JPS63265172A - Measuring apparatus of hydroplaning characteristics - Google Patents

Abstract

PURPOSE:To perform tests under the same conditions as actual running conditions of a vehicle, by differentiating the difference between the speed of a body and the rotating speed of a following wheel, and identifying the hydroplaning state of the following wheel when the differentiated value is a specified value or more. CONSTITUTION:A driving-wheel rotary-speed sensor 10 and right and left following-wheel rotary-speed sensors 11 and 12 output pulse numbers corresponding to the rotary speeds. A CPU 5a in a counting and analyzing device 5 computes the body speed V0 of a vehicle 3 and the rotary speed V of the following wheel and records the speeds in a recorder 15. The difference between the body speed V0 and the rotary speed V of the following wheel is obtained and stored in a RAM 5c. Whether the difference exceeds a specified value or not is judged. The time, the speed difference and the like are outputted to a printer 17.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for measuring hydroplaning characteristics of a vehicle, and more particularly to a device for measuring hydroplaning characteristics of both heavy driven wheels.

[Prior Art] Conventionally, devices for measuring the hydroplaning characteristics of a vehicle have been used to detect the phenomenon in which when the drive wheels of a vehicle cause hydroplaning, the drive wheels lift off the road surface and their rotational speed exceeds the ground speed of the vehicle. There is a known method that uses this fact to measure the state of occurrence of the hydroplaning phenomenon.

Inventions and proposals related to the hydroplaning characteristic measuring device are disclosed in Japanese Patent Application No. 60-259453.
Hydroplaning detection devices for drive wheels have been developed.

On the other hand, in the case of a driven wheel of a vehicle, unlike a driving wheel to which driving torque is applied, even if a hydroplaning phenomenon occurs, the rotational speed of the driven wheel will not exceed the ground vehicle speed. Therefore, conventionally, when investigating the condition in which the driven wheel causes hydroplaning, the vehicle is test driven on a special road surface that allows the driving condition of the vehicle to be observed from below, such as a road surface made of tempered glass, etc. The presence or absence of hydroplaning is investigated by observing the ground contact status of the driven wheels. Additionally, we are conducting research on tire tread grooves that are less susceptible to hydroplaning.

[Problems to be Solved by the Invention] However, in the case of using the above-mentioned tempered glass etc., the following problems have been considered.

(a) That is, a special road surface such as a reinforced glass surface that allows the driving state of a vehicle to be observed from below has different properties, such as a coefficient of friction, from a normal road surface for vehicle driving.

Therefore, there is a problem that the conditions that cause the hydroplaning phenomenon may be different from those when the vehicle is actually running. There was a problem that the judgment results were sometimes inconsistent.

The hydroplaning characteristic measuring device of the present invention was created in view of the above problems, and its purpose is to test the occurrence of hydroplaning phenomenon in driven wheels.
The objective is to perform the determination on a road surface similar to a road surface for normal vehicle driving and to obtain consistent determination results.

Structure of the Invention [Means for Solving the Problems] The hydroplaning characteristic measuring device of the present invention, as shown in the basic structure in FIG. , driven wheel rotation speed detection means (M2) for detecting the rotation speed of the driven wheels of the vehicle; The present invention is characterized by comprising: a differentiating means (M3); and a determining means (M4) which determines that the driven wheel is in a hydroplaning state when the differential value of the speed difference is equal to or greater than a predetermined value.

Here, the subtraction/differentiation means (M3) may be any means that calculates the speed difference between the detected vehicle speed and the rotational speed of the driven wheels, and differentiates the speed difference with respect to time. It is conceivable that the arithmetic circuit be integrated with the determining means (M4).

[Function] The hydroplaning characteristic measuring device of the present invention having the above configuration functions as follows.

The hydroplaning characteristic measuring device of the present invention subtracts and differentiates the speed difference between the vehicle body speed detected by the vehicle body speed detection means (Ml) and the rotational speed of the driven wheel detected by the driven wheel rotational speed detection means (M2). The means (M3) calculates and differentiates the speed difference, and when the differential value of the speed difference is equal to or greater than a predetermined value, the determining means (M4) operates to determine that the driven wheel is in a hydroplaning state.

[Example] Next, a preferred example will be described with reference to the drawings in order to further clarify the structure of the hydroplaning characteristic measuring device of the present invention.

The hydroplaning characteristic measuring device of this embodiment has a second
As shown in the figure, it is comprised of a vehicle 3 as a rear wheel drive vehicle to be tested, and a measurement analyzer 5 as a subtraction/differentiation means and a determination means mounted on the vehicle 3.

The vehicle 3 includes a driving wheel rotation speed sensor 10 as a vehicle body speed detection means, a left driven wheel rotation speed sensor 11 attached to the axle of the left front driven wheel of the vehicle 3, and a right front wheel as a driven wheel rotation speed detection means. A right driven wheel rotation speed sensor 12 attached to the axle of the driven wheel is provided. In this embodiment, the drive wheel rotational speed sensor 10, which is normally provided in the transmission section of the vehicle, is used as the vehicle speed detection means, but a ground vehicle speed sensor that utilizes the Doppler effect or the like may also be used. Note that the recorder 15 and printer 17 connected to the measurement analyzer 5 record and print the data at that time based on the time axis according to the output of the measurement analyzer 5.

As shown in FIG. 3, the measurement analyzer 5 includes a CPU 5a, an RO
It is configured as a logic operation circuit mainly consisting of an M5b, a RAM 50, etc., and a timer 5d, an external input circuit 5e, and an external output circuit 5f interconnected by a bus 5g.

The external input circuit 5e of the measurement analyzer 5 includes the drive wheel rotation speed sensor 10. Left and right driven wheel rotational speed sensors 11 and 12, etc. are connected, and an external output circuit 5f is connected to a recorder 15 and a printer 17.

The operation of this embodiment having the above configuration will be explained using the flowchart of the "hydroplaning detection routine" shown in FIG. 4 as appropriate.

When the test run of the vehicle 3 shown in FIG. 2 starts, the driving torque of the rear wheels as the driving wheels is also transmitted to the driven wheels through the vehicle body, and the front wheels as the driven wheels also start rotating. At this time, the driving wheel rotational speed sensor 10 and the left and right driven wheel rotational speed sensors 11 and 12 output the number of pulses corresponding to their rotational speeds.

The CPU 5a of the measurement analyzer 5 calculates the vehicle body speed Vo of the vehicle 3 and the rotational speed Vt of the driven wheels according to the number of output pulses.

That is, first, the CPU 5a clears the value of the timer 5d to zero, and then starts a counting operation (step 100).
The driving wheel rotation speed sensor 10. The number of pulses output by the left and right driven wheel rotation speed sensors 11 and 12 is read (step 110), and then the CPU
5a is the average rotational speed v of the left and right driven wheels based on the number of pulses input from the left and right driven wheel rotational speed sensors 11 and 12.
8 calculation processing is performed (step 120).

Similarly, the vehicle body speed Vo @ is calculated based on the number of pulses input from the drive wheel rotational speed sensor 10, and the process of outputting the vehicle body speed vO to the recorder 15 is performed (
Step 130). As a result, the recorder 15 is marked with
The vehicle body speed V, which changes from moment to moment, is recorded.

Next, the calculated vehicle speed Vo and the rotation speed of the driven wheels■
Find the speed difference VO-V between RA and
A process of storing the data in M5c is performed (step 140).

The processing of steps 110 to 140 described above is performed until the counter t counted by the timer 5d reaches the predetermined time t1 (>
This is continued until > exceeds (step 150).

If an affirmative determination is made in step 150, CPtJ5
a calculates the difference Δ(VO-■) between the speed difference calculated and stored in this process last time and the speed difference excluded this time, and sends the calculated difference Δ(VO-■) to the recorder 15. Output (step 160).

In the following step 170, the obtained difference Δ(Vo−V
) is greater than or equal to a predetermined setting value a. Here, if the determination is affirmative, it means that the driven wheel has caused a hydroplaning phenomenon. this is,
This is due to the following reasons.

Generally, when a vehicle's driven wheels cause hydroplaning, the driven wheels lift off the road surface, causing
The only force that rotates the driven wheel is the inertial force of the driven wheel. Therefore, the rotational speed of the driven wheel decreases due to the rolling resistance (for example, the force of a bearing used in the driven wheel) applied to the driven wheel. Here, if the rotational inertia moment, rolling resistance, radius of one rotation, coefficient of friction with the road surface, and weight of the driven wheels of the vehicle 3 are I, F, r, μ, and W, respectively,
From the rotational speed V, the following equation is established.

I/r2 xdV/dt=μW-F This gives dV/dt=r2 /IX (μW-F)d (Vo-
V>/dt=dVo/dt+(F-μW)xr2/1 holds true. Now, if the vehicle speed VO is constant, -dV
/dt= (F-μWE)xr2 /I, and if the driven wheel is causing hydroplaning, the frictional force is μ-0, so -dV/dt''5r2F/1 is approximate. holds true. In other words, since the vehicle speed Vo is constant, the rotational speed V of the driven wheel is equal to the acceleration −r2
The vehicle will be decelerated according to the F/I. As a result, if the set value a is set as a-r2F/I, when d (Vo-V)/dt≧a holds true, the driven wheel is causing a hydroplaning phenomenon.

In this embodiment, in step 170, the vehicle speed ■O
The hydroplaning phenomenon is determined when the difference Δ(VO-V) per unit time between the rotational speed V of the driven wheel and the rotational speed V of the driven wheel becomes larger than the set value a.

If an affirmative determination is made in step 170, the data at that time, for example, the time or speed difference Δ(Vo−V
), etc., to the printer 17 (step 180). After this, or if a negative determination is made in step 170, the process returns to step 100.

According to the hydroplaning characteristic measuring device of this embodiment described in detail above, it is possible to measure and detect the hydroplaning phenomenon of the driven wheels of a vehicle without using a special road surface where the driving condition can be observed from below. can. This makes it possible to test whether hydroplaning occurs in the driven wheels under the same conditions as when the vehicle is actually running, and has the excellent effect of further contributing to research on tire tread grooves. Furthermore, since the state of occurrence of the hydroplaning phenomenon is determined by comparing it with the set value a, the test results are consistent and an extremely precise test can be performed. Furthermore,
In the present embodiment, a recorder 15 and a printer 17 are used to record the running state of the vehicle 3 in detail. This has the effect of making it possible to analyze the state of the hydroplaning phenomenon in the driven wheels more closely and accurately.

The hydroplaning characteristic measuring device of the present invention is not limited to the above-mentioned embodiments, and can be implemented in various forms without departing from the gist of the present invention. For example, in order to detect more quickly when the driven wheel is causing hydroplaning, the rolling resistance F of the driven wheel is
It is also possible to have a configuration in which the value is further increased. Furthermore, the measurement analysis unit 5 of this embodiment is configured integrally with an electronic control device such as an electronic fuel injection control device normally mounted on a vehicle, so that when a driven wheel generates a hydroplaning phenomenon, the driver can It may be configured to issue a warning. This has an excellent effect in that the driver can take measures such as reducing the speed of the front driven wheels as the steered wheels when a hydroplaning phenomenon occurs. Further, in this embodiment, the average rotational speed V of the left and right driven wheels is calculated, but it is also possible to calculate the rotational speeds of the left driven wheel and the right driven wheel, respectively, and determine whether or not hydroplaning is generated for each of them. It may be configured to measure. In addition, in this embodiment, the measurement analyzer 5
Although the configuration is such that the equipment is mounted on the vehicle 3, it is also conceivable to use a so-called telemeter system (remote meter) or the like.

According to the hydroplaning characteristic measuring device of the present invention,
It is possible to measure and detect the hydroplaning phenomenon of the driven wheels of a vehicle without using a special road surface where the vA of the driving condition can be observed from below.

This makes it possible to test the occurrence of hydroplaning on the driven wheels under conditions similar to actual vehicle driving.
It has an excellent effect that it can be used for research on tire tread grooves.

Furthermore, since the state of occurrence of the hydroplaning phenomenon is determined by comparing it with a predetermined value, the test results are consistent and an extremely precise test can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the basic configuration of a hydroplaning characteristic measuring device according to the present invention, FIG. 2 is a schematic configuration diagram showing the configuration of a hydroplaning characteristic measuring device according to an embodiment of the present invention, and FIG. 3 is a measurement analysis FIG. 4 is a block diagram showing the configuration of the device 5, and FIG. 4 is a flowchart showing the processing of the "hydroplaning detection routine." 5...Measurement analyzer

Claims (1)

[Scope of Claims] Vehicle speed detection means for detecting the vehicle body speed of a vehicle; driven wheel rotation speed detection means for detecting the rotation speed of a driven wheel of the vehicle; and the detected vehicle body speed and the rotation speed of the driven wheel. and a subtracting/differentiating means for calculating the speed difference and differentiating the speed difference, and a determining means for determining that the driven wheel is in a hydroplaning state when the differential value of the speed difference is equal to or greater than a predetermined value. Characteristic hydroplaning characteristic measuring device.