US3735323A

US3735323A - Pressure-to-electric, long life transducer

Info

Publication number: US3735323A
Application number: US00182781A
Authority: US
Inventors: W Marscher; H Wertheimer
Original assignee: Bendix Corp
Current assignee: Bendix Corp; Siemens Automotive LP
Priority date: 1971-09-22
Filing date: 1971-09-22
Publication date: 1973-05-22
Anticipated expiration: 1990-05-22
Also published as: GB1343264A; JPS4841781A; DE2243721A1; CA950068A; FR2153914A5

Abstract

A pressure-to-electric transducer having increased life potential is disclosed herein. The transducer is comprised of a canister having a movable wall member, electrical means for generating an electrical signal indicative of wall movement, and means to cause displacement of the movable wall member in response to a pressure variation on one side of said wall. The improvement is comprised of means for periodically adjusting the relationship of the electrical means so that wear caused by relative movement within the electrical means is uniformly distributed. In particular, the electrical means are comprised of a wound coil of resistive wire and a movable wiper means for sliding engagement with said coil. Means are provided to alter the relative angular position of the wiper means relative to the coil so that wear caused by the wiping action is uniformly distributed around the coil.

Description

United States Patent 1191 Marscher et al.

[111 3,735,323 1451 May 22, 1973 [54] PRESSURE-TO-ELECTRIC, LONG LIFE TRANSDUCER [75] Inventors: William D. Marscher, Ithaca; Harry P. Wertheimer, l-lorseheads, both of N.Y. j [73] Assignee: The Bendix Ctirporation, Elmira,

N.Y. 3 22 Filed: Sept. 22, 19. 7 1

[21] Appl. No.: 182,781

[52] U.S. Cl ..338/4l, 338/150 [51] Int. Cl. ..H0lc 13/00 [58] Field of Search ..338/36, 41, 42, 150; 73/262, 398 AR [56] References Cited UNITED STATES PATENTS 3,173,120 3/1965 Marks et al ..338/36 3,172,069 3/1965 Marks et al ....338/4l 3,032,733 5/1962 Zuehlke et al ..338/41 Primary Examiner--C. L. Albritton Att0rneyRobert A. Benziger, William S. Thompson et al.

[5 7] ABSTRACT A pressure-to-electric transducer having increased life potential is disclosed herein. The transducer is comprised of a canister having a movable wall member, electrical means for generating an electrical signal indicative of wall movement, and means to cause displacement of the movable wall member in response to a pressure variation on one side of said wall. The improvement is comprised of means for periodically adjusting the relationship of the electrical means so that wear caused by relative movement within the electrical means is uniformly distributed. in particular, the electrical means are comprised of a wound coil of resistive wire and a movable wiper means for sliding engagement with said coil. Means are provided to alter the relative angular position of the wiper means relative to the coil so that wear caused by-the wiping action is uniformly distributed around the coil.

10 Claims, 4 Drawing Figures PATENTEBHAYZZIQH 3,735,323

SHEET 1 [1F 2 FIGURE 2 FIGURE l WILLIAM D. MARSHER HARRY I? WERTH El M ER INVENTORS QQMQAMSg Q PATENTED MAYZZIBYS 3 735,323

SHEET 2 BF 2 58 FIGURE 4 H W H 7 I INN U 11mm FIGURE 3 WILLIAM D MARSHER HARRY F. WERTHElMER INVENTORS BYQMW PRESSURE-TO-ELECTRIC, LONG LIFE TRANSDUCER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pressure-to-electric transducers which are used to convert a sensed pressure signal into a usable electrical signal. The present invention is more particularly related to such transducers which are used to provide signals for systems having unusually long life requirements.

2. Description of the Prior Art The prior art teaches that pressure-to-electric transducers may be comprised of a canister or body means having a movable wall portion responsive to variable pressure changes and an electrical means operatively associated with that movable wall portion to convert movement thereof into a variable output electrical signal. Pressure-to-electric transducers are known which have excellent life capability and which reliably produce the variable electrical output signals. However,

the excellent life capability is achieved due to the fact that the variable output signal is generated by varying the dimensional interrelationship between mechanically movable but otherwise noncontacting structure to alter an electric or electromagnetic field for an electrical means which includes a reactive type element. Such devices are expensive to manufacture and frequently have components which are difficult to fabricate such as a variably shaped movable core. Such devices also provide rapid responses to pressure variations only during periods of transient electrical activity. It is therefore an object of the present invention to provide a pressure-to-electric transducer having long life and which is simple and inexpensive to fabricate and manufacture. Since rapid response is frequently desirable from such pressure-to-electric transducers and the necessary transient electrical conditions are not always readily capable of generation, it is a still further object of the present invention to provide a pressure-to-electric transducer having a long life capability, which is simple and inexpensive to fabricate and manufacture and which provides a rapid variation in the electrical output signal in response to variations in the sensed pressure without requiring transient electrical conditions.

Pressure-to-electric transducers which are relatively simple and inexpensive to fabricate and manufacture are also well known in the art. Additionally, such pressure-to-electric transducers are known which provide excellent speed of response to variations in sensed pressure. Typically the electrical means of such transducers comprise a wound coil of resistive wire fixedly mounted to the canister or body portion and a wiper arm means pivotally mounted to the canister and coupled to the movable wall means so as execute pivotal motion in response to movement of the movable wall means. Other interrelations of canister, movable wall means and electrical means are also well known. However, such devices are generally not capable of achieving the operating life expectancy of pressure-to-electric transducers which utilize reactive type electrical means. It is therefore a particular object of the present invention to provide a mechanism for increasing the operating life expectancy of pressure-to-electric transducers which utilize resistive electrical means.

Such pressure-to-electric transducers are presently utilized to generate electrical signals indicative of the pressure within the intake manifold of internal combustion engines. The information contained within such electrical signals is utilized by an electronic fuel control system to precisely control delivery of fuel to the internal combustion engine. However, the life capability required by the automotive industry for internal combustion engine components necessitates the use of the more expensive, complex, and slower response pressure-to-electric transducer including the reactive type electrical means. It is therefore a still further object of the present invention to provide a pressure-to-electric transducer using resistive electrical means having a life expectancy compatible with the life expectancy requirements of the automotive industry.

SUMMARY OF THE PRESENT INVENTION In view of the fact that the environment in the vicinity of an internal combustion engine experiences a cyclic variation directly attributable to the operation of that engine, the present invention contemplates the use of a means to sense the cyclic variation and to communicate this variation to the resistive portion of the electrical means in a pressure-to-electric transducer which utilizes resistive electrical means to periodically vary the relationship between the movable and stationary components within the resistive electrical means to thereby more uniformly distribute wear about theresistive means caused by the relative wiping motion. The present invention further contemplates the improvement to a pressure-to-electric transducer which comprises rotatably mounting the electric resistive coil and providing that coil with a toothed ratchet wheel and further including a means responsive to the cyclic variation to rotate the toothed ratchet wheel and the coil relative to a wiper arm means. In particular, the present invention contemplates the use in an environment which experiences a cyclic variation, such as a temperature variation, of a bimetal temperature responsive element to periodically move against the teeth of the toothed ratchet wheel to cause said ratchet wheel to rotate relative to the bimetal actuating mechanism.

BRIEF DESCRIPTION THE DRAWINGS vFIG. 1 illustrates a sectional view of a pressure-toelectric transducer according to the present invention.

FIG. 2 illustrates a top sectional view of the pressureto-electric transducer of FIG. 1.

FIG. 3 shows a magnified side view of a portion of the interior of the pressure-to-electric transducer according to FIGS. 1 and 2 to more clearly illustrate the present invention.

FIG. 4 shows a top view of the mechanism illustrated in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 of the drawing, a pressureto-electric transducer 10 according to the present invention is illustrated. The transducer 10 is comprised generally of a main canister portion or body means 12, a movable wall means 14 and an electrical means 16.

The electrical means 16 are comprised of a resistive coil means 18, a coil wiper means 20, and an electrical energy input means 22. Electrical energy input means 22 are provided with electrical energy by way of the input conductors 24. This electrical energy is provided to the coil means 18 by way of the pair of brushes 26 which electrically intercommunicate the coil means 18 with the electrical energy input means 22. Coil wiper means 20 include coil wiping end portion 28 and arm portion 30 and are pivotably attached to the canister body 12 by mounting means 32 which are illustrated herein as a plurality of screws passing through mounting end portion 34. Intermediate mounting end portion 34 and wiping end portion 28 is located the actuating member 36 which is fixedly connected between the arm portion 30 and movable wall means 14 so that movement of the movable wall means 14 will be directly communicated to the wiper means 20. Depending upon the actual point of attachment, the sensed movement may be magnified or reduced.

As can be seen from FIG. 2, the wiper means 20 in this instance is comprised of a member having an arm portion 30, a wiper end portion 28 with a pair of wiper members and a mounting or attachment end portion 34.

Referring now to FIG. 3, the coil rotating mechanism of the present invention is illustrated in a magnified partial section view taken along line III-III of FIG. 2.

' A toothed ratchet wheel member 50 having a stub shaft portion 52 is fixedly attached to the resistive coil means 18. Resilient means 54 are operative to bias the resistive coil means 18, ratchet wheel 50 and stub shaft portion 52 into a stub shaft receiving bore 56 within the body means 12. A ratchet wheel rotating means 58 is illustrated in contact with one of the teeth of the toothed ratchet wheel member 50. Any suitable bearing means 57 may be interposed between ratchet wheel member 50 and body means 12 to achieve any desired friction level therebetween.

Referring now to FIG. 4, a top view of the mechanism illustrated in FIG. 3 is shown. The toothed ratchet wheel 50 is illustrated as having a plurality of ratchet teeth 60 arranged circumferentially thereabout in the normal fashion. The ratchet wheel rotating means 58 is illustrated as being in a pushing abutting relationship with one of the teeth 60a and is illustrated in this instance as being a coil 62 which is attached by any convenient mechanism at its fixed end to the canister portion 12. For a cyclic temperature environment, such as exists in proximity to an internal combustion engine, coil 62 may be of a temperature responsive birnetal construction. Additionally, an escapement mechanism is illustrated in the form of a resilient cantilever spring 64 which is operative to cause incremental rotation of the toothed ratchet wheel 50 in preselected steps of rotation, one per cycle, and is further operative to prevent reverse rotation of resistive coil means 18.

OPERATION OF THE PRESENT INVENTION When the pressure-to-electric transducer of the present invention is utilized in an environment which exhibits a cyclic change, which may be for instance a temperature variation as illustrated herein, the rotating mechanism 58 may be so calibrated that at one selected extreme of the cyclical variation the pushing end 66 of rotating means 58 may be in position 70 as illustrated by dashed lines (FIG. 4), while in the other selected extreme of the cyclical variation it may be in position 72 as also illustrated by dashed lines. Thus, for each cyclic change, the electric coil means 18 may be rotated of the resistive coil means 18. By uniformly distributing wear about the circumference of the resistive coil means 18, the operating life of the resistive coil means can be extended by a factor which is approximately the number of rotational increments available through ratchet wheel 50 and the operation of escapement means 64. Thus, for pressure-to-electric transducers as may be used for instance in an automotive electronic fuel control system, the wear rate of the pressure sensor may be made sufficiently low that its operating life expectancy compares favorably with the noncontact electrode reactive type pressure sensors, heretofore commercially acceptable, and the pressure-to-electn'c transducer of the present invention may therefore significantly reduce the cost of the pressure-to-electric transducer element of such systems. Furthermore, by providing a directly readable output voltage signal which is always present and which represents instantaneous pressure, the pressure-to-electric transducer of the present invention is much more widely applicable for use with systems of differing designs and/or operating constants and requires little or no tailoring of operation.

As illustrated, the present invention is adapted for use in an environment which experiences a predictable cyclic variation in an environmental parameter not related to the operation of the transducer (i.e., environmental temperature). The man of ordinary skill in the art will recognize that other cyclic variables may be utilized to effect the desired motion through suitably responsive actuating mechanisms which may be inertia operated and responsive to a gross cyclic motion or may be diaphragm operated and responsive to a different pressure variation such as for instance pressure in the vehicle exhaust system.

We claim: 1. A pressure-to-electric long life transducer for use in an environment having a cyclic variation other than the sensed pressure comprising in combination:

a canister body; movable wall means sealingly attached to said canister body operative to form an enclosed region within said canister body so that a variation in the pressure exterior to the canister body will create a pressure differential that moves said movable wall means; electrical signal means comprised of a resistive means, a wiper means in wiping contact with said resistive means, and means to provide electrical energy to said resistive means, one of said resistive means and said wiper means being coupled stationarily relative to said movable wall means and the other of said resistive means and said wiper means being coupled stationarily relative to said canister means whereby movement of said movable wall means produces a wiping movement of said wiper means relative to said resistive means; and

rotational means coupled to at least a portion of said electrical signal means operative to cause a periodic relative rotation of said resistive means relative to said wiper means.

2. The transducer as claimed in claim 1 wherein said rotational means comprise:

a toothed ratchet wheel having ratchet teeth; and

means responsive to a cyclic variation operative to be successively biased against different ones of said ratchet teeth;

one of said ratchet wheel and said cyclically responsive means being rotationally coupled to one of said resistive means and said wiper means relative to the other of said ratchet wheel and cyclically responsive means.

3. The transducer as claimed in claim 2 wherein said resistive means are rotationally mounted on said canister and said cyclically responsive means are fixedly coupled to said canister whereby said resistive means are rotated relative to said wiper means by said cyclically responsive means.

4. The transducer as claimed in claim 3 wherein said cyclically responsive means comprise a bimetal means responsive to predetermined environmental temperature variations operative to rotate said ratchet wheel.

5. The transducer as claimed in claim 3 including further:

escapement means operatively associated with said ratchet wheel operative to cause relative rotational movements to be in one direction.

6. In a pressure-to-electric transducer of the type having a closed canister body with deformable wall means responsive to variations in the pressure exterior to the canister body relative to the pressure interior to the canister body and electrical means including a resistive means and a wiper means responsive to wall movements operative to generate an electrical signal indicative of pressure variations for use in an environment having a nonpressure cyclic variation, the improvement comprising:

means responsive to the nonpressure cyclic variation operative to vary the relationship of the resistive means relative to the wiper means in a predetermined manner.

7. The transducer as claimed in claim 6 wherein said means responsive to nonpressure cyclic variation comprise:

a toothed ratchet wheel having ratchet teeth; and

means responsive to said nonpressure cyclic variation operative to be successively biased against different ones of said ratchet teeth;

one of said ratchet teeth wheel and said cyclically responsive means being rotationally coupled to one of said resistive means and said wiper means rela tive to the other of said ratchet wheel and cyclically responsive means.

8. The transducer as claimed in claim 7 wherein said resistive means are stationarily and rotationally mounted on said canister and said cyclically responsive means are fixedly coupled to said canister whereby said resistive means are rotated relative to said wiper means by said cyclically responsive means.

9. The transducer as claimed in claim 8 wherein said cyclically responsive means comprise a bimetal means responsive to predetermined environmental temperature variations operative to rotate said ratchet wheel.

10. The transducer as claimed in claim 8 including further:

Claims

1. A pressure-to-electric long life transducer for use in an environment having a cyclic variation other than the sensed pressure comprising in combination: a canister body; movable wall means sealingly attached to said canister body operative to form an enclosed region within said canister body so that a variation in the pressure exterior to the canister body will create a pressure differential that moves said movable wall means; electrical signal means comprised of a resistive means, a wiper means in wiping contact with said resistive means, and means to provide electrical energy to said resistive means, one of said resistive means and said wiper means being coupled stationarily relative to said movable wall means and the other of said resistive means and said wiper means being coupled stationarily relative to said canister means whereby movement of said movable wall means produces a wiping movement of said wiper means relative to said resistive means; and rotational means coupled to at least a portion of said electrical signal means operative to cause a periodic relative rotation of said resistive means relative to said wiper means.

2. The transducer as claimed in claim 1 wherein said rotational means comprise: a toothed ratchet wheel having ratchet teeth; and means responsive to a cyclic variation operative to be successively biased against different ones of said ratchet teeth; one of said ratchet wheel and said cyclically responsive means being rotationally coupled to one of said resistive means and said wiper means relative to the other of said ratchet wheel and cyclically responsive means.

5. The transducer as claimed in claim 3 including further: escapement means operatively associated with said ratchet wheel operative to cause relative rotational movements to be in one direction.

6. In a pressure-to-electric transducer of the type having a closed canister body with deformable wall means responsive to variations in the pressure exterior to the canister body relative to the pressure interior to the canister body anD electrical means including a resistive means and a wiper means responsive to wall movements operative to generate an electrical signal indicative of pressure variations for use in an environment having a nonpressure cyclic variation, the improvement comprising: means responsive to the nonpressure cyclic variation operative to vary the relationship of the resistive means relative to the wiper means in a predetermined manner.

7. The transducer as claimed in claim 6 wherein said means responsive to nonpressure cyclic variation comprise: a toothed ratchet wheel having ratchet teeth; and means responsive to said nonpressure cyclic variation operative to be successively biased against different ones of said ratchet teeth; one of said ratchet teeth wheel and said cyclically responsive means being rotationally coupled to one of said resistive means and said wiper means relative to the other of said ratchet wheel and cyclically responsive means.

10. The transducer as claimed in claim 8 including further: escapement means operatively associated with said ratchet wheel operative to cause relative rotational movements to be in one direction.