JP2007010511A - Inclination detection device and vehicle equipped with inclination detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inclination detection device capable of detecting the angle of inclination of a vehicle by installing a sensor hardly influenced by a disturbance, while suppressing cost increase, and a vehicle equipped with the inclination detection device. <P>SOLUTION: In this inclination detection device equipped with buffer members whose each length is changed corresponding to a load applied to a plurality of wheels positioned on the front and the back of the vehicle, the angle of inclination in the front-to-back direction of the vehicle is detected based on a length variation of each buffer member. In each buffer member having an inner cylinder filled with working fluid, an outer cylinder for forming an air chamber between itself and the inner cylinder, a piston movable with respect to the inner cylinder, an orifice for guiding the working fluid from the inner cylinder into the air chamber by movement of the piston, and a thermistor arranged in the air chamber. In the device, the length variation of each buffer member is detected based on the electrical quantity relative to the thermistor, and the angle of inclination in the front-to-back direction of the vehicle is calculated based on the length variation of each buffer member installed on each wheel positioned in the front and the back, and the calculated angle of inclination is transmitted to the outside. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inclination detection device that detects an inclination angle in the front-rear direction of the vehicle by detecting a load applied to the vehicle from the outside for each wheel, and a vehicle including the inclination detection device.

  As electronic control of vehicles progresses, many systems have been developed to increase the safety level of night driving by adjusting the optical axis direction of the headlamp that illuminates the front at night by accurately grasping the vehicle's tilt state. Has been. For example, in Patent Document 1, two ultrasonic sensors are installed in the vehicle width direction, and the inclination angle of the vehicle is estimated by measuring the time difference for receiving the reflected wave of the ultrasonic wave emitted from the ultrasonic sensor. An optical axis adjusting device that adjusts the optical axis direction of the optical axis is disclosed.

In Patent Document 1, two ultrasonic sensors are arranged substantially horizontally in the left-right direction of the vehicle, and the ultrasonic waves emitted from the ultrasonic sensors are emitted toward the road surface. Then, by receiving the reflected wave from the road surface, a difference in ultrasonic reflection time is obtained, a vehicle height difference is calculated based on the reflection time difference, and a vehicle inclination angle is calculated.
JP-A-5-221251

  However, the vehicle tilt angle detection method described above has a problem that it is necessary to provide an expensive ultrasonic sensor, and the cost of the entire apparatus is increased. In order to eliminate such high cost, for example, a method for detecting the tilt angle using a relatively inexpensive sensor such as a magnetic displacement sensor for detecting the length of the coil spring has been developed.

  However, when obtaining the tilt angle based on the length of the coil spring, the sensor must be installed near the vehicle wheel, and the sensor may be damaged by disturbances such as collision of foreign matter such as mud, pebbles, etc. It is easy to be affected by the occurrence of. Therefore, it is necessary to provide protective tools such as a sensor cover and a protective container, and there is a problem that the cost reduction effect is halved.

  The present invention has been made in view of such circumstances, and by attaching a sensor that is less susceptible to disturbances such as collisions of foreign matter such as mud and pebbles that are splashed from the road surface while suppressing high costs. An object of the present invention is to provide a tilt detection device capable of detecting the tilt angle of a vehicle based on the length of a buffer member installed for each wheel, and a vehicle including the tilt detection device.

  In order to achieve the above object, a tilt detection apparatus according to a first aspect of the present invention includes a buffer member whose length varies according to loads applied to a plurality of wheels positioned in front and rear of a vehicle, and variation in the length of the buffer member. In the inclination detection device that detects the inclination angle of the vehicle in the front-rear direction based on the amount, the buffer member includes an inner cylinder filled with hydraulic fluid, and an outer cylinder that forms an air chamber between the inner cylinder, A piston movable relative to the inner cylinder; an orifice for guiding hydraulic fluid from the inner cylinder to the air chamber by movement of the piston; and a thermistor disposed in the air chamber; Detecting means for detecting the amount of fluctuation of the length of each buffer member based on the amount of electricity, and the longitudinal direction of the vehicle based on the amount of fluctuation of the length of the buffer member installed on the front and rear wheels. Inclination angle calculation means for calculating the inclination angle , Characterized in that it comprises a sending means for sending the tilt angle calculated externally.

  In addition, in the tilt detection device according to the second invention, in the first invention, the vehicle is a four-wheeled vehicle, and an average value of the lengths of the buffer members installed on the wheels located at the front of the vehicle, and the rear of the vehicle The inclination angle in the front-rear direction of the vehicle is calculated on the basis of the average value of the lengths of the buffer members installed on the wheels located in the vehicle.

  According to a third aspect of the present invention, in the first or second aspect, the thermistor has a characteristic that the resistance value increases as the degree of immersion in the hydraulic fluid increases.

  According to a fourth aspect of the present invention, there is provided a vehicle including any one of the tilt detection devices according to the first to third aspects.

  In the first invention, the inner cylinder filled with the working fluid, the outer cylinder forming an air chamber between the inner cylinder, the piston movable with respect to the inner cylinder, and the movement of the piston from the inner cylinder A buffer member having an orifice for guiding the hydraulic fluid to the air chamber and a thermistor disposed in the air chamber is provided, and the amount of fluctuation of the length of each buffer member based on the amount of electricity related to the thermistor, for example, the current value Is detected. An inclination angle in the front-rear direction of the vehicle is calculated based on the detected variation in length for each buffer member. Accordingly, the sensor is not affected by disturbances such as the collision of foreign matter such as mud and pebbles that are splashed from the road surface without the need for a protection tool for the sensor portion. Therefore, high reliability of the detection value from the sensor can be maintained while avoiding high cost due to a complicated configuration, and the tilt angle in the front-rear direction can be calculated with high accuracy.

  In the second invention, in the case of a four-wheeled vehicle, the average value of the lengths of the buffer members installed on the wheels located at the front of the vehicle and the lengths of the buffer members installed on the wheels located at the rear of the vehicle Based on the average value, the inclination angle of the vehicle in the front-rear direction is calculated. This makes it possible to calculate the tilt angle in the front-rear direction while minimizing errors due to the tilt in the left-right direction.

  In the third invention, the thermistor has a characteristic that the resistance value increases as the degree of immersion in the hydraulic fluid increases. As a result, a load is applied to the piston, and the electrical resistance value increases and the current value decreases as the degree of immersion of the thermistor into the hydraulic fluid flowing out of the orifice increases. Therefore, the load applied to the piston, that is, the load applied to the wheel can be estimated in substantially real time, and the tilt angle of the vehicle can be reliably detected.

  In the fourth aspect of the invention, by including the above-described inclination detection device, it is possible to accurately detect the inclination angle in the front-rear direction of the vehicle using an inexpensive sensor.

  According to the first aspect of the present invention, the sensor is not affected by a disturbance such as a collision of foreign matter such as mud and pebbles splashed from the road surface without requiring a protective tool for the sensor portion. Therefore, the reliability of the detection value from the sensor can be maintained high while avoiding the high cost due to the complicated configuration, and the tilt angle in the front-rear direction can be calculated with high accuracy.

  According to the second invention, in the case of a four-wheeled vehicle, it is possible to calculate the tilt angle in the front-rear direction while minimizing the error due to the tilt in the left-right direction.

  According to the third aspect of the invention, the electrical resistance value increases and the current value decreases as the load is applied to the piston and the degree of immersion of the thermistor into the hydraulic fluid flowing out of the orifice increases. Therefore, the load applied to the piston, that is, the load applied to the wheel can be estimated in substantially real time, and the tilt angle of the vehicle can be reliably detected.

  In the fourth aspect of the invention, by including the above-described tilt detection device, it is possible to accurately detect the tilt angle in the front-rear direction of the vehicle using an inexpensive sensor.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

  FIG. 1 is a block diagram showing a configuration of a tilt detection apparatus according to an embodiment of the present invention. The inclination detection device according to the present embodiment buffers a load applied to the wheel 1, for example, a load from the road surface, by the buffer member 2 provided for each wheel 1 of the vehicle. The buffer member 2 is connected to a current detection circuit 3 that detects a current value output according to the degree of expansion / contraction, and the current value detected by the current detection circuit 3 is transmitted to the arithmetic device 5 via the in-vehicle LAN 6. . Further, the arithmetic device 5 is connected to another arithmetic device 5 via the in-vehicle LAN 6, and transmits and receives various data.

  FIG. 2 is a perspective view showing a configuration of the buffer member 2 of the inclination detecting device according to the embodiment of the present invention. As shown in FIG. 2, the cushioning member 2 of the tilt detection device according to the present embodiment includes an outer cylinder 22 and an inner cylinder 23 that are movable together with the cover 21 as an integral part of a substantially cylindrical cover 21. I have. The inner cylinder 23 is filled with a hydraulic fluid (for example, hydraulic oil) 25, and a valve function for taking the hydraulic fluid 25 into and out of the outer cylinder 22 and the air chamber 24 disposed between the inner cylinder 23. Is provided with an orifice 26.

  When the piston 28 disposed at the tip of the working fluid 25 and the rod 27 provided in the cover 21 is pushed down, the orifice 26 is pushed down and flows into the air chamber 24. That is, the air chamber 24 serves as a reservoir for the hydraulic fluid 25 pushed out through the orifice 26. 3 and 4 are partial cross-sectional views showing the relationship between the position of the piston 28 and the state of the hydraulic oil 25. FIG. 3 shows an inflow state of the hydraulic oil 25 into the air chamber 24 in each case when the piston 28 is pushed down, and FIG. 4 shows a case where the piston 28 is pulled up.

  As shown in FIG. 3, when the piston 28 is pushed down, the working fluid 25 flows into the space after the piston 28 has moved downward through the orifice 29 disposed in the piston 28 itself, It can move smoothly while buffering the load. A part of the hydraulic fluid 25 flows into the air chamber 24 through the orifice 26 provided in the inner cylinder 23. Therefore, the liquid level of the working fluid 25 in the air chamber 24 rises.

  As shown in FIG. 4, when the piston 28 is pulled up, the working fluid 25 that has flowed into the space after the piston 28 has moved upward passes through the orifice 29 disposed in the piston 28 itself. The piston 28 can smoothly move while buffering the load. Further, the working fluid 25 in the air chamber 24 flows into the inner cylinder 23 through the orifice 26 provided in the inner cylinder 23. Therefore, the liquid level of the working fluid 25 in the air chamber 24 is lowered.

  In the air chamber 24, a thermistor 30 for detecting the liquid level of the working fluid 25 that moves up and down is provided. The thermistor 30 has a lower ambient temperature and a higher resistance value as the surface area immersed in the hydraulic fluid 25 increases. Therefore, when a constant voltage is applied to the thermistor 30, the liquid level can be estimated according to the fluctuation of the current value flowing through the load resistance.

  Further, the buffer member 2 is protected by the outer cylinder 22 and the inner cylinder 23, and does not require special protective tools, and is detected by disturbance such as collision of foreign matter such as mud and pebbles that are splashed from the road surface. There is no risk of malfunction. Therefore, it is easy to maintain the liquid level detection accuracy of the detected hydraulic fluid 25 at a certain level.

  FIG. 5 is a diagram schematically showing the arrangement state of the thermistor 30. The liquid level of the hydraulic fluid 25 moves up and down according to the vertical movement of the piston 28, and the liquid level at which the thermistor 30 is immersed in the hydraulic fluid 25 varies. The current detection circuit 3 applies a constant voltage V to the load resistor R, and detects the current I flowing through the load resistor R. In the thermistor 30, when the piston 28 is pushed down, the liquid level of the hydraulic fluid 25 increases, and the surface area immersed in the hydraulic fluid 25 increases. As the surface area immersed in the hydraulic fluid 25 increases, the temperature around the thermistor 30 decreases and the electrical resistance value of the thermistor 30 increases. Therefore, the current I flowing through the load resistance R decreases. Conversely, when the piston 28 is pulled up, the liquid level of the hydraulic fluid 25 decreases, and the surface area immersed in the hydraulic fluid 25 decreases. As the surface area immersed in the hydraulic fluid 25 decreases, the temperature around the thermistor 30 increases and the electrical resistance value of the thermistor 30 decreases. Therefore, the current I flowing through the load resistance R increases.

  The resistance value R of the thermistor 30 varies according to (Equation 1) when the thermistor constant is B and the resistance value at the temperature T0 is R0.

  If the applied voltage is V, and the current value is I, the resistance value R is R = V / I. Therefore, the temperature T of the thermistor 30 can be obtained from (Equation 2).

  Therefore, the liquid level h can be obtained as an experimental value represented by (Equation 3) with reference to the liquid level h0 at the temperature T0. K1 is a constant based on experience values.

  When the liquid level h is obtained, the arithmetic device 5 estimates the load applied to the wheel 1.

  FIG. 6 is a block diagram showing a schematic configuration of the arithmetic device 5 according to the embodiment of the present invention. The arithmetic device 5 includes at least an MPU 51, a ROM 52, a RAM 53, a communication interface 54 connected to the in-vehicle LAN 6, and an internal bus 55 connecting the hardware described above.

  The MPU 51 is connected to each hardware unit as described above of the arithmetic device 5 via the internal bus 55, and controls each hardware unit described above and performs various software-like operations according to the processing program stored in the ROM 52. Perform the function.

  The ROM 52 includes an SRAM, a flash memory, etc., and a program for calculating the amount of fluctuation of the length of the buffer member 2 based on the amount of change in voltage or current acquired by the current detection circuit 3, and the calculated length of the buffer member 2 A program or the like for calculating a tilt angle in the front-rear direction of the vehicle based on the amount of fluctuation is stored.

  The RAM 53 is configured by SRAM, flash memory, or the like, and stores temporary data generated when software is executed. The communication interface 54 is connected to the internal bus 55 and transmits / receives data required for processing by being connected to the in-vehicle LAN 6.

  FIG. 7 is a flowchart showing a processing procedure of the MPU 51 of the arithmetic unit 5 of the tilt detection apparatus according to the embodiment of the present invention. The MPU 51 of the arithmetic unit 5 acquires the current value I flowing through the load resistance from the current detection circuit 3 for each wheel 1 (step S701), and calculates the liquid level h according to (Equation 2) and (Equation 3) (step S702). ).

  The MPU 51 stores the relationship between the liquid level h and the length L of the buffer member 2 as a length table in advance in the RAM 53, for example, using the calculated liquid level h as key information, and stores the stored length table. The length L of the buffer member 2 is estimated by referring to it (step S703).

  The MPU 51 calculates the inclination angle α based on the calculated length L of the buffer member 2 for each wheel (step S704). FIG. 8 is a diagram illustrating a method of calculating the inclination angle α in the front-rear direction when the vehicle is a four-wheeled vehicle. Hereinafter, the wheel identification symbols are f for the front wheel, r for the rear wheel, 1 for the right wheel, and 2 for the left wheel.

  First, an average value Lf of the lengths Lf1 and Lf2 of the buffer member 2 disposed on the front wheel is calculated by Lf = (Lf1 + Lf2) / 2, and the length Lr1 of the buffer member 2 disposed on the rear wheel is calculated. The average value Lr of Lr2 is calculated by Lr = (Lr1 + Lr2) / 2.

  Next, based on the calculated average value Lf of the length of the buffer member 2 arranged on the front wheel and the average value Lr of the length of the buffer member 2 arranged on the rear wheel, (Equation 4) Is used to calculate the inclination angle α. In (Equation 4), A is the wheelbase length.

  In (Equation 4), the inclination angle α is calculated based on the average value of the lengths of the left and right shock absorbing members 2 for both the front wheels and the rear wheels. However, the present invention is not particularly limited to this. The inclination angle α may be calculated using the length of any of the buffer members 2.

  The MPU 51 sends the calculated inclination angle α to the ECU that controls the operation of various devices provided outside the arithmetic unit 5 (step S705). For example, the calculated tilt angle α in the front-rear direction is sent to the ECU that controls the operation of the actuator that changes the optical axis direction of the headlight. By changing the direction of the optical axis of the headlight, it is possible to reliably irradiate the front of the vehicle and to ensure safety during night driving.

  In this case, the MPU 51 transmits an instruction signal for instructing the optical axis direction of the headlight based on the calculated inclination angle α to the ECU that controls the operation of the actuator that changes the irradiation direction of the headlight. The ECU that has received the instruction signal operates the actuator to adjust the headlight in the optical axis direction indicated by the instruction signal.

  In addition, the direction of the obstacle sensor provided for detecting the obstacle present in the front blind spot is changed, and the angle of the imaging device that captures the image is changed to detect the obstacle present in the front blind spot. This makes it possible to control the operation of various devices.

  As described above, according to the present embodiment, by using a hydraulic shock-absorbing member for the sensor portion, collision of foreign matter such as mud and pebbles jumped up from the road surface without the need for special protective equipment is required. Failures such as affecting the detection value do not occur due to disturbances such as. Therefore, high reliability of the detection value from the sensor can be maintained while avoiding high cost due to a complicated configuration, and the tilt angle in the front-rear direction can be calculated with high accuracy.

  The thermistor 30 is not limited to the characteristic that the ambient temperature decreases and the resistance value increases as the surface area immersed in the hydraulic fluid 25 increases. You may do it.

It is a block diagram which shows the structure of the inclination detection apparatus which concerns on embodiment of this invention. It is a perspective view which shows the structure of the buffer member of the inclination detection apparatus which concerns on embodiment of this invention. It is a figure which shows the inflow state to the air chamber of hydraulic fluid at the time of pushing down a piston. It is a figure which shows the inflow state to the air chamber of hydraulic fluid at the time of pulling up a piston. It is a figure which shows typically the arrangement | positioning state of a thermistor. It is a block diagram which shows schematic structure of the arithmetic unit which concerns on embodiment of this invention. It is a flowchart which shows the process sequence of MPU of the arithmetic unit of the inclination detection apparatus which concerns on embodiment of this invention. It is a figure which shows the calculation method of the inclination-angle (alpha) of the front-back direction in case a vehicle is a four-wheeled vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wheel 2 Buffer member 3 Current detection circuit 5 Arithmetic device 6 Car-mounted LAN
21 Cover 22 Outer cylinder 23 Inner cylinder 24 Air chamber 25 Hydraulic fluid 26, 29 Orifice 28 Piston 30 Thermistor 51 MPU
52 ROM
53 RAM
54 Communication interface 55 Internal bus

Claims (4)

Inclination detection that includes a buffer member whose length varies according to loads applied to a plurality of wheels positioned in front of and behind the vehicle, and detects a tilt angle of the vehicle in the front-rear direction based on the amount of variation in the length of the buffer member In the device
The buffer member is
An inner cylinder filled with hydraulic fluid, an outer cylinder forming an air chamber between the inner cylinder, a piston movable with respect to the inner cylinder, and the movement of the piston causes the hydraulic fluid to flow from the inner cylinder An orifice that leads to the air chamber, and a thermistor disposed in the air chamber,
Detecting means for detecting a variation in length of each buffer member based on an amount of electricity relating to the thermistor;
A tilt angle calculating means for calculating a tilt angle in the front-rear direction of the vehicle based on a fluctuation amount of the length of the buffer member installed on the front and rear wheels;
A tilt detecting device comprising: a sending means for sending the calculated tilt angle to the outside.   The vehicle is a four-wheeled vehicle, and the average value of the length of the buffer member installed on the wheel located at the front of the vehicle and the average value of the length of the buffer member installed on the wheel located at the rear of the vehicle The inclination detection apparatus according to claim 1, wherein an inclination angle in the front-rear direction of the vehicle is calculated based on the following.   The inclination detection device according to claim 1, wherein the thermistor has a characteristic that the resistance value increases as the degree of immersion in the hydraulic fluid increases. A vehicle comprising the tilt detection device according to any one of claims 1 to 3.

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