JP2004101373A - Liquid level detector for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fuel liquid level sensor 2 from being damaged due to collision against a foreign matter when a vehicle travels, by devising the peripheral shape of a mounting part for the fuel level sensor 2 of a fuel tank 3. <P>SOLUTION: The liquid level detector is formed so that a protector 36 is provided to the circumference of the fuel level sensor 2 on the bottom surface 33 of the fuel tank 3, and that the sticking out length H of the protector 36 from the bottom surface 33 is larger than the sticking out length h of the fuel level sensor 2 from the bottom surface 33. Thus, even when the foreign matter such as a stone, which is flicked by a tire when the vehicle travels, collides against the fuel tank, the fuel level sensor 2 is prevented from being damaged. Because the protector 36 and the fuel tank 3 are integrally formed by the molding of a resin, the protector 36 can be easily provided to the fuel tank 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid level detecting device for a vehicle that is mounted on a vehicle and detects a liquid level of a liquid, and is suitable for use in, for example, an application for detecting a liquid level in a fuel tank mounted on an automobile. is there.
[0002]
[Prior art]
Conventionally, as a vehicle liquid level detecting device for detecting the amount of fuel in an automobile or the like, that is, a fuel level, a rotating arm is provided on a float floating on the surface of the fuel, and the position of the float is changed according to a change in the liquid level. In general, a turning arm is turned, and a change in the turning angle is converted into a change in electric resistance, for example. However, this type of liquid level detection device has problems such as a large physique, a limited installation place, and poor detection accuracy.
[0003]
In order to solve such a problem, for example, in a liquid level detection device disclosed in Japanese Patent Laid-Open No. 6-249697, an ultrasonic sensor having an ultrasonic vibrator is mounted on the bottom of a fuel tank, and the ultrasonic sensor is used. Ultrasonic waves are emitted to the fuel in the fuel tank, and the ultrasonic waves are reflected on the fuel level and received by the ultrasonic sensor again, and the time for the ultrasonic waves to reciprocate between the ultrasonic sensor and the liquid level is measured. The liquid surface position is detected based on this. However, Japanese Patent Application Laid-Open No. 6-249697 has no specific description of the structure for mounting the ultrasonic vibrator to the tank.
[0004]
On the other hand, as a liquid level detecting device using an ultrasonic sensor, there are other devices disclosed in JP-A-2000-314651 or JP-A-2001-208595.
[0005]
In the liquid level detecting device disclosed in Japanese Patent Application Laid-Open No. 2000-314651, the ultrasonic sensor is pressed against the tank by the elastic force of a spring and is fixed to the tank by the magnetic force of a magnet.
[0006]
In the liquid level detection device disclosed in Japanese Patent Application Laid-Open No. 2001-208595, the ultrasonic sensor is fixed to the outer surface of the tank with a plurality of screws.
[0007]
The above-described ultrasonic sensors disclosed in JP-A-2000-314651 and JP-A-2001-208595 are both exposed and fixed to the outer surface of the tank.
[0008]
[Problems to be solved by the invention]
By the way, consider the case where the above-described ultrasonic sensor is used for a vehicle, for example, attached to the outer surface of a fuel tank and used for detecting the liquid level of fuel. When the vehicle is traveling, particularly when traveling on unpaved roads, foreign substances such as stones may be hit by the tires and fly toward the fuel tank. At this time, the ultrasonic sensor exposed and fixed to the outer surface of the tank may be damaged by hitting a foreign substance such as a stone. Further, it is necessary to transport the fuel tank from the step of attaching the ultrasonic sensor to the fuel tank to the step of attaching the fuel tank to the vehicle (normally, both steps are carried out at different business establishments). An ultrasonic sensor fixed to the outer surface of the tank may collide with other objects and be damaged.
[0009]
The present invention has been made in view of the above points, and an object of the present invention is to devise a shape of an attaching portion of an ultrasonic sensor to a tank so that the tank is damaged during traveling of a vehicle or during transport of the tank. It is an object of the present invention to provide a liquid level detecting device for a vehicle which can prevent the occurrence of the liquid level.
[0010]
[Means for Solving the Problems]
The present invention employs the following technical means to achieve the above object.
[0011]
According to a first aspect of the present invention, there is provided a liquid level detecting device for a vehicle, comprising: a tank for storing a liquid; and an ultrasonic detector having a built-in ultrasonic vibrator and attached to an outer surface of the tank. In a liquid level detection device for vehicles that emits ultrasonic waves to the liquid in the tank to measure the liquid level, a protection section is provided on the outer surface of the tank and around the ultrasonic detector, and the protection section from the outer surface of the tank is provided. The projecting height was formed to be larger than the projecting height of the ultrasonic detector from the outer surface of the tank. Thus, if a foreign object collides with the tank while the vehicle is running, or if the tank comes into contact with another object while transporting the tank with the fixed ultrasonic detector, the above-described foreign object or other object is repelled by the protection unit. Is returned and does not collide with the ultrasonic detector. Therefore, it is possible to prevent the ultrasonic detector from being damaged by a foreign object or another object.
[0012]
In the liquid level detecting device for a vehicle according to the second aspect of the present invention, the protection unit is arranged on the outer peripheral side of the ultrasonic detector and substantially coaxially with the ultrasonic detector. Accordingly, the protection unit can reliably prevent the foreign object or another object from colliding with the ultrasonic detector.
[0013]
The liquid level detecting device for a vehicle according to the third aspect of the present invention includes a cover that covers the ultrasonic detector on the side opposite to the tank, and the cover is fixed to the protection unit. Thus, when a foreign object collides with the tank while the vehicle is traveling, or when the tank comes into contact with another object while transporting the tank with the ultrasonic detector fixed thereto, the above-described foreign object or other object is not covered or protected. And does not collide with the ultrasonic detector. Therefore, it is possible to prevent the ultrasonic detector from being damaged by a foreign object or another object.
[0014]
In the liquid level detecting device for a vehicle according to a fourth aspect of the present invention, the tank is made of a resin material, and the protective portion is formed integrally with the tank. Thereby, a protection part can be easily formed on the outer surface of the tank. Further, the number of parts can be reduced, and the cost can be reduced.
[0015]
In the liquid level detecting device for a vehicle according to the fifth aspect of the present invention, the ultrasonic detector is attached to the bottom surface or the side surface of the tank. Thereby, the ultrasonic wave emitted from the ultrasonic detector can be reliably advanced in the liquid in the tank, and the liquid level can be detected.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example in which a vehicle liquid level detecting device according to an embodiment of the present invention is applied to a fuel level detecting device 1 for detecting a fuel level position in a fuel tank of an automobile will be described with reference to the drawings. I do.
[0017]
(1st Embodiment)
FIG. 1 is a cross-sectional view showing a mounting state of a fuel level sensor 2 which is an ultrasonic detector to a fuel tank 3 which is a tank in a fuel level detecting apparatus 1 according to a first embodiment of the present invention. FIG. 2 is an enlarged sectional view of a part I in FIG. FIG. 2 is an overall external view of the fuel liquid level detecting device 1. FIG. 3 is a view taken in the direction of the arrow III in FIG. In each drawing, the same components are denoted by the same reference numerals.
[0018]
As shown in FIG. 2, the fuel level sensor 2, which is an ultrasonic detector, is fixed to a bottom surface 33, which is an outer surface of a fuel tank 3 of an automobile, which is a tank for storing liquid. The vertical direction in FIG. 2 is the vertical direction of the automobile, and the upper side of FIG. 2 is the upper side of the automobile.
[0019]
Hereinafter, the configuration of the fuel level detecting device 1 will be described.
[0020]
First, the fuel level sensor 2 which is an ultrasonic detector will be described.
[0021]
The ultrasonic vibrator 21 is formed of a substance having a piezo effect (a property of changing a volume when a voltage is applied and generating a voltage when externally applied), for example, PZT (lead zirconate titanate). ing. As shown in FIG. 1, the ultrasonic transducer 21 is connected to a lead wire 26 for applying a voltage from the outside or outputting a generated voltage signal to the outside. The ultrasonic transducer 21 is fixed to the housing 22 by, for example, bonding.
[0022]
The housing 22 is formed of a highly rigid material, for example, a metal (stainless steel plate or the like), and serves to protect the ultrasonic vibrator 21 and reliably transmit the vibration of the ultrasonic vibrator 21 to the outside. The housing 22 is held by a resin case 24. Here, the housing 22 is held by a resin case 24 via a vibration isolating member 23 made of a material that is flexible and can absorb vibration. This prevents the vibration of the ultrasonic transducer 21 from being transmitted to other than the fuel in the fuel tank 3 and maintains a good fuel level detection function.
[0023]
The case 24 is formed in a substantially disk shape as shown in FIG. As shown in FIGS. 1 and 3, the case 24 is provided with two protruding portions 25 that engage with holes 32 of the fuel tank 3, which will be described later, and oppose each other with the center therebetween. When the fuel level sensor 2 is attached to the fuel tank 3, the protruding portion 25 engages with and abuts on the hole 32 of the fuel tank 3 to move the fuel level sensor 2 away from the bottom surface 33 of the fuel tank 3. Is regulated. In other words, the protruding portion 25 is engaged with and abutted on the hole 32 of the fuel tank 3, and the fuel level sensor 2 is held and fixed to the fuel tank 3.
[0024]
Next, the fuel tank 3, which is a tank, will be described.
[0025]
The fuel tank 3 is formed of a resin material. As shown in FIGS. 1 and 3, a support wall for restricting the movement of the fuel level sensor 2 along the bottom surface 33, that is, the movement in the horizontal direction in FIG. Two 31 are provided so as to face each other. The support wall 31 is formed in an arc shape corresponding to the outer shape of the fuel level sensor 2 as shown in FIG. The support wall 31 is provided with a hole 32 that regulates movement of the fuel level sensor 2 in a direction away from the bottom surface 33. As shown in FIG. 1, the hole 32 is formed in a shape of a through hole substantially parallel to the bottom surface 33. The support wall 31 is formed integrally with the fuel tank 3 during resin molding of the fuel tank 3. 1 and 3, a protector 36 is provided on the bottom surface 33 of the fuel tank 3 around the fuel level sensor 2. As shown in FIGS. The protector 36 is made of a resin material and is formed integrally with the fuel tank 3. As shown in FIG. 3, four protectors 36 are provided substantially concentrically with the fuel level sensor 2. Further, as shown in FIG. 1, the protruding length H of the protector 36 from the bottom surface 33 is formed larger than the protruding length h of the fuel level sensor 2 from the bottom surface 33. That is, the fuel level sensor 2 is disposed so as to be retracted from the protector 36. Thus, even if foreign matter such as stones is hit by the tires and flies toward the fuel tank while the vehicle is running, the foreign matter such as stones hits the protector 36 described above. Damage due to collision with a foreign substance such as a stone can be prevented. In the course of transporting the fuel tank 3 to which the fuel level sensor 2 has been mounted to the vehicle assembling step, that is, the step of mounting the fuel tank 3 to the vehicle, for example, the fuel tanks 3 come into contact with each other, or Even if the fuel tank 3 is placed on the floor or the like with the sensor 2 down, the fuel level sensor 2 is not directly in contact with other parts or the floor by the protector 36, so that the fuel level sensor 2 is damaged. Can be prevented.
[0026]
Next, a method of attaching the fuel level sensor 2 to the fuel tank 3 in the assembling step of the fuel level detecting device 1 according to the first embodiment of the present invention will be described.
[0027]
First, the substantially circular sheet-like adhesive 4 is set between the two support walls 31 on the bottom surface 33 of the fuel tank 3.
[0028]
Next, the circumferential position of the projecting portion 25 of the fuel level sensor 2 and the hole 32 of the support wall 31 of the fuel tank 3 is set between the two support walls 31 of the fuel tank 3 by positioning the fuel level sensor 2. Then, the housing 22 is pushed in with the housing 22 facing the bottom surface 33. That is, the fuel level sensor 2 is pressed in a direction toward the bottom surface 33 of the fuel tank 3. As a result, the support wall 31 is elastically deformed in the left-right direction in FIG. When the fuel level sensor 2 is further pushed in, the protrusion 25 of the fuel level sensor 2 engages with the hole 32 of the support wall 31 of the fuel tank 3, that is, the end face 25a of the fuel level sensor 2 By contacting the portion 32, the operation of mounting the fuel level sensor 2 to the fuel tank 3 is completed. At this time, the adhesive 4 is completely in contact with both the bottom surface 33 of the fuel tank 3 and the housing 22 of the fuel level sensor 2. Thereby, the air between the ultrasonic oscillator 21 and the fuel in the fuel tank 3 is eliminated, and the ultrasonic emission from the ultrasonic oscillator 21 to the fuel and the reception of the reflected wave from the liquid surface are stabilized, The liquid level detection accuracy by the fuel level sensor 2 can be improved.
[0029]
Next, a fuel level detection operation in the fuel level detection device 1 according to the first embodiment of the present invention will be described with reference to FIG.
[0030]
FIG. 4 shows an electric circuit configuration diagram of the fuel liquid level detecting device 1 according to the first embodiment of the present invention.
[0031]
The fuel level sensor 2, that is, the ultrasonic vibrator 21 is connected to the control circuit 6, which is connected to the display unit 7.
[0032]
The control circuit 6 includes a pulse generation circuit 61 for controlling the application of a voltage to the ultrasonic vibrator 21, an arithmetic circuit 62 for processing the voltage signal from the ultrasonic oscillator 21 and calculating the liquid surface position, and a signal from the arithmetic circuit 62. The driving circuit 63 outputs a driving signal for driving the display unit 7 based on the liquid level detection signal.
[0033]
The display unit 7 includes, for example, a pointer gauge and the like, and displays a liquid level position in the fuel tank 3 so that the driver can recognize it. Generally, the display unit 7 is installed in a combination meter in front of a driver's seat of an automobile (not shown).
[0034]
When the ultrasonic vibrator 21 emits a pulsed ultrasonic wave into the fuel 5 in the fuel tank 3 by a signal from the pulse generation circuit 61, the ultrasonic pulse proceeds as shown by an arrow in FIG. 5 is reflected by the liquid surface 51 and returns to the ultrasonic transducer 21 again. The ultrasonic transducer 21 vibrates by the reflected pulse to generate a voltage signal, and the voltage signal is input to the arithmetic circuit 62. The arithmetic circuit 62 calculates the time from when the pulse generating circuit 61 issues a signal to the ultrasonic transducer 21 to when the reflected wave is detected, and, based on the calculated time, determines the position of the liquid surface 51, that is, the liquid in FIG. The surface height H is calculated. The drive circuit 63 is a signal for displaying the liquid level H calculated by the arithmetic circuit 62 on the display unit 7, for example, to rotate a pointer shaft (not shown) to an angle corresponding to the liquid level H. Output the driving signal.
[0035]
In the fuel level detecting device 1 according to the first embodiment of the present invention described above, the protector 36 is provided around the fuel level sensor 2 on the bottom surface 33 of the fuel tank 3 and the length of the protector 36 protruding from the bottom surface 33. The height H is formed larger than the length h of the fuel level sensor 2 protruding from the bottom surface 33. That is, the fuel level sensor 2 is disposed so as to be retracted from the protector 36. Thus, even if foreign matter such as stones is hit by the tires and flies toward the fuel tank while the vehicle is running, the foreign matter such as stones hits the protector 36 described above. Damage due to collision with a foreign substance such as a stone can be prevented. In the course of transporting the fuel tank 3 to which the fuel level sensor 2 has been mounted to the vehicle assembling step, that is, the step of mounting the fuel tank 3 to the vehicle, for example, the fuel tanks 3 come into contact with each other, or Even if the fuel tank 3 is placed on the floor or the like with the sensor 2 down, the fuel level sensor 2 is not directly in contact with other parts or the floor by the protector 36, so that the fuel level sensor 2 is damaged. Can be prevented.
[0036]
In the fuel level detecting device 1 according to the first embodiment of the present invention described above, the fuel tank 3 is formed of resin, and the protector 36 is integrated with the fuel tank 3 when the fuel tank 3 is molded with resin. Has formed. Thereby, the number of parts can be reduced, the cost can be reduced, and the protector 36 can be easily provided in the fuel tank 3. Further, the positional accuracy between the protector 36 and the fuel level sensor 2 can be improved.
[0037]
FIG. 5 shows a plan view of a modified example of the fuel level detecting device 1 according to the first embodiment of the present invention. This corresponds to FIG.
[0038]
In this modification, the shape of the protector 36 provided on the bottom surface 33 of the fuel tank 3 is changed. That is, as shown in FIG. 5, the four independently disposed protectors 36 are one continuous cylindrical protector 36. In this case as well, similarly to the case of the fuel level detection device 1 according to the first embodiment described above, it is possible to prevent the fuel level sensor 2 from being damaged due to collision or contact with a foreign substance such as a stone or another member.
[0039]
FIG. 6 shows a partial cross-sectional view of another modified example of the fuel level detecting device 1 according to the first embodiment of the present invention.
[0040]
In this other modification, the function of the support wall 31 for holding and fixing the fuel level sensor 2 is also used for the protector 36. That is, as shown in FIG. 6, the hole 32 is provided in the protector 36 by combining the support wall 31 with the protector 36. In this case as well, similarly to the case of the fuel level detection device 1 according to the first embodiment described above, it is possible to prevent the fuel level sensor 2 from being damaged due to collision or contact with a foreign substance such as a stone or another member. Furthermore, the cost can be reduced by simplifying the shape of the fuel tank 3 for resin molding.
[0041]
(2nd Embodiment)
FIG. 7 is a sectional view of the fuel level detecting device 1 according to the second embodiment of the present invention, and corresponds to an enlarged sectional view of a portion I in FIG.
[0042]
As shown in FIG. 7, the fuel level detecting device 1 according to the second embodiment of the present invention includes a resin cover 8 that covers the fuel level sensor 2 on the side opposite to the fuel tank 3. It is fixed to the protector 36. That is, the locking portion 81 is provided on the cover 8, and the locking portion 8 is engaged with the step portion 37 provided on the protector 36, whereby the cover 8 is fixed to the protector 36.
[0043]
The cover 8 can be easily attached to the protector 36 by pressing the cover 8 toward the fuel tank 3 (upward in FIG. 7).
[0044]
In the above-described fuel level detecting device 1 according to the second embodiment of the present invention as well, the fuel level sensor 2 may be damaged by the protector 36 and the cover 8 due to collision or contact with foreign matters such as stones or other members. Can be prevented.
[0045]
Furthermore, in the fuel level detection device 1 according to the second embodiment of the present invention, even when foreign matter such as stones fly from directly below the fuel level sensor 2, the foreign matter such as stones is applied to the fuel level sensor 2 by the cover 8. Collision can be prevented.
[0046]
Further, in the fuel liquid level detecting device 1 according to the second embodiment of the present invention, since the fuel liquid level sensor 2 is substantially sealed by the protector 36 and the cover 8, it is possible to prevent water and dust from adhering.
[0047]
In the fuel level detecting device 1 according to the second embodiment of the present invention described above, the cover 8 is made of resin, but may be made of another material. For example, a steel plate may be formed by pressing.
[0048]
Further, in the fuel level detecting device 1 according to the first, second and second embodiments of the present invention described above and the modifications, the fuel level sensor 2 is attached to the bottom surface 33 of the fuel tank 3. The mounting position does not need to be limited to the bottom surface 33, but may be anywhere on the outer surface of the fuel tank 3.
[0049]
Further, in the fuel liquid level detecting device 1 according to the first, second and second embodiments of the present invention described above, and the modified example, the adhesive 4 is formed in a sheet shape, but is not limited to the sheet shape. For example, it may be in the form of jelly.
[0050]
Further, in each of the embodiments and the modified examples described above, the case where the vehicle liquid level detecting device of the present invention is applied to the vehicle fuel level detecting device 1 has been described as an example. You may apply other than. For example, it may be used for engine oil level detection, brake fluid level detection, or window washer level detection.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of a fuel level detecting device 1 according to a first embodiment of the present invention, and is an enlarged sectional view of a portion I in FIG.
FIG. 2 is an overall external view of a fuel liquid level detecting device 1 according to the first embodiment of the present invention.
FIG. 3 is a view taken in the direction of the arrow III in FIG. 1;
FIG. 4 is an electric circuit configuration diagram of the fuel level detecting device 1 according to the first embodiment of the present invention.
FIG. 5 is a plan view of a modified example of the fuel level detecting device 1 according to the first embodiment of the present invention.
FIG. 6 is a partial sectional view of another modified example of the fuel level detecting device 1 according to the first embodiment of the present invention.
FIG. 7 is a partial sectional view of a fuel level detecting device 1 according to a second embodiment of the present invention.
[Explanation of symbols]
1. Fuel level detector (vehicle level detector)
2 Fuel level sensor (ultrasonic detector)
21 Ultrasonic vibrator 22 Housing 23 Anti-vibration member 24 Case 25 Projecting part 25a End face 26 Lead wire 3 Fuel tank (tank)
31 support wall 32 hole 33 bottom surface (outer surface)
36 Protector (Protection Department)
4 Adhesive 5 Fuel (liquid)
51 liquid level 6 control circuit 61 pulse generation circuit 62 arithmetic circuit 63 drive circuit 7 display section 8 cover 81 locking section D liquid level height H protruding length h protruding length

Claims (5)

A tank for storing liquid,
An ultrasonic detector built-in and equipped with an ultrasonic detector attached to the outer surface of the tank,
In a vehicle liquid level detection device that measures the liquid level by emitting ultrasonic waves from the ultrasonic transducer to the liquid in the tank,
Providing a protection portion around the outer surface of the tank and the ultrasonic detector,
The protruding height of the protection portion from the outer surface is formed larger than the protruding height of the ultrasonic detector from the outer surface. The liquid level detecting device for a vehicle according to claim 1, wherein the protection unit is disposed substantially coaxially with the ultrasonic detector on an outer peripheral side of the ultrasonic detector. The vehicle liquid level detecting device according to claim 1, further comprising a cover that covers a side of the ultrasonic detector opposite to the tank, wherein the cover is fixed to the protection unit. The liquid level detecting device for a vehicle according to any one of claims 1 to 3, wherein the tank is made of a resin material, and the protection part is formed integrally with the tank. The liquid level detecting device for a vehicle according to any one of claims 1 to 4, wherein the ultrasonic detector is attached to a bottom surface or a side surface of the tank.

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