JP3308111B2 - Oil pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating oil pump used in a two-stroke engine.

[0002]

2. Description of the Related Art Conventionally, as an oil pump used in a two-stroke engine, one having a construction shown in FIGS. 4 and 5 is known. The oil pump shown in these figures rotates by being driven by the engine, and has a hole 51 formed at an eccentric position on one end side, and a suction hole and a discharge hole (FIGS. 4 and 5) for communicating this hole 51 to the outside. (Not shown), a plunger slidably fitted in the hole 51 to define a pump chamber 53 together with the hole 51 and to be urged in a direction to come out of the hole 51. And a cam 55 arranged on the side of the pulling-out direction of the plunger 54 and abutting on the urged plunger 54 to reciprocate the plunger 54 revolving by the rotation of the shaft 52.

[0003] Such an oil pump includes a plunger 5.
4 is in one revolution range due to the rotation of the shaft portion 52, the volume of the pump chamber 53 is increased by the shape of the cam 55 as shown by the arrow A in FIG. The oil is sucked through the suction hole. Then, when the plunger 54 moves to another revolution range by further rotation of the shaft portion 52, the plunger 54 reduces the volume of the pump chamber 53 as shown by an arrow B in FIG. The oil is discharged from the discharge hole through the discharge hole. In this way, one rotation of the shaft portion 52 causes the oil to be suctioned and discharged once.

[0004] Here, the oil pump is provided with a plunger 54 by changing the shape of a cam 55 in accordance with the throttle opening.
A stroke adjusting mechanism 56 for adjusting the stroke amount, that is, the oil supply amount, is provided. That is, in the stroke adjusting mechanism 56, a cam 55 is formed on an adjusting shaft 57 that is rotated according to the throttle opening, and the cam 55 is moved by the rotating position of the adjusting shaft 57.
In the case where the shape of the portion where the vehicle 4 contacts and runs is different and the throttle opening is small as shown in FIG. 6, the stroke amount of the plunger 54 is reduced to suppress the oil discharge amount, and the throttle opening is reduced. As the size increases, the stroke amount of the plunger 54 is increased to increase the oil discharge amount.

[0005]

Here, the amount of oil discharged by the oil pump is set in consideration of prevention of seizure of the engine at high rotation and high load. For example, FIG. Based on the oil supply amount required when the engine is running at a high speed of 8000 rpm, the oil discharge amount per unit time at the same throttle opening is the engine speed, that is, the shaft 52 driven by the engine.
6, the same characteristics when the engine speed is 4000 rpm as shown by the line D in FIG. 6 or the same characteristics when the engine speed is 2000 rpm as shown by the line E in FIG. In this case, the oil discharge amount is determined by the above ratio and cannot be adjusted. Therefore, especially 2
At low rotation and low load such as 000 rpm, the supply of oil, which may be zero, becomes excessive.

Therefore, in the oil pump having the above structure, in order to eliminate the discharge of the oil in the low rotation speed range,
Assuming that the throttle opening is small during low rotation, the shape of the cam 55 of the stroke adjusting mechanism 56 when the throttle opening is small is set so that the stroke amount of the plunger 54 becomes zero. As shown, it is conceivable that the oil discharge amount at this time is set to zero. However, when such a configuration is adopted, when the throttle opening is rapidly reduced from a state where the engine speed is in the high speed range, a state where the engine speed does not drop completely and oil is not discharged occurs. , The engine burns.

For this reason, an electromagnetic valve is arranged between the discharge side of the oil pump and the engine, the engine speed, the vehicle speed, the engine temperature, the carburetor flow rate, and the like are monitored using a controller. Although it is conceivable to adopt a configuration in which the solenoid valve is switched and controlled by a controller, it is difficult to realize this because a great increase in cost is involved.

Accordingly, an object of the present invention is to provide an oil pump capable of stopping the discharge of oil when the engine speed is in a low rotation range without a significant increase in cost.

[0009]

In order to achieve the above object, an oil pump according to the present invention is driven by an engine and rotates, and a hole is formed at a position eccentric with respect to a rotation axis of the oil pump. A shaft portion formed with a suction hole and a discharge hole communicating the portion with the outside, and slidably fitted in the hole portion to define a pump chamber together with the hole portion and to urge in a direction of coming out of the hole portion. The plunger and the plunger which is disposed on the side of the plunger withdrawal direction and abuts on the energized plunger and revolves around the rotation of the shaft portion to reciprocate, to the pump chamber through the suction hole. In an oil pump having a cam for sucking oil and discharging the oil from the pump chamber through the discharge hole, a substantially spherical valve body is communicated with the hole, and the valve body communicates with the suction hole. A valve seat that is opened and closed, a valve body spring that urges the valve body in a direction in which the valve seat part closes, and a centrifugal force generated in the valve body due to rotation of the shaft part, to an urging force of the valve body spring. A cut valve having an inclined portion acting as a resisting force is provided.

[0010]

According to the oil pump of the present invention, a cut valve is provided at an eccentric position of the shaft, and the valve body of the cut valve is used when the engine, that is, the rotational speed of the shaft is low. The valve seat portion disposed between the suction hole and the discharge hole is closed by being biased by the spring, thereby preventing the oil from being sucked. On the other hand, when the rotation speed of the shaft portion is high, the centrifugal force generated by the rotation of the shaft portion increases,
The inclined portion moves against the urging force of the valve body spring to open the valve seat. As a result, oil is sucked from the suction hole.

[0011]

【Example】

(1) Configuration of Embodiment An oil pump according to an embodiment of the present invention will be described below mainly with reference to FIGS. In the drawing, reference numeral 10 denotes a casing, and reference numeral 11 denotes a shaft portion that is fitted into a fitting hole 12 formed in the casing 10 while one side is projected outward. A casing 13 having a larger diameter than the fitting hole 12 is formed on one side of the fitting hole 12 in the casing 10, and a fitting hole 12 is formed in a portion of the chamber 13 opposite to the fitting hole 12. An orthogonal hole 14 is provided with one end side open to the outside.

The casing 10 is provided with an opening 16 at one end at a predetermined position in the middle of the fitting hole 12 so that
The other end of the suction passage 17 is connected to an oil tank (not shown). Further, on the side of the suction flow path 17 different from the opening 16 by 180 degrees, the position of the discharge flow path 19 is shifted to the chamber 13 side (the left side in FIG. 1).
One end opening 20 of the discharge passage 19 is opened.
Is connected to an intake manifold of an engine (not shown).

The shaft portion 11 is rotatably fitted in the fitting hole 12 in a state where the movement in the axial direction is restricted by the pin 22, and its protruding side is connected to an engine (not shown). The rotation of the engine is transmitted at a reduced speed as necessary. At one end of the shaft portion 11 on the side of the chamber 13, a hole 24 is located at a position (eccentric position) shifted from the center axis of the shaft portion 11, slightly over the opening 16 of the suction flow channel 17. Extending parallel to the central axis. On the bottom side of the hole 24, the shaft 1
A suction hole 25 is formed on the outer peripheral surface of the shaft 1 so that the opening 16 of the suction channel 17 is aligned with the axial direction of the shaft portion 11 and the fitting hole 12. Thereby, the hole 2
4, as shown in FIG. 1, when the shaft portion 11 is at a rotational position that allows the suction hole 25 to communicate with the opening 16 of the suction flow channel 17, the shaft portion 11 can communicate with the suction flow channel 17.

Further, on the side of the chamber 13 from the suction hole 25 of the hole 24, a discharge hole 26 opening on the outer peripheral surface of the shaft 11 is formed with the opening 20 of the discharge passage 19, the shaft 11 and the fitting hole 12. , The suction hole 25 and the shaft 1
1 are formed so as to be aligned in the circumferential direction,
Thereby, as shown in FIG.
Can be communicated with the discharge channel 19 when is located at a rotational position that allows the discharge hole 26 to communicate with the opening 20 of the discharge channel 19.

A plunger 30 having a head portion 28 and a rod portion 29 having a smaller diameter than the head portion 28 is provided in the hole portion 24.
And a plunger spring 31 that urges the plunger 30 in a direction of coming out of the hole 24 is provided between the head portion 28 and the shaft portion 11. Here, a space defined by the plunger 30 and the hole 24 in a state where the rod 29 is fitted into the hole 24 is a pump chamber 32.

A stroke adjusting mechanism 34 is provided on the side of the plunger 30 in the direction in which the plunger 30 is pulled out by the plunger spring 31. This stroke adjusting mechanism 34
Has an adjustment shaft 35 rotatably fitted to the orthogonal hole 14 in a state where the movement in the axial direction is restricted by the pin 37. The adjustment shaft 35 is interlocked with a throttle wire (not shown). The cam 36 is formed to rotate, and a cam 36 is formed on the outer peripheral side.

The head 28 of the plunger 30 urged by the plunger spring 31 is in contact with the cam 36. The cam 36 rotates the plunger 30 by rotation of the shaft 11.
Is revolved, the plunger 30 rotates during the 360-degree revolution.
Is moved from a position closest to the center axis of the adjustment shaft 35 to a position farthest away from the center axis of the adjusting shaft 35, and then returned to a position closest to the center axis.
5 is in a position to communicate with the suction flow path 17, the plunger 30 is closest to the center axis of the adjustment shaft 35, and when the shaft portion 11 is in a position to communicate the discharge hole 26 with the discharge flow path 19, the plunger 30 Is most distant from the center axis of the adjustment shaft 35.

As a result, the plunger 30 is connected to the shaft 11
When the orbit revolves, the volume of the pump chamber 32 is increased as shown by an arrow A in FIG.
5 is communicated with the suction flow path 17, so that the pump chamber 32 can suck oil from the suction flow path 17. Then, when the plunger 30 revolves due to the further rotation of the shaft portion 11, the volume of the pump chamber 32 is reduced as shown by the arrow B in FIG. 2, and at this time, the discharge hole 26 is communicated with the discharge flow path 19, The pump chamber 32 is ready to discharge oil. In this way, one rotation of the shaft portion 11 enables one suction and discharge.

Here, the adjusting shaft 35 rotates in conjunction with the throttle wire, that is, according to the throttle opening. The stroke of the plunger 30 is changed by changing the shape of the cam 36 according to the rotational position. Is to be adjusted. That is, the adjustment shaft 35 has a constant distance from the closest plunger 30 irrespective of its rotational position, and when the throttle opening is in a predetermined range from 0 to near 0, the distance between the adjustment shaft 35 and the closest plunger 30, that is, Reduce the stroke amount of plunger 30 (however,
However, when the throttle opening is further increased, the distance from the plunger 30 which is farthest away, that is, the stroke amount of the plunger 30 is increased in proportion to the throttle opening, and finally, the predetermined opening at which the throttle is fully opened from the vicinity of the fully opened state. In the range, the shape of the cam 36 is set so as to maximize the distance between the plunger 30 and the plunger 30, ie, the maximum stroke distance.

As shown in FIG. 3, the main portion is enlarged in FIG. 3. In this embodiment, the hole 24 has a small-diameter hole 38 on the bottom side and a large-diameter hole on the opposite side. The small-diameter hole 38 and the large-diameter hole 39 are formed.
A tapered hole portion (inclined portion) 40 having a tapered shape is formed between them to make them continuous. Here, the suction hole 25 is formed on the small-diameter hole 38 side, and the discharge hole 26 is formed on the large-diameter hole 39.

The large diameter hole 39 is provided with a spherical valve element 41 having a smaller diameter than the large diameter hole 39 and a larger diameter than the small diameter hole 38. The valve element 41 is urged toward the small-diameter hole 38 by a valve element spring 43 inserted into a spring hole 42 formed on the opposite side to the head 28 of the plunger 30. When contacted, the communication between the suction hole 25 and the discharge hole 26 of the pump chamber 32 is cut off. When the valve element 41 moves against the urging force of the valve element spring 43 and separates from the tapered hole section 40, the suction hole 25
And the discharge hole 26 are communicated with each other.

Here, the rotation of the shaft portion 11 causes the valve body 4 to rotate.
1, a centrifugal force acts so that the tapered hole 40 is pressed outward in the radial direction of the shaft 11, and the tapered hole 40 has a large diameter on the valve element spring 43 side. Therefore, this centrifugal force acts on the valve element 41 as a propulsive force against the urging force in the direction of the valve element spring 43.

The portion of the tapered hole portion 40 which comes into contact with the valve body 41 to block the communication between the suction hole 25 and the discharge hole 26 is as follows.
Valve seat portion 44 disposed between suction hole 25 and discharge hole 26
It has been. Further, the rotation speed of the shaft portion 11 when the valve body 41 is separated from the valve seat portion 44, that is, the engine speed, is adjusted by the urging force of the valve body spring 43. For example, when the engine speed is 2100 rpm or the like. The valve body 41 is set so as to be separated from the valve seat portion 44.
The tapered hole 40 including the valve element 41, the valve element spring 43, and the valve seat 44 mainly constitutes a cut valve 45 provided at an eccentric position of the shaft 11.

(2) Operation of Embodiment After the engine is started, when the engine, that is, the rotation speed of the shaft portion 11 is low, the centrifugal force acting on the valve element 41 of the cut valve 45 is small. As shown,
When the valve element 41 is biased by the valve element spring 43, the tapered hole 4
0 of the suction flow path 17
The communication between the discharge hole 26 and the suction hole 25, i.e., the oil tank, is interrupted even if the communication between the discharge hole 26 and the suction hole 25 is established. As a result, the oil discharge flow path 1 in the low rotation range of the engine
Unnecessary ejection from the nozzle 9 is prevented.

On the other hand, the rotation speed of the engine, that is, the shaft portion 11 is increased, and the centrifugal force generated in the valve body 41 by the rotation of the shaft portion 11 is increased.
When the propulsive force generated in the valve body 43 becomes larger than the urging force of the valve body spring 43, the valve body 41 moves against the urging force of the valve body spring 43 and moves as shown in FIG. The seat 44 is opened. As a result, the rotation of the shaft portion 11 causes the plunger 30 to move by the cam 36 and the pump chamber 3
2 and the suction channel 17 and the suction hole 25
The oil is sucked from the oil tank into the pump chamber 32 at the time when the communication is established. The plunger 30 is further moved by the cam 36 by the rotation of the shaft portion 11 to reduce the volume of the pump chamber 32, and when the discharge hole 26 and the discharge flow path 19 are communicated, the discharge flow from the discharge hole 26 Road 1
The oil in the pump chamber 32 is discharged to 9. In this way, oil is sucked and discharged once per rotation of the shaft portion 11.

Here, even when the throttle opening is rapidly reduced from a state where the engine rotation is in the high rotation range, even if the engine rotation does not completely decrease, the valve body 41 provided on the shaft portion 11 rotated by the engine can be used. Is separated from the valve seat portion 44 by the propulsive force of the centrifugal force and communicates the suction hole 25 and the discharge hole 26. Therefore, the adjustment shaft 35 is controlled by the throttle opening.
Although the cam 36 has the smallest stroke amount of the plunger 30 but does not become zero, oil can be sucked from the suction passage 17 into the pump chamber 32 and discharged from the discharge passage 19 toward the engine. .

Therefore, when the engine speed is in the low speed range, the cut valve 45 can stop the oil discharge. Specifically, by setting the shaft portion 11 when the valve body 41 separates from the valve seat portion 44, that is, the rotation speed of the engine to 2100 rpm as described above, for example, the line C and the line C in FIG. 8000 indicated by D
rpm, the oil discharge amount of 4000 rpm is the same,
The oil discharge amount at 2000 rpm can be set to zero. In addition, oil can be discharged even when the throttle opening is rapidly reduced from a state where the engine speed is in the high rotation range. In addition, mainly the valve element 41 and the valve seat 4
Since only the cut valve 45 having a simple configuration including the tapered hole portion 40 including the valve member 4 and the valve body spring 43 is provided, the manufacturing cost can be reduced.

(3) Modifications In the above embodiment, a coil spring is used as the valve body spring 43, but the type thereof such as a leaf spring is arbitrary. Further, the tapered hole portion 40 having a truncated cone shape is formed as a guide for the valve body 41 to move by centrifugal force, but may be a flat inclined surface.

[0029]

According to the oil pump of the present invention, a cut valve is provided at an eccentric position of the shaft. The valve body of the cut valve is a valve body when the engine, that is, the rotational speed of the shaft is low. Energized by a spring, the valve seat portion disposed between the suction hole and the discharge hole is closed, and when the rotation speed of the engine, that is, the shaft portion increases, the centrifugal force generated by the rotation of the shaft portion increases. The valve seat is moved by the inclined portion against the urging force of the valve body spring to open the valve seat portion.

Therefore, when the engine speed is in the low speed region, the valve body of the cut valve is seated on the valve seat to cut off the communication between the suction hole and the discharge hole, thereby stopping the oil discharge. Even when the throttle opening is rapidly reduced from a state where the engine speed is in the high speed range, even if the engine speed does not drop completely, the valve element provided on the shaft rotated by the engine is separated from the valve seat. As a result, communication is established between the suction hole and the discharge hole, so that oil can be discharged. In addition, since only a simple cut valve having a valve element, a valve seat, a valve element spring, and an inclined portion is provided, cost increase can be minimized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an oil pump according to an embodiment of the present invention, showing a state where a pump chamber communicates with a suction flow path.

FIG. 2 is a cross-sectional view showing the oil pump according to one embodiment of the present invention, showing a state where a pump chamber communicates with a discharge flow path.

FIG. 3 is an enlarged sectional view showing a cut valve of the oil pump according to one embodiment of the present invention, wherein FIG.
(B) shows an open state.

FIG. 4 is a sectional view showing a conventional oil pump, showing a state at the time of oil suction.

FIG. 5 is a cross-sectional view showing a conventional oil pump, showing a state at the time of oil discharge.

FIG. 6 is a characteristic diagram showing an example of a relationship between a throttle opening of a conventional oil pump and an oil discharge amount.

FIG. 7 is a characteristic diagram showing another example of the relationship between the oil discharge amount and the throttle opening of the oil pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Shaft part 24 Hole part 25 Suction hole 26 Discharge hole 30 Plunger 32 Pump chamber 36 Cam 40 Tapered hole part 41 Valve element 44 Valve seat part 45 Cut valve

Claims (1)

(57) [Claims] 1. A shaft portion which is driven by an engine to rotate and has a hole formed at a position eccentric with respect to a rotation axis thereof, and a shaft having a suction hole and a discharge hole communicating the hole with the outside. A plunger which is slidably fitted in the hole, defines a pump chamber together with the hole, and is urged in a direction of coming out of the hole; The plunger revolving by the rotation of the shaft portion in contact with the plunger is reciprocated, oil is sucked into the pump chamber through the suction hole, and is discharged from the pump chamber through the discharge hole. An oil pump having a cam, a substantially spherical valve body in the hole, a valve seat communicating with the suction hole and being opened and closed by the valve, and a direction in which the valve seat closes the valve. Attached to A cut valve having a biasing valve body spring and an inclined portion for causing a centrifugal force generated in the valve body by rotation of the shaft portion to act as a force against a biasing force of the valve body spring is provided. Oil pump.