JP3919442B2 - Pneumatic detection device for hydraulic brake for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air entry detection device for a hydraulic brake for a vehicle for detecting entry of air into a brake pipe from a brake pedal to a wheel cylinder via a booster and a master cylinder with a reservoir tank.
[0002]
[Prior art]
When injecting brake fluid into the vehicle in the assembly line, the brake system piping is evacuated and injected from the reservoir tank, but the vacuum is actually low and air may remain in the piping. Therefore, in the inspection process, the entry of air is determined by measuring the braking force and sensory evaluation of the operator.
[0003]
[Problems to be solved by the invention]
Therefore, skill is required for the determination, and the results are likely to vary. In addition, when accurately measuring the remaining amount of air, air must be collected from the bleeder cap of the wheel cylinder to make a pass / fail judgment, and it takes time to remove and install tires and collect air. Is possible.
[0004]
In view of the above, the present invention provides an intrusion detection device for a hydraulic brake for a vehicle that can automatically determine in a short time whether air is in excess of a predetermined amount based on the depression characteristics of a brake pedal. With the goal.
[0005]
[Means for Solving the Problems]
In order to achieve this object, the present invention provides a hydraulic brake air for a vehicle for detecting the entry of air into a brake pipe extending from a master cylinder to a wheel cylinder, the hydraulic pressure of which is controlled by a brake pedal via a booster. An on-line detection device, an actuator for depressing and driving a brake pedal, a load sensor for detecting a depressing force and a displacement amount sensor for detecting a depressing amount respectively attached to the actuator, and detection of these load sensor and displacement amount sensor The data creation means for creating the characteristic curve data of the pedaling force with respect to the stepping amount using the signal as input, and the second order differential curve data obtained by second-order differentiation of the characteristic curve data with respect to the stepping amount are created . 2 in the depression area to be substantially kept constant after the reaction force of the change rate gradually increases The subtracted value to the standard peak value of the peak value of the derivative curve data, the rate of change of rate of change determining means for determining air remaining of more than a predetermined amount to determine whether the standard rate of change predetermined amount Shitamawaru And an output means for outputting the determination result.
[0006]
In the characteristic curve data of the pedaling force with respect to the stepping amount created by the data creating means, the mechanical play or the booster does not operate effectively at the initial stepping, and therefore, the amount of change in the stepping force with respect to the stepping amount becomes slight. When the booster starts to function effectively past this initial region, the spring constant of the brake system gradually increases as the various elastic elements associated with the brake system are compressed as the amount of depression increases. It becomes almost constant. If air bubbles are present, the spring characteristics are added in series with the original spring characteristics, and the spring constant is delayed in the compression process. The judging means is that the rate of change of the spring constant, which is the rate of change of the stepping force in the stepping region where the rate of change gradually increases and stabilizes after the initial stepping on the characteristic curve data, is attributed to a predetermined amount of air mixing. Determine whether the standard rate of change is below a specified amount.
[0007]
For this purpose, the judging means creates second-order differential curve data obtained by second-order differentiation of the characteristic curve data with respect to the depression amount, and the peak value of the second-order differential curve corresponding to the maximum rate of change of the change rate with respect to the standard peak value. more subtraction value, the change speed is determined whether or not a predetermined amount Shitamawaru standard rate of change.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of a pneumatic brake detecting device for a hydraulic brake according to an embodiment of the present invention. FIG. 3 shows a hydraulic brake stored in a reservoir tank 1 as is well known. A brake system in which the brake fluid is boosted by the booster 4 that amplifies the pedaling force by the intake pressure of the engine in response to the depression of the brake pedal 5 and is supplied to the wheel cylinder 6 via the brake hose 8. Consists of.
[0009]
The air entry detection device depresses and drives the brake pedal 5 in order to detect air that exceeds a predetermined amount in the fluid in the brake pipe that reaches the wheel cylinder 6 via the master cylinder 3 with the reservoir tank 1. An air cylinder 10 as an actuator for performing the operation, a load sensor 12 provided at the tip of the cylinder rod 11 for detecting a pedaling force, and a linear scale 13 for detecting a forward movement amount of the cylinder rod 11 as a displacement amount sensor for detecting a depression amount; The signal processing device 20 is configured to determine whether the air has entered using these detection signals as inputs.
[0010]
The air cylinder 10 is supported by a base portion 15 that inclines the cylinder rod 11 so as to come into contact with the footstep of the brake pedal 5 and advances the cylinder rod 11 by a predetermined stroke in response to a start signal. A control circuit for returning to the original position is included.
[0011]
The signal processing device 20 is configured by using a personal computer in which a program for determining whether air enters is installed, and the detection signals of the load sensor 12 and the linear scale 13 are A / D converted at the interface unit, and the amount of depression x Data creation means 21 for creating characteristic curve data of the pedaling force F with respect to the pedal, standard data storage means 22 for storing standard change rate data of the pedaling force F with respect to the depression amount x, and characteristic curve data created by the data creation means 21 The rate of change of the stepping force F with respect to the increase of the stepping amount x after the booster 4 starts to function, that is, the rate of change of the rate of change of the stepping region b, which will be described later, gradually approaches a constant rate of change (spring constant) as the spring constant gradually increases. Determining means 23 for determining whether or not the change rate of the air is lower than a predetermined amount and determining whether the air exceeds the predetermined amount, and a screen display 24a. Output means 24 for notifying the judgment data and the pass / fail result, and further notifying light or sound, for example, an abnormal amount of air with an alarm lamp 24b, and data recording means 25 for successively recording the judgment results in the memory are provided. . A start signal is supplied to the air cylinder 10 through the interface in response to the operation of the keyboard 26.
[0012]
FIG. 2 shows a typical depression-depression force characteristic curve, which is a change in the depression force F with respect to the depression amount x, where the solid line indicates that no air is mixed and the dotted line indicates that the air is included. The judging means 23 first differentiates the stepping-force characteristic curve data (A) in the dotted line, which is a change in the pedaling force F with respect to the pedaling amount x, by differentiating the pedaling amount x by the pedaling amount x, and the pedaling force F with respect to the change in the pedaling amount corresponding to the spring constant. Curve data of the change rate of the curve (B in the figure), and then the second-order differential value obtained by differentiating the curve by the amount of depression x, that is, the second-order differential curve data that is the rate of change of the spring constant is generated ( Fig. C). Subsequently, the peak value of the second-order differential pulse waveform A detected in the stepping area b is sequentially stored in the data recording unit 25 together with the vehicle body number registered in advance for each vehicle, and stored in the standard data storage unit 22. Pass / fail is determined based on whether or not it falls below a predetermined amount compared to the standard peak value of the standard second-order differential curve data corresponding to the solid line in FIG.
[0013]
In the brake system from the brake pedal 5 to the wheel cylinder 6, the brake pad from the brake pedal to the wheel cylinder via the booster and the master cylinder with the reservoir tank, the volume elastic modulus of the brake fluid, the reservoir tank 1 The expansion / contraction rigidity of the pipe between the master cylinder 3 and the wheel cylinder 6 acts as an elastic element, and when air is mixed, the spring characteristics of the bubbles are added in series. Therefore, in general, the depression-depression force characteristic curve is a polygonal line. That is, FIG. 3 shows actual measurement data of the pedaling force with respect to the change in the depression amount when the booster is activated for a certain vehicle type with the cycle of the brake pedal being about 10 seconds. The dotted line shows the results of two tests with about 1 cc of air.
[0014]
That is, in FIG. 3, the depression area “a” is an initial area where the play of the brake pedal 5 or the booster 4 does not operate effectively. The stepping area b is an actual operating area of the brake including a process in which the booster 4 is effectively operated and the above-described original elastic element of the brake system is compressed by adding bubbles. Therefore, as the brake is depressed, the spring constant of the brake system gradually increases and becomes substantially constant. At this time, if bubbles are present, the difference in the rate of change of the spring constant during the process of compressing the volume is depressed. This is reflected in the characteristic curve of region b. The stepping region c is an operating region in which the remaining air bubbles in the brake system are further compressed and the spring constant gradually increases again to become substantially constant and reaches the maximum stepping amount, that is, the booster operating ratio increases and increases with respect to the stroke. This is the operating range where the pedal effort is maximized. In this region, the bubbles are compressed to such an extent that they do not substantially exhibit a spring action. Therefore, even if the bubbles are present, they are only a polygonal line having the same rate of change as the standard characteristic curve. The relative difference between the peak value of the pulse waveform and the waveform width due to the presence or absence of air mixing is less noticeable than the beginning of the stepping region b.
[0015]
The operation of the air bleeder thus configured is as follows. The load sensor 12 attached to the tip of the cylinder rod 11 of the air cylinder 10 is brought into contact with the brake pedal 5 of the vehicle carried into the inspection process, and the air cylinder 10 is reciprocated.
[0016]
Thereby, the data creation means 21 takes in the digitized detection signals at the time of forward movement of the load sensor 12 and the linear scale 13 and creates xF characteristic curve data. The judging means 23 detects the second-order differential pulse waveform A generated at the beginning of the stepping region b where the spring constant starts to rise substantially for this characteristic curve data, and uses the peak value as the maximum value of the change rate of the spring constant. The abnormal air amount is determined based on whether or not the peak value of the change rate of the standard spring constant is below a predetermined amount. The result of the determination is displayed on screen display 24a along with the peak value of pulse-shaped waveform A, etc., and data related to this is sequentially stored for each vehicle, and if an abnormality is detected, alarm lamp 24b also displays. Informed. The peak value of the pulse waveform A is easily calculated and serves as an index of the degree of air entry.
[0017]
When the vehicle type to be inspected changes, it can be configured so that the standard data in the standard data storage means 22 is changed by operating the keyboard 26 and the judgment reference value of the judgment means 23 is changed.
[0018]
Further, as shown in FIG. 3, the characteristic curve of the depression amount-depression force shows a hysteresis characteristic with respect to the reciprocation degree of the brake pedal 5, but in some cases, it is determined based on the curve data when the brake pedal 5 is moved backward. Also good. As an actuator for depressing and driving the brake pedal 5, a motor for driving a pinion and a rack may be used, and a displacement sensor at that time may be a rotational speed sensor.
[0019]
Furthermore, although the description has been given of the case where the brake pipe air entry detecting device of the present invention is adopted in the vehicle manufacturing process, the remaining amount of air can be measured in a short time, and the brake pedal is automatically depressed, Air inspection work that was previously performed by two people can be performed by one person.
[0020]
【The invention's effect】
According to the present invention, in the characteristic curve data of the pedaling force with respect to the depression amount, it is determined whether or not the peak value of the change rate of the rate of change falls below the standard peak value by a predetermined amount, and is mixed into the brake system. A certain amount of air can be automatically detected. Therefore, it is possible to inspect the air entry in a short time in the vehicle production line.
[Brief description of the drawings]
FIG. 1 shows a configuration of a pneumatic entry detection device for a hydraulic brake for a vehicle according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operation of the apparatus.
FIG. 3 is a diagram for explaining actual measurement data of depression characteristics depending on presence / absence of air.
[Explanation of symbols]
3 Master cylinder 4 Booster 5 Brake pedal 6 Wheel cylinder 10 Air cylinder 12 Load sensor 13 Linear scale

Claims (1)

An air entry detection device for a hydraulic brake for a vehicle for detecting the entry of air into a brake pipe extending from a master cylinder to a wheel cylinder, the fluid pressure of which is controlled by a brake pedal via a booster,
An actuator for depressing the brake pedal, a load sensor for detecting the depressing force, a displacement sensor for detecting the depressing amount, and a depressing signal of these load sensor and displacement sensor as inputs. Data creation means for creating characteristic curve data of the treading force with respect to the amount; second-order differential curve data obtained by second-order differentiation of the characteristic curve data with respect to the stepping amount; and the booster starts to function and the change with respect to the stepping amount changes The rate of change of the rate of change differs from the standard rate of change by subtracting the peak value of the second-order differential curve data from the standard peak value in the stepping region that becomes substantially constant after the rate of change of the pedal force gradually increases. Judgment means for judging whether or not the air amount exceeds the predetermined amount by judging whether or not the amount is below the fixed amount, Air entering the detection device for a vehicle hydraulic brake, characterized in that an output means for outputting.

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