JP2868086B2 - Braking force holding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking force holding device, and in particular, holds a braking force by controlling an electromagnetic check valve as a braking force holding valve under a certain condition. It concerns the device. [Prior Art] When starting a vehicle stopped on an uphill road, in a conventional vehicle, a driver uses a parking brake (handbrake) with one hand, gradually applies a braking force to the vehicle, and gradually releases a clutch while maintaining the vehicle in a stopped state. And go down the accelerator pedal at the same time. During this time, the parking brake is gradually released. However, since a complicated operation is required while coordinating such a brake and an accelerator, skill is required to perform a smooth start, and a so-called engine stall or vehicle retreat is caused. Accordingly, the present applicant has filed Japanese Patent Application No. 58-117483 (Japanese Unexamined Patent Application Publication No.
No. 11719), a control electromagnetic check valve is provided between a master cylinder and a wheel cylinder associated with a brake pedal, and this electromagnetic check valve can be started smoothly from a stopped state on an uphill road. Accelerator pedal sensor, clutch stroke sensor, engine rotation sensor,
Output signals from the brake pedal switch, gear position switch, select position switch, and vehicle speed sensor are input to the electronic control unit (CPU), and the electronic control unit applies an electromagnetic check valve under certain conditions based on these input signals. The braking force is held or released by the wheel cylinder by vibrating or deenergizing. Such a braking force holding device is excellent in that the operation of the electromagnetic check valve and the operation of the friction clutch can be controlled synchronously, so that starting on an uphill road can be performed smoothly without any skill. However, due to wear of clutch-driven plates, changes over time, and variations, as well as variations in clutch stroke sensors and variations during assembly, the braking force at the time of starting was released too quickly, causing the vehicle to retreat on an uphill road. Or it was too slow, causing the brake to drag. In order to solve this drawback, the present inventor has previously proposed a braking force holding device shown in FIG. 4 in Japanese Patent Application No. 62-94042 of the present applicant. Hereinafter, this apparatus will be schematically described. In FIG. 4, reference numeral 1 denotes an accelerator switch which is turned on (contact connection) when the accelerator pedal 2 is released and turned off when a depression is detected. Reference numeral 3 denotes a variable resistor which detects a stroke amount (position) when the clutch pedal 4 is depressed. A clutch position sensor 5; a parking brake switch 5 which is turned on when the parking (hand) brake 6 is pulled to perform a braking operation; a foot brake (stop lamp) switch 7 which is turned on when a brake pedal 8 is depressed; Is a neutral switch that turns on when gear neutral of the transmission (T / M) 10 is detected, and 11 is a transmission
A vehicle speed sensor for detecting the speed of the vehicle from the rotation of the output shaft 12 of 10; a variable resistor 13 for manual setting as a clutch connection determination adjusting element provided near the driver's seat; 14 a switch 1;
5, 7, 9 and detection signals and variable resistance of sensors 3 and 11
A control unit (CPU) 15 serving as a control means for inputting the output signal of the brake pedal 13 when the brake pedal 8 is deenergized by the output signal from the control unit 14.
When the brake pedal 8 is depressed, the braking oil sent to the wheel brake 17 through the hydraulic routes 16a and 16b flows back through the route 16b when the brake pedal 8 is released to release the braking force. This is a braking electromagnetic check valve that prevents the control oil from flowing back together with the hydraulic route 16a and maintains the braking force at that time. Note that the output signal of the sensor 3 and the output signal of the variable resistor 13 are once A / D converted by an A / D converter at the entrance of the control unit 14 in the same manner as in normal analog signal processing.
After the / D conversion, it is used for control. FIG. 5 is a diagram showing a flowchart of a program stored in the control unit 14 in advance. In this apparatus, the accelerator 2 is depressed as a condition for putting the electromagnetic check valve 15 for holding the braking force in the braking force holding state. The clutch position is larger than the value of the adjustment position by the adjusting element 13 or the gear is in the neutral state (step S2), and the foot brake is depressed (step S3). , The vehicle speed must be lower than a certain value (step S5). The condition for setting the check valve 15 to the braking force release state is that the gear is not in the neutral state and the clutch position is smaller than the adjustment value and is on the clutch contact side (steps S2 and S1).
1). The braking force holding conditions include whether the parking brake is applied (step S4), whether the deceleration of the vehicle speed has fallen below a predetermined value (step S6), whether the vehicle speed sensor is normal (step S7), and It is also checked whether a series of steps has continued for a predetermined time (steps S8 and S10). As described above, the variable resistor 13 for manual setting as the clutch connection determination adjusting element is used, so that the driver can adjust the determination of the amount of depression of the clutch, and this is compared with the output of the clutch sensor 3 to control without variation. The power is being maintained. In addition to this, the inventor turned on / off the adjusting element in order to avoid the abnormal setting of the variable resistance adjusting element for manual setting.
There has also been proposed a braking force holding device in which an upper limit and a lower limit are set in an adjustment position using an off switch. [Problems to be Solved by the Invention] Such a conventional braking force holding device energizes (turns on) a braking electromagnetic check valve when certain conditions are satisfied, and thereby the braking force by the foot brake at that time. The brake fluid (brake oil) of the check valve is held during the holding of the braking force.
Leaks due to aging or the like and lowers the holding pressure. Therefore, when the vehicle is stopped on a slope, there is a problem that the vehicle moves forward or backward and is extremely dangerous. Therefore, an object of the present invention is to realize a device that can notify a driver of a danger of maintaining braking force. [Means for Solving the Problems] As means for solving the above problems, in the braking force holding device according to the present invention, between the braking fluid pressure generating means linked to the brake pedal and the brake operating means, A braking force holding valve for holding and releasing a braking force under predetermined conditions; and a braking force holding time when the braking force holding valve is controlled by controlling the braking force holding valve. Control means for generating an alarm signal for urging the resetting of the braking force holding when the pressure becomes equal to or higher than a set value at which the pressure drop due to the leakage of the braking fluid of the holding valve occurs. [Operation] In the braking force holding device of the present invention, when the braking force holding valve is energized and the braking force is being held, the set time during which the braking force holding pressure of the braking fluid decreases due to aging or the like. When the time has elapsed, an alarm is generated to prompt the driver to increase the brake or use the parking brake in advance. [Embodiment] Hereinafter, an embodiment of the braking force holding device according to the present invention will be described. FIG. 1 shows a hardware configuration according to an embodiment of a braking force holding device according to the present invention.
In addition to the configuration shown in the figure, a timer counter TC is provided in the control unit 14, and an indicator (may be a buzzer) 20 for generating an alarm is provided. FIG. 2 shows an embodiment of a flowchart of a program stored in the control unit of FIG.
The operation of the present invention will be described with reference to this flowchart. This embodiment focuses on the holding time that causes the holding braking force to be lost. First, the control unit 14 as the control means determines whether the check valve 15 is ON (braking force holding state) or OFF (braking force holding state). It is checked whether or not the braking force is released (step T2 in FIG. 2). If it is ON, the timer counter TC in the control unit 14 is incremented by "1" (step T6). When the count value exceeds the set value at which the braking force can be reduced, the indicator 20 is energized (at step T4), and the vehicle moves to the driver even while the braking force is being held. Notify that you may be As a result, the driver steps on the foot brake 8. When the braking force is released, the timer counter TC
Is reset (step T8), and the indicator 20 is deactivated (step T5). Also, when the count value of the timer counter TC does not exceed the set value, the indicator 20 is deactivated similarly (step T5). FIG. 3 shows a flowchart of a program for turning on / off the electromagnetic check valve 15 for braking which is executed after the flowchart of FIG. 2, and is substantially the same as the flowchart shown in FIG. It is. That is, in this flowchart as well, the parking brake is in the braking state, or the gear is shifted, and the actual clutch position is smaller than the adjustment position by the adjustment element 13 on the contact side (the value is smaller on the contact side of the clutch). ), The check valve 15 is turned off to release the braking force. However, in step T25, the values of the foot brake switch 7, the neutral switch 9, the clutch position sensor 3, the parking brake switch 5, and the adjustment element 13 have been read. In this way, if the driver depresses the foot brake pedal 8 after issuing the alarm in the routine of FIG. 2, the braking force at that time is newly held, and the forward or backward movement of the vehicle can be prevented. It is needless to say that it is easy for those skilled in the art to configure the above software control with a hardware circuit as shown in Japanese Patent Application No. 62-94042. [Effects of the Invention] As described above, in the braking force holding device of the present invention, a decrease in the held braking force is detected based on the elapsed time of the holding state of the braking force and an alarm is issued, so that the vehicle on a slope is provided. Thus, there is an effect that a safe stop state can be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hardware configuration diagram showing one embodiment of a braking force holding device according to the present invention, and FIG. 2 is a diagram showing one example stored and executed in a control unit of FIG. FIG. 3 is a flowchart of a program as an embodiment, FIG. 3 is a known flowchart for holding and releasing a braking force connected to the flowchart of FIG. 2, and FIG. 4 is a braking force holding according to a conventional example. FIG. 5 is a hardware configuration diagram of an embodiment of the device, FIG. 5 is stored in the control unit of FIG. 4,
FIG. 4 is a flowchart of the same program as the flowchart of FIG. 3. In FIG. 1, TC indicates a timer counter, 14 indicates a control unit, 15 indicates an electromagnetic check valve for braking, and 20 indicates an indicator. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A braking force holding valve that is provided between the braking fluid pressure generating means associated with the brake pedal and the brake operating means and holds and releases a braking force under predetermined conditions; and controls the braking force holding valve. When the braking force holding time is equal to or greater than a set value at which the pressure drop due to the leakage of the braking fluid of the braking force holding valve is performed when the braking force holding is performed, an alarm prompting to reset the braking force holding. Control means for generating a signal;
A braking force holding device comprising: