CA1050857A - System for providing auxiliary power - Google Patents
System for providing auxiliary powerInfo
- Publication number
- CA1050857A CA1050857A CA255,942A CA255942A CA1050857A CA 1050857 A CA1050857 A CA 1050857A CA 255942 A CA255942 A CA 255942A CA 1050857 A CA1050857 A CA 1050857A
- Authority
- CA
- Canada
- Prior art keywords
- auxiliary
- output
- flow
- primary
- pump
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Power Steering Mechanism (AREA)
- Details Of Reciprocating Pumps (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Abstract of the Disclosure A system for providing auxiliary power comprises a primary circuit including a primary pump, an output line for providing primary power, and a return line. An auxiliary circuit includes an auxiliary pump, an output line for pro-viding the auxiliary power and a return line. The auxiliary circuit also includes a valve for controlling fluid flow in the output and return line of the auxiliary circuit.
reservoir is connected to the primary return line and to the auxiliary return line. A controlled leakage apparatus for cooling the auxiliary pump is connected to the auxiliary circuit, the reservoir and the primary circuit, and in response to a predetermined output in the primary circuit directs a portion of auxiliary output fluid to the reservoir. Approxi-mately all of the auxiliary output fluid is directed to the auxiliary output line when the primary circuit provides less than the predetermined output. The auxiliary circuit includes a drive apparatus connected to a vehicle for operating the auxiliary pump whenever the vehicle is moving.
reservoir is connected to the primary return line and to the auxiliary return line. A controlled leakage apparatus for cooling the auxiliary pump is connected to the auxiliary circuit, the reservoir and the primary circuit, and in response to a predetermined output in the primary circuit directs a portion of auxiliary output fluid to the reservoir. Approxi-mately all of the auxiliary output fluid is directed to the auxiliary output line when the primary circuit provides less than the predetermined output. The auxiliary circuit includes a drive apparatus connected to a vehicle for operating the auxiliary pump whenever the vehicle is moving.
Description
~l050~S7 SYSTEM FOR P~OVIDING AUXILIARY POWER
1. ` ' ~' ~''' ,..... . .
... , . ' .' . ,: , Background of the Invention ~
While the invention is subject to a wide rang~ of ; ' applications, it is especially suited for use in a vehicle power steering system and will be particularly described in that connection.
10. In hydraulic power steering systems of vehicles, the general practice is to have a primary steering pump driven by the vehicle engine and supplying hydraulic fluid ' ~ , to a steering valve which is controlled by a steerin~ wheel'.
In the event of a ~ailure o the primary pumpj fluid is not supplied to the steering valve and manual steering of the vehicle is extremely difficult. Assuming the ,failure occurs' to a large, off-road, mobile construction machine, the ~ ~^
operator may be in a hazardous position because of the extreme dificulty in steering due to the loss of power.
20. Consequently, it is a well-known expedient to include a backup system capable,of supplying suficlent power to a steering valve in the event o a primary power failùre and thereby enable,an operator to safely steer the crippled -vehicle~
In the past, one attempt to solve the above~mentioned '~
problem was to provide a back-up system which stored emergency fluid in an accumulator. In this type of system, a pressurized -accumulator, for example, a cylinder of oil, delivers flu~.d to a steering valve in the event t~at the primary pump fails to '30. supply the necessary fluid. Accumulator systems are expensive due to the complex apparatus required. Further they are -.
--1-- .
~5~1~57 :
1. unreliable as they sit idle whene~er the primary pump is work-ing properly, and when the accumulator is finally needed, an unseen defect in the system can easily have occured. Addition-ally, accumulators are not practical for providing steering during long distance moving of vehicles which have lost their primary power.
Another solution to the problem of steering failure is the addition of a backup system including a ground driven pump. This purnp, driven directly or indirectly by the vehicle 10. wheels, is automatically connected to the steering valve upon failure of the primary pump or the hydraulic circuitry connected thereto. An example of a ground drive pump system is disclosed in U.S. Patent No. 3,747,725 to ~an Wicklin et al. This patent discloses, for example, "in accordance with the present inven- ;
tion, a vehicle power steering system having a primary and a secondary or an auxiliary pump includes a transfer valve for ~;
altering the fluid flow circuits of the primary and auxiliary ~
pumps... Should the mass flow rate become insufficient in magni- ~ -tude, the transfer valve disconnects the primary hydraulic ~ ;
20- supply circuit from the steering assist mechanism and connects the auxiliary hydraulic supply circuit to the steering assist mechanism so that power assisted steering is retained. Il The auxiliary pump disclosed in this patent is always delivering its total output to ~he transfer valve whenever a vehicle, which includes this system, is moving.
The problem with a syst~m of -the type disclosed above is that a significant hydraulic horespower loss is created by the flow of hydraulic fluid from an auxiliary pump through a transfer valve~ The following equation for hydraulic horsepower loss may be derived from the S~E ~Iandbook, 1973, Procec1ure J 745 C:
1. HHL = P171~Q
where:
HHL = Hydraulic Horsepower Loss P = Differential Pressuxe (psi) Q a Flow Rate (gpm) ;~
Thus, a hydraulic horsepower loss is present whenever a fluid from an auxiliary pump crosses a differential pressure in the flow path, such as, or example, the differential pressure across a transfer valve. In a system of the type where the ;
10- auxiliary pump is always delivering its total output to a -~
transfer valve, the horesepower loss may be significant. With the increased cost in fuel, efficiency of a machine becomes very important.
Another disadvantag~ of many prior art ground drive pump systems is the complexity of the apparatus. The transer valve is a separate unit which may receive an input~flow from both a main pump and an auxiliary pump and directs the output flow to the proper locatlon. Thus,~a transfer val~e is rela~
tively large and requires some extensive plumbing for installa~
20- tion. Also, a reservoir in this type of system requires a capacity to handle the total supply capabilities of both pumps. ~-Another example of a ground drive pump steering system is disclosed in U.S. Patent No. 3,631,937 to Joyce.
This patent discloses, for example, "a supplementary steering system for use with the primary hydraulic steering system of a - ~
vehicle having-a steering valve. The supplementary steering ~ ;
system includes a supplementary pump driven by the drlven shaft of the vehicle and a supplementary valve that discharges the output of the supplementary pump in the right direction to 30. the steering valve regardless of the direction of the rotation of the supplementary pump so that supplementary hydraulic fluid is available for use Ln steering so long as the vehicle is ~a35~35~7 1- moving and even when the engine of the vehicle is not in opera-tion." One major dif~erence between the Joyce patent and the present disclosure is that the supplementary pump of Joyce is always directing fluid to the steering valve ~henever the vehicle is moving. In the present disclosurel the auxiliary pump does not deliver fluid to the steering valve unless the primary pump is not providing fluid at a predetermined flow to -the valve.
It is an object of the present invention to provide 10. a ground drive safety steer pump circuit which has a low horsepower reduction loss. , It is a ~urther object of the present invention -to provide a system for providing auxiliary power which responds quickly to a failure of the primary pump.
It is a further object of the present invention to provide a system for providing auxiliary power ~hich is compact.
It is a further object of the present invention to ~-provide a system for providing auxiliary power which is relatively easy to install.
20. It is a further object of the present invention to provide a system for providing auxiliary power which is efficient.
It is a further object of the present invention to provide a system for providing auxiliary power which is inexpensive to manufacture.
'~L~
In accordance with the present invention, a system ~or providing auxiliary power comprises a primary circuit including a primary pump, an output line ~or providing primary 30O power, and a return line. An auxiliary circuit includes an auxiliary pump, an output line for providing said auxi:Liary power and a return line. The auxiliary circuit includes a lQ5()8~7 1. valve for controlling fluid flow in the output and return lines of the auxiliary circuit. A reservoir is connected to both the primary return line and the auxiliary return line.
A controlled leakage apparatus for cooling the auxiliary pump is connected to the auxiliary circuit, the reservoir and primary structure. The controlled leakage apparatus directs a portion of the auxiliary output fluid to the reservoir when the primary circuit provides a predetermined output flow and directs substantially all of the auxiliary output fluid to the ~^
10. auxiliary output line when the primary circuit provides less than the predetermined output flow. ~ ;
To be more specific, the system may include a primary circuit which includes a primary pump, an output line for providing primary power to a vehicle and a return line. An auxiliary circuit includes an auxiliary pump, an output line for providing auxiliary power and a return line. A drive mechanism operates the auxiliary pump whenever the vehicle is moving. The improvement comprises a horsepower loss reduction apparatus for allowing the auxiliary structure to provide the 20. auxiliary power only when the primary pump fails to provide a predetermined amount o~ power.
For a better understanding of the present invention, together with other and urther objects thereof, reference is made to the following description, taken in connection with the accompanying drawings, while its scope will be pointed out in the appended claims.
Brief Descri tion of the Drawings - _ P _ .
Figure 1 is a schematic illustration of a first embodiment o~ a system for providing auxiliary power;
30- Figure 2 is a side view of the ground driven pump of the present invention;
Figure 3 is a rear view of the ground driven pump : - . . .: . ~ , ; ., i;7 1. of the presellt invention;
Figure 4 is a sectional view taken along the line A - A of Figure 2; ., Figu.re 5 is a sectional view taken along the l.ine B - B of Figure 3;
Figure 6 is a sectional view taken along the line C - C of Figure 3;
Figure 7 is a schematic illustration of a second embodiment of the present invention;
10. Figure ~ is a sectional view illustrating a portion of the ground driven pump used in the second embodiment of the .' :
present invention.
Descri tion of the Pre~e~red Fmbodiments ' ;
A system for providing auxiliary power comprises a primary means including primary circuit 20 having a primary ~ ' pump 22, an output line 24 to provide primary power for a work function area 30, and a line 26 connecting pump inlet and reservoir. An auxiliary means includes an auxiliary circuit 60 having an auxiliary pump 62, an output line 64 for providing 20. auxiliary power to a work function area 30, and a return line 66 connecting a valve 80 with a reservoir 125. The auxiliary circuit 60 includes valve 80 for controlliny fluid flow in the auxiliary output and return lines 64 and 66. A reservoir 125 is connected to primary return line 26 and auxiliary return line 66. A controlled leakage circuit 130 is connected to auxiliary circuit 60, reservoir 125, and primary circuit 20. Controlled leakage circuit 130 functions to cool auxiliary pump 62 and is responsive to the output flow in primary circuit 20 to direct a portion of auxiliary pump output fluid to 30. reservoix 125 when primary circuit 20 provides a predetermined output flow and directs substantially all of the auxiliary pump output fluid to auxiliary output line 64 when primary circuit 1C! S0}357 1. 20 provides less than the predetermined output flow.
Referring to Figure 1, there is shown a schematic illustration of a motor vehicle power steering system havin~
the components which may be utilized in practicing the in- A
vention. The auxiliary circuit 60 is adapted to be used in conjunction with a primary power circuit 20 for any vehicle that requires power steering, particularly large equipment such as the well-known rubber-tired articulated type vehicle having an engine 28. Work ~unction area 30 is of any suitable 10. construction to provide power steering for the vehicle. In addition to motors 32 and 34, work function area 30 i~cludes a suitable conventional steering ~alve 36 to direct the flow of hydraulic fluid selectively to the piston rod or head end of the motors 32 and 34 and to exhaust the fluid from the opposite end of the motors and thereby steer the vehicle. When steexing wheel 38 is rotated in one direction, fluid flows from input line 39, through valve 36 to motors 32 and 34. Fluid enters the motors through the line 4~ and branches 42 and ~4 to steer the vehicle in one direction. Conversely, when s-teering wheel 20- 38 is rotated in the opposite direction, the ~luid flows to the opposite ends of motors 32 and 34 through line 46 and branches 48 and 50 to cause steering in the opposite direction. Fluid returning from motors 32 and 34 passes throucJh valve 36, out-put line 52 and into reservoir 125.
It is undexstood that the invention is not intended to be limited to the use with an articulated vehicle and may be adaptad to steer one or more steerable wheels as desixed.
Additionally, work function area 30 may be used to provicle power for some other function required in the operation of a 30- particular vehicle.
A primary circuit 20 includes a primary pump 22 pre~erably of the fixed displacement type, such as, for .
~, .
1- example, a Model No. 22 P~ 220 506, manufactured by Hydreco, a Unit of General Signal Corporation. Pump 22 is powered by an engine 28 which is connected to the vehicle. Pump 22 is pro-vided with an output line 24 connected to work function area 30 and a line 26 connected to reservoir 125. A primary check valve 29 is located in output line 24 to prohibit drainage of fluid from work function area 30 through pump 22 in the event of failure of primary circuit 20.
An auxiliary circuit 60 includes an auxiliary pump 10. 62 preferably of the gear type, such as, for example, a Model NoO HD 1512 DIBI manufactured by Hydreco, a Unit of General Signal Corporation. Gears 72 are connected to the drive shaft of the vehicle so as to operate pump 62 whenever the vehicle is moving. Pump 62 is provided with lines 68 and 70, leading to valve 80 and serving as pump input and output lines for the pump depending upon the direction of pump rotation.
Valve 80, in auxiliary circuit 60, controls fluid flow in both auxiliary output line 64, connected to work function area 30, and auxiliary return line 66, connected to 20. reservoir 1250 Referring generally to Figures 2 and 6, and more specifically to Figures 4 and 5, valve 80 includes a valve body 82 having an inlet port 84 connected to auxiliary return line 66 and an output port 86 connected -to auxiliary output line 64. An upper passageway 88 contains opposed valve seats 90 and 92 and a central portion 94O Transverse passage-ways 96 and 97 provide communication between upper passageway 88 and auxiliary pump lines 68 and 70, respectively. Transverse passageways 96 and 97 each intersect upper passageway 88 on the side of valve seats 90 and 92 opposite central portion 94.
30. Check valves 102 and 103 are located in upper passageway 88 and are normally biased by springs 104 and 105 against valve seats 90 and 92, respectively. Check valves 102 and 103 are .
01501~5~7 1. cylindrical in shape with frusto-conical portions 106 and 107 on one end. The frusto-conical portions 106 and 107 contact valve seats 90 and 92, respectivel~, along their surfaces so as to make contact between the tip of check valves which are in communication with central portion 94 and the conical shape, or in other words, intermediate frusto-conical portions 106 and 107. Upper passage-way 88 includes cylindrical chambers 108 and 109 in which check valves 102 and 103 reciprocate, respectively. Intermediate pas-sages 110 and 112 are connected to transverse passageways 96 and 10. 97, respectively. An output passage 114 connects intermediate passages 110 and 112 to output port 86. A pair of check valves 116 and 117 are located in intermediate passages 110 and 112 and transverse to output passage 114. Check valves 116 and 117 seat against their respective valve seats 118 and 119 and are spring biased to their closed positions by springs 190 and 191, respec-tively, to control flow from intermediate passages 110 and 112 to output port 86.
A controlled leakage circuit 130, also referred to as a horsepower loss reduction circuit, is connected to reservoir 125, 20. primary circuit 20, and auxiliary circuit 60. In order to pro-vide a co~ltrolled leakage from auxiliary circuit 60, check valves 102 and 103 (located in valve 80) are provided with frusto-conical end portions 106 and 107 as described above. ~urther, check valves 102 and 103 have a smaller diameter than chambers 108 and 109, and thus, a small leakage of fluid passes through the restrictions 132 and 134 into chambers 108 and 109, respec-tively. Passages 136 and 138, see Figure 4, are connected be-tween chambers 108 and 109 and switch valve 140 described herein-below. It is understood that the scope of the invention also 30. includes providin~ restrictions 132 and 134 by other means such as a flat portion on the check valves or a restrictive passageway through valve body 82 between the transverse passagewa~s 96 and - ~5~57 ; ~
1. 97 and chambers 108 and 109, respectively.
Means responsive to the output of the primary pump 22 are provided in order to furnish a control signal for the controlled leakage circuit 130. This output responsive means :~
consists preferably of a flow responsive sensing circuit. ~ ~ .
Line 175 is connected to the primary pump output line 24 to thereby sense the pressure at the pump output. A restriction 176, for example an orifice, is placed in line 24 between ~ ~`
check valve 29 and the junction between line 24 and line 64.
10. In addition, signal line 177 is connected between line 64 and switch valve 140 to thereby sense the pressure downstream of the restriction 176. Thus, a circuit has been set up whereby diferential pressure across (and therefore flow through) the restriction 176 is sensed by lines 175 and 177 The controlled leakage ci.rcuit 130 further includes switch valve 140, see Figure 6, having a passageway 142 con-nected at one end 144 to signal line 175 and at the other end ~ :
146 to a passage 148. Passa~e 148 has a port 150 on one end which is connected to signal line 177. First and second lateral 20. passages 152 and 154 communicate with passages 136 and 138 to allow leakage to enter switch valve 14a. Lateral passase 154 ~: :
preferably communicates with passa~ewa~ 142 by means of an annular port 160 which surrounds passageway 142. A plunger 156 ~ '~
reciprocates in passageway 142 and is normally biased by a spring 158 towards end 144. Plunger 156 is solid to permit it to be responsive to the differential pressures between 144 and 146.
A third lateral passage 157 is provided and has a port ;~
159 on one end thereof which is connected to drain line 164. .~ :
30. Solid plunger 156 includes annular slots 161 and 162 on the surface thereof which are positioned in such a manner so as to ~ .
permit passages 152 and 154 to communicate with passage 1.57 --1 0-- ' i7 1. through annular port 160 when the plunger 156 is biased in thedownward position. The plunger 156 urther includes an annular slot 163 which serves to radially balance plunger 156 within passageway 142. It should be understood that physical arrange-ments for the above passageways other than those shown in Figure 6 could be designed without departing Erom the spirit and scope of the present invention.
The controlled leakage circuit 130 also includes check valves 11~ and 117 as described above. Although prior 10- art ground drive pump circuits required a device to allow flow to go to a work function regardless of the direction of rota~
tion of the auxiliary pumpr it was not necessary to use check valves for this funct7on, and frequently a shuttle valve was used. However, in this embodiment of the present invention the check valve serves both the function of allowing flow to a work function regardless of the direction of rotation of the auxiliary pump as well as stopping any flow to and from the work function when the primary circuit is providing a predetermined flo~.
20. The unique features of the present invention can be more fully understood from the following description of its typi-cal operation. Assume that a vehicle includes a primary power steering circuit and an auxiliary power circuit of the present invention. When the vehicle moves and engine 28 operates properly, primary pump 22, see ~igure 1, delivers fluid from reservoir 125 to output line 24. The fluid crosses check valve 29 and enters steering valve 36 via input line 39. By turning wheel 38 in one direction, the fluid passes through line 40, 5 branches 42 and 44 and into motors 32 and 34. The output from 30. motors 32 and 34 returns through branches 50 and 48, line 46, valve 36, and finally through line 52 to reservoir 125. Thus, by turning wheel 38, motors 32 and 34 move, and the wheels o-f .
``` 11DSO8~7 1. the vehicle change their direction with respect to the vehicle.
In the case being described, work function area 30 is receiving an adequate amount of power to steer the vehicle and the auxiliary circuit 60 is not needed to provide power to steer the vehicle.
Since the vehicle is assumed to be moving, gears 72, being connected to the drive shaft, are turning and auxiliary pump 62 is supplying fluid to line 68 or 70, depending upon the direction of movement of the vehicle. Referring to Figure 5, 10. assume that pump 62 is turning in a direction that draws fluid from passageway 96 and pumps fluid into passageway 97. For pur-poses of the discussion, assume that the pump is delivering twent~ gallons per minute (gpm) at this time. Pump 62 creates a suction in transverse passageway 96 and chamber 108, allowing check valve 102 to open from a greater pressure in central por~
tion 94. Fluid from return line 66 enters inlet port 84, crosses valve seat 90 and flows into passageway 96 and through pump line 68. The fluid, delivered to transverse passageway 97, acts on ;
a portion of frusto-conical portion 107 Further, the fluid 20. enters passage 112 and acts against check valve 117. Check valve 117 remains closed, however, since spring 191 is selected to apply sufficient force so that check valve 103 will open before check valve 117.
Since the main pump 22 is operating properly, signal ;
lines 175 and 177 communicate a predetermined pressure differen-tial (which is greater than a predetermined minimum of e.g. 25 psi) which acts against the top and bottom surfaces of plunger 156 to bias the plunger against the force of spring 158 and the pressure from line 177 to maintain the plunger 156 in its down ~
30. position. This serves to communicate chambers 108 and 109 with ~ -reservoir 125 as described above.
At the same time, restricted orifice 134 permits a l.leakage flow to pass into chamber 109. The leakage pa~ses through passageway 138 into switch valve passage 154 in-to port 160, passage 157 and line 164, which communicates with reservoir 125. Leakage may also flow to passage 152, chamber 108 and passageway 96, but because of restriction 132 it tends to flow to reservoir 125.
Since chamber 10~ is drained to reservoir 125 and passageway 96 through valve 140, the differential pressure across orifice 134 allows pressure to build in passageway 97 lO.and work against a portion of 107 which causes check valve 103 to open against the bias of spring 105. The quantity of leak-age flow is determined by the ratio of area between the orifice formed between seat 92 and face 107 and the orifice 134. For the purpose of the discussion, one gpm is the leakage flow which passes across orifice 134.
At this time r the remaining nineteen gpm crosses check ~alve 103, into central passage portion 94, and is recirculated into pump 62. However, the pump 62 is still drawing twenty gpm ~ ~;
and the other one gpm must be made up from another source. The 20.one gpm is drawn from reservoir 125 and passed through re-turn line 66 into passageway 88. There it joins the nineteen gpm, ~ -recirculating through valve 60, and twenty gpm is available for the pump. `
It is extremely important to draw off some of the pump output flow in order to dissipate heat being developed in pump 62. A ground driven pump becomes hot since it is constantly turning and creating friction. It is important to stop over-heating of the pump as it decreases the life expectancy of a pump. In practice, it has been found that a one gpm leakage 30~provides adequate cooling for the auxiliary pump disclosed above. ~`
As the area of restrictions 132 and 134 decreases, the amount of cooling decreases, while enlarging the area of the orifices 8s7 l.increases the amount of cooling.
In the situation where the vehicle moves in the oppo-site direction, the fluid flow throuyh auxiliary pump circuit 60 and controlled leakage circuit 130 is reversed to that described above. The reversal of rotation of pump 62 does not change the functions of the various componentr, in a.ny other way. :~
The next situation to be described :is when primary circuit 20 does not deliver the propar amount of fluid to work function area 30 and the operator is not able to steer the ; :~
lO.vehicle. In this case, the pressure differen-tial across orifice .~
176, as sensed by signal lines 175 and 177, drops to a low value - ~:
and plunger 156 o switch valve 140 is biased by spring 158 to :
the position illustrated in Figure 6. The plunger now blocks lateral passages 152, 154, and 157 and the leakage flow from the back of check valve 103 (assuming the vehicle is moving in the direction described above) cannot pass through switch valve 140 into reservoir 125. Therefore, the pressure in chamber 109 and passageway 97 is equalized and check valve 103 is biased by spring 105 against valve seat 92 and stops fluid from passing 20.into passage 94. Check valve 103 is biased by spring 105 against valve seat 92 and stops fluid from passing into passage 94. ;.
Thus, pump 62 will receive its required supply of fluid through .
valve seat 90 and from reservoir 125 as described above. ~ .
Since auxiliary pump 62 is supplying fluid to trans~
verse passageway 97 of valve 80 and since it cannot pass through ..
valve seat 92, the fluid enters passage 112, crosses check valve . ::
117 (see Figure 4) and enters output line 64. The fluid is able to open check valve 117 because the fluid in passage 112 builds pressure, and pressure in line 64 from primary pump 22, under 30.the assumed operating condition, is not high enough to close valve 117.
Work function area 30 is again receiving the required 85~
1. power to operate motors 32 and 34. Since no leakage is passing through switch valve 140, the entire twenty gpm from auxiliary pump 62 is delivered to steering valve 36 until that -time when primary circuit 20 is again operating properly. If the vehicle .is moving in the opposite direction from the one assumed in the above description, the fluid from pump 62 passes through passage 110, across check valve 116, and into output line 64 to thereby supply work function area 30 as described above~
A second embodiment of the present invention, as 10. depicted in Figures 7 and 8, is similar to the first embodiment except for the details of valve 80 and a portion of the con- :
trolled leakage circuit 130. Parts of the second embodiment, which are like khe first embodiment, receive the same numerals~
Referring to Figure 8~ a shuttle plunger 170 with three lands 172, 174, and 176 is slidably received within passage 114. Plunger 170 is biased by springs 178 and 180 which act against lands 172 and 176 to keep plunger 170 in a cen-tral posi tion. Output line 64 includes a check valve 184 which is biased against a valve seat 188 by a spring 186. A passage 182 inter- .
20. sects passage 114 and receives a shuttle check valve 184. A
spring 186 biases valve 184 against a seat 188. Passage 182 is connected to output line 64 and work function area 30 as best seen in Figure 7. : .
The embodiment of the invention shown in Figure 7 operates the same way as the first embodiment explained above with the exception of the specifics of valve 80 and check valve 184. In the event that primary circuit ~0 is operating properly, switch valve 140 allows a leakage flow from valve 80 to reservoir 125. Fluid also recirculates through auxiliary pump 62 and 30- enters passage 138 to act against land 174 and bias shuttle : .
plunger 170 against the force of spring 178. The fluid then :`
acts against shuttle check valve 184 but the pressure in line 1.64, see Figure 7, in col~ination with spring 186 and the act that valve 103 opens more easily than valve 184, does not permit valve 184 to open.
If the auxiliary pump 62 rotates in the opposite direction, fluid enters passage 136 and moves shuttle valve 170 toward the left against spring 180. Again, shuttle check valv~ -184 remains closed for the reasons described above. If primary -~
circuit 20 was not providing the proper amount of fluid, shuttle check valve 184 opens and work function area 30 receives fluid lo.as in the first embodiment.
One skilled in the art will realize that there ha~
been disclosed a system for providing power that requires a minimum of horsepower loss when the auxiliary system is not required, is a compact installation, is responsive and efficient, is inexpensive to manufacture, and is easy to install.
While there has been described what is at present considered a preferred embodiment of the invention, it will be obvious to those skilled in the art that changes and modifica , tions may be made therein without departing from the invention, 20.and it is, therefore, aimed in the appended claims to cover all .
such changes and modifications as followed in the true spirit ~ ;
and scope of the invention.
:
"' ', ' 30~
. .
1. ` ' ~' ~''' ,..... . .
... , . ' .' . ,: , Background of the Invention ~
While the invention is subject to a wide rang~ of ; ' applications, it is especially suited for use in a vehicle power steering system and will be particularly described in that connection.
10. In hydraulic power steering systems of vehicles, the general practice is to have a primary steering pump driven by the vehicle engine and supplying hydraulic fluid ' ~ , to a steering valve which is controlled by a steerin~ wheel'.
In the event of a ~ailure o the primary pumpj fluid is not supplied to the steering valve and manual steering of the vehicle is extremely difficult. Assuming the ,failure occurs' to a large, off-road, mobile construction machine, the ~ ~^
operator may be in a hazardous position because of the extreme dificulty in steering due to the loss of power.
20. Consequently, it is a well-known expedient to include a backup system capable,of supplying suficlent power to a steering valve in the event o a primary power failùre and thereby enable,an operator to safely steer the crippled -vehicle~
In the past, one attempt to solve the above~mentioned '~
problem was to provide a back-up system which stored emergency fluid in an accumulator. In this type of system, a pressurized -accumulator, for example, a cylinder of oil, delivers flu~.d to a steering valve in the event t~at the primary pump fails to '30. supply the necessary fluid. Accumulator systems are expensive due to the complex apparatus required. Further they are -.
--1-- .
~5~1~57 :
1. unreliable as they sit idle whene~er the primary pump is work-ing properly, and when the accumulator is finally needed, an unseen defect in the system can easily have occured. Addition-ally, accumulators are not practical for providing steering during long distance moving of vehicles which have lost their primary power.
Another solution to the problem of steering failure is the addition of a backup system including a ground driven pump. This purnp, driven directly or indirectly by the vehicle 10. wheels, is automatically connected to the steering valve upon failure of the primary pump or the hydraulic circuitry connected thereto. An example of a ground drive pump system is disclosed in U.S. Patent No. 3,747,725 to ~an Wicklin et al. This patent discloses, for example, "in accordance with the present inven- ;
tion, a vehicle power steering system having a primary and a secondary or an auxiliary pump includes a transfer valve for ~;
altering the fluid flow circuits of the primary and auxiliary ~
pumps... Should the mass flow rate become insufficient in magni- ~ -tude, the transfer valve disconnects the primary hydraulic ~ ;
20- supply circuit from the steering assist mechanism and connects the auxiliary hydraulic supply circuit to the steering assist mechanism so that power assisted steering is retained. Il The auxiliary pump disclosed in this patent is always delivering its total output to ~he transfer valve whenever a vehicle, which includes this system, is moving.
The problem with a syst~m of -the type disclosed above is that a significant hydraulic horespower loss is created by the flow of hydraulic fluid from an auxiliary pump through a transfer valve~ The following equation for hydraulic horsepower loss may be derived from the S~E ~Iandbook, 1973, Procec1ure J 745 C:
1. HHL = P171~Q
where:
HHL = Hydraulic Horsepower Loss P = Differential Pressuxe (psi) Q a Flow Rate (gpm) ;~
Thus, a hydraulic horsepower loss is present whenever a fluid from an auxiliary pump crosses a differential pressure in the flow path, such as, or example, the differential pressure across a transfer valve. In a system of the type where the ;
10- auxiliary pump is always delivering its total output to a -~
transfer valve, the horesepower loss may be significant. With the increased cost in fuel, efficiency of a machine becomes very important.
Another disadvantag~ of many prior art ground drive pump systems is the complexity of the apparatus. The transer valve is a separate unit which may receive an input~flow from both a main pump and an auxiliary pump and directs the output flow to the proper locatlon. Thus,~a transfer val~e is rela~
tively large and requires some extensive plumbing for installa~
20- tion. Also, a reservoir in this type of system requires a capacity to handle the total supply capabilities of both pumps. ~-Another example of a ground drive pump steering system is disclosed in U.S. Patent No. 3,631,937 to Joyce.
This patent discloses, for example, "a supplementary steering system for use with the primary hydraulic steering system of a - ~
vehicle having-a steering valve. The supplementary steering ~ ;
system includes a supplementary pump driven by the drlven shaft of the vehicle and a supplementary valve that discharges the output of the supplementary pump in the right direction to 30. the steering valve regardless of the direction of the rotation of the supplementary pump so that supplementary hydraulic fluid is available for use Ln steering so long as the vehicle is ~a35~35~7 1- moving and even when the engine of the vehicle is not in opera-tion." One major dif~erence between the Joyce patent and the present disclosure is that the supplementary pump of Joyce is always directing fluid to the steering valve ~henever the vehicle is moving. In the present disclosurel the auxiliary pump does not deliver fluid to the steering valve unless the primary pump is not providing fluid at a predetermined flow to -the valve.
It is an object of the present invention to provide 10. a ground drive safety steer pump circuit which has a low horsepower reduction loss. , It is a ~urther object of the present invention -to provide a system for providing auxiliary power which responds quickly to a failure of the primary pump.
It is a further object of the present invention to provide a system for providing auxiliary power ~hich is compact.
It is a further object of the present invention to ~-provide a system for providing auxiliary power which is relatively easy to install.
20. It is a further object of the present invention to provide a system for providing auxiliary power which is efficient.
It is a further object of the present invention to provide a system for providing auxiliary power which is inexpensive to manufacture.
'~L~
In accordance with the present invention, a system ~or providing auxiliary power comprises a primary circuit including a primary pump, an output line ~or providing primary 30O power, and a return line. An auxiliary circuit includes an auxiliary pump, an output line for providing said auxi:Liary power and a return line. The auxiliary circuit includes a lQ5()8~7 1. valve for controlling fluid flow in the output and return lines of the auxiliary circuit. A reservoir is connected to both the primary return line and the auxiliary return line.
A controlled leakage apparatus for cooling the auxiliary pump is connected to the auxiliary circuit, the reservoir and primary structure. The controlled leakage apparatus directs a portion of the auxiliary output fluid to the reservoir when the primary circuit provides a predetermined output flow and directs substantially all of the auxiliary output fluid to the ~^
10. auxiliary output line when the primary circuit provides less than the predetermined output flow. ~ ;
To be more specific, the system may include a primary circuit which includes a primary pump, an output line for providing primary power to a vehicle and a return line. An auxiliary circuit includes an auxiliary pump, an output line for providing auxiliary power and a return line. A drive mechanism operates the auxiliary pump whenever the vehicle is moving. The improvement comprises a horsepower loss reduction apparatus for allowing the auxiliary structure to provide the 20. auxiliary power only when the primary pump fails to provide a predetermined amount o~ power.
For a better understanding of the present invention, together with other and urther objects thereof, reference is made to the following description, taken in connection with the accompanying drawings, while its scope will be pointed out in the appended claims.
Brief Descri tion of the Drawings - _ P _ .
Figure 1 is a schematic illustration of a first embodiment o~ a system for providing auxiliary power;
30- Figure 2 is a side view of the ground driven pump of the present invention;
Figure 3 is a rear view of the ground driven pump : - . . .: . ~ , ; ., i;7 1. of the presellt invention;
Figure 4 is a sectional view taken along the line A - A of Figure 2; ., Figu.re 5 is a sectional view taken along the l.ine B - B of Figure 3;
Figure 6 is a sectional view taken along the line C - C of Figure 3;
Figure 7 is a schematic illustration of a second embodiment of the present invention;
10. Figure ~ is a sectional view illustrating a portion of the ground driven pump used in the second embodiment of the .' :
present invention.
Descri tion of the Pre~e~red Fmbodiments ' ;
A system for providing auxiliary power comprises a primary means including primary circuit 20 having a primary ~ ' pump 22, an output line 24 to provide primary power for a work function area 30, and a line 26 connecting pump inlet and reservoir. An auxiliary means includes an auxiliary circuit 60 having an auxiliary pump 62, an output line 64 for providing 20. auxiliary power to a work function area 30, and a return line 66 connecting a valve 80 with a reservoir 125. The auxiliary circuit 60 includes valve 80 for controlliny fluid flow in the auxiliary output and return lines 64 and 66. A reservoir 125 is connected to primary return line 26 and auxiliary return line 66. A controlled leakage circuit 130 is connected to auxiliary circuit 60, reservoir 125, and primary circuit 20. Controlled leakage circuit 130 functions to cool auxiliary pump 62 and is responsive to the output flow in primary circuit 20 to direct a portion of auxiliary pump output fluid to 30. reservoix 125 when primary circuit 20 provides a predetermined output flow and directs substantially all of the auxiliary pump output fluid to auxiliary output line 64 when primary circuit 1C! S0}357 1. 20 provides less than the predetermined output flow.
Referring to Figure 1, there is shown a schematic illustration of a motor vehicle power steering system havin~
the components which may be utilized in practicing the in- A
vention. The auxiliary circuit 60 is adapted to be used in conjunction with a primary power circuit 20 for any vehicle that requires power steering, particularly large equipment such as the well-known rubber-tired articulated type vehicle having an engine 28. Work ~unction area 30 is of any suitable 10. construction to provide power steering for the vehicle. In addition to motors 32 and 34, work function area 30 i~cludes a suitable conventional steering ~alve 36 to direct the flow of hydraulic fluid selectively to the piston rod or head end of the motors 32 and 34 and to exhaust the fluid from the opposite end of the motors and thereby steer the vehicle. When steexing wheel 38 is rotated in one direction, fluid flows from input line 39, through valve 36 to motors 32 and 34. Fluid enters the motors through the line 4~ and branches 42 and ~4 to steer the vehicle in one direction. Conversely, when s-teering wheel 20- 38 is rotated in the opposite direction, the ~luid flows to the opposite ends of motors 32 and 34 through line 46 and branches 48 and 50 to cause steering in the opposite direction. Fluid returning from motors 32 and 34 passes throucJh valve 36, out-put line 52 and into reservoir 125.
It is undexstood that the invention is not intended to be limited to the use with an articulated vehicle and may be adaptad to steer one or more steerable wheels as desixed.
Additionally, work function area 30 may be used to provicle power for some other function required in the operation of a 30- particular vehicle.
A primary circuit 20 includes a primary pump 22 pre~erably of the fixed displacement type, such as, for .
~, .
1- example, a Model No. 22 P~ 220 506, manufactured by Hydreco, a Unit of General Signal Corporation. Pump 22 is powered by an engine 28 which is connected to the vehicle. Pump 22 is pro-vided with an output line 24 connected to work function area 30 and a line 26 connected to reservoir 125. A primary check valve 29 is located in output line 24 to prohibit drainage of fluid from work function area 30 through pump 22 in the event of failure of primary circuit 20.
An auxiliary circuit 60 includes an auxiliary pump 10. 62 preferably of the gear type, such as, for example, a Model NoO HD 1512 DIBI manufactured by Hydreco, a Unit of General Signal Corporation. Gears 72 are connected to the drive shaft of the vehicle so as to operate pump 62 whenever the vehicle is moving. Pump 62 is provided with lines 68 and 70, leading to valve 80 and serving as pump input and output lines for the pump depending upon the direction of pump rotation.
Valve 80, in auxiliary circuit 60, controls fluid flow in both auxiliary output line 64, connected to work function area 30, and auxiliary return line 66, connected to 20. reservoir 1250 Referring generally to Figures 2 and 6, and more specifically to Figures 4 and 5, valve 80 includes a valve body 82 having an inlet port 84 connected to auxiliary return line 66 and an output port 86 connected -to auxiliary output line 64. An upper passageway 88 contains opposed valve seats 90 and 92 and a central portion 94O Transverse passage-ways 96 and 97 provide communication between upper passageway 88 and auxiliary pump lines 68 and 70, respectively. Transverse passageways 96 and 97 each intersect upper passageway 88 on the side of valve seats 90 and 92 opposite central portion 94.
30. Check valves 102 and 103 are located in upper passageway 88 and are normally biased by springs 104 and 105 against valve seats 90 and 92, respectively. Check valves 102 and 103 are .
01501~5~7 1. cylindrical in shape with frusto-conical portions 106 and 107 on one end. The frusto-conical portions 106 and 107 contact valve seats 90 and 92, respectivel~, along their surfaces so as to make contact between the tip of check valves which are in communication with central portion 94 and the conical shape, or in other words, intermediate frusto-conical portions 106 and 107. Upper passage-way 88 includes cylindrical chambers 108 and 109 in which check valves 102 and 103 reciprocate, respectively. Intermediate pas-sages 110 and 112 are connected to transverse passageways 96 and 10. 97, respectively. An output passage 114 connects intermediate passages 110 and 112 to output port 86. A pair of check valves 116 and 117 are located in intermediate passages 110 and 112 and transverse to output passage 114. Check valves 116 and 117 seat against their respective valve seats 118 and 119 and are spring biased to their closed positions by springs 190 and 191, respec-tively, to control flow from intermediate passages 110 and 112 to output port 86.
A controlled leakage circuit 130, also referred to as a horsepower loss reduction circuit, is connected to reservoir 125, 20. primary circuit 20, and auxiliary circuit 60. In order to pro-vide a co~ltrolled leakage from auxiliary circuit 60, check valves 102 and 103 (located in valve 80) are provided with frusto-conical end portions 106 and 107 as described above. ~urther, check valves 102 and 103 have a smaller diameter than chambers 108 and 109, and thus, a small leakage of fluid passes through the restrictions 132 and 134 into chambers 108 and 109, respec-tively. Passages 136 and 138, see Figure 4, are connected be-tween chambers 108 and 109 and switch valve 140 described herein-below. It is understood that the scope of the invention also 30. includes providin~ restrictions 132 and 134 by other means such as a flat portion on the check valves or a restrictive passageway through valve body 82 between the transverse passagewa~s 96 and - ~5~57 ; ~
1. 97 and chambers 108 and 109, respectively.
Means responsive to the output of the primary pump 22 are provided in order to furnish a control signal for the controlled leakage circuit 130. This output responsive means :~
consists preferably of a flow responsive sensing circuit. ~ ~ .
Line 175 is connected to the primary pump output line 24 to thereby sense the pressure at the pump output. A restriction 176, for example an orifice, is placed in line 24 between ~ ~`
check valve 29 and the junction between line 24 and line 64.
10. In addition, signal line 177 is connected between line 64 and switch valve 140 to thereby sense the pressure downstream of the restriction 176. Thus, a circuit has been set up whereby diferential pressure across (and therefore flow through) the restriction 176 is sensed by lines 175 and 177 The controlled leakage ci.rcuit 130 further includes switch valve 140, see Figure 6, having a passageway 142 con-nected at one end 144 to signal line 175 and at the other end ~ :
146 to a passage 148. Passa~e 148 has a port 150 on one end which is connected to signal line 177. First and second lateral 20. passages 152 and 154 communicate with passages 136 and 138 to allow leakage to enter switch valve 14a. Lateral passase 154 ~: :
preferably communicates with passa~ewa~ 142 by means of an annular port 160 which surrounds passageway 142. A plunger 156 ~ '~
reciprocates in passageway 142 and is normally biased by a spring 158 towards end 144. Plunger 156 is solid to permit it to be responsive to the differential pressures between 144 and 146.
A third lateral passage 157 is provided and has a port ;~
159 on one end thereof which is connected to drain line 164. .~ :
30. Solid plunger 156 includes annular slots 161 and 162 on the surface thereof which are positioned in such a manner so as to ~ .
permit passages 152 and 154 to communicate with passage 1.57 --1 0-- ' i7 1. through annular port 160 when the plunger 156 is biased in thedownward position. The plunger 156 urther includes an annular slot 163 which serves to radially balance plunger 156 within passageway 142. It should be understood that physical arrange-ments for the above passageways other than those shown in Figure 6 could be designed without departing Erom the spirit and scope of the present invention.
The controlled leakage circuit 130 also includes check valves 11~ and 117 as described above. Although prior 10- art ground drive pump circuits required a device to allow flow to go to a work function regardless of the direction of rota~
tion of the auxiliary pumpr it was not necessary to use check valves for this funct7on, and frequently a shuttle valve was used. However, in this embodiment of the present invention the check valve serves both the function of allowing flow to a work function regardless of the direction of rotation of the auxiliary pump as well as stopping any flow to and from the work function when the primary circuit is providing a predetermined flo~.
20. The unique features of the present invention can be more fully understood from the following description of its typi-cal operation. Assume that a vehicle includes a primary power steering circuit and an auxiliary power circuit of the present invention. When the vehicle moves and engine 28 operates properly, primary pump 22, see ~igure 1, delivers fluid from reservoir 125 to output line 24. The fluid crosses check valve 29 and enters steering valve 36 via input line 39. By turning wheel 38 in one direction, the fluid passes through line 40, 5 branches 42 and 44 and into motors 32 and 34. The output from 30. motors 32 and 34 returns through branches 50 and 48, line 46, valve 36, and finally through line 52 to reservoir 125. Thus, by turning wheel 38, motors 32 and 34 move, and the wheels o-f .
``` 11DSO8~7 1. the vehicle change their direction with respect to the vehicle.
In the case being described, work function area 30 is receiving an adequate amount of power to steer the vehicle and the auxiliary circuit 60 is not needed to provide power to steer the vehicle.
Since the vehicle is assumed to be moving, gears 72, being connected to the drive shaft, are turning and auxiliary pump 62 is supplying fluid to line 68 or 70, depending upon the direction of movement of the vehicle. Referring to Figure 5, 10. assume that pump 62 is turning in a direction that draws fluid from passageway 96 and pumps fluid into passageway 97. For pur-poses of the discussion, assume that the pump is delivering twent~ gallons per minute (gpm) at this time. Pump 62 creates a suction in transverse passageway 96 and chamber 108, allowing check valve 102 to open from a greater pressure in central por~
tion 94. Fluid from return line 66 enters inlet port 84, crosses valve seat 90 and flows into passageway 96 and through pump line 68. The fluid, delivered to transverse passageway 97, acts on ;
a portion of frusto-conical portion 107 Further, the fluid 20. enters passage 112 and acts against check valve 117. Check valve 117 remains closed, however, since spring 191 is selected to apply sufficient force so that check valve 103 will open before check valve 117.
Since the main pump 22 is operating properly, signal ;
lines 175 and 177 communicate a predetermined pressure differen-tial (which is greater than a predetermined minimum of e.g. 25 psi) which acts against the top and bottom surfaces of plunger 156 to bias the plunger against the force of spring 158 and the pressure from line 177 to maintain the plunger 156 in its down ~
30. position. This serves to communicate chambers 108 and 109 with ~ -reservoir 125 as described above.
At the same time, restricted orifice 134 permits a l.leakage flow to pass into chamber 109. The leakage pa~ses through passageway 138 into switch valve passage 154 in-to port 160, passage 157 and line 164, which communicates with reservoir 125. Leakage may also flow to passage 152, chamber 108 and passageway 96, but because of restriction 132 it tends to flow to reservoir 125.
Since chamber 10~ is drained to reservoir 125 and passageway 96 through valve 140, the differential pressure across orifice 134 allows pressure to build in passageway 97 lO.and work against a portion of 107 which causes check valve 103 to open against the bias of spring 105. The quantity of leak-age flow is determined by the ratio of area between the orifice formed between seat 92 and face 107 and the orifice 134. For the purpose of the discussion, one gpm is the leakage flow which passes across orifice 134.
At this time r the remaining nineteen gpm crosses check ~alve 103, into central passage portion 94, and is recirculated into pump 62. However, the pump 62 is still drawing twenty gpm ~ ~;
and the other one gpm must be made up from another source. The 20.one gpm is drawn from reservoir 125 and passed through re-turn line 66 into passageway 88. There it joins the nineteen gpm, ~ -recirculating through valve 60, and twenty gpm is available for the pump. `
It is extremely important to draw off some of the pump output flow in order to dissipate heat being developed in pump 62. A ground driven pump becomes hot since it is constantly turning and creating friction. It is important to stop over-heating of the pump as it decreases the life expectancy of a pump. In practice, it has been found that a one gpm leakage 30~provides adequate cooling for the auxiliary pump disclosed above. ~`
As the area of restrictions 132 and 134 decreases, the amount of cooling decreases, while enlarging the area of the orifices 8s7 l.increases the amount of cooling.
In the situation where the vehicle moves in the oppo-site direction, the fluid flow throuyh auxiliary pump circuit 60 and controlled leakage circuit 130 is reversed to that described above. The reversal of rotation of pump 62 does not change the functions of the various componentr, in a.ny other way. :~
The next situation to be described :is when primary circuit 20 does not deliver the propar amount of fluid to work function area 30 and the operator is not able to steer the ; :~
lO.vehicle. In this case, the pressure differen-tial across orifice .~
176, as sensed by signal lines 175 and 177, drops to a low value - ~:
and plunger 156 o switch valve 140 is biased by spring 158 to :
the position illustrated in Figure 6. The plunger now blocks lateral passages 152, 154, and 157 and the leakage flow from the back of check valve 103 (assuming the vehicle is moving in the direction described above) cannot pass through switch valve 140 into reservoir 125. Therefore, the pressure in chamber 109 and passageway 97 is equalized and check valve 103 is biased by spring 105 against valve seat 92 and stops fluid from passing 20.into passage 94. Check valve 103 is biased by spring 105 against valve seat 92 and stops fluid from passing into passage 94. ;.
Thus, pump 62 will receive its required supply of fluid through .
valve seat 90 and from reservoir 125 as described above. ~ .
Since auxiliary pump 62 is supplying fluid to trans~
verse passageway 97 of valve 80 and since it cannot pass through ..
valve seat 92, the fluid enters passage 112, crosses check valve . ::
117 (see Figure 4) and enters output line 64. The fluid is able to open check valve 117 because the fluid in passage 112 builds pressure, and pressure in line 64 from primary pump 22, under 30.the assumed operating condition, is not high enough to close valve 117.
Work function area 30 is again receiving the required 85~
1. power to operate motors 32 and 34. Since no leakage is passing through switch valve 140, the entire twenty gpm from auxiliary pump 62 is delivered to steering valve 36 until that -time when primary circuit 20 is again operating properly. If the vehicle .is moving in the opposite direction from the one assumed in the above description, the fluid from pump 62 passes through passage 110, across check valve 116, and into output line 64 to thereby supply work function area 30 as described above~
A second embodiment of the present invention, as 10. depicted in Figures 7 and 8, is similar to the first embodiment except for the details of valve 80 and a portion of the con- :
trolled leakage circuit 130. Parts of the second embodiment, which are like khe first embodiment, receive the same numerals~
Referring to Figure 8~ a shuttle plunger 170 with three lands 172, 174, and 176 is slidably received within passage 114. Plunger 170 is biased by springs 178 and 180 which act against lands 172 and 176 to keep plunger 170 in a cen-tral posi tion. Output line 64 includes a check valve 184 which is biased against a valve seat 188 by a spring 186. A passage 182 inter- .
20. sects passage 114 and receives a shuttle check valve 184. A
spring 186 biases valve 184 against a seat 188. Passage 182 is connected to output line 64 and work function area 30 as best seen in Figure 7. : .
The embodiment of the invention shown in Figure 7 operates the same way as the first embodiment explained above with the exception of the specifics of valve 80 and check valve 184. In the event that primary circuit ~0 is operating properly, switch valve 140 allows a leakage flow from valve 80 to reservoir 125. Fluid also recirculates through auxiliary pump 62 and 30- enters passage 138 to act against land 174 and bias shuttle : .
plunger 170 against the force of spring 178. The fluid then :`
acts against shuttle check valve 184 but the pressure in line 1.64, see Figure 7, in col~ination with spring 186 and the act that valve 103 opens more easily than valve 184, does not permit valve 184 to open.
If the auxiliary pump 62 rotates in the opposite direction, fluid enters passage 136 and moves shuttle valve 170 toward the left against spring 180. Again, shuttle check valv~ -184 remains closed for the reasons described above. If primary -~
circuit 20 was not providing the proper amount of fluid, shuttle check valve 184 opens and work function area 30 receives fluid lo.as in the first embodiment.
One skilled in the art will realize that there ha~
been disclosed a system for providing power that requires a minimum of horsepower loss when the auxiliary system is not required, is a compact installation, is responsive and efficient, is inexpensive to manufacture, and is easy to install.
While there has been described what is at present considered a preferred embodiment of the invention, it will be obvious to those skilled in the art that changes and modifica , tions may be made therein without departing from the invention, 20.and it is, therefore, aimed in the appended claims to cover all .
such changes and modifications as followed in the true spirit ~ ;
and scope of the invention.
:
"' ', ' 30~
. .
Claims (28)
1. A system for providing auxiliary power which comprises:
a primary means including a primary pump, an output line to provide primary power to a work function means, and a return line;
an auxiliary means including an auxiliary pump, an output line to provide said auxiliary power, a return line and a valve means for controlling fluid flow in said output and return lines of said auxiliary means;
a reservoir connected to said primary return line and said auxiliary return line;
a controlled leakage means for cooling said auxiliary pump being connected to said auxiliary means, said reservoir and said primary means and being responsive to the output from said primary means for directing a portion of auxiliary output fluid to said reservoir when the primary means provides a pre-determined output and directing a desired amount of said auxil-iary output fluid to said auxiliary output line when said primary means provides less than said predetermined output.
a primary means including a primary pump, an output line to provide primary power to a work function means, and a return line;
an auxiliary means including an auxiliary pump, an output line to provide said auxiliary power, a return line and a valve means for controlling fluid flow in said output and return lines of said auxiliary means;
a reservoir connected to said primary return line and said auxiliary return line;
a controlled leakage means for cooling said auxiliary pump being connected to said auxiliary means, said reservoir and said primary means and being responsive to the output from said primary means for directing a portion of auxiliary output fluid to said reservoir when the primary means provides a pre-determined output and directing a desired amount of said auxil-iary output fluid to said auxiliary output line when said primary means provides less than said predetermined output.
2. The system defined in Claim 1, wherein said controlled leakage means is responsive to the output flow from said primary means.
3. The system defined in Claim 2, further including a flow responsive sensing circuit for delivering a control signal to said controlled leakage means indicative of the out-put flow in said primary means.
4. The system defined in Claim 3, wherein said flow responsive sensing circuit includes a restriction in said primary output line and sensing means for sensing the differential pressure across said restriction.
5. The system defined in Claim 4, wherein said con-trolled leakage means directs substantially all of said auxil-iary output fluid to said auxiliary output line when said primary means provides less than said predetermined output.
6. The system defined in Claim 5, wherein said con-trolled leakage means includes a switch valve means for causing said valve means to direct a portion of auxiliary pump output fluid to said reservoir and to recirculate the remainder of said pump output fluid through said auxiliary pump when said primary means provides a predetermined flow and for directing substan-tially all of said auxiliary pump output fluid to said auxiliary output line when said primary means provides less than said pre-determined flow.
7. The system defined in Claim 6, wherein said con-trolled leakage means further includes restriction orifice means for directing said portion of auxiliary output fluid from said valve means through said switch means and to said reservoir when said primary means provides said predetermined flow.
8. The system defined in Claim 7, wherein said con-trolled leakage means includes a check valve means for prevent-ing flow from said auxiliary output line to said work function means when said primary means provides said predetermined flow.
9. The system defined in Claim 8, wherein said check valve means comprises first and second check valves to permit flow from said auxiliary output line to said work function means irrespective of the direction of rotation of said auxiliary pump.
10. The system defined in Claim 9, wherein said valve means includes a valve body having an inlet port connected to said auxiliary return line, an output port connected to said auxiliary output line, an upper passageway containing first and second opposed valve seats, said inlet port being in communica-tion with a central portion of said upper passageway between said valve seats, first and second transverse passageways pro-viding communication between said upper passageway and first and second auxiliary pump ports respectively, said first and second transverse passageways each intersecting said upper passageway on the side of one of said valve seats opposite said central portion, said check valve means including first and second check valves located in said upper passageway and each normally biased against said first and second valve seats, respectively, said upper passage includes a first and second chamber in which said first and second check valves reciprocate, said first check valve allows fluid flow from said inlet port to said first auxiliary pump port when said auxiliary pump is rotated in one direction and blocks this flow when said auxiliary pump is rotated in a second direction, said second check valve allows fluid flow from said inlet port to said second auxiliary pump port when said auxiliary pump is rotated in said second direction and blocks this flow when said auxiliary pump is rotated in said first direction, a first intermediate passage connected to said first transverse passageway, a second inter-mediate passage connected to said second transverse passageway, a third passageway connecting said first and second intermediate passages to said output port, said third passageway includes said check valve means for permitting flow from said first inter-mediate passage to said output port when said auxiliary pump rotates in said first direction and to block this flow when said pump rotates in said second direction, said check valve means also permits flow from said second intermediate passage to said output port when said auxiliary pump rotates in said second direction and blocks this flow when said pump rotates in said first direction, whereby fluid is available at said outlet port whenever said primary means provides less than said predetermined flow.
11. The system defined in Claim 10, wherein said sensing means includes a first pressure sensing line connected to said primary output line upstream of said restriction and a second pressure sensing line connected to said output line down-stream of said restriction.
12. The system defined in Claim 11, wherein said switch valve means includes:
a first passageway connected at a first end to said first pressure sensing line and at a second end to said second sensing line;
first and second lateral passages intersecting said first passageway and communicating with said first and second chambers, respectively;
a third lateral passage which intersects said first passageway and communicates with said reservoir; and a plunger disposed so as to reciprocate in said first passageway, said plunger being actuated by flow in excess of said predetermined flow to move toward said second end and permit said first and second lateral passages to communicate with said third lateral passage to thereby permit said portion of said auxiliary pump output fluid to flow from said valve means through said switch valve to said reservoir, and said plunger being biased toward said first end when said primary means provides less than said predetermined flow to block flow in said first, second, and third lateral passages to thereby stop the flow of said portion of auxiliary pump fluid from said valve means.
a first passageway connected at a first end to said first pressure sensing line and at a second end to said second sensing line;
first and second lateral passages intersecting said first passageway and communicating with said first and second chambers, respectively;
a third lateral passage which intersects said first passageway and communicates with said reservoir; and a plunger disposed so as to reciprocate in said first passageway, said plunger being actuated by flow in excess of said predetermined flow to move toward said second end and permit said first and second lateral passages to communicate with said third lateral passage to thereby permit said portion of said auxiliary pump output fluid to flow from said valve means through said switch valve to said reservoir, and said plunger being biased toward said first end when said primary means provides less than said predetermined flow to block flow in said first, second, and third lateral passages to thereby stop the flow of said portion of auxiliary pump fluid from said valve means.
13. The system de-fined in Claim 12, wherein said restrictive orifice means includes a first and second orifice between said first and second transverse passageways and said first and second chambers, respectively; first and second chambers passages communicating said chambers with said switch valve means so that when said primary means provides said pre-determined pressure, said portion of auxiliary output fluid flows from said first transverse passageway through said first orifice to said first chamber passage and through said switch valve means into said reservoir when said auxiliary pump is rotating in a first direction and said portion of auxiliary output fluid flow from said second transverse passageway through said second orifice into said second chamber passage and through said switch valve means into said reservoir when said auxiliary pump is rotating in a second direction.
14. The system defined in Claim 13, wherein a primary check valve is located in said primary output line between said first pressure sensing line and said restriction.
15. The system defined in Claim 14, wherein said controlled leakage means includes a check valve means for preventing flow from said auxiliary output line to said work function means when said primary means provides said pre-determined pressure.
16. The system defined in Claim 15, wherein said first and second chambers are cylindrical, said first and second check valves include a cylindrical portion on a first end, said cylindrical portion having a smaller diameter than said first and second cylindrical chambers so as to provide said first and second orifices.
17. The system defined in Claim 16, wherein said first and second check valves include a frusto-conical portion on a second end, said frusto-conical portion contacting said first and second valve seats along said frusto-conical surface so that a portion of said frusto-conical surface communicates with said first and second transverse passageways wherein high pressure fluid from said auxiliary pumping act on said frusto-conical surface to open one of said chack valves and allow fluid to recirculate through said auxiliary pump when said primary means provides said predetermined flow.
18. The system defined in Claim 1, wherein said controlled leakage means includes a switch valve means for causing said valve means to direct a portion of auxiliary pump output fluid to said reservoir and to recirculate the remainder of said pump output fluid through said auxiliary pump when said primary means provides a predetermined output and for directing substantially all of said auxiliary pump output fluid to said auxiliary output line when said primary means provides less than said predetermined output.
19. The system defined in Claim 18, wherein said controlled leakage means further includes restrictive orifice means for directing said portion of auxiliary output fluid from said valve means through said switch means and to said reservoir when said primary means provides said predetermined output.
20. The system defined in Claim 1, wherein a primary check valve is located in said primary output line.
21. The system defined in Claim 1, wherein said controlled leakage means includes a check valve means for preventing flow from said auxiliary output line to said work function means when said primary means provides said predetermined output.
22. The system defined in Claim 1, wherein said controlled leakage means includes a check valve means for preventing flow from said auxiliary output line to said work function means when said primary means provides said pre-determined output.
23. The system defined in Claim 22, wherein said check valve means comprises first and second check valves to permit flow from said auxiliary output line to said work func-tion means irrespective of the direction of rotation of said auxiliary pump.
24. The system defined in Claim 23, wherein said valve means includes a valve body having an inlet port connected to said auxiliary return line, an output port connected to said auxiliary output line, an upper passageway containing first and second opposed valve seats, said inlet port being in communica-tion with a central portion of said upper passageway between said valve seats, first and second transverse passageways providing communication between said upper passageway and first and second auxiliary pump ports respectively, said first and second trans-verse passageways each intersecting said upper passageway on the side of one of said valve seats opposite said central portion, said check valve means including first and second check valves located in said upper passageway and each normally biased against said first and second valve seats, respectively, said upper pas-sage includes a first and second chamber in which said first and second check valves reciprocate, said first check valve allows fluid flow from said inlet port to said first auxiliary pump port when said auxiliary pump is rotated in one direction and blocks this flow when said auxiliary pump is rotated in a second direction, said second check valve allows fluid flow from said inlet port to said second auxiliary pump port when said auxil-iary pump is rotated in said second direction and blocks this flow when said auxiliary pump is rotated in said first direction, a first intermediate passage connected to said first transverse passageway, a second intermediate passage connected to said second transverse passageway, a third passageway connecting said first and second intermediate passages to said output port, said third passageway includes said check valve means for permitting flow from said first intermediate passage to said output port when said auxiliary pump rotates in said first direction and to block this flow when said pump rotates in said second direction, said check valve means also permits flow from said second inter-mediate passage to said output port when said auxiliary pump rotates in said second direction and blocks this flow when said pump rotates in said first direction, whereby fluid is available at said outlet port whenever said primary means provides less than said predetermined output.
25. The system defined in Claim 1, wherein said valve means includes a shuttle valve means for permitting flow from said auxiliary pump to said auxiliary output line irrespective of the direction of rotation of said auxiliary pump; said check valve means includes a shuttle check valve to permit flow from said valve means to said auxiliary output line when the primary means provides less than said predetermined output.
26. The system defined in Claim 25, wherein said valve means includes a valve body having an inlet port connected to said auxiliary return line, an output port connected to said auxiliary output line, an upper passageway containing first and second opposed valve seats, said inlet port being in com-munication with a central portion of said upper passageway between said valve seats, first and second transverse passage-ways providing communication between said upper passageway and first and second auxiliary pump ports respectively, said first and second transverse passageways each intersecting said upper passageway on the side of one of said valve seats opposite said central portion, first and second check valves located in said upper passageway and each normally biased against said first and second valve seats, respectively, said upper passage includes a first and second chamber in which said first and second check valves reciprocate, a first intermediate passage connected to said first transverse passageway, a second intermediate passage connected to said second transverse passageway, a third passage-way connecting said first and second intermediate passageways to said output port, shuttle valve means located in said third passageway for permitting flow from said first intermediate passage to said output port when said auxiliary pump rotates in said first direction and to block this flow when said pump rotates in said second direction, said shuttle valve means also permits flow from said second intermediate passage to said output port when said auxiliary pump rotates in said second direction and blocks this flow when said pump rotates in said first direction, said check valve means includes a shuttle check valve in said output port to permit flow from said valve means to said work means whereby fluid is available at said outlet port whenever said primary means provides less than said predetermined output.
27. In a system for providing auxiliary power to a vehicle including a primary means which includes a primary pump, an output line for providing primary power to a work function means, and a return line;
an auxiliary means which includes an auxiliary pump, an output line for providing said auxiliary power, and a return line;
drive means for operating said auxiliary pump whenever said vehicle is moving;
a reservoir connected to said primary return line and said auxiliary return lines;
the improvement comprising:
horsepower loss reduction means for allowing said auxiliary means to provide said auxiliary power only when said primary pump fails to provide a predetermined amount of flow, wherein said auxiliary means includes valve means for controlling fluid flow in said auxiliary output and return line; said horse-power loss reduction means being connected to said auxiliary means, said reservoir and said primary means and being responsive to said primary means for directing a portion of said output fluid from said auxiliary means to said reservoir when the pri-mary means provides a predetermined flow and directing substan-tially all of auxiliary output fluid to said auxiliary output line when the primary means provides less than said predetermined flow.
an auxiliary means which includes an auxiliary pump, an output line for providing said auxiliary power, and a return line;
drive means for operating said auxiliary pump whenever said vehicle is moving;
a reservoir connected to said primary return line and said auxiliary return lines;
the improvement comprising:
horsepower loss reduction means for allowing said auxiliary means to provide said auxiliary power only when said primary pump fails to provide a predetermined amount of flow, wherein said auxiliary means includes valve means for controlling fluid flow in said auxiliary output and return line; said horse-power loss reduction means being connected to said auxiliary means, said reservoir and said primary means and being responsive to said primary means for directing a portion of said output fluid from said auxiliary means to said reservoir when the pri-mary means provides a predetermined flow and directing substan-tially all of auxiliary output fluid to said auxiliary output line when the primary means provides less than said predetermined flow.
28. The system defined in Claim 27, wherein said horsepower loss reduction means includes a switch valve means for causing said valve means to direct a portion of auxiliary pump output fluid to said reservoir and to recirculate the remainder of said pump output fluid through said auxiliary pump when said primary means provides said predetermined flow and for directing substantially all of said auxiliary output fluid to said auxiliary output line when said primary means provides less than said predetermined flow.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/597,603 US3975908A (en) | 1974-05-31 | 1975-07-21 | System for providing auxiliary power |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1050857A true CA1050857A (en) | 1979-03-20 |
Family
ID=24392188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA255,942A Expired CA1050857A (en) | 1975-07-21 | 1976-06-29 | System for providing auxiliary power |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5213231A (en) |
| AU (1) | AU507759B2 (en) |
| BR (1) | BR7604713A (en) |
| CA (1) | CA1050857A (en) |
| DE (1) | DE2632751C2 (en) |
| FR (1) | FR2319033A1 (en) |
| GB (1) | GB1552954A (en) |
| IT (1) | IT1076460B (en) |
| SE (1) | SE408779B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5464332A (en) * | 1977-10-17 | 1979-05-24 | Honda Motor Co Ltd | Automotive power steering device |
| DE102018101996A1 (en) | 2018-01-30 | 2019-08-01 | Voith Patent Gmbh | Adapter part for adapting a coupling head, coupling head with adapter part and method for adapting a coupling head |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3434282A (en) * | 1967-03-14 | 1969-03-25 | Dura Corp | Safety backup system for power steering |
| BE755754A (en) * | 1969-09-04 | 1971-03-04 | Caterpillar Tractor Co | Additional supply system for the hydraulic components of a vehicle. |
| US3747725A (en) * | 1971-03-15 | 1973-07-24 | Ford Motor Co | Power steering system with auxiliary pump |
| DE2211360C2 (en) * | 1972-03-09 | 1982-04-08 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen | Hydraulic steering system automatic changeover valve - has spring chamber extending axial plunger bore, and has constant cross=section throttle |
| US3791775A (en) * | 1972-06-19 | 1974-02-12 | United Aircraft Corp | Hydraulic fluid supply apparatus for a hydraulic servomechanism |
| FR2219691A5 (en) * | 1973-02-27 | 1974-09-20 | Poclain Sa | |
| US3896618A (en) * | 1974-05-31 | 1975-07-29 | Gen Signal Corp | System for providing auxiliary power |
-
1976
- 1976-06-29 CA CA255,942A patent/CA1050857A/en not_active Expired
- 1976-07-16 JP JP51084911A patent/JPS5213231A/en active Pending
- 1976-07-19 GB GB29907/76A patent/GB1552954A/en not_active Expired
- 1976-07-19 IT IT50498/76A patent/IT1076460B/en active
- 1976-07-20 FR FR7622070A patent/FR2319033A1/en active Granted
- 1976-07-20 SE SE7608259A patent/SE408779B/en unknown
- 1976-07-20 BR BR7604713A patent/BR7604713A/en unknown
- 1976-07-21 DE DE2632751A patent/DE2632751C2/en not_active Expired
- 1976-07-23 AU AU16203/76A patent/AU507759B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2319033B1 (en) | 1982-02-26 |
| JPS5213231A (en) | 1977-02-01 |
| DE2632751A1 (en) | 1977-01-27 |
| GB1552954A (en) | 1979-09-19 |
| AU507759B2 (en) | 1980-02-28 |
| AU1620376A (en) | 1978-01-26 |
| SE408779B (en) | 1979-07-09 |
| DE2632751C2 (en) | 1983-02-24 |
| BR7604713A (en) | 1977-08-02 |
| SE7608259L (en) | 1977-01-22 |
| IT1076460B (en) | 1985-04-27 |
| FR2319033A1 (en) | 1977-02-18 |
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