Flow sensor

• US 5,765,432 A
• Filed: 11/08/1996
• Issued: 06/16/1998
• Est. Priority Date: 03/16/1995
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Konzelmann, Uwe, Lock, Andreas
• Primary Examiner(s): Dombroske, George M.
• Assistant Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US08/737,530
• Time in Patent Office: 585 Days
• Field of Search: 73/204.11, 73/204.26, 73/204.14, 73/204.15, 73/204.16, 73/204.19, 73/204.25
• US Class Current: 73/204.11
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01F 1/692 Thin-film arrangements
• CPC Class Codes: G01F 1/696 Circuits therefor, e.g. constant-current flow meters

Abstract

A flow sensor has a diaphragm and a resistive film positioned on the diaphragm. A heater is formed from the resistive film and temperature sensors are arranged on both sides of the heater. On both sides of the heater are additional temperature sensors, which are interconnected by an interconnect resistor and formed from the resistive film.

Claims

1. A flow sensor, comprising:

a measuring element having a diaphragm and a resistive film, the resistive film positioned on the diaphragm;

at least one heater formed from the resistive film and having a first side and a second side;

first temperature sensors provided on the first and second sides of the at least one heater;

second temperature sensors provided on the first and second sides of the at least one heater; and

an interconnect resistor interconnecting the second temperature sensors,

wherein the second temperature sensors and the interconnect resistor are positioned on the diaphragm and are formed from the resistive film.

2. The flow sensor according to claim 1, wherein the first and second temperature sensors have meander-shaped resistor run designs, the first temperature sensors being nested into the second temperature sensors.

3. The flow sensor according to claim 1, wherein the first and second temperature sensors have meander-shaped resistor run designs, the second temperature sensors being nested into the first temperature sensors.

4. The flow sensor according to claim 1, wherein the first temperature sensors are positioned closer to the at least one heater than the second temperature sensors.

5. The flow sensor according to claim 1, wherein the second temperature sensors are positioned closer to the at least one heater than the first temperature sensors.

6. The flow sensor according to claim 1, further comprising:

leads for contacting at least one of the at least one heater, the first temperature sensors, the second temperature sensors and the interconnect resistor, wherein the leads are formed from the resistive layer.

7. The flow sensor according to claim 1, further comprising:

a measuring bridge including a first branch, a second branch and a center tap, the first branch formed using the first temperature sensors, the center tap positioned between the first temperature sensors, the second branch formed using the interconnect resistor and the second temperature sensors,

wherein the interconnect resistor is positioned between the second temperature sensors, and wherein the second branch includes two taps, each of the two taps being arranged between the interconnect resistor and each of the second temperature sensors.

8. The flow sensor according to claim 6, further comprising:

adjustable resistors coupled in series between the two taps of the second bridge branch; and

a compensated tap provided between the adjustable resistors.

9. The flow sensor according to claim 8, wherein the adjustable resistors have a higher resistance than the interconnect resistor.

10. The flow sensor according to claim 1, wherein the first temperature sensors are formed from the resistive film.