JP2007223449A - Vehicular brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the consumption of the power stored in an on-vehicle battery by driving a vacuum pump without using any electric motor in a vehicular brake device for generating the braking force by operating a brake booster with the negative pressure generated in the vacuum pump. <P>SOLUTION: A vehicular brake device comprises a vacuum pump 10 and a brake booster 2. The vacuum pump 10 is driven by a rotating axle or a rotary shaft other than the axle. The brake booster 2 is operated by the negative pressure fed from the vacuum pump 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automobile brake device suitable for use in an electric vehicle (so-called EV) or a hybrid vehicle (so-called HV) using both an engine and a motor.

  A general automobile brake device has a structure in which a driver's operation force is amplified by a brake booster, and a master cylinder is operated by the amplified force to generate a required braking force. A vacuum booster that is operated at a negative pressure is the mainstream of the brake booster used in this automobile brake device.

  As for the negative pressure supplied to the vacuum booster, the intake manifold of the engine is used as a supply source in the gasoline vehicle. For diesel engine vehicles without throttle or electric vehicles without engine, a vacuum pump is installed, and the negative pressure generated by the vacuum pump is temporarily stored in the vacuum tank and then supplied from the vacuum tank to the vacuum booster. It has been.

  As a conventional example of an automobile brake device employing the vacuum pump, for example, there is one disclosed in Patent Document 1 below.

  In the brake device of Patent Document 1, the drive source of the vacuum pump is an electric motor. Particularly, in an electric vehicle using electricity as energy, the operation of the vacuum pump leads to a reduction in the travelable distance by one charge. There is.

The brake device of Patent Document 1 operates when a so-called panic brake (abrupt braking operation during high-speed driving of a vehicle) is performed by operating a vacuum pump when the deceleration of the vehicle reaches a predetermined value. The negative pressure on the booster side suddenly drops to the lower limit value and the brake operation feeling is changed without setting the lower limit value high, and compared to those that set the lower limit value high. The increase in electricity consumption can be suppressed.
JP 05-338528 A

  Since the vacuum tank is installed in the engine room of an automobile, its size is restricted by the arrangement relationship with other equipment and devices, and it is assumed that no negative pressure is replenished. Can only secure the capacity to become. On the other hand, in a vehicle in which a motor-driven vacuum pump including the brake device of Patent Document 1 is adopted as a brake device, electric power is consumed every time the vacuum pump is operated. If it is performed continuously for a long time, the operating frequency of the vacuum pump increases and the power consumption by the vacuum pump becomes significant. As a result, in an electric vehicle, the travelable distance by one charge is shortened.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the consumption of electric power stored in an in-vehicle battery in an automobile brake device that generates a braking force by operating a brake booster with a negative pressure generated by a vacuum pump. Yes.

  In order to solve the above problems, in the present invention, in an automobile brake device having a vacuum pump and a brake booster (vacuum booster), the vacuum pump is driven by a rotating shaft other than an axle or a rotating shaft, and the vacuum The brake booster is operated by the negative pressure supplied from the pump.

  The rotation axis other than the axle here refers to an axis included in the power transmission system of the vehicle, an axis that rotates following the vehicle traveling, or the like. The output shaft of the electric motor is not included. There are two types of rotating shafts: an axis that rotates while the vehicle is stopped and an axis that stops rotating while the vehicle is stopped. The shaft used as a drive source for the vacuum pump is preferably a shaft that rotates even when the vehicle is stopped. However, the object of the invention (reduction of electricity consumption) can be achieved by using a shaft that stops rotating while the vehicle is stopped.

  When this automobile brake device is applied to an electric vehicle or a hybrid vehicle, a remarkable effect can be obtained. Therefore, what was comprised for electric vehicles or a hybrid vehicle is preferable.

  In addition, if the vacuum pump is driven by an axle or the like, the negative pressure supply amount when the vehicle is stopped will decrease compared to the negative pressure supply amount during vehicle travel due to the stoppage of the axle rotation or the decrease in the rotation speed of the rotation shaft. When the operation is repeated or the brake operation is continued for a long time, it is considered that the negative pressure is insufficient, and the braking force obtained by reducing the output of the brake booster is less than the target braking force.

  In order to cope with this problem, in a vehicle having an ESC (vehicle stability control) function and an EPB (electric parking brake), the vacuum pump is driven by the axle of the vehicle or the rotating shaft of the power system of the vehicle that rotates even when the vehicle is stopped. The brake booster is operated by the negative pressure supplied from the vacuum pump, and when the negative pressure supplied to the brake booster becomes less than the threshold value, it is assisted by ESC or EPB. It is recommended to make up for the shortage of braking force against power.

  The exhaust of the vacuum pump is preferably discharged into the intake manifold or drive motor of the engine in order to reduce exhaust noise.

In the automobile brake device of the present invention, the vacuum pump is driven by a rotating shaft other than the axle included in the axle or the power transmission system of the vehicle, so that the power consumption by the vacuum pump is eliminated and the consumption of the electric power stored in the battery is reduced. There is. As a result, in an electric vehicle, the travelable distance by one charge can be increased.

Although the brake device of the present invention can be applied to a gasoline vehicle, the gasoline vehicle can supply negative pressure from an intake manifold, and it is not economically advantageous to provide a vacuum pump. On the other hand, electric vehicles and hybrid vehicles that stop the engine when in motor driving mode and have a brake booster that operates with negative pressure need to have a vacuum pump to constantly supply negative pressure during driving Therefore, when the present invention is applied to a brake device for an electric vehicle or a hybrid vehicle (one that does not include a hydraulic booster), the effectiveness of the present invention is particularly remarkable.

  Further, in a vehicle having an ESC (vehicle stability control) function and an EPB (electric parking brake), when the negative pressure supplied from the vacuum pump becomes equal to or lower than a threshold value, the ESC or EPB assists to control the target braking force. When the shortage of power is compensated, the target braking force is secured even when the negative pressure supplied to the brake booster is insufficient due to repeated braking operations while the vehicle is stopped, etc., and braking reliability is improved. Rise.

  In addition, when exhausting the vacuum pump into the intake manifold or drive motor of the engine, the exhaust exhaust that has been throttled from the vacuum pump is exhausted into a large space in the intake manifold or motor, resulting in a muffler effect. An effect of reducing exhaust noise can be obtained. Electric cars and hybrid cars are less noisy than engine cars, and even small sounds are more noticeable. Therefore, it can be said that reducing the exhaust noise of the vacuum pump is extremely effective.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 has an ESC function, and includes a brake pedal 1, a tandem master cylinder 4 with a brake booster 2 and a reservoir 3, and first and second hydraulic circuits 5. , and 6, the wheel cylinders ₇ -1 _{to 7 -4} respective wheels, and ESC8 configured as a unit, and ECU (electronic control unit) 9, a vacuum pump 10 for generating negative pressure, generated by the vacuum pump 10 A vacuum tank 12 that stores the negative pressure that has been generated via the check valve 11 and a pressure sensor 13 that detects the magnitude of the negative pressure supplied to the brake booster 2 via the vacuum tank are combined.

One ESC 8 is provided in each of the hydraulic circuits 5 and 6 to control the hydraulic pressure supplied from the master cylinder to a value corresponding to the energization current and flow toward the wheel cylinders 7 _{-1 to} 7 _{-4. -1,} and _{14 -2,} the pressure increasing valve ₁₅ -1 _{to 15 -4} increase the hydraulic pressure of the wheel cylinders ₇ -1 _{to 7 -4} individually, to depressurize the hydraulic pressure of the wheel cylinders ₇ -1 _{to 7 -4} individually a pressure reducing valve ₁₆ -1 _{to 16 -4,} a reservoir _{17 -1} for storing the wheel cylinders _{7-1, 7 -2} to pressure reducing valve ₁₆ -1, _{16 -2} discharged hydraulic oil via a (brake fluid), wheels cylinder _{7 -3, 7-4} reducing valve ₁₆ -3 to _{16 -4} reservoir ₁₇ for storing hydraulic oil discharged via _-2 respective reservoirs ₁₇ -1, it pumps up hydraulic oil accumulated in the _{17 -2} Hydraulic circuit 5, Pump ₁₈ -1 to reflux, and _{18 -2,} a motor 19 for driving the pump, pump ₁₈ -1, ₁₈ a check valve ₂₀ -1 to insert respectively into the discharge circuit _{-2, 20 -2,} master A pressure sensor 21 for detecting the cylinder pressure (the output pressure of the master cylinder) is combined.

Linear control valve ₁₄ -1 of this ESC8, _{14 -2,} the check valve ₂₂ -1 to prevent flow to the master cylinder side of the hydraulic oil, is disposed in parallel with _22-2, and each pressure increasing valve 15 _{- 1-15 -4,} and allows the flow of hydraulic fluid from the wheel cylinder to the master cylinder side, is arranged in parallel with the check valve ₂₃ -1 _{to 23 -4} to prevent flow in the opposite direction. The reservoirs 17 _-1 and 17 _-2 are cut valves 24 _-1 and 24 that _connect the suction ports of the pumps 18 _-1 and 18 _-2 to the master cylinder 4 when hydraulic oil is not stored in the reservoirs. _-2 (an electromagnetic on-off valve may be used instead of the cut valve shown in the figure), and when the hydraulic oil is not stored in the reservoirs 17 _-1 and 17 _-2 pump ₁₈ -1, it is possible to generate a hydraulic pressure pumping hydraulic oil in _{18 -2.}

The linear control valves 14 _-1 and 14 _-2 , the pressure increasing valves 15 _-1 to 15 _-4 , the pressure reducing valves 16 _{-1 to} 16 _-4 , and the motor 19 that drives each pump operate in response to a command from the ECU 9. The ECU 9 captures vehicle behavior information from various sensors such as a wheel speed sensor, a yaw rate sensor, and a lateral G sensor (not shown) of each wheel. For example, the vehicle tends to oversteer or understeer. It is determined whether or not each wheel has a tendency to lock, and when it is determined that such a tendency exists, a control command for reducing the tendency is issued.

  2 further includes a pedaling force sensor 25 for detecting a pedaling force applied to the brake pedal 1, a pressure sensor 26 for detecting a wheel cylinder pressure (wheel cylinder hydraulic pressure), and an assisting braking force. An ECU 27 for control is additionally provided. The pedal force sensor 25 can be replaced with a stroke sensor that detects a pedal stroke.

  In the automobile brake device of FIG. 2, the ECU 27 detects the negative pressure value obtained from the pressure sensor 13, the pedal depression force obtained from the depression force sensor 25 (this may be estimated from the pedal stroke and the master cylinder pressure), and the pressure sensor. 26, the necessity of assisting the braking force by the ESC 8 is determined by taking in the pressure information from the engine 26, the magnitude of the braking force (required braking force) to be assisted when it is determined to be necessary, and the calculation result is transmitted to the ECU 9. To do. In response to the signal, the ECU 9 issues a control command so that the required braking force is assisted by the ESC 8. The control for the assistance will be described in detail later. Other ESC controls are well known and will not be described.

  The vacuum pump 10 is driven using a vehicle axle or the like as a drive source. An example of a general vacuum pump for automobiles is shown in FIG. The vacuum pump 10 in FIG. 3 is a vane pump, but a bankel type pump (see Japanese Patent Application Laid-Open Nos. 2003-314476 and 2003-314479 proposed by the present applicant), a scroll pump, and the like It may be.

In FIG. 4, an example of the drive form of the vacuum pump 10 is shown. In FIG. 4, 30 denotes a wheel, 31 denotes a disc brake, and 32 denotes a transmission. Here, the rotation of the front drive shaft 33 is transmitted via the gear 34 to drive the vacuum pump 10. The vacuum pump 10 is driven by the rotation of the propeller shaft 35, the rear drive shaft 36, and the differential 37. Further, in a two-wheel drive vehicle, the vehicle can be driven by an axle of a driven wheel that is driven to rotate when the vehicle is running. The propeller shaft and the rotating portion of the differential are rotating shafts other than the axles referred to in the present invention.
Further, in a vehicle having a wheel-in motor 39 as shown in FIG. 6, the wheel-in motor 39 is provided with a motor shaft 40 integrated with the rotor of the motor, and the rotation of the motor shaft 40 is vacuumed via the gear 34. The vacuum pump 10 can be driven by transmitting to the pump 10.

  Here, if the vacuum pump 10 is driven by an axle or a rotating shaft other than the axle, for example, the propeller shaft or the motor shaft of a wheel-in motor, the vacuum pump 10 cannot be moved when the vehicle is stopped, or the vehicle is in an idling state. The rotation speed of the vacuum pump 10 falls.

  Therefore, if the brake operation is repeated many times while the vehicle is stopped, or if the brake operation is continued for a long time, the negative pressure in the vacuum tank decreases and the negative pressure supplied to the brake booster is insufficient. It can be considered that the obtained braking force is lower than the target braking force. Since it is not preferable that such a situation occurs when the vehicle stops on a hill or the like, in a vehicle having an ESC function or EPB, the braking force is assisted by ESC or EPB when the negative pressure supplied from the vacuum pump falls below a threshold value. It is better to make it happen.

The automobile brake device of FIG. 2 has the assist function. The control for the assistance is performed as follows. The booster boost ratio (the boost ratio by the brake booster 2) is known in advance. When the ECU 27 determines that the vehicle is stopped based on information from the wheel speed sensor, the front / rear G sensor, etc., the ECU 27 starts the control, and determines the pedal depression force (or pedal stroke and master cylinder pressure) detected by the booster boost ratio and the depression force sensor 25. The target braking force at the detected pedaling force is calculated from the estimated pedaling force). Further, when the negative pressure detected by the pressure sensor 13 falls below a threshold value, the difference between the braking force obtained by multiplying the negative pressure value at that time by the booster boost ratio and the target braking force is calculated as the required braking force. And transmitted to the ECU 9 of the ESC 8. In response to the signal, the ECU 9 issues a control command to the ESC 8. In response to the command, the normally open linear control valves 14 _-1 and 14 _-2 are closed, and the motor 19 is activated to operate the pumps 18 _-1 and 18 _{-2 and} are supplied from each pump. pressures of the wheel cylinders ₇ -1 _{to 7 -4} raised hydraulically. The pressure increasing valves 15 _-1 to 15 _-4 and the pressure reducing valves 16 _{-1 to} 16 _-4 are controlled so that the pressure increase corresponds to the required braking force.

  By the control, the target braking force (wheel cylinder pressure I in FIG. 5) is maintained. The braking force (wheel cylinder pressure II in FIG. 5) generated by amplifying the driver's brake operation force using negative pressure is supplied to the brake booster when the brake pedal is operated for a long time. Since the negative pressure becomes smaller, it gradually decreases with time. The difference between the braking force generated using the negative pressure and the target braking force, that is, the difference between the wheel cylinder pressure I and the wheel cylinder pressure II (the hatched portion in FIG. 5) is the required braking force. In this assist control, the braking force is reduced by the decrease in the output of the brake booster (required braking force), and braking by the target braking force is performed.

  In addition, said assistance control can be implemented also in the vehicle which has EPB (electric parking brake). Since EPB is well known (see, for example, Japanese Patent Application Laid-Open No. 2001-322537), a drawing and detailed description thereof are omitted.

The vacuum pump 10 has an intake port 10a and an exhaust port 10b shown in FIG. Among these, the intake port 10a is connected to the vacuum tank 12 shown in FIG.1, FIG.2, FIG.4.
The exhaust port 10b may be opened to the atmosphere. However, in an electric vehicle, it is preferable to connect the exhaust port 10b to a drive motor 38 (see FIG. 3) as a travel drive source and exhaust the exhaust into the housing of the drive motor 38. . Similarly, in a hybrid vehicle, it is preferable to exhaust the exhaust into the housing of the drive motor or into the intake manifold of an engine (not shown) that is used together.

  Since electric vehicles and hybrid vehicles are less noisy than engine vehicles, and even small sounds are conspicuous, it is better to make the exhaust sound of the vacuum pump as small as possible. The exhaust from the vacuum pump is discharged into the drive motor or into the intake manifold of the engine, and the throttled exhaust is discharged into a large space in the motor or intake manifold, resulting in the effect of reducing exhaust noise by the muffler effect. It becomes possible to meet the above requirements.

Hydraulic circuit diagram of an example of the automobile brake device of the present invention Hydraulic circuit diagram of another example of the automobile brake device of the present invention (A): Cross-sectional view showing an example of a vacuum pump, (b): Cross-sectional view along line XX in FIG. 3 (a) The figure which shows an example of the drive method of a vacuum pump The figure which shows the required braking force in braking force assistance control The figure which shows the other example of the drive method of a vacuum pump

Explanation of symbols

1 Brake pedal 2 brake booster 3 reservoir 4 master cylinder 5,6 hydraulic circuit ₇ -1 _{to 7 -4} wheel cylinders 8 ESC
9, 27 ECU
10 vacuum pump 10a inlet 10b exhaust port 11 check valve 12 vacuum tank 13,21,26 pressure sensor ₁₄ -1, _{14 -2} linear control valve ₁₅ -1 _{to 15 -4} booster valve ₁₆ -1 _{to 16 -4} vacuo valve ₁₇ -1, _{17 -2} reservoir ₁₈ -1, _{18 -2} pump 19 motor ₂₀ -1, _{20 -2} check valve _{22 -1,} 22 _-2, 23 -1 _{to 23 -4} check valve _{24 -1} , 24- ₂ cut valve 25 Treading force sensor 30 Wheel 31 Disc brake 32 Transmission 33 Front drive shaft 34 Gear 35 Propeller shaft 36 Rear drive shaft 37 Differential 38 Drive motor 39 Wheel-in motor 40 Motor shaft

Claims (4)

A vacuum pump (10) and a brake booster (2);
10) Drives by the rotating axle (33) or the rotating shaft (35) other than the axle, and the brake booster is operated by the negative pressure supplied from the vacuum pump.   The automobile brake device according to claim 1, which is configured for an electric vehicle or a hybrid vehicle.   It has an ESC (8) or EPB, and further has a vacuum pump (10) and a brake booster (2), and an axle (33) on which the vacuum pump (10) rotates or a rotating shaft (35) other than the axle ) And the brake booster operates with the negative pressure supplied from the vacuum pump, and the negative pressure supplied to the brake booster falls below a threshold value, the ESC (8) Alternatively, the automobile brake device is configured to be supplemented with an insufficient amount of braking force with respect to the target braking force by being assisted by EPB.   The automobile brake device according to any one of claims 1 to 3, wherein the exhaust of the vacuum pump (10) is discharged into an intake manifold or a drive motor (38) of the engine.

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