A Radial Piston Pump, Particularly a Fuel Injection Pump for Diesel Engines

Europaisches Patentamt 0 304 750 European Patent Office © Publication number: A1 Office europeen des brevets

EUROPEAN PATENT APPLICATION

(§) Date of filing: 12.08.88

© Priority: 25.08.87 IT 6773987 © Applicant: WEBER S.r.l. Corso Marconi, 20 © Date of publication of application: 1-10125 Torino(IT) 01.03.89 Bulletin 89/09 © Inventor: Filippi, Renato © Designated Contracting States: Via Parisetto, 31 AT BE CH DE ES FR GB GR IT LI LU NL SE 1-10048 Vlnovo Torino(IT) Inventor: Turchi, Sergio Via Bussoleno, 16 1-10040 Rivalta Torino(IT) Inventor: Valetto, Alessandro Via Castellino, 11 1-10141 Torino(IT)

© The pump comprises a body formed by two chamber (5). An electrically-controlled device (si ) is elements (2, 3) sealingly clamped together, between provided in this passage (50) and is adapted to which is defined a central chamber (5) in which a control the flow of fluid through the passage (50) in a drive shaft (6) carrying an eccentric (7) is rotatably predetermined manner. mounted. A plurality of cylinders (9) which open into the central chamber (5) of the body (2, 3) and are arranged radially around the shaft (6) is mounted in one element (2) of the body (2, 3), and pistons (13) which cooperate with the eccentric (7.) are slidably ^mounted therein. These cylinders (9) are in commu- ^nication with a supply chamber (18) defined in the body (2, 3) between the first and second elements §(2, 3). The supply chamber (18) is annular in shape |X and is formed in a position radially outside the , central chamber (5). q At least one sealing member (31) for separating PQthe supply chamber (18) from the central chamber Q(5) is interposed between the first and second elements (2, 3) of the body. ^ At least one passage (50) is formed in one (3) of ^the elements (2, 3) of the body to put the supply chamber (18) into communication with the central

Xerox Copy Centre 1 EP 0 304 750 A1 2

A radial piston pump, particularly a fuel injection pump for dlesel engines

The present invention relates to a radial piston 14 against which acts a helical spring 15 disposed pump and, more specifically, to a pump of the type around the cylinder and tending to urge the piston defined in the preamble of the appended Claim 1 . towards the eccentric 7. The pump according to the invention is charac- The element 3 of the pump body is substan- terised in that at least one passage is formed in 5 tially cup-shaped and has a side wall 3b which one of the elements of the pump body and is able surrounds the projecting portion 2a of the element to put the supply chamber into communication with 2 of the body with clearance. the central chamber; electrically-operated control A sealing .ring 17 (Figure 1) is clamped be- means being provided for enabling the controlled tween the upper portion of the wall 3b of the flow of fluid through the said passage. io element 3 and the portion facing the outer lateral By means of these control means (which may surface of the element 2 of the pump body. comprise, for example, a solenoid cut-off valve An annular chamber defined in the pump body which can be piloted in an on/off mode by means between the side wall 3b and the projecting portion of an electrical control signal, or a solenoid flow 2a of the element 2 is indicated 18. This annular modulating valve) it is possible at the extreme to 75 chamber acts as a supply or intake chamber of the prevent communication between the supply cham- pump and communicates with an inlet connector ber and the central chamber of the pump or, in 19 (Figure 1) through a passage, indicated 20. The some circumstances, when useful, to enable con- liquid which is to be pumped is supplied through trolled communication between the central cham- this connector. In the case of a fuel injection pump ber and the supply chamber, for example, when 20 in a diesel engine, this liquid is diesei oil. slight pre-heating of the fuel to be pumped would The working chamber 12 of each cylinder can be useful. be put into communication with the chamber 18 Further characteristics and advantages of the through the respective intake valve 10, when the present invention will become clear from the de- piston 13 effects its induction stroke under the tailed description which follows with reference to 25 action of the spring 15 which tends to keep it in the appended drawings, provided by way of non- contact with the surface of the eccentric 7. This limiting example, in which: working chamber can be put into communication Figure 1 is an axial section of a radial piston with a delivery manifold through the respective pump according to the invention. delivery valve 11, however, when the associated Figures 2 and 3 are cross-sections taken on 30 piston 13, pushed by the eccentric 7, effects its the lines ll-ll and Ill-Ill of Figure 1 . delivery stroke. With reference to the drawings, a radial piston An annular recess 30 housing a sealing ring 31 pump 1 according to the invention comprises a (Figure 1) is formed in that surface of the projec- body formed by two elements 2 and 3 clamped ting portion 3a of the element 3 of the pump body together by means of bolts 4. 35 which is in frontal contact with the projecting por- In the embodiment illustrated, the element 2 tion 2a of the element 2. This sealing ring, which is has an annular projection, indicated 2a, on its face clamped between the two elements 2 and 3 of the facing the element 3. The element 3 of the pump pump body, en sures the sealed separation of the body has a corresponding annular projection 3a central chamber 5 from the supply chamber 18 of facing and in contact with the end surface of the 40 the pump. projection 2a of the element 2. Operating conditions can actually occur in A central cavity or chamber is indicated 5 and which controlled pre-heating of the fuel to be is defined between the elements 2 and 3 of the pumped may be useful or desirable. With the pump body. A drive shaft 6 carrying an eccentric 7 pump according to the invention it is possible to is rotatably mounted in this chamber. 45 achieve such controlled preheating of the fuel. Three equi-angularly spaced apertures 8 are In the operation some fuel inevitably leaks be- formed in the projecting portion 2a of the element tween the pistons 13 and the cylinders 9 and flows 2 of the pump body, the axes of which intersect in into the central chamber 5. The fuel thus leaked correspondence with the axis of the drive shaft 6. A into the chamber 5 is at a high temperature. cylinder 9 is fixed in each of these apertures and is 50 The central chamber 5 of the pump can be put provided in known manner with an intake valve and into communication with the chamber 18 through a a controlled valve, generally indicated 1 0 and 1 1 . A passage illustrated by broken lines in Figure 1 and respective piston 13 is mounted for sliding in the indicated 50. An electrically-operated control de- working chamber 12 formed in each cylinder. The vice is associated with this passage and is adapted end of each piston 1 3 facing the shaft 6 has a head to control the flow of fuel between the chambers 5

2 :P 0 304 750 A1 ind 18 through the passage 50. The control device wall (3b) surrounds the projection (za) ot tne Tirst 51 may comprise, for example, a solenoid cut-off element (2) of the body in spaced relationship to /alve which can be piloted in an on/off mode by define therewith the supply chamber (18). neans of an electrical control signal, or a solenoid 4. A radial piston pump according to Claim 1 , low-modulating valve. 5 characterised in that the control means comprise a The passage 50 may be closed completely by solenoid cut-off valve which can be piloted' in an tie control device 51, and in this case, the tem- on/off mode by means of an electrical control sig- Derature of the fuel within the central chamber nal. — ends to increase without noticeably affecting the 5. A radial piston pump according to Claim 1 , :emperature of the fuel which is being pumped. o characterised in that the control means comprise Moreover, the device 51 may be piloted so as solenoid flow-modulating valve. :o allow some communication between the cham- Ders 5 and 18 in some circumstances, with a consequent increase in the temperature of the fuel Dumped. r5

Claims

1. A radial piston pump comprising a body 20 formed by two elements (2, 3) sealingly clamped together, between which is defined a central chamber (5) in which a drive shaft (6) carrying an eccentric (7) is rotatably mounted; a plurality of cylinders (9) which open into the central chamber 2s (5) and are disposed radially around the shaft (6) being mounted in one element (2) of the body (2, 3) and pistons (13) which cooperate with the eccentric (7) being siidably mounted therein, the cylinders (9) being able to communicate with a supply 30 chamber (18) defined in the body (2, 3) between the first and second elements (2, 3); the supply chamber (18) being annular in shape and formed in a position radially outside the central chamber (5); sealing means (31) for separating the 35 supply chamber (18) from the central chamber (5) being provided between the first and second elements (2, 3) of the body; characterised in that at least one passage (50) is formed in one element (3) of the body (2, 3) and is able to put the supply 40 chamber (18) into communication with the central chamber (5), electrically-operated control means (51) being provided to allow the controlled flow of fluid through the passage (50). 2. A radial piston pump according to Claim 1, 45 characterised in that the element (2) of the body (2,3) in which the cylinders (9) are mounted has, on its surface facing the other element(3),an annular projection (2a) having seats (8) formed in equian- gularly spaced positions and in which the cylinders 50 (9) are disposed, the other element (3) of the body (2, 3) having a surface (3a) clamped in contact with the projection (2a) of the first element (2) of the body with the interposition of at least one sealing member (31). 55 3. A radial piston pump according to Claim 2, characterised in that the other element (3) of the body (2, 3) is substantially cup-shaped and its side

3 EP 0 304 750 A1 EP 0 304 750 A1 Application Number

EP 88 11 3154

DOCUMENTS CONSIDERED TO BE RELEVANT

Category Citation of document with indication, where appropriate, Relevant CLASSIFICATION OF THE of relevant passages to claim APPLICATION (Int. C1.4) A FR-A- 366 337 (MONIN) 1-3 F 04 B 1/04 * Whole document; figures 1-2 *

A DE-B-1 096 750 (HEILMEIER) 1-3 * Whole document *

A GB-A- 966 635 (MACTAGGART) 1-3 * Whole document *

A DE-A-1 453 664 (TEVES) 1-3 * Page 7, paragraph 3 - page 8, paragraph 1; figures 1-4 *

TECHNICAL FIELDS SEARCHED ant. C1.4)

F 04 B F 02 M

The present search report has been drawn up for all claims Place of search Date of completion of the search Examiner THE HAGUE 26-10-1988 VON ARX H.P.

CATEGORY OF CITED DOCUMENTS T : theory or principle underlying the invention E : earlier patent document, but published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L : document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document