JP2010247730A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control device capable of attaining both a vehicle braking characteristic and a vehicle running stability characteristic at towing and non-towing of a vehicle to be towed. <P>SOLUTION: The vehicle control device includes a control means 54 in which a distribution control is carried out for restricting the rear wheel braking force of a vehicle 2 in the case that the decelerating speed D of the vehicle 2 is more than a predetermined value Da that is pre-set in response to a vehicle speed V. The vehicle control device further includes a discriminating means 52 for discriminating whether or not the vehicle 2 tows a vehicle 4 to be towed. The control means 54 does not perform the distribution control in the case that it is discriminated by the discriminating means 52 that the vehicle 2 tows the vehicle 4 to be towed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle control device that controls a braking force of a vehicle.

  2. Description of the Related Art Conventionally, there is known a vehicle control device that performs distribution control for limiting the rear wheel braking force of a vehicle in comparison with the front wheel braking force when the vehicle deceleration is equal to or higher than a predetermined value set in advance according to the vehicle speed. (For example, refer to Patent Document 1). In general, as the vehicle deceleration increases, the vehicle load is applied to the front wheel side, the front wheel load increases, and the rear wheel load decreases. Therefore, the vehicle control device described in Patent Document 1 restricts the rear wheel braking force in comparison with the front wheel braking force when the vehicle deceleration is greater than or equal to a predetermined value, thereby locking the rear wheel ahead of the front wheel. To effectively prevent side slipping of the vehicle and improve running stability. Further, the vehicle control device described in Patent Document 1 sets a predetermined value in advance according to the vehicle speed (sets the predetermined value to a smaller value as the vehicle speed increases), so that the vehicle is likely to become unstable. Even when the deceleration is small, the above control is performed to increase the stability of the vehicle. In other words, in the low-speed state where the vehicle is relatively stable, the above control is not performed until the deceleration becomes relatively large in order to ensure braking performance. As a result, both braking performance and running stability can be achieved.

  Further, conventionally, the distribution characteristics of the rear wheel braking force and the front wheel braking force of the vehicle (tractor) are corrected when the towed vehicle (trailer) is towed and not towed to prevent the rear wheel from being locked. A technique is known (for example, refer to Patent Document 2).

JP 2001-171502 A Japanese Utility Model Publication No. 3-22057

  However, the vehicle control device described in Patent Document 1 does not mention the towed vehicle. When the towed vehicle is towed, the vehicle rear wheel load is larger than when the towed vehicle is not towed. In particular, in the semi-trailer system, since the front part of the towed vehicle is placed at the rear part of the vehicle, the rear wheel load of the vehicle increases. Thus, since the rear wheel load of the vehicle changes between when the towed vehicle is towed and when it is not towed, the braking force that causes the rear wheel to be locked changes. Therefore, both the braking performance and the running stability of the vehicle cannot be achieved both when the towed vehicle is towed and not towed.

  Further, in the technique described in Patent Document 2, since a distribution characteristic between the rear wheel braking force and the front wheel braking force is corrected, a valve device that can block the supply of compressed air at a predetermined pressure or higher when not towing is used. The technique described in 2 cannot be directly applied to the vehicle control apparatus described in Patent Document 1.

  The present invention has been made in view of the above, and provides a vehicle control device that can achieve both braking performance and running stability of a vehicle when the towed vehicle is towed and not towed. The purpose is to do.

In order to achieve the above object, the present invention performs distribution control for limiting the rear wheel braking force of the vehicle in comparison with the front wheel braking force when the deceleration of the vehicle is equal to or higher than a predetermined value set in advance according to the vehicle speed. In a vehicle control device comprising a control means,
A determination means for determining whether or not the vehicle is towing the towed vehicle;
The control unit does not perform the distribution control when the determination unit determines that the vehicle is towing the towed vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus for vehicles which can make compatible the braking performance of a vehicle and driving | running | working stability both at the time of towing of a towed vehicle and a non-towing is obtained.

It is a block diagram which shows the structure of the control apparatus for vehicles of one Embodiment of this invention. It is a side view which shows the external appearance of the vehicle carrying the vehicle control apparatus. FIG. 3 is a hydraulic circuit diagram of a braking system of the vehicle control device. It is a map which shows the correspondence of the vehicle speed V and predetermined value Da. It is a flowchart which shows an example of the process implement | achieved by ECU50. Changes in vehicle speed V, deceleration D, front wheel braking force (front wheel FR, wheel cylinder pressure Pf on the FL side), rear wheel braking force (rear wheel RR, wheel cylinder pressure Pr on the RL side) under the control of the ECU 50 It is a figure which shows an example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a vehicle control apparatus according to an embodiment of the present invention. 2A and 2B are side views showing the appearance of a vehicle equipped with the vehicle control device, wherein FIG. 2A is a side view showing a state where there is no towed vehicle, and FIG. 2B shows a state where the towed vehicle is pulled. It is a side view. The vehicle control device is a device that controls the braking force of the vehicle (tractor) 2 that can pull the towed vehicle (trailer) 4.

  The vehicle control device may be a part of a system that performs well-known ABS control or EBD (Electronic Bracket Force Distribution) control. The ABS control is a control for suppressing the lock of the wheel during braking by calculating the slip amount (rate) of each wheel based on the vehicle speed estimated from each wheel speed and each wheel speed. The EBD control is a control for suppressing a rear wheel slip at the time of braking by calculating a speed difference between the wheel speeds of the front and rear wheels.

  FIG. 3 is a hydraulic circuit diagram of a braking system of the vehicle control device. When the brake pedal 10 is depressed by the driver, hydraulic pressure corresponding to the depression force is generated in the master cylinder 11. The master cylinder 11 is connected to wheel cylinders 25 to 28 provided corresponding to the respective wheels FR to RL via liquid passages. The wheel cylinders 25 to 28 generate a braking force corresponding to the internal pressure (wheel cylinder pressure P). FR represents a right front wheel, FL represents a left front wheel, RR represents a right rear wheel, and RL represents a left rear wheel.

  The master cylinder 11 is connected to the wheel cylinders 25 and 26 of both front wheels FR and FL via solenoid valves 12 and 13. The solenoid valves 12 and 13 are electromagnetic valves that are normally closed and are opened when an electromagnetic coil provided therein is energized. Master pressure sensors 38 and 39 for detecting internal pressure (master pressure) are provided in the liquid passages between the master cylinder 11 and the solenoid valves 12 and 13, respectively. A reservoir tank 16 is connected to the master cylinder 11.

  The reservoir tank 16 is connected to the pump 17. When the pump 17 is driven by the motor 18, the pump 17 sucks the hydraulic oil, pressurizes it, and discharges it. An accumulator 19 that stores high-pressure hydraulic oil discharged from the pump 17 and a brake pressure sensor 31 that detects hydraulic pressure (brake pressure) are provided on the downstream side (discharge side) of the pump 17. Each wheel cylinder 25-28 is connected to the discharge port of the pump 17 via each linear valve 21a-24a. The linear valves 21a to 24a are electromagnetic valves that are normally opened and are closed when an electromagnetic coil provided therein is energized.

  Each of the wheel cylinders 25 to 28 is connected to the reservoir tank 16 via a corresponding pressure reducing valve 21b to 24b. The pressure reducing valves 21b to 24b are electromagnetic valves that are normally closed and are opened when an electromagnetic coil provided therein is energized. On the upstream side of each of the wheel cylinders 25 to 28, wheel cylinder pressure sensors 32 to 35 for detecting the wheel cylinder pressure P of each of the wheel cylinders 25 to 28 are provided.

  As shown in FIG. 1, the vehicle control device is configured around an electronic control unit 50 (hereinafter referred to as “ECU 50”). The ECU 50 is configured as a microcomputer including a CPU, a ROM, a RAM, and the like that are connected to each other via a bus (not shown). The CPU executes a program stored in the ROM or the like. Data generated during execution of the CPU is stored in a RAM or the like.

  As shown in FIG. 1, the ECU 50 is connected to the solenoid valves 12 and 13, the motor 18, the accumulator 19, the linear valves 21 a to 24 a, the pressure reducing valves 21 b to 24 b, and various sensors 31 to 46 through an in-vehicle network. . Output signals from the various sensors 31 to 46 are supplied to the ECU 50. The ECU 50 controls the wheel cylinder pressure P of each wheel FR to RL by controlling the linear valves 21a to 24a and the like based on output signals from the various sensors 31 to 46, as will be described in detail later. Thereby, the braking force of each wheel FR-RL is controlled.

  As various sensors, in addition to the above-described brake pressure sensor 31, wheel cylinder pressure sensors 32 to 35, master pressure sensors 38 and 39, a brake sensor 40 for detecting the depression amount of the brake pedal 10, and an depression amount of the accelerator pedal are detected. An accelerator sensor 41, wheel speed sensors 42 to 45 for detecting the wheel speeds of the wheels FR to RL, an engine speed sensor 46 for detecting the engine speed, and the like are included.

  Next, the basic operation of the hydraulic circuit under the control of the ECU 50 will be described.

  When the brake pedal 10 is depressed, a hydraulic pressure (master pressure) corresponding to the depression force is generated in the master cylinder 11. At normal times, the solenoid valves 12 and 13 are closed, so that the master pressure is not directly transmitted to the wheel cylinders 25 and 26 of both front wheels FR and FL.

  On the other hand, when the braking system is abnormal (failure), the solenoid valves 12 and 13 are energized and opened, so that the master pressure is supplied to the wheel cylinders of the front wheels FR and FL via the solenoid valves 12 and 13. 25, 26. Thereby, braking of both front wheels FR and FL is performed.

  On the other hand, during normal operation, the hydraulic oil sent from the reservoir tank 16 according to the depression amount of the brake pedal 10 is boosted by the pump 17 and the accumulator 19, and then responds via the linear valves 21a to 24a. Is supplied to the wheel cylinders 25 to 28 of the wheels FR to RL. As a result, wheel cylinder pressure P is generated, and braking of each wheel FR to RL is performed.

  At this time, the ECU 50 can independently adjust the wheel cylinder pressures P by independently controlling the open / close states of the linear valves 21a to 24a. In this way, the braking force applied to each wheel FR to RL can be controlled independently.

  When the depression of the brake pedal 10 is released, the pressure reducing valves 21b to 24b are opened, and the hydraulic oil is recovered from the wheel cylinders 25 to 28 to the reservoir tank 16 via the pressure reducing valves 21b to 24b. The cylinder pressure P is reduced. In this way, braking of the wheels FR to RL is released.

  As shown in FIG. 1, the ECU 50 is connected to a towed vehicle detection switch 48 that detects the presence or absence of the towed vehicle 4 via an in-vehicle network. The towed vehicle detection switch 48 is provided at a position that can be operated by the driver, for example, and outputs an ON signal in response to an operation by the driver when the towed vehicle 4 is connected to the vehicle 2. In case it stays off. An output signal from the towed vehicle detection switch 48 is supplied to the ECU 50.

  In the present embodiment, the towed vehicle detection switch 48 outputs an ON signal in response to an operation by the driver when the towed vehicle 4 is connected to the vehicle 2, but the present invention is not limited to this. . For example, the towed vehicle detection switch 48 may be configured to automatically output an on signal in conjunction with the towed vehicle 4 being connected to the vehicle 2.

  As shown in FIG. 1, the ECU 50 includes a determination unit (determination unit) 52 and a control unit (control unit) 54. The ECU 50 stores a control program corresponding to each of the units 52 and 54 in a ROM or the like, and causes the CPU to execute and process each control program, thereby realizing the functions of the units 52 and 54.

  When the deceleration D of the vehicle 2 is equal to or greater than a predetermined value Da, the control unit 54 uses the rear wheel braking force (rear wheel RR, wheel cylinder pressure Pr on the RL side) as the front wheel braking force (front wheel FR, wheel cylinder pressure on the FL side). Pf) has a function of performing distribution control (hereinafter referred to as “high-speed distribution control”) that is restricted as compared to Pf). The deceleration D of the vehicle 2 is calculated, for example, by differentiating the vehicle speed V estimated from each wheel speed with respect to time.

  When the deceleration D of the vehicle 2 is equal to or greater than a predetermined value Da, generally, the load of the vehicle 2 is applied to the front wheels FR and FL, the front wheel load increases, and the rear wheel load decreases. Therefore, in this case, the rear wheel braking force is limited in comparison with the front wheel braking force, so that the rear wheels RR and RL are prevented from locking before the front wheels FR and FL, and the side slip of the vehicle 2 is effectively prevented. Suppress. Thereby, running stability is improved.

  On the other hand, when the deceleration D is less than the predetermined value Da, it has a function of performing normal distribution control such as EBD control (hereinafter referred to as “normal distribution control”).

  The predetermined value Da is set in advance according to the vehicle speed V, and is set to a smaller value as the vehicle speed V increases. Therefore, the control unit 54 performs high-speed distribution control in order to increase the stability of the vehicle 2 even when the deceleration D is small on the high speed side where the vehicle 2 is likely to become unstable. In other words, the control unit 54 does not perform the high speed distribution control until the deceleration becomes relatively large in order to ensure the braking performance on the low speed side where the vehicle 2 is relatively stable. Therefore, both braking performance and running stability can be achieved.

  FIG. 4 is a map showing an example of the correspondence relationship between the vehicle speed V and the predetermined value Da. A map, a function, or the like indicating the correspondence relationship between the vehicle speed V and the predetermined value Da is stored in advance in a ROM or the like and is read out as necessary. The predetermined value Da may be appropriately set according to the type of the vehicle 2, the shift position of the transmission, and the like.

  In the example shown in FIG. 4, the predetermined value Da is set to a sufficiently large value (substantially infinite) in the first region (0 ≦ V <Va), and the vehicle speed V and the function f (V) in the second region (Va ≦ V). ). The function f (V) is a function that takes a smaller value as the vehicle speed V increases as shown in FIG.

  In the first region, since the vehicle speed is sufficiently small and the vehicle 2 is relatively stable, the braking performance is ensured without performing the high-speed distribution control. In the second region, as described above, the braking performance is ensured without performing the high-speed distribution control until the deceleration D becomes relatively large as the vehicle 2 is relatively stable and the low-speed side.

  The determination unit 52 has a function of determining whether or not the vehicle 2 is towing the towed vehicle 4. The determination unit 52 performs determination based on an output signal from the towed vehicle detection switch 48.

  The control unit 54 has a function of not performing high-speed distribution control (performing normal distribution control) when the determination unit 52 determines that the vehicle 2 is towing the towed vehicle 4.

  Generally, when the towed vehicle 4 is towed, the rear wheel load of the vehicle 2 becomes larger than when the towed vehicle 4 is not towed. In particular, in the semi-trailer system, the rear portion of the vehicle 2 is increased because the front portion of the towed vehicle 4 is placed on the rear portion of the vehicle 2. Therefore, when the towed vehicle 4 is towed, the braking force that causes the rear wheel lock is larger than when the towed vehicle 4 is not towed.

  Therefore, in this embodiment, when the towed vehicle 4 is towed, normal distribution control is performed without performing high-speed distribution control that restricts the rear wheel braking force compared to the front wheel braking force, thereby improving braking performance. Therefore, both the braking performance and the running stability of the vehicle 2 can be achieved both when the towed vehicle 4 is towed and when it is not towed.

  FIG. 5 is a flowchart illustrating an example of processing realized by the ECU 50. The process of FIG. 5 is repeatedly executed at predetermined time intervals, for example, from when the engine is turned on until the engine is turned off.

  In S <b> 100 of FIG. 5, the determination unit 52 determines the presence or absence of the towed vehicle 4 based on the output signal from the towed vehicle detection switch 48. When there is no towed vehicle (S100, YES), the process proceeds to S102. In S102, the control unit 54 determines whether or not the vehicle speed V is equal to or higher than a predetermined value Va. When the vehicle speed V is equal to or higher than the predetermined value Va (S102, YES), the process proceeds to S104. In S104, the control unit 54 determines whether the deceleration D is greater than or equal to a predetermined value Da. When the deceleration D is equal to or greater than the predetermined value Da (S104, YES), the process proceeds to S106. In S106, the control unit 54 performs high-speed distribution control, and the current process ends.

  On the other hand, if there is a towed vehicle in S100 (S100, NO), if the vehicle speed V is less than a predetermined value Va in S102 (S102, NO), or if the deceleration D is less than a predetermined value Da in S104 (S104). , NO), the process proceeds to S108. In S108, the control unit 54 performs normal distribution control, and the current process is terminated.

  FIG. 6 is a diagram illustrating an example of changes in the vehicle speed V, the deceleration D of the vehicle 2, and the wheel cylinder pressure P (braking force) under the control of the ECU 50.

  When the brake pedal 10 is depressed at time t0 shown in FIG. 6, the ECU 50 controls the linear valves 21a to 24a and the like to control the front wheel FR, the wheel cylinder pressure Pf (front wheel braking force) on the FL side, The wheel cylinder pressure Pr (rear wheel braking force) on the wheels RR and RL side is increased as shown in FIG. Thereby, the deceleration D increases and the vehicle speed V decreases.

  When the deceleration D becomes greater than or equal to a predetermined value Da set in advance according to the vehicle speed V at time t1 shown in FIG. 6, the ECU 50 performs high-speed distribution control. For example, as shown in FIG. 6, the control is performed to close the linear valves 23a, 24a on the rear wheels RR, RL, and the wheel cylinder pressure Pr on the rear wheels RR, RL is held at the hydraulic pressure P1. . Thereby, it is possible to prevent the rear wheels RR and RL from being locked before the front wheels FR and FL at a high speed, and to improve running stability.

  Subsequently, when the deceleration D increases and the vehicle speed V decreases, the deceleration D becomes less than the predetermined value Da at time t2, so the ECU 50 performs normal distribution control. For example, as shown in FIG. 6, control is performed to open the linear valves 23a, 24a on the rear wheels RR, RL, and control is performed to increase the wheel cylinder pressure Pr on the rear wheels RR, RL from the hydraulic pressure P1. .

  As a result, when the deceleration D increases, the deceleration D again becomes equal to or greater than the predetermined value Da at time t3, so the ECU 50 performs high-speed distribution control. For example, as shown in FIG. 6, the control is performed again to close the rear wheels RR and RL side linear valves 23a and 24a, and the rear wheel RR and RL side wheel cylinder pressure Pr is maintained at the hydraulic pressure P2. Do.

  In this way, the high-speed distribution control and the normal distribution control are repeated, and when the vehicle speed V becomes less than the predetermined value Va at the time t4, only the normal distribution control is performed and sufficient braking force can be ensured.

  In the example shown in FIG. 6, the wheel cylinder pressure Pr on the rear wheels RR and RL side is changed stepwise for the sake of explanation. However, the wheel cylinder pressure Pr may be changed smoothly so that the passenger does not feel uncomfortable.

  As mentioned above, although one embodiment of the present invention has been described in detail, the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the control unit 54 performs the high-speed distribution control by independently controlling the linear valves 21a to 24a, but the present invention is not limited to this. For example, the control unit 54 may perform high-speed distribution control by independently controlling the pressure reducing valves 21b to 24b.

  In the embodiment described above, the hydraulic circuit shown in FIG. 3 is used, but the present invention is not limited to this.

DESCRIPTION OF SYMBOLS 10 Brake pedal 11 Master cylinder 16 Reservoir tank 17 Pump 18 Motor 19 Accumulator 21a-24a Linear valve 21b-24b Pressure-reducing valve 25-28 Wheel cylinder 32-35 Wheel cylinder pressure sensor 42-45 Wheel speed sensor 48 Towed vehicle detection switch 50 ECU
52 determination unit (determination means)
54 Control unit (control means)

Claims (1)

In a vehicle control device comprising control means for performing distribution control for limiting a rear wheel braking force of a vehicle in comparison with a front wheel braking force when the deceleration of the vehicle is equal to or greater than a predetermined value set in advance according to the vehicle speed,
A determination means for determining whether or not the vehicle is towing the towed vehicle;
The control unit is a vehicle control device that does not perform the distribution control when the determination unit determines that the vehicle is towing a towed vehicle.