JPS60154905A - Nose dive control method for car - Google Patents

Abstract

PURPOSE:To avoid a nose-dive by giving a sink resistance to a front suspension when a car runs at more than a set speed, brake pressure is higher than a set brake pressure on a lower pressure side, the longitudinal acceleration is less than the set value thereof and the brake pressure is more than a set brake pressure on higher pressure side. CONSTITUTION:A car speed V, a brake pressure BP, and a longitudinal accleration G are detected respectively and they are inputted to comparators 12, 16A, 16B and 20. And when the car speed V is greater than a set car speed VN, the brake pressure BP is greater than a set brake pressure BPL on a lower pressure side, and the acceleration G is smaller than a set value GN, it is judged as generation of a nose-dive, and an AND circuit 22 outputs a nose-dive start signal. Further when the brake pressure BP is greater than a set brake pressure BPH on a higher pressure side, the nose-dive start signal is outputted irrespective of the car speed. By the nose-dive start signal, a sink resistance is given to a front suspension through a flip-flop 26. Thus, a nose-dive can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vehicle nose dive control method for suppressing the phenomenon in which the front part of the vehicle sinks inward from the rear part during braking of the vehicle.

[Wagon of invention]

Generally, when a brake is operated while a vehicle is running, a phenomenon occurs in which the front of the vehicle sinks below the rear due to the inertia of the vehicle, ie, nose dive. Since this phenomenon causes the vehicle running attitude to become unstable, attitude control is performed to prevent the nose dive.

Conventionally, methods for controlling this nose dive include a method in which a nose dive is determined by a signal for turning on the brake lamp at a speed higher than the caster speed, or a nose dive is determined when the acceleration in the longitudinal direction of the vehicle exceeds a certain value. There is a known method, and furthermore, a method of determining a nose dive when the brake pressure exceeds a certain value. Then, a signal that is determined to be a nose dive is used to apply resistance to the front suspension to prevent the nose dive from occurring.

However, the method of determining based on vehicle speed and brake lamp lighting cannot detect nose dive at low speeds, such as when the brake pedal is pressed too hard just before stopping. Further, with only longitudinal acceleration, a υ longitudinal acceleration component may be generated due to road surface input that is not caused by braking, which causes a problem of malfunction. Furthermore, with the method based on the brake pressure signal, the deceleration due to the braking force proportional to the brake pressure can be regarded as the same as the actual deceleration when the vehicle speed is above a certain level (the tire roller has a friction area of 9), but at very low speeds When braking, they do not match and an unnecessary judgment signal appears.

[Purpose of the invention]

The present invention focuses on the above-mentioned conventional problems, and reliably detects nose dive over a wide range from pressing the brake too much just before stopping to braking while driving at high speed, regardless of the vehicle speed. However, it is an object of the present invention to provide a vehicle nose dive control method that can perform control to prevent this from occurring.

[Summary of the invention]

In order to achieve the above object, the vehicle nose dive control method according to the present invention compares a set vehicle speed, a set brake pressure on the low pressure side, and a set acceleration in the longitudinal direction of the vehicle with these detected values, and detects the vehicle speed and brake pressure. Outputs a nose dive signal when the value is above the set value and the detected acceleration is below the set acceleration, or compares the set brake pressure on the high pressure side with the detected brake pressure and outputs a nose dive signal when the detected value is above the set value. Based on these nose dive signals, vehicle 7
It is configured to provide sinking resistance to the 0-side suspension.

With this configuration, in a coordinate system determined by brake pressure and vehicle speed, when the vehicle speed is below a predetermined set vehicle speed, there is an unconditional nose dive judgment area with the brake pressure set at high pressure as the boundary, and when the vehicle speed is above the set vehicle speed and low pressure is set as the boundary. In a region where the brake pressure is equal to or higher than the set brake pressure, the longitudinal acceleration is used as a determining factor to determine a nose dive determination region. Therefore, nose dive can be reliably determined over the entire range of running speeds, and posture control can be performed without causing malfunctions.

[Embodiments of the invention]

Embodiments of the vehicle nose dive control method according to the present invention will be described in detail below.

FIG. 1 shows a nose dive detection circuit used in a nose dive control method according to an embodiment. As shown in the figure, the detection factors for nose dive are vehicle speed v1, brake pressure BP, and acceleration G in the forward direction inside the vehicle, which are taken in from the vehicle as detected values. These detections may be performed using a general vehicle speed sensor, brake pressure sensor, or longitudinal G sensor.

First, since the detected vehicle speed V is generally detected as a pulse signal, this is converted into a voltage value by the F'/V converter 10 and output to the vehicle speed comparator 12.

A set vehicle speed VN is input to the vehicle speed comparator 12, and a signal is output when the detected vehicle speed V exceeds the set vehicle speed VN, for example, when the vehicle speed becomes 10 Km/A or higher.

Further, the detected brake pressure BP is output through the entire buffer 14 to the low pressure comparator 16A and the high pressure comparator 16B. The low pressure side set brake pressure BPL is input to the low pressure comparator 16A, and the high pressure comparator 16BK
, the high pressure side set brake pressure BPH is input, and when the detected value exceeds the set value, each comparator 16A, 16B
A signal is output from. Each set brake pressure differs depending on the vehicle's brake system, but for example, the low pressure side is B
PL ”” 10~20 Kf/+J, still pressure 1
1111 is set to BPH=60 to 70Kf/lI7.

Next, the detected acceleration G, like the brake pressure BP, is outputted to the acceleration comparator 20 through the buffer 18, where it is compared with a preset acceleration GN inputted therein.

In this embodiment, the acceleration detector outputs a positive value when the vehicle accelerates, and a negative value when it decelerates, so the comparator 20 detects a value different from the vehicle speed and brake pressure. A signal is output when the acceleration G becomes equal to or less than the setting IDIGN. This set acceleration is based on, for example, GN = -0,3f.

Therefore, when the acceleration detector is designed to output a positive value when the vehicle decelerates, the polarity of the comparator 20 in the embodiment of FIG. 1 is reversed, and a positive value is set as the set acceleration. For example, it is sufficient to give GN=+0.3P.

In this way, each detected value V, BPXG is calculated by the comparator 12.16A.
, 16B, and 20, the vehicle speed comparator 12, low voltage comparator 16A, and acceleration comparator 20 are connected to an AND circuit 22.
It is connected to the. Therefore, the AND circuit 22 outputs a signal when the detected vehicle speed V and the detected brake pressure BP exceed the set values VN, BPL, and the detected acceleration G becomes below the set value GN. The output signal from the AND circuit 22 in this case is used as the nose dive start signal. This means that in a coordinate system with vehicle speed and brake pressure as coordinate axes, as shown in Fig. 2, within region 1 whose boundaries are set vehicle a VN and low-pressure side brake set pressure BPL, the acceleration G in the longitudinal direction Means to determine nose dive.

Further, the AND circuit 22 is connected to an OR circuit 24, and the AND circuit 22 is connected to an OR circuit 24.
The circuit 24 is configured to receive an output signal from the high voltage comparator 16B. In this case, the output signal of the high voltage comparator 16B is compared with the preset brake pressure BPH, and it can be assumed that nose dive will occur regardless of the vehicle speed, so this is used as the nose dive start signal. Therefore, in the coordinate system, the area (2) where the brake pressure is higher than the set brake pressure on the high pressure side BPH is set as the nose dive determination area regardless of the vehicle speed (see FIG. 2). As a result, nose dive due to over-depression of the brake at low vehicle speeds of less than 10 km/A can be determined based on the brake pressure. The OR circuit 24 is connected to the 7 lip 70 gate 26, and based on the nose dive start signal from the OR circuit 24,
Seven-bit output is applied as a nose dive signal to provide sinking resistance to the front suspension.

By the way, since it is necessary to cancel the nose dive after detecting the nose dive, a cancellation circuit is configured using output signals from the high voltage comparator 16B and the acceleration comparator 20. That is, the high voltage comparator 16B is connected to the AND circuit 3 through the inverter 28, and the acceleration comparator 20 is also connected to the AND circuit 3 through the inverter 32 and the delay circuit 34.
0 VC connected. The delay time by the delay circuit 34 is, for example, 3 seconds. Therefore, the AND circuit 3o determines that the detected brake pressure BP is lower than the high-pressure side brake setting pressure BPH and the longitudinal acceleration G is less than or equal to the set acceleration when the state is equal to or greater than the set delay time. At this time, a reset signal, that is, a nose dive end signal is output to the 7-lip flop 26. To illustrate this, the longitudinal acceleration G
and brake pressure BP as the coordinate axes, as shown in Fig. 3, set acceleration GN and high pressure side set brake pressure BPH
The shaded area surrounded by Toyoshi is the end of the nose dive IJj
area.

The nose dive control method using the above-mentioned detection circuit is as follows:
The vehicle speed, brake pressure, and longitudinal acceleration are used as nose dive discrimination factors, and the discrimination area is determined based on the vehicle speed and brake pressure.If the vehicle speed is above a certain level, even a small amount of brake pressure will cause nose dive, so this can be discriminated based on the longitudinal acceleration. That's what I do. If the vehicle speed is extremely high, nose dive will occur due to over-depression of the brake, so the brake pressure that can be recognized as over-depression is set as the high-pressure side brake pressure, and if higher brake pressure occurs, Regardless of the vehicle speed, it is unconditionally determined to be a nose dive. Then, when a nose dive determination signal is output from either of them, sinking resistance is applied to the front suspension to suppress the nose dive. This resistance can be achieved by increasing the aperture resistance of the suspension.

According to such an embodiment, vehicle speed, brake pressure, and longitudinal acceleration are all taken in as factors suitable for nose dive discrimination, and these are compared with set values to make a discrimination. It is possible to detect a wide range of conditions, including nose dive caused by over-pressing the brake just before stopping. Even if there is a longitudinal acceleration component from the road surface that is not caused by braking, no malfunction will occur, and no unnecessary discrimination signal will appear.

〔Effect of the invention〕

As described above, according to the present invention, a nose dive can be reliably determined during any driving, and a signal to prevent this can be output to the front suspension, so that a vehicle with excellent attitude control can be achieved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a nose dive detection circuit, FIG. 2 is an explanatory diagram showing a nose dive determination area, and FIG. 3 is an explanatory diagram showing a nose dive end area. 10...F/V converter, 12.16A, 16B. 20...Comparator, 14.18...Buffer, 22.
30...AND circuit, 24...OR circuit, 26...
·flip flop. Agent: Tatsuyuki Unuma (and 1 other person) Procedural amendment (voluntary) March 7, 1980 Commissioner of the Patent Office Kazuo Wakasugi Display of 1711 cases 1980 Patent Application No. 9753 2 Name of invention Vehicle nose Dive control method 3 Relationship with the case of the person making the amendment Patent applicant address World Trade Center Building, 2-4-1 Hamamatsucho, Minato-ku, Tokyo 4 Subject of amendment 1) Claims column of the specification 2) Specification In Column 5, Contents of Amendment in Detailed Description of the Invention, the statement "Attachment 0" C, L-42) has been amended to read ``When entering the speed area''. 2) The scope of claims in the specification shall be amended as follows. Note 2, Claims (1) The set vehicle speed, the set brake pressure on the low pressure side, and the set acceleration in the longitudinal direction of the vehicle are compared with these detected values, and if the detected values of the vehicle speed and brake pressure are equal to or higher than the set values, and the detected acceleration is Outputs a nose dive signal when the set acceleration is Δ1, or compares the set brake pressure on the high pressure side with the detected brake pressure, and outputs a nose dive signal when the detected value is higher than the set value. A vehicle nose dive control method characterized by applying sinking resistance to a front suspension of a vehicle based on a dive signal.

Claims (1)

[Claims] (1) Compare these detected values with the set vehicle speed, low pressure side set brake pressure, and vehicle longitudinal direction set acceleration, and when the detected values of vehicle speed and brake pressure are above the set values and the detected acceleration is below the set acceleration, the nose Outputs dive signal,
Alternatively, it compares the set brake pressure on the high pressure side with the detected brake pressure, outputs a nose dive signal when the detected value is greater than the set value, and applies sinking resistance to the front suspension of the vehicle based on these nose dive signals. Features: Vehicle no-X dive control method.