US3067688A - Fuel supply pump - Google Patents

Description

1962 R. J. WIRSCHING 3,

FUEL SUPPLY PUMP Filed July 6, 195a INVENTOR. ROBERT J. WIRSCHING uwau wwzy A TTORNE United States Patent Office 3,067,688 Patented Dec. 11, 1962 3,067,688 FUEL SUPPLY PUMP Robert J. Wirschiug, Korntal, Stuttgart, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart- Unterturkheim, Germany Filed July 6, 1959, Ser. No. 825,042

Claims priority, application Germany July 15, 1958 4 Claims. (Cl. 10337) The present invention relates to a further development and improvement of fuel supply pumps for internal combustion engines provided with a supply piston member located within the pump cylinder.

In the pump constructions known in the prior art, the supply piston is arranged as a plunger member co-axial with respect to the oppositely disposed pump piston. However, these prior art constructions entailed the disadvantages of an undesirable, relatively large structural length and relatively small pump and supply piston diameters.

The present invention obviates the disadvantages encountered in the prior art constructions by providing a pump piston which is effective also directly as supply piston, a feature which is achieved by subjecting the pump piston, on the one hand, to the influence or action of an outer supply spring for the pressure stroke thereof and, on the other, subjecting the piston to the influence or action of an inner spring arranged within the pump cylinder for the suction stroke thereof which inner spring rests with the end thereof facing the piston against an entrainment abutment member, arranged directly in front of the piston, of a plunger or push rod supported within the piston in a manner to be axially displaceable with respect thereto whereby a control arrangement, of any known construction acts against the end of the plunger or push rod protruding beyond the piston and pump housing.

Accordingly, it is an object of the present invention to provide a fuel supply pump construction which obviates the disadvantages of the prior art devices.

It is another object of the present invention to provide a fuel supply pump arrangement which is simple in construction, which utilizes only relatively few parts, and which requires a relatively smaller space than the prior art devices.

Still another object of the present invention is the provision of a fuel supply pump which is compact and utilizes a single piston member for filling the twofold purposes of suction and supply action.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows in the single FIGURE thereof, for purposes of illustration only, one embodiment in accordance with the present invention.

Referring now to the drawing which shows in the single figure thereof a cross sectional view through a fuel supply pump in accordance with the present invention, reference numeral 1 generally designates the T-shaped pump housing which is provided with a suction line 2 and a pressure line 3 arranged opposite each other essentially co-axially. The pump cylinder 4 provided in the housing 1 is thereby arranged essentially perpendicularly to the suction and pressures lines 2 and 3. One spring-loaded check valve 5 and 6 each is arranged in front of the suction and pressure line 2 and 3 as seen from within the pump cylinder 4. A piston 7 provided with a central bore is adapted to reciprocate within the pump cylinder 4 whereby the piston 7 is supported on a plunger or push rod 8 extending through the central bore provided in the piston 7 in such a manner as to be axially displaceable with respect thereto. An entrainment abutment member 9 is mounted on the inner end of push rod 8 in front of the inner end of piston 7 facing the pump space which entrainment abutment member 9 simultaneously is constructed to form the abutment for fro movements under the influence of such control mechanism and under the influence of the spring 10.

The spring force of the spring 19 may also be appropri ately adjusted by a threaded cap 13 closing off the pump cylinder 4. An overflow or return-flow bore 14 is arranged within the range of valving movement of the piston 7 which bore is released or opened up by the piston '7 when the latter approaches its outermost storing or supplying position in order to prevent excessive pressures to build up within the pump housing 1, for example, if the discharge of the sucked-in fluid quantities becomes zero at the pressure line 3.

OPERATION The operation of the fuel supply pump in accordance with the present invention is as follows:

During normal fuel consumption, the pump supplies the amount just required therefor. The pressure stroke is thereby realized by the fact that during immersion of the plunger or push rod 8 into the pump space, i.e., during the upward movement thereof as seen in the drawing, the abutment member 9 arranged in front of the piston 7 is taken along and thereby also recedes upwardly; the piston 7 follows such upward movement of the abutment member 9 under the influence of the spring force exerted by spring 11 whereby the spring force decreases with the expansion of spring 11 up to a point Where the spring force of spring 11 is efiectively insufiicient to move the piston 7 further in the upward direction thereof. On the other hand, with the inward, i.e., upward movement of the plunger or push-rod 8 caused by the external control means, the spring 10 has been compressed to such an extent that the force thereof now exceeds the other relatively weak or spring force of spring 11. Corresponding to the cessation of the external control force effecting the inward or upward movement of the plunger member or push-rod 8, the spring 10 which now seeks to untension itself, again forces the abutment member 9 together with the piston 7 outwardly, i.e., in the downward direction as viewed in the drawing. As a result thereof, the piston 7 carries out the suction stroke.

If now the consumption of the supplied fuel quantity decreases in line 3, then the excess of the sucked-in fluid quantity is accommodated within the pump cylinder by the pump piston 7 in that the latter under the continu ously increasing compression of the supply spring 11, ever more recedes with respect thereto, i.e., ever more moves downwardly with respect thereto, until it finally is lifted off the abutment member 9 and from then on no longer carries out any reciprocating pumping movement at all after the pump movement had previously continuously decreased or become ever smaller. If the discharge at the pressure line 3 becomes zero or if the piston 7 reaches its outermost, i.e., lowermost supply end position, then the overflow bore 14 is released or opened up by piston 7 in order to avoid an excess pressure withacezsss in the pump space which might damage the pump housing 1. As soon as more fiuid pressure again flows oil into the pressure line 3, the supply piston 7 again moves upwardly into the pump space to the extent that the pump space becomes free by the fuel discharged through pressure line 3 until piston 7 again abuts against the abutment member 9 and resumes its piston operation.

While I have shown and described one embodiment in accordance with the present invention is is understood that the same is not limited thereto but is susceptible of many changes and modifications within the spirit and scope of the present invention and I, therefore, do not wish to be limited to the particular details described and shown herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What is claimed is:

1. A pump, especially a fuel supply pump for internal combustion engines, comprising, pump cylinder means including a suction inlet and a pressure outlet, check valve means in both said suction inlet and said pressure outlet, and piston means movable within said pump cylinder means, said piston means being efiective as a suction and a discharge assembly and including a piston having a bore extending therethrough, first spring means disposed on one side of said piston and second spring means disposed on the other side of said piston, abutment means disposed within said pump cylinder means adjacent said other side of the piston and operatively connected to said second spring means, said first spring means being operative to move said piston in one direction and said second spring means being operative indirectly to move said piston means through movement of said abutment means, and push rod means freely slidable in said bore and operatively connected with said abutment means to lift the same from said piston in opposition to said second spring means and accordingly control operation of said piston means.

2. A pump as defined in claim 1, wherein said pump cylinder means includes an overflow bore provided therein within the area of said piston means, said overfiow bore being valved by said piston means and being opened when said piston means is in the end position in the direction of the suction stroke of the pump.

3. A pump as defined in claim 2, further comprising means for adjusting the spring force of said second spring means.

4. A pump, especially a fuel supply pump for an internal combustion engine having means for driving said pump, comprising a pump cylinder having a suction inlet and a pressure outlet, check valves in both said suction inlet and said pressure outlet, and pump means effective as a suction and supply means arranged within said pump cylinder, said pump means including a piston slidable in said pump cylinder, said piston having a bore extending therethrough, a push rod slidably arranged within said bore, an abutment member disposed adjacent the side of said piston facing the interior of said pump cylinder, said push rod extending through said piston and being operatively connected to said abutment member, a first spring arranged within said pump cylinder operative to press said abutment member against said piston, and a second spring operative to press said piston against said abutment member, said first spring having a stronger spring force than said second spring, said push rod being adapted to be reciprocably driven in said bore by said driving means and said first spring to thereby effect the pressure and suction strokes of said pump means.

References Cited in the file of this patent UNITED STATES PATENTS 1,369,915 Church Mar. 1, 1921 1,589,246 Scott June 15, 1926 1,781,404 McNab Nov. 11, 1930 l,829,451 McNab Oct. 27, 1931 1,883,459 Auigdor Oct. 18, 1932 1,915,832 Mantle June 27, 1933 1,981,667 Rockwell Nov. 20, 1934 1,984,614 Welch Dec. 18, 1934 2,183,510 Thomas Dec. 12, 1939 2,301,435 Mercier Nov. 10, 1942 FOREIGN PATENTS 260,175 Great Britain Oct. 28, 1926 318,461 Italy July 13, 1934 375,048 Great Britain June 23, 1932 772,507 France Oct. 31, 1934

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