GB2192434A

GB2192434A - Fuel pumpimg apparatus

Info

Publication number: GB2192434A
Application number: GB08712573A
Authority: GB
Inventors: Ian Roy Thornthwaite; Robin Edward Wardley
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1986-06-04
Filing date: 1987-05-28
Publication date: 1988-01-13
Also published as: GB8613465D0; DE3718607A1; FR2599786B1; JPS6318181A; GB2192434B; GB8712573D0; FR2599786A1; US4807583A

Description

1 GB 2 192_ 434 A - 1 SPECIFICATION valve means energised, and means for

energising said valve means to allow starting of the associated Fuel pumping apparatus engine.

An example of a fuel pumping apparatus in - This invention relatesto a fuel pumping-apparatus 70 accordance with the invention will now be described for supplying fuel to a compression ignition -engine with referencetO the accompanying drawings in and of the kind comprising a high pressure pump which:

which in use is actu ated in timed relationship with the Figure 1 is a diagrammatic layoutof the pump ing associated engine and an engine driven low pressure apparatus,and pump for supplying fuel under-pressure to the high 75 - Figure 2 is an electrical circuit diagram rusewit pressure pump, the apparatus further including liquid the apparatus shown in Figure 1.

pressure operable meansfor controlling thequantity Referring to Figure 1 of the drawings the apparatus of fuel delivered bythe high pressure purTp,- aid low comprises a high pressure pump 10 having a Plurality pressure pump constituting the source of liquid under of outlets 11 for connection in use to the injection pressureforsaid pressure operable means. 80 nozzles respectively of the associated'engine. The One example of such an apparatus is a distributor high pressure pump 10 is driven in timed relationship type-fuel pump in which the flow of fuel to-the high with the associated engine and it is supplied-with fuel pressure pump from the low pressure pump is by a low pressure pump 12 which is also driven.bythe controlled bya throttle memberwhich is subjected to engine. The inlet 13 of the low pressure pump is the outlet pressure of the lbw press. ure pump and is 85 connected to a sou rce'of fuel such for example as a movable againstthe action of a spring to reduce the -fuel tank and the- Outlet 14of the low pressure pump is -fuel flOWto the high Pressure pump and therefore to connected byway of a throttle 15 and an onloff valve the engine, as the engine speed increases. The force 16 to the inlet of the high pressure pump. The inlet and exerted by the spring can beadjusted manually and a outlet of the low pressure pump are interconnected by governing action is obtained since as the engine 90 a pressure regulating valve 17 which actSto Control - - speed decreases, so-also will the outlet pressure of the - the outlet pressure of the low-pressure pump so that it low pressure pump causing the pressure operable varies in accordance with the speed atWhich the means to moveto increase the amountof fuel apparatus is driven.

In operation, with the valve 16 in ttie-open position, - supplied tothe engine and vice versa.

Another example of an apparatus of the aforesaid 95.'fuel is supplied bythe low pressure pump to the high kind is described in British Published Specification pressure pump which in turn suppliesfuel to the

2037365A and in which the-distributor member is combustion chambers ofthe associated engine. The movable axially against the action of a.spring to quantity of fuel is determined bythe setting of the - reducethefuelflowto the engine by means of fuel throttle 15 which comprises a throttle memberwhich under pressure derived from the low pressure pump, 100 is movable axially against the action of 0 governor the fuel pressure applied to the distributor member - spring, by means ofthefuel pressure atthe outlet 14 of beling adjusted by means of an electronic control the low pressure pump. The throttle i ' s arranged sa system. thatas it is moved further againstthe action of the Afurtherexample of an apparatus having an axially - spring with increasing foe] pressurei the quantity of movable distributor member is described in-British 105 fuel which is supplied to the high pressure pump-and Published Specification 2069722A. In this exam-pie the hence tothe associated engine, is decteased. The - press. we applied to the-distributor member is control- - force exerted bythe spring is adjustable by manually led by a mechanical governor mechanism.

operable means and the arrangement provides a In each form of apparatus outlined above in the speed governing action.

everitthatthe output pressure of the low pressure -110 - As explained it is possible for airta enter the inlet 13 pump falls due for example to air being drawn into the. of the low pressure pump to cause a reduction in the low pressure pump, there will be a tendency forthe outlet pressure and by virtue of the disposition& the quantity of fuel supplied to the engine to increase. This throttle, this can respond-to the reduction of pressure is because although the pressure of fuel delivered by to allow more fuel to flow to the associated engine.

the low pressure pump may fail,-it_may-not fall _ 115 The governing action is therefore lost and this can sufficiently to reduce the flow of fuel to the h ig h leadto a dangerous situation particularly if the engine pressure pump. In any casethe high pressure pump - is driving a road vehicle.

itself can drawfuel through its supply channel - In orderto overcome the aforesaid liroblem a fuel particularly asthe engine speed increases. The effect pressure responsive device 18 is provided whichIs is that the govern i ng action maybe lost- - -120 responsive to the pressure atthe ouilefl 4 of the low The object of the present invention is to provide an pressure pump. The device 18 controlslhe energisa apparatus of the aforesaid kind asset out in thefirst tion of the valve 16 and it is arranged that when the paragraph, in a simple and c onvenientform. outlet pressure fails below a predetermined value, the According to the invention an apparatus ofthe kind valve 1 Gis moved to the closed position thereby specified comprises electromagnetic valve means 125 preventing further supply offuel to the associated which when energised allows fuel flow to the associ- engine.

ated engine,.a pressure responsive devicewhich is The valve 16 can be replaced by a valve 19 which responsiveto the pressure of fuel developed bythe when closed, allows fuel flowto the associated-engine low pressure pump and which when thefuel pressure- but which when open, causes the fuel which is - is above a predetermined value acts to maintain said 130 pumped bythe high pressure pump.toflowtoajdrain 2 GB 2 192 434 A - -2 thereby preventing the supply of fuel to the associated the apparatus and particularly those ofthe high engine. pressure pumpto facilitate rapid restarting of the Thevalves 16and 19 are electromagnetically engine.

controlled and itis arranged that the valves haveto be - In orderto achievethis afurthervalve 26 is provided energised when it is required to supply fuel to the 70 and as shown in Figure 2 this is connected in parallel associated engine. In this man nerthe valves can also with the relay 22 so that it will be-energised when the serve to stop the engine when so required. The starting motor of the associated engine is in operation.

pressure responsive device 1.8 can becorinected The valve 26 when energised, assumes an open electrically in series with the valves 16 or 19, the device position and it is arranged to that it communicates 18 being in the form of a switch which is arranged to 75 with the pumping chamber of the high pressure pump be closed when the pressure is above a predeter- during the filling periods thereof. This is achieved mined value. With this arrangement howeverthere using suitable porting on the distributor member and occurs a problem when trying to startthe engine since in the.surrounding body. In this manner during p filling the output pressure of the low pressure pump will be periodo the high pressure pump the valve 26 below the aforesaid predetermined value. It is necesprovides a flow path to drain facilitating the purging of sary therefore to provide some sort of temporary air from the passages within the apparatus. The flow supply circuit to the valves when starting the associpath through the valve 26 must be such asto restrict atedengine. theflowoffuel but a] lowsubstantially free flow of air Referring nowto Figure2 of the drawings, the otherwisethe pumping chamberofthe high pressure engine starting motor is shown at-20 and has-one of its 85 pump would notfill with fuel.

supplyterminals connected to earthand to one Alternatively the valve 26 and the porting may be terminal of the storage accumulatoi-21.7he other arrangedto allow air andfuel to escape to drain during terminal of the motor can be connected to the other the initial portion only of a delivery stroke of the high term - inal of the storage accumulator by way of a relay pressure pump.

Claims

22 having a winding which is energised,when 90 CLAIMS switches 23 and 24

are closed. Switch 23is the 1. Afuel pumping apparatus for supplying fuel to a conventional key switch of the vehicle electrical compression ignition engine comprising a high press system anwhich is closed when it is required torun ure pump which in use is actuated in timed rela the vehicle,the switch also serving to control the tionship with the associated engine and an engine supply of powertovarious vehicles accessories. The 95 driven low pressure pump for supplying fuel under switch 24 is a switch which is closed usually Uyturning pressure to the high pressure pump, the apparatus the key switch beyond its normal position to an engine further including liquid pressure operable means for start. position. When the switches 23-and 24are closed, controlling the quantity of fuel delivered bythe high - the relay 22 is energised causing operation of the pressure pump, said low-pressure pump constituting starting motor of the engine.-A point intermediate the 100 the source of liquid under pressure for said pressure switches 23,24 is con nectedto the valve 16 byway of operable means, electromagnetic valve means which the sensor 18 which in this example is a simple when energised allows fuel flow to the associated pressure operated switch. In-normal running of the engine, a pressure responsive device which-is respon engine therefore the switch 23 will be closed, the sive to the pressure of fuel developed by the low switch 24 opened and the switch constituted by the, 105 pressure pump and which when the fuel pressure is sensor 18 closed so thatthe valve 16 will be energised above a_predetermined value acts to maintain said to allow fuel flow. valve means energised, and means for energising For starting purposes a diode 25 is provided which said valve means to allow starting of the associated upon closure of the switch 24 provides a supplyto the engine.

-valve 16to energise the valve so long as the starter - 110
2. An apparatus according to Claim 1 in which the motor is in operation. -Once the engine has started the means for energising said valve means comprises a switch constituted by the sensor 18 will be closed and switch which is closed to.achieve operation of the - the engine can run normallywith the switch 24 starting motor of the associated engine.

opened. The diode acts to prevent energisation of the
3. An apparatus according to Claim 2inclUding a relay 22 once the switch 24.has been opened. When it 115 d iode co n nected i n series with sa id switch a rid said is requ i red to sto p the eng in e, th e switch 23 is opened valve mea ns, saiddiode acti rig to p revent th e su pply - a rid th is d eenerg ises the va Ive 16 to p reventfu rth e r of electric current to otherelectrical components supply of fuel to the high pressure pump and therefore when said switch is-opened following starting of the to the associated engine. - - engine.

- In the case of the pumps described in British 120
4. An apparatus according to anyone of Claims.1-3 - Published Specificat ions No. 2037365A and 2069722A including furthervalve means operating during start thethrottle 15 is replaced by a pressure control system ing of the associated engine,to allow airto escape which controlsthe pressure applied to the endof the fromthe high pressure pump.

distributor memberof the apparatus. In this.casetKe
5. An apparatus as claimed in anyone of Claims valve 16 is connected directlyto the outlet 14 of the 125 -1-4 in which said first mentioned valve means is - low pressure pump so thatwhen the valve 16 is connected in series between the high pressure pump deenergised the supply of fuel tothe associated and the low pressure pump.

- engine is prevented. -
6. An apparatus as claimed in anyone of Claims - In both forms of-apparatus described it is some- 1-4 in-which said first mentioned valve means is times necessary to purge air from the passages within 130 associated with the high pressure pump and-whictr 3 GB 2 192 434 A 3 when opened, diverts fuel pumped bythe high preSsureto a drain.
7. A fuel pumping apparatusfor supplying fuel tG a compression ignition engine comprisfrig-the corn- bination and arrangement of parts substantially as herein before described with- reference to the accompanying drawings.

Printed in the United Kingdom for Her Majesty's Stationery Office by the Tweeddale Press Group, 8991685, 1188 18996. Published at the Patent Office, 25 Southampton Buildings,. London WC2MAY, from which copies may be obtained.