JPH06249230A - Crankshaft for internal combustion engine - Google Patents

Abstract

PURPOSE:To restrain excessive temperature rise at the bearing of a crankshaft without wasting the output of an engine. CONSTITUTION:A crankshaft 1 which consists of a crank spindle 4, a crank pin 5 and a web 8 has an oil passage which contains oil holes 10-12 and a circular oil passage 18. The crank pin 5 is provided with the hollow portion 17. The circular oil passage 18 communicates with the hollow portion 17 through an oil discharge passage which contains oil discharge holes 21, 22. An oil discharge valve 19 is assembled in a position from which the crankshaft center is the farthest in the circular oil passage 18, so that the oil discharge hole 22 can be open during the high-speed rotation of an engine when the temperature of a crank pin bearing 7 exceeds a preset value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft of an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional crankshaft of an internal combustion engine, there is a crankshaft as shown in FIG.
-34209 gazette etc.).

The crankshaft 101 is a main bearing 102.
Crankshaft 1 supported by a crankshaft 104 and a connecting rod crankpin bearing 103
05, and a web 108 connecting the crank main shaft 104 and the crank pin shaft 105.

A through hole 113 is formed in the crankshaft 101 of the crankshaft 101. A metal pipe 114 having a recess at the center in the longitudinal direction is press-fitted into the through hole 113. The crankpin shaft 105 and the metal pipe 114 form an annular oil passage 118 on the outer circumference of the metal pipe 114, and at the same time, the inside of the metal pipe 114 forms a hollow portion 117 with both ends open.

The oil hole 110 opening on the outer surface of the crankshaft 104 and the annular oil passage 118 are connected by an oil hole 112 provided in the crankshaft 101. The oil hole 111 opening on the outer surface of the crankpin shaft 105 communicates with the annular oil passage 118. The oil holes 110 to 112 and the annular oil passage 118 form an oil passage.

The lubricating oil supplied to the crank main bearing portion 106 flows into the crank chamber through a gap (oil clearance S1) between the main bearing 102 and the crank main shaft 104, and part of the lubricating oil passes through the oil passage to form a crank pin bearing. Part 1
07, and flows out into the crank chamber from the gap (oil clearance S2) between the crankpin bearing 103 and the crankpin shaft 105.

The lubricating oil forms an oil film on the sliding surfaces of the bearings 106 and 107 to reduce friction and wear, and also cools the bearings 106 and 107.

[0008]

In such a conventional crankshaft, the ability to cool the bearings 106, 107 is determined by the flow rate of the lubricating oil flowing through the bearings 106, 107. , 107 are overheated, it is necessary to supply a larger amount of lubricating oil to the bearings 106, 107.

However, the flow rate of the lubricating oil flowing through the bearings 106 and 107 depends on the oil clearances S1 and S2.
Equal to the flow rate flowing out from the oil clearance S1,
Since it is limited by the size of S2, when the bearings 106 and 107 are overheated,
There is a possibility that a sufficient flow rate cannot be secured, the bearings 106 and 107 may overheat beyond the heat resistance limit, and the durability of the bearings 106 and 107 may not be maintained. In particular, the main bearing 1
The bearing metal is provided on the sliding surfaces of the No. 02 and the crankpin bearing 103, and when the temperature exceeds 180 ° C., the durability of the bearing metal is remarkably reduced and seizure or the like occurs.

As a countermeasure against this, in addition to suppressing the engine speed, the oil clearance S of each bearing 106, 107
It is conceivable to secure a flow rate of lubricating oil that can sufficiently cool the bearings 106 and 107 regardless of the operating condition of the engine by taking 1 and S2 large. However, in this case, when it is not necessary to cool the bearings at low rotation and low load, the required amount of lubricating oil is supplied to each of the bearings 106 and 107, and the oil pump driven using the engine output is used. The fuel consumption of the engine increases because the work is wasted. Further, the oil clearances S1 and S2 have a limit in size due to problems with sound and vibration, and the oil clearance S is not always sufficient to ensure a sufficient flow rate for cooling.
1 and S2 are not always provided.

An object of the present invention is to provide a crankshaft structure which suppresses an excessive rise in temperature of the bearing portion of the crankshaft without wasting engine output.

[0012]

[Means for Solving the Problems]
Therefore, the present invention provides a crank spindle that is axially supported by a main bearing,
Clan to which crankpin bearing of connecting rod is attached
Cup pin shaft, the crank main shaft and the crank pin shaft
A web connecting the outer surface of the crank spindle and the
An opening is formed in the outer surface of the crankpin shaft, and the main bearing and the
Supplied to the crank main bearing consisting of the crank main shaft
Lubricate the crank pin bearing and the crank pin shaft.
And an oil passage leading to the crank pin bearing
A crankshaft of an internal combustion engine having
Link spindle or at least one of the crankpin shafts
On one side, a hollow portion that opens to the crank chamber is formed, and
An oil discharge passage communicating the hollow passage with the oil passage.
In the oil discharge passage, the bearing portion exceeds a predetermined temperature.
Installed an oil release valve that opens when the engine is operating
It is characterized by

The oil discharge valve is preferably opened when the bearing portion exceeds a predetermined temperature and the engine rotates at a high speed.

[0014]

The operation will be described based on the above configuration.

The lubricating oil supplied to the crank main bearing portion is
It flows out into the crank chamber through a gap between the main bearing and the crank main shaft, a part of the oil reaches the crank pin bearing through the oil passage, and flows out through the gap between the crank pin bearing and the crank pin shaft into the crank chamber.

The lubricating oil forms an oil film on the sliding surface of each bearing to reduce friction and wear, and also cools each bearing.

In an engine operating state in which each bearing portion is sufficiently cooled by the lubricating oil flowing out from the gap between each bearing and shaft, the oil discharge valve is closed.

When the bearing portion including the shaft provided with the cooling structure according to the present invention and the bearing thereof is in an engine operating state in which the temperature exceeds a predetermined temperature, the oil release valve opens, and lubricating oil is formed on the shaft through the oil release passage. It is released into the hollow part. The lubricating oil discharged into the hollow portion cools the shaft from the inside and prevents the bearing portion from overheating. Further, the lubricating oil released into the hollow portion flows out from the opening provided in the hollow portion.

Focusing on the engine rotation speed as the engine operating state, the engine rotation speed directly affects the temperature of the sliding surface of the bearing portion. At high engine speed, frictional heat on the sliding surface increases and the temperature of the bearing portion increases. Rises. Accordingly, by providing the oil release valve that opens when the engine is rotating at high engine speeds where the temperature of the bearing exceeds a predetermined temperature, it is possible to perform cooling corresponding to the temperature change of the bearing.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to FIGS.

In this embodiment, the crankpin shaft is provided with the cooling structure according to the present invention.

The crankshaft 1 includes a crankshaft 4 supported by a main bearing 2, a crankpin shaft 5 to which a crankpin bearing 3 of a connecting rod is attached, and a web 8 connecting the crankshaft 4 and the crankpin shaft 5. And have.

The crankshaft 1 is provided with a through hole 13 in the crankpin shaft 5. The through hole 13 has a recess 16 with an outer diameter d1 of both ends 15 slightly larger than the inner diameter of the through hole 13 and an outer diameter d2 (d2 <d1) at the center in the longitudinal direction. The metal pipe 14 having the expansion coefficient is press-fitted. Then, the metal pipe 14 is formed by the crankpin shaft 5 and the metal pipe 14.
An annular oil passage 18 is formed on the outer periphery of the metal pipe 14, and at the same time, the inside of the metal pipe 14 forms a hollow portion 17 with both ends open.

The oil hole 10 opening on the outer surface of the crank spindle 4 and the annular oil passage 18 are
The oil holes 12 provided inside communicate with each other.
The oil hole 11 opening on the outer surface of the crankpin shaft 5 communicates with the annular oil passage 18. These oil holes 1
The oil passages 0 to 12 and the annular oil passage 18 form an oil passage.

An oil discharge valve 19 is incorporated at a position farthest from the crankshaft center of the annular oil passage 18. The check ball case 20 has an oil discharge hole 2 that opens toward the inside of the annular oil passage 18.
1 and an oil discharge hole 22 opening toward the hollow portion 17 are provided. The two oil discharge holes 21 and 22 form an oil discharge passage that connects the annular oil passage 18 and the hollow portion 17 to each other.

Details of the oil discharge valve 19 are shown in FIG. The check ball 23 in the check ball case 20 is urged toward the center of the crankshaft by the spring 24 and closes the oil discharge hole 22. The check ball 23 opens and closes the oil discharge hole 22 depending on the magnitude relationship between the biasing force of the spring 24 and the centrifugal force applied to the check ball 23 when the engine is operated. Reference numeral 25 denotes an oil escape hole which constantly communicates the inside of the check ball case 20 with the annular oil passage 18. For example, when the check ball 23 moves upward in FIG. 2, the lubricating oil in the check ball case 20 is As indicated by the middle arrow C, the oil escapes to the annular oil passage 18 through the oil escape hole 25, so that the movement of the check ball 23 is not restricted by the lubricating oil.

The operation will be described based on the above configuration.

The lubricating oil supplied to the crank main bearing portion 6 flows out into the crank chamber through the gap (oil clearance s1) between the main bearing 2 and the crank main shaft 4, and a part of the lubricating oil is provided in the oil holes 10-12 and the annular oil. It reaches the crank pin bearing portion 7 through an oil passage formed by the passage 18 and flows out into the crank chamber from a gap (oil clearance s2) between the crank pin bearing 3 and the crank pin shaft 5.

The lubricating oil forms an oil film on the sliding surfaces of the bearings 6 and 7 to reduce friction and wear, and also cools the bearings 6 and 7.

When the crankpin bearing portion 7 is sufficiently cooled with the amount of lubricating oil flowing out from the oil clearance s2, the urging force of the spring 24 is greater than the centrifugal force exerted on the check ball 23 at low engine speeds. The check ball 23 blocks the oil discharge hole 22.

At high engine speed, the centrifugal force applied to the check ball 23 becomes larger than the spring force of the spring 24, the check ball 23 moves in the direction away from the crankshaft center, and the oil discharge hole 22 opens. In this way, the oil discharge valve 19 opens when the crankpin bearing portion 7 exceeds a predetermined temperature. Here, the predetermined temperature is assumed to be a temperature slightly lower than the heat-resistant limit temperature with a margin based on the heat-resistant limit temperature at which the crankpin bearing part 7 will seize, and when the crankpin bearing part 7 exceeds the predetermined temperature. Check the engine rotation speed of the
Set the spring constant of 4 appropriately. For example, in the case of an engine in which the heat resistance limit temperature of the crankpin bearing portion 7 is 180 ° C,
The predetermined temperature is 170 ° C and the engine speed at this time is 65
If it is 00 rpm, considering that the temperature slightly changes depending on the load condition even if the rotation speed is the same, 6
It suffices to open the valve at about 000 rpm.

When the oil discharge valve 19 is opened, the lubricating oil in the annular oil passage 18 is not only supplied to the crankpin bearing portion 7 through the oil hole 11, but also the arrow B in FIG.
As shown by, the oil is discharged into the hollow portion 17 through the oil discharge holes 21 and 22. The amount of lubricating oil discharged can be changed by setting the oil discharge holes 21 and 22.

The lubricating oil discharged into the hollow portion 17 flows out from the openings at both ends of the hollow portion 17.

As described above, when the crank pin bearing portion 7 exceeds a predetermined temperature and the engine rotates at a high speed, the lubricating oil discharged into the hollow portion 17 is cooled by the lubricating oil flowing through the crank pin bearing portion 7. 5 is cooled from the inside to prevent the crankpin bearing portion 7 from overheating to the heat resistant limit temperature, and the durability of the crankpin bearing portion 7 is maintained. Further, the engine speed at which the crankpin bearing portion 7 is overheated is higher than that of the conventional engine, so that a high-rotation engine can be used.

Further, since the oil release valve 19 is opened / closed by the engine rotation speed which directly affects the temperature of the sliding surface of the bearing portion, the temperature of the crankpin bearing portion 7 can be directly detected without directly detecting the temperature of the crankpin bearing portion 7. Cooling corresponding to temperature changes can be performed.

The oil discharge valve 19 utilizing the centrifugal force can have a relatively simple structure. Crankshaft 1
Is a member that rotates at a high speed, it is very important that the structure provided in the crankshaft 1 is simple in terms of durability and weight reduction.

Lubricating oil is required to be supplied only in a required amount corresponding to the engine rotation speed, and an oil pump driven by using the engine output does not perform useless work.

When the lubricating oil is being discharged to the hollow portion 17 of the crankpin shaft 5, the amount of lubricating oil passing through the crank main bearing portion 6 will increase by the amount of the discharge.
Cooling of the crank main bearing portion 6 is also slightly better than in the conventional case.

A second embodiment according to the present invention will be described with reference to FIGS.

Hollow portion 17 provided on the crankpin shaft 5
The oil passage is formed in the same manner as in the first embodiment. However, in this embodiment, the metal pipe 14b inserted into the through hole 13 is made of a material such as amber steel whose coefficient of thermal expansion is extremely smaller than that of the material of the crankshaft 1, and its outer diameter d3.
Is determined from the viewpoint described later.

Between the through hole 13 of the crankpin shaft 5 whose inner diameter increases as the temperature rises and both ends 15b of the metal pipe 14b whose outer diameter hardly changes even when the temperature rises, A gap corresponding to the temperature is generated, and this gap serves as an oil discharge passage that connects the oil passage and the hollow portion 17. In the case of this embodiment, there is no independent oil release valve, but the crankpin shaft 5
It can be said that the entire metal pipe 14b constitutes an oil discharge valve.

The metal pipe 14b is restrained from moving in the axial direction of the through hole 13 by the pipe stopper rings 26 provided at both ends. The pipe stop ring 26 has a tooth-shaped inner diameter, and the lubricating oil passing through the gap between the crankpin shaft 5 and the metal pipe 14b easily flows out from the tooth-shaped concave portion to the hollow portion 17.

The operation will be described based on the above configuration.

Similar to the first embodiment, the crank main bearing portion 6
Lubricating oil is constantly supplied to the crankpin bearing portion 7.

When the temperature of the crankpin bearing portion 7 is low, there is almost no gap between the crankpin shaft 5 and the metal pipe 14b, and the oil discharge valve is in a closed state.

When the temperature of the crankpin bearing portion 7 rises and exceeds a predetermined temperature, both end portions 15b of the metal pipe 14b.
A gap is formed between the oil discharge valve and the crankpin shaft 5, and the oil discharge valve is opened. The lubricating oil is discharged into the hollow portion 17 through this gap.

The outer diameter d3 of both end portions 15b of the metal pipe 14b is set so that the above-mentioned gap generated when the crankpin bearing portion 7 exceeds a predetermined temperature is such that lubricating oil necessary and sufficient for cooling flows. ing. For example, in the case of an engine in which the shaft diameter of the crankpin shaft 5 is about 30 mm, the gap may be several tens of microns when the temperature of the crankpin bearing portion 7 is 170 ° C., which is close to the heat resistance limit temperature. If the gap is about several tens of microns, the problem of sound vibration does not occur.

In this embodiment, in addition to the effect of preventing the temperature of the crank pin bearing portion 7 from excessively increasing without wasting the engine output, the structure for obtaining this effect is very simple. Has the advantage of. That is, since the crankpin shaft 5 and the metal pipe 14b constitute not only the annular oil passage 18 but also the oil discharge passage and the oil discharge valve, it is not necessary to provide a separate oil discharge passage and oil discharge valve. . As mentioned above, the crankshaft 1
The simple structure provided inside is a great advantage.

A third embodiment of the present invention will be described with reference to FIGS. 6 and 7.

Both the hollow portion 17 and the oil passage are formed in the same manner as in the first embodiment. The coefficient of thermal expansion of the metallic pipe 14 is substantially the same as that of the crankshaft 1.

The recess 16 of the metallic pipe 14 is provided with an oil discharge hole 27 as an oil discharge passage. A bimetal oil release valve 28 that opens and closes the oil release hole 27 according to changes in the lubricating oil temperature is attached to the metal pipe 14 so as to be located in the lubricating oil in the annular oil passage 18. The oil release valve 28 made of bimetal is deformed to open the oil release hole 27 as the temperature of the lubricating oil rises.

The operation will be described based on the above configuration.

When the temperature of the lubricating oil is low, the oil discharge valve 28 is closed, and the stress in the direction of closing the oil discharge hole 27 remains inside the oil discharge valve 28.

At the lubricating oil temperature at which the crankpin bearing portion 7 reaches a predetermined temperature, the stress inside the oil release valve 28 disappears, and when the lubricating oil temperature is higher than the predetermined temperature, the oil release valve 28 opens in the direction to open the oil release hole 27. The valve is deformed and opened. The lubricating oil is passed through the oil discharge hole 27 and the hollow portion 1
It will be released to 7.

The valve opening timing can be adjusted depending on the magnitude of the initial stress applied when the oil discharge valve 28 is attached. Temperature of crankpin bearing 7 and annular oil passage 18
Since it is considered that the temperature of the lubricating oil is substantially equal to the temperature of the lubricating oil inside, the oil discharge valve 28 may be opened when the temperature of the lubricating oil rises to a temperature slightly lower than the heat resistance limit temperature of the crankpin bearing portion 7. . Also, the amount of oil discharged is the oil discharge hole 27.
It can be easily changed depending on the size.

Although the three embodiments described above are provided with the cooling structure according to the present invention only on the crank pin shaft, they can be applied to only the crank main shaft or both the crank main shaft and the crank pin shaft in some cases.

Further, a method is provided in which the oil discharge passage is opened on the outer surface of the shaft so that the bearing portion and the hollow portion communicate with each other, and the lubricating oil supplied to the bearing portion is discharged into the hollow portion when the oil discharge valve is opened. Is also possible.

Further, in order to make the structure as simple as possible, a construction such as a detector for detecting the engine operating state is not used, but the oil release valve is opened based on the signal from the rotation speed detector or the oil temperature gauge. A method of doing it is also possible.

[0059]

As described above, the present invention is
When the bearing part of the crankshaft exceeds the prescribed temperature and the engine is in operation, the oil discharge valve opens, and the lubricating oil is discharged into the hollow part through the oil discharge passage to cool the bearing part, which has become hot, from the inside. Therefore, it is possible to prevent the temperature of the bearing portion of the crankshaft from rising excessively without wasting the engine output. Thereby, the durability of the bearing portion can be improved.

Further, the one in which the oil release valve is opened depending on the engine rotation speed can perform cooling corresponding to the temperature change of the bearing portion without directly detecting the temperature of the bearing portion.

[Brief description of drawings]

FIG. 1 is a sectional view of a crankshaft showing a first embodiment according to the present invention.

[FIG. 2] Similarly, a detailed cross-sectional view of the oil discharge valve

3 is a sectional view taken along line AA of FIG.

FIG. 4 is a crankshaft sectional view showing a second embodiment according to the present invention.

5 is a sectional view taken along line DD of FIG.

FIG. 6 is a crankshaft sectional view showing a third embodiment according to the present invention.

7 is a sectional view taken along line EE of FIG.

FIG. 8 is a crankshaft sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crank shaft 2 Main bearing 3 Crank pin bearing of connecting rod 4 Crank main shaft 5 Crank pin shaft 6 Crank main bearing part 7 Crank pin bearing part 8 Web 10-12 Oil hole (oil passage) 17 Hollow part 18 Annular oil passage (oil passage) ) 19, 28 Oil release valve 21, 22, 27 Oil release hole (oil release passage)

Claims (2)

[Claims] 1. A crank main shaft pivotally supported by a main bearing, a crank pin shaft to which a crank pin bearing of a connecting rod is attached, a web connecting the crank main shaft and the crank pin shaft, and an outer surface of the crank main shaft. To the outer surface of the crankpin shaft, and the lubricating oil supplied to the crank main bearing portion including the main bearing and the crank main shaft is supplied to the crankpin bearing including the crankpin bearing and the crankpin shaft. A crankshaft of an internal combustion engine having an oil passage leading to a crank portion, a hollow portion opening to a crank chamber is formed in at least one of the crank main shaft or the crankpin shaft, and the oil passage and the hollow portion are formed. An oil discharge passage communicating with the oil discharge passage is provided in the engine discharge state in which the bearing portion exceeds a predetermined temperature. An crankshaft for an internal combustion engine, which is provided with an oil discharge valve that is sometimes opened. 2. The crankshaft of an internal combustion engine according to claim 1, wherein the oil discharge valve is opened when the bearing portion has a high engine speed exceeding a predetermined temperature.