JP2003004448A - Mounted sensor assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounted sensor assembly hardly subjected to vibrations transmitted from a vehicle body. SOLUTION: The sensor assembly 21 comprises an angular velocity sensor 2 for detecting the angular velocity of a vehicle, boards 4-6, having mounted processor circuits for processing with use of signals from the sensor 2 and a case 1 covering the boards 4-6, and the sensor 2 directly fixed to the case 1. The sensor assembly 21 is fixed to the vehicle body 3 via a vibration attenuating member 17, such as damping rubber. This attenuates vibrations applied to a radar system 21 and prevents vibration which is amplified by the resonance of the boards 4-6, etc., form being applied to the sensor 2, thereby preventing damages to the sensor or increasing the output error.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted sensor device that detects a vehicle state using a built-in sensor and performs processing according to the detected value.

[0002]

2. Description of the Related Art In a vehicle such as a passenger vehicle, various vehicle-mounted sensor devices which incorporate a sensor to detect the state of the vehicle, perform signal processing according to the detected value, and control the vehicle are known. It is used. Since vibration from the vehicle body is transmitted to these built-in sensors, measures have conventionally been taken to prevent damage to the built-in sensors and increase in output error due to the vibration. For example, Japanese Unexamined Patent Publication No. 2000-745937 describes a method of preventing damage to a built-in sensor by supporting the built-in sensor on a vehicle body via a high-damping rubber in a vibration-proof manner. Further, Japanese Patent Application Laid-Open No. 9-159689 describes a method of fixing the other end of a sensor mounted on a printed circuit board to a case to prevent erroneous detection of vehicle vibration.

[0003]

However, even when the above-mentioned conventional method is used, when the built-in sensor is mounted on the processing substrate, the vibration from the vehicle body is amplified due to the resonance of the substrate and the built-in sensor is damaged. There was a problem that the output error increased.

The present invention has been made to solve the above problems, and an object thereof is to provide an in-vehicle sensor device which is not easily affected by the vibration of the vehicle body.
This is to prevent damage to the built-in sensor and increase in output error due to substrate resonance.

[0005]

An on-vehicle sensor device of the present invention which achieves the above-mentioned object is equipped with a built-in sensor which detects a vehicle state and outputs a signal, and a processing circuit which performs processing using the signal. And a casing that surrounds the substrate and the built-in sensor and that fixes the built-in sensor directly to the processing circuit via the substrate, and fixes the casing to the vehicle body via a vibration damping member. It is characterized by that. A damping rubber is used for the vibration damping member, for example.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a block diagram of an inter-vehicle distance warning device to which the present invention is applied. The inter-vehicle distance warning device is a millimeter wave radar 2 mounted in front of the automobile 41.
1 and an inter-vehicle distance warning display device 22 mounted in the vehicle compartment.

The millimeter wave radar 21 includes a transmitting / receiving antenna section 4
2, a signal processing unit 43, an alarm determination unit 44, and an angular velocity sensor 2. The transmitting / receiving antenna unit 42 is
It serves to transmit electromagnetic waves in the millimeter wave band to the front of the automobile 41 and receive reflected waves from the target 46. The signal processing unit 43 performs signal processing on the received reflected wave to target 4
6 functions to calculate the relative speed with respect to the vehicle 6, the inter-vehicle distance and the azimuth angle. The alarm determination unit 44 compares the calculated relative speed and the inter-vehicle distance with a preset safe inter-vehicle distance set value to determine whether the measured inter-vehicle distance is less than or equal to the safe inter-vehicle distance set value.

As shown in FIG. 2, the road on which the host vehicle is traveling using the yaw rate ω of the vehicle 41 from the angular velocity sensor 2 built into the millimeter wave radar 21 and the host vehicle speed v from the vehicle speed sensor 45. The curve radius R (= v / ω) is estimated and it is determined whether the target 46 is in front of the own lane. When the inter-vehicle distance to the target 46 is less than the safe inter-vehicle distance set value and the target 46 is in front of the own lane, it is determined that there is a possibility of a rear-end collision.

The inter-vehicle distance warning display device 22 is connected to the millimeter-wave radar 21 via a serial communication line, and when the warning determination unit 44 of the millimeter-wave radar 21 determines that there is a possibility of a rear-end collision, a warning light and a warning are given. It sounds to alert the driver of the danger.

Thus, in the inter-vehicle distance warning device,
The information of the angular velocity sensor 2 is important information for determining whether there is a risk of collision. The fact that the angular velocity sensor 2 is easily damaged or outputs an incorrect value due to vibration from the vehicle body 35 does not give an alarm although there is a risk of collision, and there is no risk of collision. It may cause a false alarm such as issuing an alarm without doing so.

For example, while traveling on a straight road at a vehicle speed of 60 km / h, the detection value of the angular velocity sensor 2 is 1.0 deg.
In the case of a deviation of / s, the curve radius is erroneously calculated and the target 46 in front of the front 60 m of the host vehicle is laterally shifted by a half lane and output. Therefore, it is determined that the target 46 exists in the adjacent lane, which causes a false alarm.

FIG. 3 is a mounting view of a millimeter wave radar including a conventional angular velocity sensor. FIG. 6 is a cross-sectional view of the millimeter wave radar 21 when the angular velocity sensor 2 is mounted on the power supply board 4 and the millimeter wave radar 21 and the vehicle body 35 are directly fixed. The processing boards are the power supply board 4, the digital board 5, and the analog board 6.
It has a single-sheet structure, and these three substrates are fixed by inter-substrate spacers 7 and inter-substrate spacer screws 8.
The angular velocity sensor 2 is fixed on the power supply board with a screw 40, and the output of the angular velocity sensor 2 is input to the power supply board 4 via the harness 3. In addition, this board set has a board fixing screw 1
It is fixed to the housing 1 by 2. The bush 10 is fitted to the radar mounting portion 11 of the housing 1, and the bush 10 is scraped by screwing the radar mounting screw 20 having a specific diameter to form a female thread.
The radar mounting screw 20 is fixed. The washer 18 and the double nut 19 fix the radar mounting screw 20 and the vehicle 35.

When the angular velocity sensor 2 is attached as shown in FIG. 3, the vibration from the vehicle body is transmitted to the power supply substrate 4 through the housing 1 and is amplified by the resonance of the substrate, so that the output of the angular velocity sensor 2 has an error at the resonance frequency. Occurs. If the vibration acceleration is large, the angular velocity sensor 2 may be damaged.

FIG. 4 is a sectional view of the millimeter wave radar according to this embodiment. The angular velocity sensor 2 is attached to the housing 1 by sensor fixing means 3
It is fixed at 8. When the angular velocity sensor 2 is mounted in this way, since it is not affected by the resonance of the power supply board 4, the vibration from the vehicle body 35 is not amplified and is directly transmitted to the angular velocity sensor 2. As a result, the output error of the angular velocity sensor 2 can be reduced and the possibility of damage to the angular velocity sensor 2 can be reduced compared to the mounting method of FIG.

FIG. 5 is a sectional view of a millimeter wave radar according to another embodiment. The angular velocity sensor 2 is fixed to the housing 1 by the sensor fixing means 38, and the millimeter wave radar 21 is a damping rubber 17
It is attached to the vehicle body 35 via. The method of fixing the angular velocity sensor is the same as in FIG.

In the method of fixing the millimeter wave radar 21, a cylindrical damping rubber 17 is provided between the vehicle body 35 and the millimeter wave radar 21.
Is inserted to dampen vibrations from the vehicle body 35. A metal hollow cylindrical collar 39 is inserted into the cylindrical hole of the vibration damping rubber 17, and the length thereof is adjusted so that the vibration damping effect of the vibration damping rubber 17 is maximized. Has been done.

The characteristics of the vibration damping rubber 17 will be described. FIG. 6 is a graph showing the vibration transmission characteristics of the damping rubber. The horizontal axis shows the vehicle body 35, damping rubber 17, millimeter wave radar 2
The frequency ratio λ = f / fn of the frequency f of the vibration generated in the vehicle body 35 to the natural frequency fn of the vibration system of 1. The vertical axis represents the vibration transmissibility Tr (= A / A0) which is the ratio of the amplitude A of the vibration transmitted to the millimeter wave radar 21 to the amplitude A0 of the vibration generated in the vehicle body 35.

That is, the vibration transmissibility Tr <1 means that the applied vibration is attenuated, and Tr> 1 means that the applied vibration is amplified. As shown in FIG. 6, when the frequency ratio λ is √2 or less, the vibration transmissibility Tr is 1 or more in the resonance region, and when λ = 0.8, the maximum value Tr =
It becomes 1.5. In the region where the frequency ratio λ exceeds √2, the vibration transmissibility is a damping region of less than 1, and when λ = 2, the Tr
= 0.5 to 0.6, λ = 3, and Tr = 0.1 to 0.2. In the damping region, the larger the frequency ratio λ, the smaller the vibration transmissibility Tr.

When the angular velocity sensor 2 is fixed as shown in FIG. 5, the vibration applied from the vehicle body 35 is attenuated by the damping rubber 17 and transmitted to the millimeter wave radar 21. Therefore, compared with the mounting method shown in FIG. Further, the output error can be reduced.

According to the above-described embodiment, it is possible to effectively prevent the vibration transmitted from the vehicle body from being amplified by the resonance of the substrate and the like, thereby damaging the built-in sensor and increasing the output error. . That is, it is possible to improve the reliability of the output of the built-in sensor incorporated in the vehicle-mounted sensor device, that is, the reliability of the processing performed according to the detection value of the built-in sensor. Also, by directly mounting the built-in sensor to the housing, the heat of the built-in sensor can be released to the housing.

The embodiment of the present invention is not limited to the above-mentioned embodiment, but may be modified as follows. (1) The method of supporting the built-in sensor is not limited to the angular velocity sensor. If it is applied to a built-in sensor that may be damaged or increase in output error due to vibration amplified by the resonance of the board, such as an acceleration sensor, a temperature sensor, a pressure sensor, etc., the built-in sensor can be protected from vibration from the vehicle body. it can. (2) The housing for fixing the built-in sensor is not limited to the millimeter wave radar. An in-vehicle sensor device that incorporates a sensor to detect the state of the vehicle and performs processing according to the detected value, such as a navigation system or ACC (Adaptive Cruise Control)
If implemented in a control unit, ECU (Engine Control Unit), etc., the built-in sensor can be protected from the vibration of the vehicle body. (3) The processing performed according to the output value of the angular velocity sensor is not limited to the curvature calculation processing of the curve in which the vehicle is traveling. For example, it may be vehicle lightness detection or drowsiness detection. (4) In fixing the on-vehicle sensor device to the vehicle body, the vibration damping member is not limited to the vibration damping rubber. A member having characteristics comparable to the vibration transmission characteristics of the damping rubber, for example, a rubber ball in which a highly viscous fluid is enclosed may be used. (5) When fixing the on-vehicle sensor device to the vehicle body, the shape of the damping rubber is not limited to the cylindrical shape. The vibration damping rubber may have a shape that does not significantly impair the vibration transmission characteristics, for example, a mat shape. (6) The sensor fixing means may be a method such as an adhesive, a screw or a bolt as long as the built-in sensor can be fixed to the housing. (7) The vehicle equipped with the in-vehicle sensor device is not limited to a passenger vehicle. The method of supporting a sensor built in an in-vehicle sensor device mounted on an industrial vehicle such as a cargo handling vehicle, a construction vehicle, a civil engineering vehicle, or a commercial vehicle such as a truck.

[0022]

According to the present invention, since the vehicle-mounted sensor device is less susceptible to the vibration of the vehicle body, there is an effect that the reliability of the processing performed according to the detection value of the built-in sensor can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a processing function of a millimeter wave radar.

FIG. 2 is an explanatory diagram showing a method of estimating a curve radius by an angular velocity sensor.

FIG. 3 is a sectional view of a millimeter wave radar including a conventional angular velocity sensor.

FIG. 4 is a sectional view of a millimeter wave radar including an angular velocity sensor according to an embodiment.

FIG. 5 is a sectional view of a millimeter wave radar including an angular velocity sensor according to another embodiment.

FIG. 6 is a graph showing a vibration transmissibility with respect to a frequency ratio of a damping rubber.

[Explanation of symbols]

1 ... Housing, 2 ... Angular velocity sensor, 4 ... Power supply board, 5 ... Digital board, 6 ... Analog board, 7 ... Board-to-board spacer,
10 ... Bushing, 11 ... Radar mounting part, 13 ... Car body bracket, 17 ... Damping rubber, 20 ... Radar mounting screw, 35 ... Car body, 38 ... Sensor fixing means.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01P 9/00 G01P 9/00 Z G01S 13/93 G01S 13/93 F term (reference) 2F105 AA02 BB01 5J070 AB24 AE01 AF03 AK22 BD10 BF02 BF19

Claims (4)

[Claims] 1. A built-in sensor that detects a state of a vehicle and outputs a signal, a board on which a processing circuit that performs processing using the signal is mounted, and a built-in sensor in a housing that surrounds the board and the built-in sensor. An in-vehicle sensor device, comprising: a casing for directly fixing the processing circuit via a substrate, the casing being supported by a vehicle body via a vibration damping member. 2. The method according to claim 1, The in-vehicle sensor device, wherein the vibration damping member is a damping rubber. 3. The in-vehicle sensor device according to claim 1, wherein the built-in sensor is an angular velocity sensor that detects an angular velocity of the vehicle when the vehicle turns. 4. The vehicle-mounted sensor device according to claim 1, wherein the vehicle-mounted sensor device is a radar device that transmits a radio wave, receives a reflected wave from a target, and detects a distance to the target and a relative speed. Sensor device.