Liquid level detecting apparatus

• US 20050284217A1
• Filed: 09/30/2004
• Published: 12/29/2005
• Est. Priority Date: 10/02/2003
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yasuda, Atsushi, Miyagawa, Isao
• Granted Patent: US 7,117,738 B2
• Time in Patent Office: Days
• US Class Current: 73/290.00V
• CPC Class Codes: G01F 23/2962 Measuring transit time of reflected waves
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level

Abstract

A guide pipe is formed from a metal material, and its internal cross section has a circular shape whose diametric dimension gradually becomes smaller with a distance from an ultrasonic sensor. That is, the guide pipe is formed so that a route for transmitting an ultrasonic wave generated from the ultrasonic sensor may be tapered from this ultrasonic sensor toward a reflector plate. Thus, the acoustic pressure level of the ultrasonic wave which enters the reflector plate can be made higher than a value in a prior-art liquid level detecting apparatus. Accordingly, the energy of the ultrasonic wave generated from the ultrasonic sensor can be utilized for liquid level detection at a high efficiency, so that a fuel liquid level detecting apparatus capable of accurate liquid level detection can be provided.

Claims

1. A liquid level detecting apparatus comprising:

an ultrasonic sensor installed in a bottom of a tank storing a liquid and detecting a liquid level of the liquid by generating an ultrasonic wave and receiving the ultrasonic wave reflected by the liquid level;

a reflector turning the ultrasonic wave to the liquid level;

a first cylinder enclosing a first route transmitting the ultrasonic wave between the ultrasonic sensor and the reflector and shaped to have an internal sectional area thereof perpendicular to the first route, the area gradually decreasing toward the reflector; and

a second cylinder enclosing a second route transmitting the ultrasonic wave between the reflector and the liquid level.

2. The liquid level detecting apparatus according to claim 1, wherein each of the first and the second cylinders has a generally round cross-sectional shape perpendicular to a longitudinal axis thereof.

3. The liquid level detecting apparatus according to claim 2, wherein a diametric dimension of an end of the first cylinder on the side of the reflector is set to be generally equal to a diametric dimension of an end of the second cylinder on the side of the reflector.

4. The liquid level detecting apparatus according to claim 3, wherein the second cylinder has a generally uniform diametric dimension over the entire length thereof.

5. The liquid level detecting apparatus according to claim 1, wherein the first and the second cylinders are made of metallic material.

6. The liquid level detecting apparatus according to claim 1, further comprising:

a baffle plate whose lower surface is generally in parallel to and at the height of a maximum level of the liquid level, wherein at least one of the second cylinder and the baffle plate comprises a passage communicating one side of the baffle plate with another side thereof.

7. The liquid level detecting apparatus according to claim 1, wherein the first cylinder comprises a step therein reflecting the ultrasonic wave generated by the ultrasonic sensor back to the ultrasonic sensor.

8. A liquid level detecting apparatus comprising:

an ultrasonic sensor installed in a bottom of a tank storing a liquid and detecting a liquid level of the liquid by generating a ultrasonic wave and receiving the ultrasonic wave reflected by the liquid level;

a reflector turning the ultrasonic wave to the liquid level;

a first cylinder enclosing a first route transmitting the ultrasonic wave between the ultrasonic sensor and the reflector and shaped as an internal sectional area thereof perpendicular to the first route gradually becomes smaller toward the ultrasonic sensor;

a second cylinder enclosing a second route transmitting the ultrasonic wave between the reflector and the liquid level and extending from the bottom to a height below a ceiling surface within the tank and over a maximum level of the liquid level; and

a baffle plate installed in the second cylinder, a lower surface of the baffle plate generally in parallel to and at the height of the maximum level,

wherein the baffle plate and/or on an internal surface of the second cylinder has a passage to communicate both sides of the baffle plate.

9. The liquid level detecting apparatus according to claim 8, wherein the lower surface of the baffle plate is above the liquid level when an amount of the liquid is 90% of the amount of the liquid when the liquid level is at the maximum level.

10. The liquid level detecting apparatus according to claim 8, wherein the partition plate covers a longitudinal central axis of the second cylinder.

11. The liquid level detecting apparatus according to claim 8, wherein the partition plate is formed separately from and fixed to the second cylinder.

12. The liquid level detecting apparatus according to claim 8, wherein the first cylinder comprises a step therein reflecting the ultrasonic wave generated by the ultrasonic sensor back to the ultrasonic sensor.

13. A liquid level detecting apparatus comprising:

an ultrasonic sensor installed in a bottom of a tank storing a liquid and detecting a liquid level of the liquid by generating a ultrasonic wave and receiving the ultrasonic wave reflected by the liquid level;

a reflector turning the ultrasonic wave to the liquid level;

a first cylinder enclosing a first route transmitting the ultrasonic wave between the ultrasonic sensor and the reflector, holding the ultrasonic sensor at one end thereof, an internal section along a longitudinal axis of the first cylinder having a step reflecting the ultrasonic wave generated by the ultrasonic sensor back to the ultrasonic sensor.

14. The liquid level detecting apparatus according to claim 13, wherein:

the first cylinder has a generally round cross-sectional shape perpendicular to a longitudinal axis thereof; and

an inner and an outer circumferences of the step are coaxially arranged to each other.

15. The liquid level detecting apparatus according to claim 13, wherein the reflector is formed in a body with the first cylinder at an another end thereof, which is opposite to the one end.

16. The liquid level detecting apparatus according to claim 13, further comprising:

a second cylinder fixed onto the first cylinder and enclosing a second route transmitting the ultrasonic wave between the reflector and the liquid level.