US3435914A

US3435914A - Oil pump for an engine

Info

Publication number: US3435914A
Application number: US589015A
Authority: US
Inventors: Kunio Atsumi
Original assignee: Suzuki Motor Corp
Current assignee: Suzuki Motor Corp
Priority date: 1965-10-28
Filing date: 1966-10-24
Publication date: 1969-04-01
Anticipated expiration: 1986-04-01

Description

v Filed Oct. 24. 1966 Sheet APril 1, 1959 KuNlb ATSUMI 3,435,914

OIL PUMP FOR AN ENGINE A ril 1, 1969 on. PUMP'F'OR AN'ENGINE Filed Oct. 24, 1966 Sheet 2 of 2 KUNIO ATSUMI 3,435,914 7 3,435,914 OIL PUMP FOR AN ENGINE Kunio Atsumi, Hamamatsu, Japan, assignor t0 Suzuki .Iidosha Kogyo Kabushiki Kaisha (trade name: Suzuki Motor Co., Ltd.), Hamana-gun, Shizuoka Prefecture, Japan, a corporation of Japan Filed Oct. 24, 1966, Ser. No. 589,015 Claims priority, application Japan, Oct. 28, 1965, 40/ 87,665 Int. Cl. F01m 1/02; F16n 7/36; F04d 15/00 US. Cl. 184-6 4 Claims ABSTRACT OF THE DISCLOSURE Oil pump in which the oil distributor is driven by a pump shaft interlocked with the engine and said pump shaft drives sumultaneously a camshaft synchronized therewith. The cam carried by said camshaft is in contact with a plunger which extends into the cylinder chamber of said oil distributor. The oil is supplied by sliding said plunger and successively connecting the oil hole communicating with said cylinder chamber to the suction and discharge holes surrounding the distributor through rotation of said distributor. The profile of the cam changes in the axial direction in dependence on the relation between the contact position of said cam and said plunger and the opening of the engine thorttle.

The present invention relates to an improvement in an oil pump for supplying lubricating oil to those parts of an engine such as the crankshaft, the connecting rod, the cylinder, the piston, etc., which are subject to frictional wear, or more specifically to an oil pump for automatically adjusting the supply of lubricating oil to such parts.

In this type of oil pumps it is generally desirable that the amount of oil pumped increase with an increase in the r.p.=m. of the engine, so as to be proportional to the latter, and also that it increase with an increase in the engine load. Moreover, such pumps are required to be capable of providing an uninterrupted supply of oil in an accurate amount to a working engine and to be so compact as to be suitable even for small engines such as those used for motorcycles.

In order to meet these requirements, the present invention provides an oil pump which is equipped with an oil :distributor interlocked with the engine, the quantity of oil supplied from said distributor being dependent upon the degree of opening of the engine throttle.

In this invention, the oil distributor is driven by a pump shaft interlocked with the engine and said pump shaft drives simultaneously a camshaft synchronized therewith. The cam carried by said camshaft is in contact with a plunger which extends into the cylinder chamber of said oil distributor. The oil is supplied by sliding said plunger and successively connecting the oil hole communicating with said cylinder chamber to the suction and discharge holes surrounding the distributor through rotation of said distributor. The profile of the cam changes in the axial direction in dependence on the relation between the contact position of said cam and said plunger and the opening of the engine throttle.

Thus, in this invention, since both the pump distributor and the camshaft are simultaneously driven -'by the engine, the oil supply is made proportional to the r.p.m. of the engine and through proper selection of the rotational position of the distributor and the cam profile, the plunger reciprocation can be exactly synchronized with the opening and closing of the suction and discharge holes. Moreover, since the cam profile changes in the axial direction nited States Patent Ofice Patented Apr. 1, 1969 of camshaft and the cam-plunger contact position varies in dependence on the throttle opening of the engine, the plunger stroke changes with the engine load, thus assuring the supply of oil which is necessary for lubrication.

In the present invention a plurality of discharge holes may be provided on the pump casing which encloses the oil distributor, and said oil distributor may be cylindrical. In this case it is possible for one reciprocation of the plunger to distribute the desired amount of oil to a plurality of parts by matching the cam profile to the angular positions of the desired discharge holes. Moreover, a cylindrical form of distributor will not only be easier to manufacture, but will also assure very reliable valve action in the distributor, by providing very accurate connection and disconnection between the cylinder oil hole and the successively opening suction and discharge holes.

In this invention the cam profile of the camshaft has the shape of a truncated cone, and it is proposed to pivot said camshaft to the pump casing so that it is axially movable and to interlock thus axial motion of said camshaft 'with the accelerator rod of the engine.

Thus, the cam profile will have a continuously smooth change of shape, assuring the desired stepless change; and this will give the advantage of precise synchronous motion directly interlocked with the working of the engine accelerator.

Also according to this invention, it is possible to provide an arrangement such that the axes of the oil distriIbutOr, pump shaft and camshaft cross at right angles.

In consequence the whole pump can be designed very compactly without any elongation of the plunger in the stroke direction. Only a small space is therefore for installation.

The other objects and features of this invention will be clearly understood from the following description, with reference to the attached drawing, in which:

FIGURE 1 is a longitudinal section taken through an oil pump according to the present invention;

FIGURE 2 is a cross-sectional view taken along the line IIII of FIGURE 1, in the direction indicated by the arrow;

FIGURE 3 is a cross-sectional view taken along the line III- III of FIG. 1, in the direction indicated by the arrow;

FIGURE 4 is a developmental view showing the relation between the plunger stroke and the corresponding opening positions of the oil suction and discharge holes;

FIGURE 5 is an elevational view showing the oil pump installed in a two-cycle engine, with the side of its crankcase cut away; and

FIGURE 6 is a side view showing the oil pump as attached to an engine, illustrating the interrelation be tween said pump and the opening of the throttle valve supplying the fuel.

Referring to FIGS. 1, 2 and 3, it will be seen that the oil pump P comprises a cylindrical distributor 3 which is an oil-tight fit into the top longitudinal hole 2 in the pump casing 1.

The lower part of the distributor is formed into a worm gear 5 in an exposed position within the cavity 4 in said casing 1 and the plunger 7 freely slides in a cylinder chamber 6, which is centrally positioned in said distributor. A spring 9 extends between said plunger 7 and the cover 8 which closes the top longitudinal hole 2 in the casing 1. This spring normally biasses said plunger downward. The distributor 3 has an oil hole 10 communicating with the chamber 6 and extending radially outward on one side. This oil hole 10 is in the same radial plane as the suction hole 11 on one side of said pump casing 1 and a plurality of

discharge holes

12, 12 spaced at predetermined angles on the other side of the casing.

(Two such discharge holes are shown in the example illustrated in FIG. 2.) Consequently the oil hole may come into communication with said suction hole and discharge holes successively as the distributor 3 rotates in a manner hereinafter described. As seen from FIG. 5, the suction hole 11 communicates through the duct M with the oil tank T, while the discharge holes 12, 12' respectively communicate through the ducts N N with the friction producing parts of engine E such as the crank shaft, connecting rod, piston and cylinder.

In the lower part of the pump casing 1, as shown in FIGS. 3 and 5 the pump shaft S connected to the crank shaft C of the engine E fits into the lower cavity 4 above the bottom plate 13, said pump shaft being rotatably mounted in the bearing 14 at the end of pump casing 1. On the pump shaft is formed a worm 15 which meshes with the worm gear 5 at the bottom of the distributor 3 and drives said gear. Below the pump shaft S, is a camshaft 16, which extends perpendicularly to pump shaft and runs beneath said distributor. The camshaft 16 is rotatably mounted in both sides of the casing 1 by means of the

bearings

17, 18. Said camshaft 16 carries a worm gear 19, which meshes with the worm 15 and has the same number of teeth as the worm gear 5 and a cam 20 which engages the plunger 7 which extends from the bottom of said distributor 3 under the pressure of the spring 9. There is a recess 21 in the right end of the camshaft 16 and a spring 22 positioned between the bearing 18 and the end wall of this recess normally urges the camshaft 16 toward the bearing 17 at the opposite side. The cam 20, as shown in FIG. 1, has the shape of a truncated cone when viewed in an axial plane, and is normally in contact with the lower end of the plunger 7. But the cam 20, as seen from the developmental view shown in FIG. 4 (in which the solid line indicates the end of this truncated cone having the smallest diameter, while the dotted line indicates the end having the largest diameter), has a peripherally stepped cam surface. Beyond the bearing 17 which receives the camshaft 16 is a control member 23 which is screwed into said bearing 17 so that its tip is held against the end face of camshaft 16. At the outer end of the control member is a lever 24, which, as indicated in FIG. 6, is connected through a wire or a link with accelerator rod A to operate the throttle valve of the carburetter G. Therefore, when the rod A, shown in FIG. 6, is operated, the throttle valve of the carburetter G will move at the same time as the lever 24. The action of the lever 24 will cause an axial movement of the control member 23 along the screw threaded groove within the bearing 17, thus moving the camshaft 16 in an axial direction. Consequently, the plunger stroke, which depends on where the plunger strikes the truncated cone cam 20, will change depending on the throttle opening of the carburetter G. Thus, with an increase in the r.p.m. of the engine E, the rotation of camshaft 16 will be accelerated, resulting in a faster reciprocating motion of the plunger 7. On the other hand, if the load on the engine E increases, or the throttle of carburetter G opens wider, the cam 20 will be shifted, so that the plunger will contact a portion of the cam which will increase the stroke of the plunger. FIGURE 4 illustrates the above relationships, showing the shape of cam 20 the suction hole 11 and the discharge holes 12, 12', the solid line showing the change of the stroke a of the plunger 7 when the opening of the throttle -valve of carburetter G is narrow and the broken line showing the change of the stroke b of the plunger 7 when the opening of said valve is wide.

When the rotation of the crank shaft C is transmitted from the worm 15 through the pump shaft S to the worm gears 5 and 19, which have the same number of teeth, and the distributor 3 and the camshaft 16 are thereby synchronously rotated, the plunger 7 is actuated by the cam surface of the cam 20 so that it reciprocates within the distributor 3, thereby effecting the suction and discharging of the oil. As shown in FIG. 4, while the oil hole 10 of the distributor 3 is in communication with the suction hole 11, the plunger 7 is in the suction stage and draws the oil from the oil tank T into the cylinder chamber 6. While the oil hole 10 is in communication with the discharge holes 12, 12', the plunger 7 is in the discharge stage and supplies oil from the cylinder chamber 6 through the ducts N N to each part of engine E which is subject to frictional wear. If thereby the discharge hole 12 is brought into communication with the crankshaft at the same time that the discharge hole 12 is brought into communication with the engine cylinder, a single reciprocation of the plunger 7 will suffice to distribute the oil to a plurality of parts. As the worm 15 assures synchronized rotation of the distributor 3 and the cam shaft 16, the timing of the suction and discharge of the oil can be accurately predetermined by proper selection of the rotational position of the distributor 3 and the stepped shape of the cam.

From the above detailed description, it will be readily understood how the present invention attains its intended objectives. The foregoing description, however, merely illustrates one possible embodiment of this invention and it goes without saying that various modifications and changes can be made without deviating from the basic principles of the invention as defined by the following claims.

What is claimed is:

1. An oil pump for an engine, said oil pump comprising a casing, a pump shaft in said casing adapted to be driven by the engine, a rotatable oil distributor in said casing provided with a cylindrical chamber, a camshaft, both said distributor and said camshaft connected to be rotated synchronously with said pump shaft, a cam carried by said cam shaft, a plunger reciprocally mounted within the cylindrical chamber of said distributor and having an end biassed into contact with said cam, an oil hole in said distributor communicating with said distributor chamber, an oil supply hole in said casing, and at least one lubricating hole for communication with parts of said engine requiring lubrication, said supply and lubricating holes being positioned to be brought indirvidually into and out of communication with said oil hole in said distributor in dependence upon the angular position of said distributor, the radius of said cam varying both axially and circumferentially, and means for varying the axial position of said cam in dependence on the throttle opening of said engine, thereby to vary the stroke of said plunger in said chamber.

2. An oil pump as claimed in claim 1, comprising a plurality of lubricating holes, and in which the oil hole in said distributor is rotated successively into communication with the single supply hole and said plurality of lubricating holes.

3. An oil pump as claimed in claim 1, in which the cam surface of said camshaft is in the form of a truncated cone, said camshaft being mounted for axial movement in the pump casing, and said engine comprising an accelerator pedal operatively connected to said camshaft to produce axial movement of said cam shaft in response to movement of said .accelerator pedal.

4. An oil pump for engines as claimed in claim 1, in which the longitudinal axes of said oil distributor, pump shaft and camshaft cross each other at right angles.

References Cited UNITED STATES PATENTS 1,553,225 9/1925 Fekete et al 18427 3,106,168 10/1963 Kolbe 10338 X 3,151,778 10/1964 Olney et a1. l03-38 3,298,238 1/1967 Lea 10338 X 3,302,752 2/1967 Shiokawa 1846 X HOUSTON S. BELL, 111., Primary Examiner.

U.S. Cl. X.R.