulator 3 is controlled by the normal temperature control procedure of FIG. 2 (S10). Since the low temperature determination is the same as that of the first embodiment, the description thereof is omitted.

  As a result of the low temperature determination in step S21, when it is determined that the temperature is low, the hydraulic pressure value filter processing means 46 performs a filter process to detect the detected pressure M-ACC (S101). Filtering means, for example, processing by changing the time interval at which the pressure accumulation sensor 13 detects the pressure of the pressure accumulator 3 based on the filter value. The detection pressure M-ACC may be temporarily reduced by setting a filter value so that the detection time interval of the detection pressure M-ACC at normal temperature is about 2 to 5 times that at low temperatures. Detecting fast fluctuations is prevented. In step S101, the detected pressure M-ACC detected by performing the filter process is set as the detected pressure M-ACC_F, and the filter value is set as the filter P [Hz].

  The subsequent processing is the same as that shown in FIG. The hydraulic pressure generation control means 40 compares M-ACC_F with a constant Pmot_on stored in advance in the storage device 33 (S102). If the detected pressure M-ACC_F is smaller than Pmot_on (Yes in step S102), it is determined that the pressure in the pressure accumulator 3 has decreased, and the hydraulic pump 4 is controlled to be turned on (S103).

  Next, the hydraulic pressure generation control means 40 compares the detected pressure M-ACC_F with a constant Pmot_off stored in advance in the storage device 33 (S104). If the detected pressure M-ACC_F is not greater than Pmot_off (No in step S104), the determination in step S104 is repeated until the detected pressure M-ACC_F is greater than Pmot_off.

  If the detected pressure M-ACC_F is larger than Pmot_off (Yes in step S104), it is determined that the pressure increase in the pressure accumulator 3 has been completed, and the hydraulic pump 4 is controlled to be turned off (S105). Thus, the pressure control of the pressure accumulator 3 at the time of low temperature in FIG. 4 is completed.

  The filter P may be a function of temperature. FIG. 5A shows an example of a temperature control MAP showing the relationship between the temperature and the filter P (T). As shown in the temperature control map of FIG. 5A, the detection pressure M-ACC is reduced by decreasing the filter P (T) as the temperature decreases (by increasing the detection time interval of the detection pressure M-ACC_F). Even if it decreases temporarily, it is possible to prevent the hydraulic pump 4 from responding excessively. Moreover, when it determines with low temperature by low temperature determination (S21), since the filter P (T) is changed according to temperature, the pressure of the pressure accumulator 3 can be accurately controlled according to temperature.

  According to the present embodiment, it is possible to prevent the hydraulic pump 4 from being frequently turned on / off by filtering the detected pressure M-ACC. In addition, the detected pressure M-ACC may be filtered, and the pressure set to Pmot_on or Pmot_off may be changed when the brake pedal 2 is depressed as in the first embodiment.

  In this embodiment, the setting values of Pmot_on and Pmot_off are not characteristic parts, but the setting values of Pmot_on and Pmot_off depend on the viscosity characteristics of the working fluid with respect to the temperature and the distance L between the pressure accumulator 3 and the pressure accumulation sensor 13. It is preferable to set.

  In this embodiment, the control procedure of the hydraulic pressure of the pressure accumulator 3 that switches the pressure set in Pmot_on according to the temperature will be described. In this embodiment, in the control of the pressure accumulator 3 at normal temperature, C [MPa] (hereinafter referred to as normal temperature pressure start pressure) is set in Pmot_on, and D [MPa] (hereinafter referred to as normal pressure pressure stop pressure) is set in Pmot_off. (C <D).

  FIG. 6 is an example of a flowchart including a control procedure of the hydraulic pressure of the pressure accumulator 3 at a low temperature. The fluid temperature calculation means 41 estimates or detects the temperature of the working fluid and determines whether or not to perform a control procedure at a low temperature (S21). If the result of the low temperature determination is normal temperature, the hydraulic pressure of the pressure accumulator 3 is controlled by the normal temperature control procedure of FIG. 2 (S10). Since the low temperature determination is the same as that of the first embodiment, the description thereof is omitted.

  As a result of the low temperature determination in step S21, when it is determined that the temperature is low, the pressure accumulation start pressure correction unit 42 sets Pmot_on from C → c1 (C> c1). By setting a value lower than the normal temperature pressure accumulation start pressure C [Mpa], the hydraulic pump 4 is less likely to be turned on even if the detected pressure M-ACC is temporarily reduced.

  The processing after the accumulation start pressure (c1 [Mpa]) at low temperature is set in Pmot_on is the same as the control procedure at normal temperature in FIG. That is, if the detected pressure M-ACC is smaller than Pmot_on, the hydraulic pump 4 is controlled to be turned on, and if the detected pressure M-ACC is higher than Pmot_off, the hydraulic pump 4 is controlled to be turned off.

  Note that the pressure Pmot_on that is set when it is determined that the temperature is low in step S201 may be a function of temperature. FIG. 5B shows an example of the temperature MAP indicating the relationship between the temperature and the set pressure of Pmot_on.

  According to the temperature control map of FIG. 5B, the set pressure of Pmot_on is corrected to decrease as the temperature decreases. As a result, the fluidity decreases as the temperature of the working fluid decreases, and even if the detected pressure M-ACC decreases temporarily, the set pressure of Pmot_on decreases as the temperature decreases, so the hydraulic pump 4 is turned on. It is less controlled and the hydraulic pump 4 can be prevented from being frequently turned on / off.

  In this embodiment, the pressure is not set to Pmot_off even at a low temperature, but a pressure higher than the normal pressure accumulation stop pressure may be set to Pmot_off at a low temperature. Since the set pressure of Pmot_off is high, once the hydraulic pump 4 is controlled to be turned on, the hydraulic pump 4 becomes difficult to be controlled to be turned off. Therefore, frequent on / off of the hydraulic pump 4 can be prevented.

  As described above, according to this embodiment, it is possible to prevent the hydraulic pump 4 from responding excessively by switching the set pressure of Pmot_on depending on the temperature. In addition, while switching the setting pressure of Pmot_on according to temperature, a filter may be applied to the detected pressure M-ACC as in the second embodiment, and when the brake pedal 2 is depressed as in the first embodiment, The pressure set for Pmot_on or Pmot_off may be changed.

  The set value of Pmot_on is preferably set according to the viscosity characteristic of the working fluid with respect to the temperature and the distance L between the pressure accumulator 3 and the pressure accumulation sensor 13.

  In the present embodiment, the control procedure of the pressure of the pressure accumulator 3 that switches the pressure set to Pmot_on according to the time elapsed since the linear pressure increasing valves 6FR to 6RR have been operated will be described. In this embodiment, in the control of the pressure accumulator 3 at normal temperature, E [MPa] (hereinafter referred to as normal temperature pressure start pressure) is set to Pmot_on, and F [MPa] (hereinafter referred to as normal pressure pressure stop pressure) is set to Pmot_off. (E <F).

  FIG. 7 is an example of a flowchart including a control procedure of the hydraulic pressure of the pressure accumulator 3 at a low temperature. The fluid temperature calculation means 41 estimates or detects the temperature of the working fluid and determines whether or not to perform a control procedure at a low temperature (S21). If the result of the low temperature determination is normal temperature, the hydraulic pressure of the pressure accumulator 3 is controlled by the normal temperature control procedure of FIG. 2 (S10). Since the low temperature determination is the same as that of the first embodiment, the description thereof is omitted.

  As a result of the low temperature determination in step S21, when it is determined that the temperature is low, the pressure increase detection means 44 determines whether or not the linear pressure increase valves 6FR to 6RR are operated and the brake cylinder brake pressure PWC is increased (S301). ). The linear pressure increasing valves 6FR to 6RR operate when the brake pedal 2 is depressed. If the brake pedal 2 is not depressed (No in step S301), the process proceeds to step S307, and the hydraulic pressure of the pressure accumulator 3 is controlled in the same manner as at normal temperature.

  When the braking pressure PWC of the wheel cylinder is increased (Yes in step S301), t_count for measuring the elapsed time is set to zero (S302). Next, it is determined based on t_count whether a predetermined time has elapsed (S303). The predetermined time is a time required for the working fluid having reduced fluidity to reach the pressure accumulation sensor 13 from the pressure accumulator 3 at a low temperature, for example, about 1 second.

  When the predetermined time has not elapsed (No in step S303), the pressure accumulation start pressure correcting means 42 sets, for example, Pmot_on as E → e1 (E> e1) [Mpa] (S305), and sets a time cycle Δt at t_count. Are added (S306). Thereby, immediately after the braking pressure PWC of the wheel cylinder starts to increase (immediately after the linear pressure increasing valves 6FR to 6RR are actuated), that is, before the working fluid reaches the pressure accumulation sensor 13 from the pressure accumulator 3, Pmot_on is set to normal temperature. Since a value smaller than the pressure accumulation start pressure is set, it is possible to reduce the hydraulic pump 4 from being turned on even if a low detected pressure M-ACC is temporarily detected.

  When the predetermined time has elapsed (Yes in step S303), the pressure accumulation start pressure correction unit 42 performs a setting to return, for example, Pmot_on to E [Mpa] (S304). Since it is assumed that the hydraulic pressure of the pressure accumulator 3 due to the working fluid has reached the position of the pressure accumulation sensor 13 after a predetermined time has elapsed, the same value as the room temperature pressure accumulation start pressure is set to Pmot_on, and the pressure accumulator 3 is increased. Even if it determines whether it is, it can reduce making the determination which deviated from the hydraulic pressure P-ACC of the actual pressure accumulator 3. FIG.

  Next, the hydraulic pressure generation control means 40 compares the detected pressure M-ACC and Pmot_on (step S307). If the detected pressure M-ACC is not smaller as a result of the comparison (No in step S307), it is subsequently determined whether a predetermined time has elapsed based on t_count (S308). When the predetermined time has elapsed (E [Mpa] is set in Pmot_on), it is determined that pressure increase is not necessary, and the control procedure of FIG. 7 ends.

  If the predetermined time has not elapsed (e1 [Mpa] is set in Pmot_on), the processes of steps S303 to S308 are performed until the predetermined time has elapsed and E [Mpa] is set in Pmot_on. Is called.

  The processing after step S12 is the same as the control procedure of FIG. 2 showing the control at normal temperature. That is, if the detected pressure M-ACC is smaller than Pmot_on (Yes in step S307), the hydraulic pump 4 is controlled to be turned on (S12), and if the detected pressure M-ACC is higher than Pmot_off (Yes in step S13). The hydraulic pump 4 is controlled to be turned off (S14). This is the end of the control procedure of FIG.

  In the present embodiment, the pressure is not set to Pmot_off regardless of the elapse of a predetermined time, but a pressure higher than the normal temperature accumulating stop pressure may be set to Pmot_off at a low temperature. Since the set pressure of Pmot_off is high, once the hydraulic pump 4 is controlled to be turned on, the hydraulic pump 4 becomes difficult to be controlled to be turned off. Therefore, frequent on / off of the hydraulic pump 4 can be prevented.

  According to the present embodiment, the value set in Pmot_on can be switched according to the time elapsed since the increase of the braking pressure PWC of the wheel cylinder is started, so that the fluidity of the working fluid has decreased. Thus, it is possible to prevent the detected pressure M-ACC from temporarily decreasing and the hydraulic pump 4 from being controlled to be turned on.

  In addition, while changing the setting pressure of Pmot_on according to elapsed time, you may set the value according to temperature to Pmot_on like Example 3, and filter processing is detected pressure M-ACC like Example 2. The pressure set to Pmot_on or Pmot_off may be changed when the brake pedal 2 is depressed as in the first embodiment.

  Further, the set value of Pmot_on and the predetermined time is preferably set according to the viscosity characteristic of the working fluid with respect to the temperature and the distance L between the pressure accumulator 3 and the pressure accumulation sensor 13.

  As described above, according to the brake device for carrying out the present invention described in the first to fourth embodiments, it is possible to prevent the hydraulic pump that generates the hydraulic pressure at low temperatures from frequently turning on and off. it can. Since excessive response of the hydraulic pump 4 is prevented, power consumption by the hydraulic pump can be reduced, and durability of the control relay can be improved.

It is a hydraulic circuit diagram of the brake device in which the braking pressure of the wheel cylinder is controlled based on the operation amount of the brake operation member. It is an example of the flowchart figure which shows the control procedure which controls the hydraulic pressure of the pressure accumulator at the time of normal temperature. It is an example of the flowchart figure which shows the control procedure which controls the hydraulic pressure of the pressure accumulator in Example 1. FIG. It is an example of the flowchart figure which shows the control procedure which controls the hydraulic pressure of the pressure accumulator in Example 2. FIG. It is a figure which shows an example of temperature control MAP. It is an example of the flowchart figure which shows the control procedure which controls the hydraulic pressure of the pressure accumulator in Example 3. FIG. It is an example of the flowchart figure which shows the control procedure which controls the hydraulic pressure of the pressure accumulator in Example 4. FIG. It is an example of the graph figure which shows the pressure of the conventional accumulator, and the pressure of the accumulator detected by the pressure sensor.

Explanation of symbols

2 Brake pedal 3 Accumulator 4 Hydraulic pump 5a, 5b MC hydraulic sensor 6FR-6RR Linear pressure increasing valve 7FR-7RR Linear pressure reducing valve 13 Pressure accumulating sensor 21 Stroke sensor 30 Brake ECU

Claims (5)

Accumulating means for accumulating the hydraulic pressure generated by the hydraulic pressure generating means for generating hydraulic pressure, accumulating pressure detecting means for detecting the hydraulic pressure value of the accumulating means, and the hydraulic pressure value detected by the accumulated pressure detecting means is accumulated. A hydraulic pressure generation control means for driving the hydraulic pressure generation means when the pressure is less than the start pressure and stopping the hydraulic pressure generation means when the pressure is equal to or higher than the accumulation stop pressure, and from the pressure accumulation means In a braking device that brakes a vehicle by supplying braking pressure,
Fluid temperature calculating means for estimating or detecting the temperature of the working fluid of the brake device;
A pressure increase detection means for detecting an increase in the braking pressure;
An accumulated pressure start pressure correcting means for lowering the accumulated pressure start pressure when the temperature of the working fluid estimated or detected by the fluid temperature calculating means is lower than a predetermined value and when the increased pressure is detected by the increased pressure detecting means; ,
When pressure increase is detected by the pressure increase detection means, pressure accumulation stop pressure correcting means for reducing the pressure accumulation stop pressure; and
Brake device characterized by having. With the hydraulic pressure generation control means driving the hydraulic pressure generation means,
When a pressure increase is detected by the pressure increase detection means, the pressure accumulation stop pressure correction means reduces the pressure accumulation stop pressure,
When no pressure increase is detected by the pressure increase detection means, the pressure accumulation stop pressure correction means sets the pressure accumulation stop pressure to the same value as when the temperature of the working fluid is equal to or higher than a predetermined value .
The brake device according to claim 1. When the temperature of the working fluid estimated or detected by the fluid temperature calculation means is lower than a predetermined value, and when no pressure increase is detected by the pressure increase detection means, the pressure accumulation start pressure correction means is
Increasing the pressure accumulation start pressure ,
The brake device according to claim 1 or 2, characterized by the above. The pressure increase detection means is a brake operation detection means for detecting an operation of a brake operation member.
The brake device according to any one of claims 1 to 3. The pressure accumulation start pressure correction means reduces the pressure accumulation start pressure only during a time that has elapsed since the time when pressure increase was detected by the pressure increase detection means during less than a predetermined time .
The brake device according to any one of claims 1 to 4, wherein

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