US3643639A

US3643639A - Pressure differential speed sensor

Info

Publication number: US3643639A
Application number: US58815A
Authority: US
Inventors: Kenneth C Bier
Original assignee: Holley Carburetor Co
Current assignee: Holley Performance Products Inc
Priority date: 1970-07-28
Filing date: 1970-07-28
Publication date: 1972-02-22
Anticipated expiration: 1989-02-22

Abstract

A pressure differential sensing device has a housing divided into two chambers on opposite sides of a diaphragm contained therein; a first of the two chambers has conduit means adapted for connection to the inlet of a fluid pump while the other chamber has a first conduit connected to the discharge of the fluid pump and a second conduit leading to some associated device to be controlled thereby; a valve carried by the diaphragm is urged into seating engagement with the inlet end of the second conduit by a spring so as to prevent communication between the other chamber and the second conduit whenever the differential of pressure between the pump inlet and pump outlet is less than a predetermined magnitude.

Description

United States Patent Bier [ Feb. 22, 1972 [72] Inventor: Kenneth C. Bier, Bloomfield Hills, Mich.

[73] Assignee: Holley Carburetor Company, Warren,

Mich.

221 Filed: July 28, 1970 211 Appl.No.: 58,815

2,361,206 10/194'4 Hoppe..... ..123/l03 EX 2,260,576 10/1941 Maybach ..l23/l03EX Kostenick "123/ 103 E Hannibal et al Walker ..417/34 X Primary Examiner-Allan D. l-lerrmann Attorney-Walter Potoroka, Sr.

[ ABSTRACT A pressure differential sensing device has a housing divided into two chambers on opposite sides of a diaphragm contained therein; a first of the two chambers has conduit means adapted for connection to the inlet 'of a fluid pump while the other chamber has a first conduit connected to the discharge of the fluid pump and a second conduit leading to some associated device to be controlled thereby; a valve carried by the diaphragm is urged into seating engagement with the inlet end of the second conduit by a spring so as to prevent communication between the other chamber and the second conduit whenever the differential of pressure between the pump inlet and pump outlet is less than a predetermined magnitude.

10 Claims, 5 Drawing Figures PRESSURE DIFFERENTIAL SPEED SENSOR BACKGROUND OF THE INVENTION Heretofore various devices have been proposed by the prior art which were intended to create an output in response to the attainment of a particular speed of an associated pump. Such prior art devices employed a characteristic of a rotary pump to determine when that particular pump speed was attained. That is, it has been known that in some pump installations, such as an automatic water pump, both pump inlet and pump discharge pressure increase generally exponentially with pump speed but that pump discharge pressure increases at a greater rate than does pump inlet pressure. This, of course, means that the pressure rise across the pump is a repeatable function of pump speed. However, the prior art not only employed such a differential in pressure in determining when a particular speed was achieved, but also employed the subsequently increasing pressure differential as the source of the power for causing actuation of the related device to be controlled thereby. Since the rate of change of increase in the pressure differential across the pump is relatively small compared to the rate of change in pump speed, the net result, in the prior art, is that the sensitivity or responsiveness of the overall system is slow and that a very wide band exists at the governed range or point.

Accordingly, the invention as herein disclosed and described is primarily concerned with the solution of the above as well as other related problems.

SUMMARY OF THE INVENTION According to the invention, a pressure differential sensing device comprises a housing, pressure responsive means within said housing, a first pressure chamber formed in said housing at one side of said pressure responsive means, a second pressure chamber formed in said housing at the other side of said pressure responsive means, first conduit means effective for completing communication between said first pressure chamber and a source of relatively low pressure, second conduit means effective for completing communication between said second pressure chamber and an associated pressure signal receiving device, a valve seat formed about said inlet of said third conduit means, spring means normally urging said pressure responsive means in a direction toward said second pressure chamber, and valve means within said second pres sure chamber and adapted to be at times urged by said spring means and pressure responsive means toward seating engagement with said valve seat, said spring means being efiective to maintain said valve means seated against said valve seat until the differential in pressure between said relatively low pressure and said relatively high pressure attains a predetermined minimum magnitude of pressure differential, said pressure responsive means and said valve means being effective to move toward said first pressure chamber against said spring means upon the attainment of said predetermined minimum magnitude and to expose an additional effective surface area for reaction by said relatively high variable pressure within said second pressure chamber, said inlet of said third conduit means being effective when said valve means moves towards said first pressure chamber to complete communication between said second pressure chamber and said third conduit means.

Various general and specific objects and advantages of the specific objects and advantages of the invention will become apparent when reference is made to the following written description considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein certain details or elements may be omitted from one or more views for purposes of clarity:

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in greater detail to the drawings, FIG. 1 illustrates an internal combustion engine 10, as might be employed, for example, in an automotive vehicle, provided with a carburetor assembly 12 and coolant system 14 comprised of a radiator 16, with coolant flow conduits l8 and 20, and a coolant or water pump assembly 22 which, as is well known in the art, has an inlet for receiving cooled water from the radiator 16 and an outlet for discharging such cooled water into the coolant circuitry formed within the engine 10. The pump 22, as is well known in the art, is driven by the engine 10 so that the rotational speed of the engine is reflected in the speed of the pump.

Portions 24 and 26 are intended to respectively depict suitable inlet and discharge taps formed on or carried by pump assembly 22 so that conduit means 28 and 30 may be respectively connected thereto and to a pressure differential sensing device or assembly 32.

FIG. 2 illustrates a graph of typical curves obtained by plotting pressure against pump speed for both the inlet and discharge sides of the pump assembly. That is, curve 34 depicts the typical pump discharge pressure versus speed, while curve 36 depicts the typical pump inlet pressure versus speed. From an inspection of

curves

34 and 36 it can be seen that a pressure differential AP occurs across the pump and that such values of pressure differentials (as, for example AP, at speed 8,, and AP at speed 8;) are repeatable functions of engine speed (pump, speed) even if the absolute values of both the inlet and discharge pressures are afiected by other factors such as, for example, temperature. 7

FIG. 3 illustrates, in enlarged axial cross section, the device 32 of FIG. 1 as comprising a housing assembly 38 consisting of

housing sections

40 and 42 operatively joined to each other, as by a bent over flange portion 44, in a manner so as to peripherally retain therebetween a pressure responsive diaphragm 46 which defines two variable chambers 48 and 50 on opposite sides thereof. A spring 52, situated within chamber 48, is contained between a wall 54 of housing section 40 and a suitable spring pad or plate 56 suitable carried by diaphragm 46. The opposite side of diaphragm 46 has a valving member 58 suitably secured thereto so as to be moveable therewith. As is shown, a passageway 60 is formed through the valve member 58, diaphragm 46 and plate 56 so as to at times complete at least a degree of communication between chambers 48 and 50. The upper housing section 40 has a conduit portion 62 formed thereon which communicates with conduit 28 while the lower housing section 42 is provided with a conduit portion 64 communicating with conduit means 30. Conduit 64 may be provided with a calibrating restriction 66, as shown. A third conduit 68 is formed in the lower housing section 42 in a manner so as to have the inner disposed end terminate in a valve seating surface 70 against which the valve 58 is at times urged by spring 52 so as to cause surface 72 thereof to be in engagement with seating surface 70.

OPERATION OF THE INVENTION Let it be assumed that P, equals pump inlet pressure while P, equals pump discharge pressure and that pressure P; can be a variable pressure at times equaling pressure I, and at other times equaling a pressure somewhat less than pressure P,. Let it be further assumed that the engine 10 is running and driving s A t n a...

pump assembly 22 and that a particular control function is desired to occur at a speed of S as depicted generally on each of FIGS. 2 and 5.

With the engine and pump speed being relatively low (to the left of S the values of both P and P will be relatively low and the preload force of spring 52 will be sufficient to cause the diaphragm 46 to be moved toward chamber 50 until valve member 58 is seated against seating surface 70 of conduit 68. During this time conduit or passageway 60 will to some degree complete communication between conduit 68 and chamber 48 so as to vent conduit 68 to pressure P,.

As should be apparent, in view of the above, during the time that valve member 58 is so held against seating surface 70, the area of diaphragm 46 which is exposed to the relatively high pressure in chamber 50 (at this time the chamber 50 defines a closed or dead-ended space therefore causing P to be equal to P is the total area of the diaphragm 46, between chambers 48 and 50, less the area included within the seating surface 70.

As engine and pump speed increase, the pressure differential across diaphragm 46 also increases generally in accordance with the graph of FIG. 2; when the speed finally reaches the predetermined speed of S the force created by such a pressure differential is sufficient to start to overcome the preload force of spring 52 thereby causing the diaphragm 46 and valve 58 secured thereto to start to move upwardly or away from seating surface 70. However, as soon as valve 58 starts to move away from seat 70, the area of valve 58 previously enclosed by seat 70 and not exposed to pressure P now becomes exposed to the high pressure P, thereby immediately adding to the total force causing diaphragm 46 and valve 58 to move upwardly away from seat 70.

This now completes communication between chamber 50 and conduit 68 so as to supply to conduit 68, and devices associated therewith a control signal, P, The actual value of P, will, of course, depend upon the value of P, which, in turn, is dependent not only on the value of P but also theeffective flow area of restriction 66 (if one is employed) and the effective flow area of bleed or vent passage 60. However, when valve 58 is seated against surface 70, the value of P, will be equal to P FIG. 5 graphically depicts a curve 74, representing the signal pressure P,, .as a partial overlay on

dashline curves

34 and 36 respectively depicting the P and P pressure curves. From FIG. 5 it can be seen that in the low speed range the pressure signal P, follows the curve 36, determined by the relatively low pressure P,, until the speed reaches the predetermined value of S atwhich point the valve 58 starts to open as described above. This in effect, determines point 76 on the curve 74. The next portion of the curve 74 as depicted between

points

76 and 78 has a relatively steep slope because of the phenomenon of having a greater effective surface area of diaphragm 46 exposed to the high pressure P as soon as it begins to move upwardly away from seat 70. Accordingly, as illustrated in FIG. 5, a very slight increase in speed, AS, from S is sufficient to cause the pressure signal P, to go to the maximum value of P (or P;, as the case may be).

As should be appreciated, the invention provides .a means whereby a particular control point can be set and achieved within very close limits of the parameter being sensed. That is, prior art structures have been proposed for using the differential in pressures between P, and P,. However, such prior art structures have attempted to employ such differentials, unmodified, as not only a control signal but also as the output for operating some related device. Since such prior art devices were dependent upon only the force created by the con tinually changing pressure differential, this required a very wide spread in speed between when the effective pressure signal was started to be created and when such signal reached its full operating value. Further, such prior art devices required the provision of two conduits leading to the related device to be operated by such differential of pressures. Such prior art devices are believed to be best emplifled by US. Pat. No. 3,204,620 issued to Brooks Walker onSept. 7, 1965.

In contrast to the prior art, it can be seen that the operative pressure signal, P,, rapidly increases once point 76 is achieved, and that only one conduit 68 is necessary in order-to cause a related device 80 to be operated by such a signal or control pressure P,. One such related device 80 to be operated by such a signal or control pressure P, One such related device 80 is illustrated in FIG. 4 wherein a fragmentarily illustrated carburetor or induction passage member 82 is shown as being comprised of a body 84 having an induction passage 86 formed therethrough with a throttle valve 88 situated therein and mounted for pivotal rotation on a transversely extending and journaled throttle shaft 90 provided with an actuating arm or lever 92. A suitable spring 94 operatively connected as to lever 92 is effective for continuously urging lever 92 and throttle valve 88 generally counterclockwise to a nominally closed throttle. position as shown. The induction device 82 may in fact be the carburetor 12 of FIG. 1 so that opening movement of the throttle valve 88 causes an increase in the rate of motive fluid to the engine 10.

A lever 96, pivoted as at 98 to a suitable support 99, has one arm 100 pivotallyv connected to one end 102 of a linkage means 104 which is pivotally connected at its other end 106 to throttle lever 92. The other arm 108 of lever 96 is pivotally connected to one end 110 of motion transmitting linkage means 112 which, in turn, is pivotally connected at its other end 114 to an operator foot-operated throttle lever 116 pivotally mounted to the vehicle floor 118 as at 120.

The motion transmitting linkage means ll2 is illustrated as being comprised of a housing 122 having an extension 124 fixedly secured thereto at one end thereof and containing a compression spring 126 therein. A linkage member 128, slideably received through one end of housing 122, has an enlarged head end 130 which is acted upon by spring 126. The force of spring 126 is greater than that developed by spring 94. Therefore, when throttle lever 116 is rotated counterclockwise about pivot 120, motion transmitting linkage means 112 acts as a solid transmitting member causing lever 96 to rotate clockwise about pivot 98, and in so doing, causes, through linkage 104, throttle valve 88 and lever, 92 to be rotated clockwise in the throttle opening direction. As previously stated, this increases the rate of flow of motive fluid to the engine l0 and, assuming normal road load conditions, increases both vehicular and engine speed. Member 131 indicates a positive wide'open throttle stop or abutment for limiting the maximum movement of lever 96. The device 80 is illustrated, in this instance, as comprising a housing assembly 132 composed of

housing sections

134 and 136 which are joined to each other, as by a tumed-over flange portion 138, in a manner so as to peripherally contain therebetween a pressure responsive wall member or diaphragm 140 defining distinct chambers 142 and 144 at opposite sides thereof. Chamber 142 is vented to the atmosphere as by orifice means 146 while chamber 144 is placed in communication with suitable conduit means 148, leading to conduit 68, as by a conduit carried by housing section 134. A plungerlike member 152, slideably received through housing section 136, is operatively connected at one end to the diaphragm 140 so as to be moveable therewith. A spring 154, contained within chamber 142 and situated generally about plunger or moveable abutment 152, is employed to generally urge the diaphragm 140 in a direction toward chamber 144.

Assuming now that in FIGS. 2 and 5 denotes a desired governed maximum engine speed, it can be seen that pressure P, admitted to chamber 144 will be at a value equal to P, for

the range of engine speeds to the left of 8;. As lever 96 and throttle valve 88 are further rotated in the opening direction, engine speed increases and pressure P, increases in accordance with segment 75 of curve 74 until such time as pressure P reaches point 76 (8,). At that time valve 58 (FIG. 3) becomes unseated pennitting the signal or actuating pressure P, to become a value equal to P; which is communicated via conduit means 148 to chamber 144 wherein the pressure P, (or P causes diaphragm 140 to move generally in the direction of chamber 142 causing moveable abutment 152 to move toward and abuttingly engage a raised portion or lug 160 on lever arm 100. The diaphragm 140 and member 152 thusly cause lever 96 and throttle 88 to be forcible rotated in the throttle closing direction so as to maintain the desired selected speed 8,. Suchclosing rotation of the throttle valve 88 continues even though the vehicle operator resists it by not releasing the foot-operated throttle lever 116 because of the lost motion connection in linkage means 112 comprised of housing 122, spring 126 and plungerlike head 130 on linkage 128.

in view of the above, it should be apparent that device 80, as shown in FIG. 1, could be any particular device or apparatus desired to be actuated in response to the attainment of a particular pump speed. For example, such devices could in fact be pressure responsive or pressure actuated electrical switches as well as suitable servomechanisms. Also, it should be apparent that the various elements disclosed herein could be substituted for by their functional equivalents. For example, it is possible to substitute pressure responsive pistonlike members for the diaphragms. Further, even though not shown, it should be apparent that the spring means 52 of FIG. 3 as well as 154 of FIG. 4 could be provided with suitable cooperating adjustment means for adjustably selecting the desired preload and thereby variably determining the value of 8;.

Even though only one preferred embodiment of the invention has been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

lclaim:

1. A pressure differential sensing device, comprising a housing, pressure responsive means within said housing, a first pressure chamber formed in said housing at one side of said pressure responsive means, a second pressure chamber formed in said housing at the other side of said pressure responsive means, first conduit means efiective for completing communication between said first pressure chamber and a source of relatively low pressure, second conduit means effective for completing communication between said second pressure chamber and a source of relatively high variable pressure, third conduit means having an inlet in said second chamber and effective for at times completing communication between said second pressure chamber and an associated pressure signal receiving device, a valve seat formed about said inlet of said third conduit means, spring means normally urging said pressure responsive means in a direction toward said second pressure chamber, and valve means within said second pressure chamber and adapted to be at times urged by said spring means and pressure responsive means toward seating engagement with said valve seat, said spring means being effective to maintain said valve means seated against said valve seat until the differential in pressure between said relatively low pressure and said relatively high pressure attains a predetermined minimum magnitude of pressure differential, said pressure responsive means and said valve means being effective to move toward said first pressure chamber against said spring means upon the attainment of said predetermined minimum magnitude and to expose an additional effective surface area for reaction against by said relatively high variable pressure within said second pressure chamber, said inlet of said third conduit means being effective when said valve means moves toward said first pressure chamber to complete communication between said second pressure chamber and said third conduit means.

2. A pressure differential sensing device according to claim 1, including additional bleed passage means formed through said pressure responsive means and said valve means, said bleed passage means being effective to complete communication between said first pressure chamber and said third conduit means whenever said valve means is seated against said valve seat.

3. A pressure differential sensing device according to claim 1, wherein said valve means is carried by said pressure responsive means including additional venting means formed through sai valve means and said pressure responsive means,

said venting means being effective to complete communication between said first pressure chamber and said third conduit means whenever said valve means is seated against said valve seat.

4. A pressure differential sensing device according to claim 1, wherein said spring means comprises a compression spring situated within said first pressure chamber, and including restriction means in said second conduit means.

5. A pressure differential sensing device according to claim 1, wherein said pressure responsive means comprises a diaphragm member, wherein said valve means is carried by said diaphragm member, and wherein said spring means comprises a compression spring situated within said first pressure chamber.

6. A pressure differential sensing device according to claim 1, wherein said pressure responsive means comprises a diaphragm member, wherein said valve means is carried by said diaphragm member, wherein said spring means comprises a compression spring situated within said first pressure chamber, and including additional bleed passage means formed through said diaphragm member and said valve means, said bleed passage means being effective to complete communication between said first pressure chamber and said third conduit means whenever said valve means is seated against said valve seat.

7. A pressure differential sensing device according to claim 1, wherein said pressure responsive means comprises a diaphragm member, wherein said valve means is carried by said diaphragm member, wherein said spring means comprises a compression spring situated within said first pressure chamber, including additional bleed passage means formed through said diaphragm member and said valve means, said bleed passage means being effective to complete communication between said first pressure chamber and said third conduit means whenever said valve means is seated against said valve seat, and including calibrated restriction means situated in said second conduit means.

8. A pressure differential sensing device according to claim 1, wherein said source of relatively low pressure comprises a pump inlet of a rotary pump assembly, and wherein said source of relatively high pressure comprises a pump discharge of a rotary pump assembly.

9. A pressure differential sensing device according to claim 3, wherein said source of relatively low pressure comprises a pump inlet of a rotary pump assembly, wherein said source of relatively high pressure comprises a pump discharge of a rotary pump assembly, wherein said third conduit means is operatively connected to a pressure responsive governor device adapted to at times adjust the position of a throttle valve in an induction passage for an internal combustion engine, said throttle valve being positionable in accordance with operator demands through interconnecting linkage means, and said governor device being effective when said valve means is unseated from said valve seat to engage said linkage means so as to move said throttle valve in the closing direction.

10. A pressure differential sensing device according to claim 9, wherein said governor device comprises a second housing, a second pressure responsive member contained within said second housing, a first signal pressure chamber formed in said second housing at one side of said second pressure responsive member, second spring means biasing said second pressure responsive member toward said first signal pressure chamber, and movable abutment means moved by said second pressure responsive member toward engagement with said linkage means whenever a signal pressure above a predetermined magnitude is directed from said third conduit means to said first signal pressure chamber.

IAIN Inna

Claims

1. A pressure differential sensing device, comprising a housing, pressure responsive means within said housing, a first pressure chamber formed in said housing at one side of said pressure responsive means, a second pressure chamber formed in said housing at the other side of said pressure responsive means, first conduit means effective for completing communication between said first pressure chamber and a source of relatively low pressure, second conduit means effective for completing communication between said second pressure chamber and a source of relatively high variable pressure, third conduit means having an inlet in said second chamber and effective for at times completing communication between said second pressure chamber and an associated pressure signal receiving device, a valve seat formed about said inlet of said third conduit means, spring means normally urging said pressure responsive means in a direction toward said second pressure chamber, and valve means within said second pressure chamber and adapted to be at times urged by said spring means and pressure responsive means toward seating engagement with said valve seat, said spring means being effective to maintain said valve means seated against said valve seat until the differential in pressure between said relatively low pressure and said relatively high pressure attains a predetermined minimum magnitude of pressure differential, said pressure responsive means and said valve means being effective to move toward said first pressure chamber against said spring means upon the attainment of said predetermined minimum magnitude and to expose an additional effective surface area for reaction against by said relatively high variable pressure within said second pressure chamber, said inlet of said third conduit means being effective when said valve means moves toward said first pressure chamber to complete communication between said second pressure chamber and said third conduit means.

3. A pressure differential sensing device according to claim 1, wherein said valve means is carried by said pressure responsive means, including additional venting means formed through said valve means and said pressure responsive means, said venting means being effective to complete communication between said first pressure chamber and said third conduit means whenever said valve means is seated against said valve seat.