JPS6337444Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an internal oil pump that is installed on the crankshaft of an engine and is rotationally driven by the crankshaft.

(Prior Art) As oil pumps for lubricating various parts of an engine, internal pumps such as crescent pumps and trochoid gear pumps and external gear pumps are often used. Among these, internal type pumps such as creselent type pumps and trochoid gear pumps have the advantage of being compact and require a small installation space, and are therefore often used particularly when space constraints are severe.

An example of an internal oil pump is a crescent pump as shown in FIGS. 1 and 2. FIG. 1 shows the engine in cross section along a vertical plane passing through the center of the crankshaft, and FIG. 2 shows the crescent pump 10 viewed from the direction indicated by arrow A--A in FIG. engine housing 3
The crankshaft 1 is rotatably supported via bearings 3a and 3b. This crankshaft 1 has an eccentric shaft 1a between supported parts by bearings 3a and 3b, and a connecting rod 2 is rotatably provided on this eccentric shaft 1a. This connecting rod 2 is connected to a piston (not shown) that moves up and down as the explosion and exhaust strokes are repeated. Therefore, the vertical movement of the piston is transmitted to the eccentric shaft 1a via the connecting rod 2.
is transmitted, and the crankshaft 1 is rotated by the action of the crank mechanism. The crankshaft 1 protrudes outward from the engine housing 3, and this protrusion 1b
A belt pulley 4 is fixed to and rotates together with the crankshaft 1. A belt (not shown) driven by the belt pulley 4 drives an alternator, a camshaft, a cooler compressor, and the like.

A crescent-type oil pump 10 is disposed on the crankshaft 1 between an engine housing 3 and a belt pulley 4. This oil pump 10 includes an outer gear 11, an inner gear 12, an outer casing 13, and an inner casing 14, and the inner gear 12 is mounted coaxially with the crankshaft 1 on the protrusion 1b of the crankshaft. The driving force from this protruding portion 1b to the inner gear 12 is transmitted from two flat portions 1C and 12 provided on both sides.
C is fitted as shown in FIG. The inner gear 12 has an external gear, and the outer gear 11 has an internal gear that partially meshes with the external gear.
is arranged with its center eccentric to the center of the inner gear 12. Both the outer gear 11 and the inner gear 12 are housed in the inner and outer casings 13 and 14 in a partially meshed state,
Of these, the outer casing 13 is fixed to the side surface of the engine housing 3 to form an oil pump. The outer periphery of the outer gear 11 is the inner periphery 1 of the outer casing.
The annular protrusion 12a protruding from the side surface of the gear portion of the inner gear 12 is also guided by the positioning hole 13d formed in the outer casing and can rotate smoothly relative to the outer casing 13. It is becoming. At this time, the positioning hole 13d of the outer casing 13 is formed so that the inner gear 12 rotates coaxially with the crankshaft 1, whereas the inner periphery 13c that guides the outer gear 11 is formed so that the outer gear 11 rotates coaxially with the crankshaft 1.
It is formed to rotate eccentrically with respect to the Therefore, the internal gear of the outer gear 11 and the external gear of the inner gear partially mesh, and a crescent (crescent-shaped portion) 13c is integrally formed in the outer casing 13 so as to fill the gap created on the opposite side in the radial direction from this meshing portion. It is formed. Furthermore, the crankshaft 1 rotates in the counterclockwise direction indicated by the arrow in FIG. A suction port 15 and a discharge port 16 are formed in the outer casing 13 so as to communicate with the discharge port 13b.

In the oil pump configured in this manner, when the engine is operated and the crankshaft 1 rotates, the protruding portion 1b having the flat portions 1c and 1c and the circular diameter portion having the flat portions 12c and 12c of the inner gear 12 fit together. Therefore, the inner gear 12 rotates at the same time as the crankshaft 1, and this rotation is transmitted to the outer gear 11 via the meshing portion. Since the inner gear 12 and the outer gear 11 are eccentrically guided to each other and rotatably guided to the outer casing 13, they rotate while being eccentric. For this reason, as both gears rotate, the gap 1 between them expands from the end of meshing of the gears.
8 is filled with oil that enters the suction port 15 from the suction port 13a, and this oil is poured into the crescent 1.
3c and each tooth and carry it to the discharge port side. The gap 19 between the teeth of the two gears (inner gear and outer gear) on the discharge port side gradually narrows and eventually mesh, so the oil carried into this gap 19 is pushed out into the discharge port 16.
It is sent to the lubricating section from the discharge port 13b.

The crescent oil pump is driven as described above.

At this time, the driving force is transmitted from the protruding part 1b of the crankshaft 1 to the inner gear 12 via the flat parts 1c and 12c formed on both parts, but in reality there are problems with assembly. Also, due to problems such as deflection caused by the cantilevered protruding portion 1b of the crankshaft 1, it is not possible to make them completely in contact with each other, so the inner gear 12 is fitted to the crankshaft 1 with a slight clearance. Therefore, when the driving force is transmitted from the crankshaft 1 to the inner gear 12, only one end of the flat surfaces of the two is in contact with each other, rather than the entire flat surfaces of the two being in contact with each other. That is, only the vicinity of one end 12b of the flat surface 12c of the inner gear 12 hits the crankshaft 1, and the driving force is concentrated on this portion. The above-mentioned one end 12b is a place where stress concentration is likely to occur at the intersection of the flat surface 12c and the inner diameter part, so during pump operation, the driving force from the crankshaft, especially torque fluctuation due to explosion in the engine combustion chamber. There is a problem that cracks are likely to occur in this part when subjected to a certain driving force. Due to the structure of the present crescent pump, the annular protrusion 12a protruding from the side surface of the gear portion of the inner gear 12 is thin, so this part is particularly weak and easily cracks, which reduces the durability of the pump.

(Purpose of the invention) In view of the above-mentioned problems, the present invention has been developed to eliminate cracks at the fitting portion of the inner gear with the crankshaft, particularly at the annular protrusion of the inner gear, and to improve durability. The object of the present invention is to provide a contact type oil pump.

(Structure of the invention) The engine oil pump of the invention is an engine oil pump that is disposed between an engine housing and a belt pulley and installed on a crankshaft protrusion, and has an external gear on its outer diameter. The inner diameter portion of the crankshaft protrusion fits into the crankshaft protrusion, and at least a portion of the fitting surface with the crankshaft protrusion is formed as a flat surface. It consists of an inner gear to be driven, an outer gear having an internal gear that meshes with the external gear, and a casing in which the inner gear and the outer gear are disposed, and the inner gear has a gear part in which the external gear is formed. The casing has an annular protrusion that protrudes laterally from the side surface of the gear portion, and the flat surface of the inner gear is formed only on the gear portion side relative to the side surface of the gear portion in the axial direction of the inner gear. , a positioning hole is provided that fits into contact with the annular projection and restricts movement of the inner gear in the radial direction.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 3 is a sectional view showing an engine equipped with the oil pump of the present invention taken along a vertical plane passing through the central axis of the crankshaft, and FIG. 4 shows the relationship between the inner gear 22 of the oil pump 20 and the crankshaft in FIG. FIG. 5 is a front view of the inner gear 22, and FIG. 5 is an enlarged cross-sectional view showing the fitting portion. The engine shown in FIG. 3 is the same as the engine shown in FIG. 1 except for the oil pump, so the same parts are given the same numbers and their explanation will be omitted.

The oil pump 20, which is sandwiched between the engine housing 3 and the belt pulley 4 and provided on the crankshaft protrusion 1b, includes an outer gear 21, an inner gear 22, an outer casing 23, and an inner casing 24. The crankshaft 1 is fitted with the part 1b.
This rotation is driven by the inner gear 22.
The oil is transmitted from the external gear to the internal gear of the outer gear 21 to rotate the outer gear 21 as well, and performs an oil pumping action in the outer and inner casings 23 and 24. Since the operation as an oil pump is exactly the same as that explained in FIGS. 1 and 2, the explanation thereof will be omitted.

The oil pump 20 of the present invention has main parts enlarged in FIG. 4, and the inner gear 22 is shown in FIG. 5. As shown in FIG. A gear portion 22 in which an annular protrusion 22a protrudes in the center direction.
The flat surface 22 is located only on the gear portion 22b side from the left side surface of b.
c and the protrusion 1b of the crankshaft 1.
It is designed to mate with the That is, the annular protrusion 22a protruding leftward from the side surface of the gear portion 22b is guided such that the outer periphery 22e fits and contacts the positioning hole 23d of the outer casing 23 so that the inner gear rotates smoothly. The portion 22d is not formed with a flat surface that fits with the flat surface of the protrusion 1b of the crankshaft, and therefore the annular protrusion 22a does not fit with the flat surface of the protrusion 1b of the crankshaft. There is.

Therefore, the driving force transmitted from the crankshaft 1 to rotate the inner gear 22 is transferred to the gear portion 2.
The driving force is transmitted only through the flat portion formed on the inner diameter portion of the driving force 2b, and is not transmitted to the annular projection portion 22a, which is thin and has relatively low strength.

(Effects of the invention) As explained above, in the engine oil pump of the invention, the rotational driving force from the crankshaft is transmitted through the gear part, which has a large thickness and sufficient strength. Since the small annular protrusion is not subjected to driving force, the problem of cracking of the inner gear is eliminated, and the durability of the pump can be improved. That is, for example, if the annular protrusion has a flat surface that fits with the flat surface of the crankshaft, the rotational driving force from the crankshaft will be transmitted to the annular protrusion through the flat surface, and the annular protrusion will However, in the present invention, as described above, the annular protrusion has no flat surface that receives such a rotational driving force, so there is no such fear.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an engine having a conventional oil pump, Fig. 2 is a side sectional view of the oil pump of Fig. 1 taken along arrow A-A, and Fig. 3 is an oil pump of the present invention. FIG. 4 is an enlarged sectional view showing the vicinity of the inner gear of the oil pump of the present invention, and FIG. 5 is a front view of the inner gear of the oil pump of the present invention. 1... Crankshaft, 2... Connecting rod, 3... Engine housing, 4... Belt pulley, 20... Oil pump, 21... Outer gear, 2
2...Inner gear, 23...Outer casing, 24...Inner casing.

Claims (1)

[Scope of Claim for Utility Model Registration] An oil pump for an engine that is disposed between an engine housing and a belt pulley and installed on a protruding part of a crankshaft, the outer diameter of which forms an external gear and the inner diameter of which is disposed on a crankshaft protrusion. It has an annular protrusion that protrudes laterally from the side surface of the gear portion that fits into the crankshaft protrusion, and at least a part of the surface that engages with the crankshaft protrusion is formed into a flat surface. an inner gear that is rotationally driven by the crankshaft protrusion through a surface, an outer gear that has an internal gear that meshes with the external gear of the inner gear, and a radial movement of the inner gear that comes into fitting contact with the annular protrusion. and a casing in which both the gears are arranged, and the flat surface of the inner gear is formed only on the gear part side from the side surface in the axial direction of the inner gear. An engine oil pump characterized by: