JPH09304511A - Ultrasonic sensor for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultrasonic sensor in which a vibration is attenuated quickly when a case and a vibration member are frozen and the vibration is transmitted to a fixation member in the vibration of the vibration member, by a configuration wherein a part of the fixation member is immersed in a sealing member by which a processing circuit is sealed inside the case and which is composed of an elastic body. SOLUTION: A fixation member 7 is constituted in such a way that its bottom part is deformed to be, e.g. a bow shape and that a part of it is immersed in a sealing member 6 as an elastic body. Thereby, even when a case 2 and a vibration member 3 are frozen in such a way that a vibration is transmitted to the fixation member 7 in the vibration of the vibration member 3, the vibration is attenuated by the sealing member 6 as the elastic body, and the reverberation time can be shortened. Consequently, an ultrasonic signal which is reflected by an obstacle is received surely as received waves, and the obstacle can be detected precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle ultrasonic sensor used for a corner sonar or the like.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic sensor for a vehicle is mounted on a bumper of a vehicle, and its mounting structure is as shown in FIG. In FIG. 3, reference numeral 1 is a bumper of the vehicle, 2 is a case made of PBT resin which is an outer frame of the ultrasonic sensor, and 3 is a piezoelectric effect that vibrates due to a piezoelectric effect to transmit an ultrasonic signal. The vibrating member is composed of a piezoelectric element having a characteristic of generating a voltage by an inverse piezoelectric effect when a reflected wave of the transmitted ultrasonic signal is received. Further, 4 is an anti-vibration member made of silicon resin that suppresses the transmission of vibration from the vibration member 3 to the case 2 when the vibration member 3 is housed in the case 2, and 5 is generated by the inverse piezoelectric effect of the vibration member 3. 6 is a sealing member made of silicon resin for hermetically sealing the processing circuit 5 in the case 2, and 7 is a fixing member made of stainless steel for fixing the case 2 to the bumper 1. is there. Reference numeral 8 denotes a harness that transmits a signal processed by the processing circuit 5 to a controller (not shown) or supplies a voltage from the controller to the vibration member 3 via the processing circuit 5.

In this ultrasonic sensor, the vibration isolator 3 vibrates at a predetermined frequency for a predetermined number of times at a predetermined time to transmit an ultrasonic signal, and if an obstacle exists at the destination of the transmission, the ultrasonic signal becomes an obstacle. The reflected wave is reflected by the vibration isolating member 3 as a received wave. And
An obstacle is detected by transmitting a voltage signal based on the received reflected wave to the controller and comparing the voltage signal with a reference value in the controller. In addition,
Even after the vibrating member 3 transmits the ultrasonic signal, the reverberation remains for a while. Therefore, the controller sets the reception time of the reflected wave after the lapse of a predetermined time (reverberation time) from the end of the transmission. The voltage signal based on the received reflected wave is compared with the reference value.

[0004]

However, when the case 2 and the vibrating member 3 are frozen, the vibrating member 3 vibrates at the time of transmitting an ultrasonic signal and vibrates the fixing member 7 through the ice and the case 2. Is transmitted, and the reverberation is not settled even if the reception time is after the predetermined reverberation time has elapsed, so that there is a problem that an obstacle cannot be detected accurately.

Therefore, the present invention has been made in view of the above problems, and even if the case and the vibrating member are frozen and the vibration is transmitted to the fixed member when the vibrating member vibrates, the present invention is promptly performed. The purpose is to damp vibrations.

[0006]

In order to achieve the above object, in the invention according to claim 1, a part of the fixing member is immersed in a sealing member made of an elastic body for sealing the processing circuit in the case. Therefore, even when the case and the vibrating member are frozen and the vibration is transmitted to the fixed member when the vibrating member vibrates, the vibration is quickly attenuated by the sealing member that is an elastic body. Therefore, the reverberation time can be shortened to accurately detect the obstacle.

According to the second aspect of the invention, since the vibration absorbing member is interposed between the fixing member and the case,
Even when the case and the vibrating member freeze, and the vibration is transmitted to the fixed member when the vibrating member vibrates, the vibration is quickly damped by the vibration absorbing member. Therefore, the reverberation time can be shortened to accurately detect the obstacle.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. In FIG. 1, the same members as those in FIG. 3 are denoted by the same reference numerals and the description thereof will be omitted. 1 is different from FIG. 3 in that the bottom portion (right end in FIG. 1) of the fixing member 7 is deformed into an arc shape and a part thereof is immersed in the sealing member 6 which is an elastic body. With such a configuration, even when the case 2 and the vibration member 3 are frozen and the vibration is transmitted to the fixed member 7 when the vibration member 3 vibrates, the processing circuit 5 of FIG. As shown in the output signal waveform of 1, the vibration is attenuated by the sealing member which is an elastic body, so that the reverberation time can be shortened.
Therefore, the ultrasonic signal reflected by the obstacle can be surely received as the received wave to accurately detect the obstacle.

In FIG. 2, the reference values set for the transmission time and the reverberation time are for detecting the disconnection of the harness 8 or the like. Next, a second embodiment will be described. In the second embodiment, instead of immersing a part of the fixing member in the sealing member, a vibration absorbing member made of a foam material is interposed between the fixing member and the case to damp the vibration. As the foam material, a tape made of chloroprene foam or urethane foam having a thickness of about 2 mm can be adopted, and this tape is used by being adhered to the entire surface or a part of the surface of the fixing member 7.

By the way, the present invention is not limited to the above embodiment, but can be variously modified as shown below. The fixing member 7 is not limited to metal fittings such as stainless steel, but resin may be used. Further, any shape may be used as long as it is immersed in the sealing member 6.

The sealing member 6 may be made of any material as long as it is an elastic body capable of hermetically sealing the processing circuit 5. Rubber may be used for the vibration absorbing member instead of the foam material.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a waveform of an output signal from a processing circuit 5 to a controller.

FIG. 3 is a cross-sectional view showing a conventional embodiment.

[Explanation of symbols]

 2 case 3 vibrating member 5 processing circuit 6 sealing member 7 fixing member

Claims (7)

[Claims] 1. A vibrating member (3) for transmitting an ultrasonic signal and receiving a reflected wave of the transmitted ultrasonic signal; and a processing circuit (5) for processing the reflected wave received by the vibrating member. A case (2) for accommodating the vibrating member, a sealing member (6) made of an elastic body for sealing the processing circuit in the case, and a fixing member (7) for fixing the case to the vehicle body. An ultrasonic sensor for a vehicle, comprising: a part of the fixing member immersed in the sealing member. 2. A vibrating member that transmits an ultrasonic signal and receives a reflected wave of the transmitted ultrasonic signal, a processing circuit that processes the reflected wave received by the vibrating member, and the vibrating member is housed. An ultrasonic sensor for a vehicle, comprising: a case, a sealing member made of an elastic body that seals the processing circuit in the case, and a fixing member that fixes the case to a vehicle body, wherein the fixing member and the case An ultrasonic sensor for a vehicle, wherein a vibration absorbing member is interposed between the ultrasonic sensor and the vehicle. 3. The ultrasonic sensor for a vehicle according to claim 1, wherein the sealing member is a silicone resin. 4. The ultrasonic sensor for a vehicle according to claim 1, wherein the vibrating member is a piezoelectric element. 5. The ultrasonic sensor for a vehicle according to claim 1, wherein the fixing member is made of stainless steel. 6. The ultrasonic sensor for a vehicle according to claim 2, wherein the vibration absorbing member is a foam material. 7. The ultrasonic sensor for a vehicle according to claim 6, wherein the vibration absorbing member is a tape adhered to the fixing member.