WO1998035849A1

WO1998035849A1 - Automotive fluid circulating system

Info

Publication number: WO1998035849A1
Application number: PCT/US1997/005763
Authority: WO
Inventors: Rashaid Ali Albader
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-02-18
Filing date: 1997-04-07
Publication date: 1998-08-20
Anticipated expiration: 1999-08-18

Abstract

An automotive fluid circulating system is provided. The circulating system includes a vehicle fluid circulating pump (60). A reservoir (74) having fluid can be provided. A pump (70) is interconnected with the reservoir (74) and operatively interconnected with and driven by an engine (22) of a vehicle. The pressure chamber (78) is interconnected with the pump (70) and receives fluid from the pump. A fluid drive element (92), located relative to the pressure chamber (78), and interconnected with the circulating pump (60), converts a passage of pressurized fluid therethrough into mechanical driving force for driving the circulating pump (60). A regulator maintains a selected level of pressure in the pressure chamber and diverts excess fluid from the pressure chamber to the reservoir so that a constant circulating pump power output is maintained.

Description

AUTOMOTIVE FLUID CIRCULATING SYSTEM RELATED APPLICATIONS

This is a continuation-in-part of co-pending U.S. Patent Application Serial No. 08/491,790, filed June 19, 1995.

FHCLD OF THE INVENTION

This invention relates to a fluid circulating system for a vehicle and more particularly to an air conditioning system that operates at a constant power level with increased reliability regardless of engine speed.

BACKGROUND OF THE INVENTION

Air conditioning and other fluid transport mechanisms are highly desirable and, in some instances, an essential feature in modern automobiles and other vehicles. In a typical air conditioning installation, a compressor is used to pressurize and propel a volatile refrigerant such as Freon through a closed-loop system. A cooling coil is provided in the closed loop within the passenger compartment of the vehicle. The com¬

pressed, liquid phase, refrigerant expands into a gaseous phase as it passes through the cooling coil causing ambient heat to be withdrawn from the surrounding air. The withdrawal of heat cools the vehicle. The heated, expanded, refrigerant is subsequently repressurized by the compressor, causing loss of heat to the outside air. So long as the compressor continues to operate, the refrigerant continues to circulate through the

system exchanging heat between the inside and the outside of the vehicle by an associ¬

ated phase change in the refrigerant.

The air conditioning compressor in most vehicles is powered by direct inter- connection with the engine which, in most cases, is an internal combustion engine powered by gasoline, diesel fuel or a similar combustible compound. The compressor

is typically interconnected with the engine's crankcase by a power transmission belt provided between a pulley on the compressor and an associated driving pulley on the

engine. The driving pulley is, similarly, connected with a variety of other engine com-

ponents including a water circulation pump, a cooling fan, and an electrical generator or alternator. The engine's driving pulley is usually driven directly from the crankcase

and, hence, rotates at a speed that is directly proportional with the speed of engine op¬

eration. Thus, when the engine operates at an idling speed of, for example, 1,000

RPM, the air conditioning compressor pulley is driven at a proportionate idle speed. Conversely, when the engine is driven at a cruising speed at, for example, 4,000 RPM, the compressor is driven at approximately four times the idle speed.

A typical air conditioning compressor is operated by simply engaging an air

conditioning-on switch which causes an electrical clutch in the compressor's pulley to

lock the pulley relative to a compressor drive shaft. When the switch is "off", the drive

shaft and pulley are disengaged and the pulley simply free wheels relative to the drive

shaft. The associated disadvantage to this arrangement is described further below.

Nevertheless, the great variation in driving speeds of the air conditioning compressor

as engine speed changes, causes a significant variation in refrigerant pressurization.

The variation in refrigerant pressurization causes a substantial variation in air condi-

tioning cooling output. For example, at idle, the compressor's cooling output can be

approximately 6,000 BTU. When the car is traveling at approximately 3, 500 RPM,

this output can be approximately 36,000 BTU. Hence, the air conditioner may not

provide sufficient cooling at a low RPM, while the cooling is more efficient at cruising

speed. At higher speeds, in which engine speed exceeds 5000 RPM, the compressor

cannot operate for long periods without becoming damaged. Hence most compressors include a shutoff control that signals the clutch to disengage from the engine. Hence at

high speeds the compressor continually cycles on and off. This can lead to discomfort

on hot days in which continual cooling is required.

Similarly, it has been shown that the compressor suffers accelerated damage

when it is operated at high RPMs. Thus, it is often desirable to deactivate the air conditioning when cruising. This can lead to discomfort on very-hot days.

As discussed above, the operation of the air conditioner compressor's clutch

can lead to further damage since, at high RPMs, the sudden activation of the clutch sends a shock through the compressor as it is "slammed on". There is also increased risk of fan belt breakage when the clutch suddenly engages the compressor at higher

speed. It would be preferable to power the compressor via a gradual acceleration to a

fully-powered state.

It is, therefore, an object of this invention to provide an air conditioning system for vehicles that operates at a substantially constant speed and cooling output regard- less of engine speed. It is a further object of this invention to provide an air condition¬

ing system that operates continuously at a speed that minimizes air conditioning com¬

pressor damage. It should be possible to activate and deactivate the compressor at will,

while the engine is operating at any speed without risk of damage to the compressor or

other engine components. Cooling output by the system should not be excessive at

high engine speed and should be sufficient at idle and low engine speed. The principles

herein should be applicable to a variety of fluid circulating system such as power

steering and power brake pumps. SUMMARY OF THE INVENTION

This invention provides an improved automotive air conditioning system that

avoids the disadvantages of the prior art by providing a regulated power supply for an air conditioning compressor that maintains the driving speed of the air conditioning

compressor at a substantially constant value. A reservoir having fluid is provided. A pump is interconnected to the reservoir and operatively interconnected with, and

driven by, an engine of the vehicle. A pressure chamber is interconnected with the pump and receives fluid from the pump. A fluid drive element, located relative to the

pressure chamber, and interconnected with an air conditioning compressor, converts

passage of pressurized fluid therethrough into a mechanical driving force that drives

the air conditioning compressor. A regulator maintains a selected level of pressure in the pressure chamber. The regulator operates by diverting excess fluid from the pres¬

sure chamber to the reservoir.

In a preferred embodiment, the regulator includes a check valve that opens in

response to a fluid pressure in the pressure chamber that exceeds a predetermined

maximum value. The regulator system can also include a control valve, typically having

a separate return line to the reservoir, that transfers a predetermined volume of fluid

from the pressure chamber in response to a control signal. This arrangement enables

the pressure in the chamber to be varied by a user in order to, likewise, vary the pres¬

sure of fluid passing through the fluid drive element. Hence, the fluid drive element

speed and corresponding air conditioning compressor speed can be varied. The check

valve can be a movable stop and spring that biases the movable stop into a sealed ori¬

entation. The spring imparts a force that is overcome by a predetermined pressure in

the pressure chamber that is greater than the maximum desired pressure. In another embodiment, the fluid pump can comprise a first impeller that is en¬

closed is an integral casing with a drive element comprising a second impeller. A

manifold pipe having three inlets is attached to the casing. The manifold pipe includes

openings upstream of the first impeller, between the first impeller and the second im-

peller and downstream of the second impeller. The first impeller is attached to a source of motive power for a vehicle such as an engine. The second impeller drives a

vehicle fluid circulating pump such as an air conditioning compressor, a power steering

pump, a power brake pump or another fluid circulating/hydraulic pump used on a ve¬

hicle. Fluid should be taken to include gases and, thus, pneumatic pumps for air brakes and the like can also be driven by the second impeller. The openings between the first

and second impellers and downstream of the second impeller include respective first

and second regulator valves. The first regulator valve can be a pressure-operated

check valve that maintains a predetermined pressure at the outlet of the first impeller.

The second regulator valve can be a control valve that regulates fluid flow through the

second impeller to control an overall speed of operation and power output of the sec¬

ond impeller. The first control valve and the second control valve can each be inter¬

connected with a controller that balances the two valves so that a desired fluid flow is

maintained. A reservoir can be provided at any point within the fluid path to absorb

excess pressure and/or to insure that a predetermined level of fluid is maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages of the invention will become

more clear with reference to the following detailed description as illustrated by the

drawings, in which: FIG. 1 is a schematic view of an air conditioning system according to this in¬

vention;

FIG. 2 is a partially-exposed schematic perspective view of a control valve for

use in the air conditioning system according to this invention in a fully closed state;

s FIG. 3 is a partially-exposed schematic perspective view of the control valve of

FIG. 2 operating at a vehicle cruising speed;

FIG. 4 is a partially-exposed schematic perspective view of the control valve of

FIG. 2 operating at a high vehicle speed;

FIG. 5 is a graph comparing the operation of a conventionally-driven air condi-

o tioning compressor to a compressor that is driven according to this invention;

FIG. 6 is a schematic cross section of a self-contained fluid pump-driving sys¬

tem according to an alternate embodiment; and

FIG. 7 is an exploded perspective view of the fluid pump-driving system of Fig.

6.

s DETAILED DESCRIPTION

An air conditioning system according to this invention is illustrated schemati¬

cally in FIG. 1. While this embodiment relates to an air conditioning compressor, a

power steering, power brake or other fluid circulating pump can be substituted. The

use of such pumps is expressly contemplated. The system 20 is part of an overall

0 automotive power system including an engine 22 that powers a drive shaft 24 for

driving vehicle wheels. The engine, according to this embodiment, comprises an inter¬

nal combustion engine that derives power from the explosive burning of conventional

fossil fuels, and exhausts combustion products of the fuel through an exhaust manifold

26. However, other types of engines can be substituted according to this invention. The engine 22 according to this embodiment also includes a front power takeoff 28

comprising a drive shaft 30 that is, in this embodiment, a portion of the engine's crank

shaft (not shown), that is also interconnected with the drive shaft 24. The power takeoff 28 includes a pulley 32 that drives a power transmission belt 34 interconnected

with an additional pulley set 36. The pulley set 36 is used to power a generator 38 via

an additional power transmission belt 40. A variety of components can be intercon¬

nected by associated power transmission belts and pulleys to the main power takeoff

28. For example, a water pump, a cooling fan, a power steering pump, and, of course, an air conditioning compressor can all be linked by associated belts that are in rota-

tional communication with the power takeoff 28. In addition, a plurality of power

takeoffs can be provided to the front of the engine using gears located within a gear

case. The generator 38 according to this embodiment powers a battery 42 for reserve electrical energy. The generator 38 and battery 42 are used, in part, to power auxiliary

systems such as climate control, lighting, radio and instrumentation via power output

cables 44.

The power takeoff 28 is interconnected with another drive pulley 48 that, in

this embodiment, is provided on the drive shaft 30. It should be clear that the pulley 48

can be provided at any position relative to the engine 22 and can be driven by gears or

another drive belt according to an alternate embodiment.

The pulley 48 drives a power transmission belt 50 that is interconnected with

an opposing drive pulley 52. According to this embodiment, the pulley 52 is intercon¬

nected to a drive shaft 54 that powers the air conditioning system 20 according to this

invention. The air conditioning system 20 will now be described in further detail.

The air conditioning system 20 includes an air conditioning compressor 60 that

circulates a refrigerant through a closed-loop comprising an output line 62 and a return line 64 that are interconnected with a condenser 66. The condenser 66 is provided ad¬

jacent a blower fan 68 that passes air (arrow 70) over the condenser 66 that is deliv¬

ered into the cockpit of the vehicle (not shown) in the form of cool air. The blower fan

68 is electrically powered and interconnected with a fan speed control 69 on a control console 71. A variety of fan speed controls such as rheostats, potentiometers and digi¬

tal/microprocessor speed controls can be utilized.

The compressor 60 according to this embodiment is similar or identical in form

to that of the prior art. However, unlike the prior art, the compressor 60 is not inter¬

connected directly with the final drive pulley 52. Rather, the final drive pulley 52 is connected by drive shaft 54 to a compressor or pump 70 that is adapted to drive a fluid

under pressure. The pump can comprise a piston, impeller or other mechanism for

transferring mechanical energy to a fluid. The fluid, according to this embodiment, can

comprise a variety of generally-available hydraulic fluids such as those used in power

brakes and power steering mechanisms. The pump 70 derives energy from the drive shaft 54 which, in turn, is powered

by the belt 50 and pulleys 48 and 52. The exact placement of the pump and other com¬

ponents described herein can be varied depending on the size and shape of the engine

compartment of the vehicle. The illustrated system 20 is, thus, to be taken only by way

of example and a variety of placements, shapes and sizes of components are expressly

contemplated.

The pump 70 receives fluid through an inlet port 72 that is interconnected with

a fluid, sump, well or reservoir 74. The fluid is impelled by the pump 70 through an

outlet port 76 into a sealed compression chamber 78. Fluid enters the compression

chamber 78 under pressure due to the mechanical action of the pump 70. The pressur-

ized fluid in the compression chamber 78 is routed selectively through a variety of channels that, in substance, control the operation of the air conditioning system 20 according to this invention. The primary outlet of the chamber 78 is a turbine housing 90

that encloses a turbine blade 92 of conventional design. Other fluid pres¬

sure-to-mechanical motion devices are also expressly contemplated. In this embodi-

ment, the turbine blade is impelled by the fluid under pressure. The fluid causes the

turbine blade to rotate a drive shaft 94 that is interconnected with the air conditioning compressor 60 according to this invention. As described below, by varying the pres¬

sure in the chamber, the rotation of the turbine blade 92 can be controlled and/or en¬

abled and disabled on command. When fluid passes through the turbine blade 92, it is

routed to a return port 96. It is transferred by a line 98 back to the reservoir 74 where it is reused by action of the pump 70.

Since the pump 70 is interconnected directly with the engine, it's speed of op¬

eration will vary in proportion to the speed of the engine. Hence, at various times

larger and smaller amounts of fluid are transferred into the pressure chamber 78, result-

ing in higher and lower fluid pressures in the chamber 78. The pressure chamber 78 and turbine 92 are sized and structured so that at an idle speed, a minimum acceptable

rotation of the air conditioner compressor 60, via the turbine 92, occurs. However, to

prevent excessive rotation at higher engine speeds, the system 20 must account for the

substantial increase in fluid pressure in the chamber 78 resulting from high speed driv-

ing of the pump 70. Accordingly, a pair of waste ports 100, 102 are provided upstream

of the turbine 92 within the chamber 78. These waste ports 100, 102 act to control the

excess pressure in the chamber 78 by routing fluid back to the reservoir 74.

Reference is made first to the control waste port 102 that is electrically con¬

nected by wires 104 to a temperature control switch 106 on the control console 71.

The temperature control switch 106, according to this embodiment, can comprise any acceptable control including, but not limited to, a digital control, a microprocessor, a

rheostat, or a settable thermostat. The temperature control 106 transmits signals on the

wires 104 to selectively open and close a valve 1 10 located at the waste port 102. The

valve 110 can comprise any acceptable valve mechanism that is electrically or mechani-

cally controlled. Note that a mechanically controlled valve may be operated by a me¬

chanical temperature controller, without electrical wires 104. The valve 110 opens and

closes differing amounts so that it varies the amount of fluid that can exit the chamber

78 at a given pressure.

In operation, by signaling the valve 1 10 to open completely (a "HIGH" tem-

perature setting), a large proportion of the fluid in the chamber 78 is transferred back

into the reservoir 74. Accordingly, insufficient pressure remains in the chamber 78 for

powering the turbine 92. Hence, the turbine 92 and air conditioner compressor pump

60 receive little or no power. Conversely, if the valve 1 10 is closed completely (a

"low" temperature setting), the pressure in the chamber 78 is maintained at a very high

value and the turbine 92 receives maximum pressure, enabling it to rotate at a maxi¬

mum speed (in this embodiment, approximately 3000 RPM), providing a maximum

cooling power to the air conditioning compressor 60. Opening the valve partially re¬

sults in an intermediate level of turbine rotational driving, resulting in an intermediate

cooling by the air conditioner compressor 60.

Thus, the control waste port 102 and valve 1 10 can variably control the cham¬

ber pressure 78 over a predetermined range of fluid pressures. However, as described

above, pressure in the chamber 78 also varies based upon the speed of operation of the

pump 70, which is, itself, based upon the speed of the engine 22. Thus, a further regu¬

lating waste port 100 is used. The regulating waste port 100 includes a check valve

112, according to this embodiment, that provides an absolute control of fluid pressure in the chamber 78. As described further below, when fluid pressure in the chamber ex¬

ceeds a predetermined maximum value, the valve 112 is signaled to open and direct

excess fluid through the line 114 back to the reservoir 74.

With further reference to FIGS. 2-4, the valve 112 is detailed in a fully closed (FIG. 2), partially opened (FIG. 3) and fully opened (FIG. 4) state of operation. As

noted, the valve 112 according to this embodiment is a form of check valve. The valve

112 consists of an inlet 116 that enables fluid (see arrows 118) to enter the valve

housing 120. The inlet 116 can include a seal or other structure that engages a moving

stop 122. The stop 122, according to this embodiment, is a hemispherical plug. It is

contemplated that any suitable shape of movable stop can be utilized according to this invention. Such stops can include an elastomeric or metallic ball, a cylinder, a cone or

any other structure that maintains a breakable seal relative to a pressure chamber 78 in

(FIG. 1). The stop 122 in this embodiment is biased against the inlet 116, in a sealed

relationship, by a spring 124. The spring 124 in this embodiment comprises a com-

pression spring that surrounds a spring guide 125 that is joined to the stop 122. The guide 125 maintains the spring 124 and stop 122 in alignment with the housing 120 as

the stop 122 moves relative to the housing 120.

The spring constant of the compression spring 124 is chosen so that the stop

122 maintains a seal against the inlet 116 until a predetermined maximum pressure is

reached in the pressure chamber 78 in (FIG. 1). At such time, the force of the spring

124 is overcome by the pressure bearing upon the stop 122 and the stop is moved

away from the inlet 116. The resultant motion breaks the seal between the stop 122

and the inlet 116 and enables fluid from the pressure chamber 78 in (FIG. 1) to flow

through the valve housing 120 and into the reservoir return line 14 In this manner, the valve 112 ensures that the pressure of fluid present in the

pressure chamber 78 never exceeds a predetermined maximum value. This maximum

pressure value ensures a maximum desired driving speed for the turbine 92 when the control valve is also fully closed.

As depicted in FIGS. 2-4, at low pressure (FIG. 2) the stop 122 remains fully

sealed against the inlet 116. Hence, all available pressure is retained within the pressure

chamber 78. Such pressure is either routed through the turbine 92 or, alternatively, is

bled from the system by the control valve 110 via line waste line 102.

At a higher pressure when, for example, the engine is driven at a cruising speed

of 3,500 RPM, the stop 122 is partially opened by the fluid pressure and a portion of

the fluid (arrows 130) is bled from the system through the line 114. It can be assumed

that all remaining pressure is relieved either by routing fluid through the turbine 92

and/or exhausting fluid through the control valve 110.

At an approximate maximum speed (FIG. 4) when, for example, the engine is

powered at approximately 6,000 RPM, the stop 122 is biased into a completely-opened position and a majority of fluid (arrows 132) is delivered through the line 114. As

noted above, any remaining pressure is routed through either the turbine 92 or the

control valve 110.

It should be clear that there is a direct relationship between the turbine 92,

control valve 110 and check valve 112. The system, by means of these 3 outlets,

maintains an equilibrium pressure in the pressure chamber 78. By varying any one of

the system's components, (e.g., check valve force, control valve opening size, chamber

pressure and turbine resistance) the equilibrium is altered. The resulting system, how¬

ever, serves to maintain a substantially constant turbine driving force at all times.

Hence, excess driving force, in the form of fluid pressure, is routed away from the tur- bine 92 so that the turbine is not driven at an excessive, potentially-damaging, speed.

Conversely, the system is set so that, at minimum engine RPM, a minimum driving

force can be provided to the turbine 92 for powering the air conditioning system. The

level of pressure is set at a predetermined "equilibrium" value that is constant through-

out the full range of engine speeds. Thus, the compressor is driven at a constant speed regardless of engine speed.

While the system provides a minimum driving force for the air conditioner

compressor 60 at low RPM, it is contemplated that auxiliary driving power may be re¬

quired since there may not exist sufficient driving power to run the compressor at low

RPM. Hence, a further clutch-operated linkage (not shown) may join the compressor

60 to the engine at low RPM. Likewise, an electric motor or similar auxiliary power

unit (not shown) can be provided to the compressor 60 for driving the compressor at

low RPM. The primary advantage of the system of the air conditioning system 20, according to this embodiment, is that excessive driving of the air conditioner system at high RPM is avoided. Likewise, the passage of pressurized fluid from the fluid cham¬

ber 78 through the turbine 92 provides a more-gentle transition to the compressor 60

at start-up than the dead-start and dead-stop that is normally associated with a di¬

rect-driven compressor having a clutch according to the prior art.

With further reference to FIG. 5, the graph illustrates the difference between a

directly-driven air conditioning compressor and an air conditioning compressor driven

according to this embodiment. The increasing curve 150 represents the RPMs of a di¬

rectly-driven compressor. Over approximately 15 miles per hour, according to this ex¬

ample, damage to the compressor can occur through excessive driving speed. Like¬

wise, under approximately 15 mph, the compressor is not operating efficiently since the

input RPMs are too low to provide an adequate cooling cycle. Conversely, the per- formance of the compressor according to this embodiment is illustrated by the substantially-flat line 152 showing a compressor speed of approximately 3,000 RPM

throughout the range of automobile speed from 0 mph to approximately 110 mph. It is contemplated that some drop in RPM may occur at very low speed. However, by pro-

viding an efficient turbine 92 and a sufficiently powerful pump 70, a fairly constant air

conditioner compressor speed can be obtained according to this invention.

Fig. 6 illustrates a self-contained vehicle fluid pump-driving system according

to an alternate embodiment of this invention. The system omits an enlarged in-line reservoir such as the reservoir 74 of Fig. 1. The system 200 includes a casing 202 that, as detailed in Fig. 7 can be provided in two halves 204 and 206. The casing in this em¬

bodiment is cylindrical, however, any acceptable outer shape is contemplated, and ap¬

propriate mounting lugs can be provided for attachment to a vehicle frame. The casing 202 defines three separate chambers 208, 210 and 212. In this embodiment, the cham¬

bers are open to one another through the center bore of the casing 202. A series of inner perimeter walls 214 and 216 are provided to separate the chambers. Within each

pair of walls 214 and 216 is mounted a respective rotor or impeller 220 and 222. The

rotors detailed have multi-bladed fan-shape, however any acceptable shape that enables

the rotors to rotate about an axis in response to passage of fluid therethrough can be

used.

The rotor 220 is interconnected with a driven shaft 230. The driven shaft 230

is sealed using a sealing bearing 232 that is seated within the casing 202. The driven

shaft 230 is interconnected with a power take off pulley 234. The pulley is intercon¬

nected with an engine such as the engine 22 in Fig. 1 by an acceptable drive belt, chain

or other power-transmission device. As described above, the driven shaft 230 can be directly driven by the motor or by some other rotating portion of the vehicle such as a

wheel or an axle. The opposite impeller 222 is interconnected with a driving shaft 240

that is seated within the casing 202 using another sealing bearing 242. The driving shaft 240 is interconnected with a fluid-circulating pump 250 that can comprise an air

conditioning compressor, a power steering pump, a power brake pump, or any other

pump that moves fluid in an automotive or other vehicle system. All such pumps are

represented by the pump 250.

The casing 202 is jointed to a manifold pipe 260. The manifold pipe includes three openings 262, 264 and 266 adjacent each of the respective chambers 208, 210

and 212. Fluid enters the manifold pipe 260 through respective openings 270, 272 and

274 in the casing 202. It is contemplated that the casing 202 and manifold pipe 260 are filled substantially completely with hydraulic fluid. Hydraulic fluid can be added through a stopcock or plug 280 in the casing 202. A reservoir (not shown, but similar

to reservoir 74) can be provided in communication with the casing 202. Such a reser-

voir can be tied to the casing by providing a pipe at, for example, the location of the

stopcock 280. This reservoir maintains a predetermined fluid level in the system 200.

The manifold pipe openings 264 and 266 adjacent respective chambers 210 and

212 include movable valves 290 and 292. Each of the valves 290 and 292 includes a

moving baffle 294 and 296 that controls the flow of fluid into the respective openings

264 and 266. The baffles can be operated mechanically, hydraulically or electrically

and are interconnected to a controller as detailed in Fig. 6. Control stems 298 and 300

(Fig. 7) can be provided to mechanically (rotatably) interconnect the baffles with an

appropriate actuator. While baffles are shown in this embodiment, it is contemplated that any acceptable valve such as a ball valve, a plug valve or a butterfly valve can be

utilized.

In operation, the driven impeller 220 rotates to cause fluid to move from the chamber 208 into the chamber 210. Pressure within the chamber 210 is regulated in

part by the position of the adjacent valve 294. If the valve 294 is fully closed, then

pressure in the chamber 210 is maximized. The valve 296 serves as a gate to enable

fluid to flow through the chamber 212 from the chamber 210 and back into manifold pipe 260. When the driving shaft 240 requires power to operate a pump, the valve 296

is opened and the valve 294 is closed. Fluid is then free to flow from chamber 208

through chamber 210 and into chamber 212, causing the impeller 222 to rotate the

driving shaft 240. Fluid then returns through the opening 274 into the manifold pipe

260 where it is directed back into the chamber 208. The valve 294 or casing 202 can include a pressure sensor 304 that can be interconnected with the controller. The valve

294 can be opened or closed to maintain a substantially constant pressure within the

chamber 210 in response to the measured pressure. In other words, when the driven

shaft 230 is driven at high speed, it may be necessary to bleed off some pressure to

prevent the driving shaft 240 from being driven at excessive RPM. Conversely, when

the driving shaft 230 is driven at low speed, it may be necessary to close the valve 294

completely to insure that sufficient pressure reaches the driven impeller 222. The valve

296 adjacent the driven impeller 222 serves as an overall regulator of impeller speed

222 since it regulates the fluid flow through the impeller 222 into the chamber 212. In

an alternate embodiment, the valve 296 can be omitted and the valve 294 can be used

individually to control pressure. However, it is generally desirable that the flow

through each of the two openings 272 and 274 be controlled simultaneously. Note that when the valve 296 is fully closed, fluid cannot flow freely through the impeller 222 and, thus, the driven shaft 240 remains stationary.

The valve 294 can be controlled mechanically by an external actuator, or it can be interconnected with a spring assembly similar to that described for the valve 100 in Fig. 1. As such, the valve 294 can act as a safety valve to bleed off excess pressure. It should be clear that the system 200 of this embodiment, like that described above with reference to Fig. 1, provides an even driving force for the pump 250 regardless of the input power from the engine. This enables more efficient operation of fluid-driven components and accessories on a vehicle without the undesirable effects brought on by engine acceleration and deceleration.

The foregoing has been a detailed description of a preferred embodiment. Various modifications and additions can be made without departing from the spirit and scope of this invention. For example, the check valve utilized herein is a mechanical ball-and-spring-type valve with a stop that seals against an inlet. A rotating valve or another type of valve that opens selectively in response to pressure can be substituted.

Additionally, an electrically operated-valve that opens and closes in response to a

sensed pressure in the pressure chamber can also be substituted. Such a valve would include a pressure transducer or other sensor within the pressure chamber and would be directed to open and close to allow a predetermined volume of fluid to escape for a predetermined time based upon the sensed pressure in the chamber. Additionally, while the fluid pump of this invention is connected to the engine, it can also be connected to other portions of the drive train such as the transmission or wheel axles. In addition a reservoir can be provided in each of the above-described embodiments to absorb excess fluid pressure at any point along the fluid flow path where desirable. As such, this description is meant to be taken only by way of example and not to otherwise limit the scope of the invention.

What is claimed is:

Claims

1. A system for powering a vehicle fluid circulating pump comprising:

a first fluid impeller having an inlet and an outlet operatively interconnected with a source of motive power of the vehicle; a first regulator valve located adjacent the outlet and in fluid communication

with the impeller and a return pipe connected to the first regulator valve and in fluid

communication with the inlet;

a second fluid impeller located adjacent the outlet and being constructed and arranged to be driven by fluid impelled by the first fluid impeller, the second fluid im-

peller being operatively connected to the vehicle fluid circulating pump; and

a controller that open and closes the first regulator valve in response to each of

a pressure level at the outlet and a desired power level at which the second fluid impel- ler is impelled.

2. The system as set forth in claim 1 further comprising a second regulator valve

located at an outlet of the second fluid impeller, the second regulator valve being con-

structed and arranged to open and close to regulate an amount of fluid passing through

the second fluid impeller.

3. The system as set forth in claim 2 further comprising a sensor located adjacent

the outlet that generates a control signal interconnected with the controller for selec-

tively varying the pressure at the outlet to, thereby, vary a pressure of fluid directed to

the second fluid impeller.

4. The system as set forth in claim 3 wherein the controller is constructed and ar-

ranged to open and close the first regulator valve to maintain a predetermined constant

pressure adjacent the second fluid impeller at predetermined times whereby the second

fluid impeller is impelled at a substantially constant power at the predetermined times.

1 5. The system as set forth in claim 1 wherein the controller is constructed and

2 arranged to open and close at least one of the first regulator valve and the second

3 regulator valve to vary a power at which the second fluid impeller is impelled.

1 6. The system as set forth in claim 1 further comprising an integral casing that

2 supports each of the first fluid impeller, the second fluid impeller and the first regulator

3 valve in fluid communication with each other.

1 7. The system as set forth in claim 1 wherein the second fluid impeller is opera-

2 tively connected with a vehicle fluid circulating pump that comprises one of an air

3 conditioning compressor, a power steering pump and a power brake pump.

i

8. The system as set froth in claim 1 further comprising a fluid reservoir for

2 maintaining a desired fluid level adjacent the first fluid impeller.

1 9. The system as set forth in claim 1 wherein the first regulator valve comprises a

2 pressure-operated check valve that opens in response to a fluid pressure level that ex-

3 ceeds a maximum fluid pressure level.

1 10. A method for driving a vehicle fluid circulating pump at a desired substan-

2 tially-constant speed of operation at predetermined time comprising:

3 providing a fluid impeller, the fluid impeller being variably driven based upon a

4 predetermined power input from a vehicle source of motive power;

5 providing a pressure chamber that receives fluid from the fluid impeller under

6 pressure;

7 maintaining substantially-constant fluid pressure in the chamber including di-

8 verting excess fluid back to the fluid impeller; and

9 directing fluid at the substantially constant pressure through a drive element

lo that is operatively interconnected with the vehicle fluid circulating pump and driving

u the vehicle fluid circulating pump with the drive element.

11. The method as set forth in claim 10 wherein the step of a valve adjacent the

pressure chamber in response to a measured pressure chamber in response to a meas-

ured pressure in the pressure chamber in response to a measured pressure in the pres- sure chamber.

12. The method as set forth in claim 11 further comprising controlling a level of

fluid passing through the drive element to vary a power output of the drive element.

13. The method as set forth in claim 12 wherein the step of controlling includes

opening and closing a control valve at an outlet adjacent a downstream end of the

drive element and directing fluid from the control valve back to the impeller.