JPH10212916A - Piston cooling device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the seizure of a piston when machine-cooling operation starts. SOLUTION: In a second oil passage 8, a brach passage 12 for supplying a lubrication oil to a crankshaft 11, an injection passage 14 for jetting the oil for cooling to a piston 13 are installed and a solenoid valve 15 is provided in the injection passage 14 and an injection nozzle 16 is provided on the tip of the injection passage 14. The solenoid valve 15 is constituted so as to open the valve element when the oil pressure of a hydraulic switch 9 installed in a first oil passage 6 exceeds 5.0kgf/cm<2> . Therefore, when the engine is started and operated with a high load and high rotation at the cooled engine time, as the oil pressure exceeds 5.0kgf/cm<2> and the oil is jet from the injection nozzle 16 to the piston 13, the seizure of the piston by the expansion of the piston can be prevented when machine-cooling operation starts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piston cooling device for an engine.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an oil-jet type piston cooling device which cools a piston portion by injecting oil to a piston portion of an engine. For example, in the oil jet type piston cooling device disclosed in Japanese Utility Model Application Laid-Open No. 6-69323, a lightening hole is provided in a crankpin of a crankshaft, and lubricating oil is supplied to the lightening hole by a pumping force of an oil pump. The lubricating oil in the lightening hole is always supplied to the piston portion.

[0003]

The above prior art has the following problems. (1) With the above conventional piston cooling device, oil for cooling the piston portion is always injected regardless of the engine state, so that the oil temperature rises excessively or the oil pressure drops during steady operation. There is a problem that you do. (2) In the conventional configuration described above, when the engine is operated under a high load immediately after the engine is started and before the warm-up operation, the thermal expansion speed of the piston portion is faster than the thermal expansion speed of the cylinder. Therefore, in severe cases, burning of the piston may occur. This is because the cylinder head and cylinder block are cooled with cooling water, so the temperature does not rise until a certain time has elapsed after operation, whereas the volume of the piston part is small and separate from the cylinder. This is because the temperature rises sharply and the difference in the thermal expansion rate causes the piston sliding friction to increase. Such seizure of the piston tends to occur particularly when the engine is started during a cold period when the temperature difference between the cylinder and the piston is large. Further, it is likely to occur in an application such as an engine mounted on a construction machine or a civil engineering machine, which is often operated under a full load state after the start and before the entire engine is warmed up.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a piston cooling device for an engine which can solve the above problems. In addition, the subject of the invention other than those described above and means for solving the problem will be described in detail in embodiments of the invention described later.

[0005]

Means for Solving the Problems The first invention is, for example,
Referring to FIG. 1, the piston portion 1 of the engine E will be described.
An oil supply unit 33 for supplying oil for cooling to the engine 3; a piston cooling device for the engine E, detecting means 32 for detecting a cold state of the engine E; Valve means 31 provided in the passage 14 for selecting between a state in which oil is supplied to the oil supply unit 33 and a state in which supply is stopped, and a time period during which the detection means 32 detects that the engine E is in the cold state. Valve control means 30 for setting the valve means 32 to supply oil to the oil supply section 33. In addition, examples of the detection unit 32 that detects the cold state of the engine E include a hydraulic pressure sensor 29, a hydraulic pressure switch 9, an oil temperature sensor, an oil temperature switch 21, a cooling water temperature sensor 28, a cooling water temperature switch 22, and the like. The simplest configuration of the valve control unit 30 is an opening / closing drive unit of the valve unit 31. For example, as such a driving unit, the electric driving units 25 and 26 of the solenoid valve 15 are used.
Can be exemplified. The advanced valve control means 30 includes:
A logic operation unit 24 (for example, an AND circuit or an OR circuit) that calculates the output from the detection unit 32 can be employed as needed.

Referring to FIG. 2, for example, the second invention is an engine piston cooling device provided with an oil supply section 33 for supplying cooling oil to the piston section 13 of the engine E. A relief valve 20 is provided in the oil passage 14 that supplies oil to the oil supply unit 33, and the relief valve 20 supplies the oil to the oil supply unit 33 only when the pressure exceeds a predetermined oil pressure when the engine E is in a cold state. Is supplied. Third
For example, referring to FIG. 1, the oil supply unit 33 is constituted by an injection nozzle 16 that injects oil, and the oil supply unit 33 is directed toward a position of the piston unit 13 that is preferable for cooling the piston unit 13. It is characterized in that oil is injected.

[0007]

According to the first aspect of the present invention, when the detecting means detects that the engine is in a cold state, the valve control means sets the valve means to a state in which oil is supplied to the oil supply section, and the detecting means determines whether the engine is in the cold state. If it is not detected that the engine is in the cold state, the valve control means sets the valve means to a state in which oil is not supplied. Therefore, when starting the engine, if the engine is in a cold state, it is possible to supply cooling oil to the piston portion of the engine from the oil supply portion,
Seizure of the piston portion can be prevented. Also,
When the engine is not cold when starting the engine, and after the engine is warmed up after the engine is started, cooling oil is not supplied to the piston of the engine.
It is possible to suppress an increase in oil temperature at a high temperature and a decrease in oil pressure during a steady operation.

According to the second aspect of the present invention, since the relief valve for supplying oil to the oil supply unit only when the oil pressure exceeds a predetermined oil pressure when the engine is in the cold state is provided, when the engine is started in the cold state, Oil flows from the relief valve to the oil supply unit, and the oil for cooling can be supplied to the piston unit, so that seizure of the piston unit can be prevented. Further, when the engine is not cold when the engine is started, and after the warm-up operation is completed after the engine is started, the oil pressure applied to the relief valve is lower than the predetermined oil pressure, so that oil flows from the relief valve to the oil supply unit. No cooling oil is supplied to the piston. Therefore, it is possible to suppress an increase in the oil temperature at a high temperature and a decrease in the oil pressure during a steady operation. According to the third aspect, the oil supply unit is constituted by an injection nozzle for injecting oil, and the oil is injected toward a position of the piston unit which is preferable for cooling the piston unit. The oil can be supplied concentratedly at the location of the piston portion which is preferable for cooling the oil.

[0009]

According to the first and second aspects of the present invention, the following effects (a) and (b) are provided. (A) Seizure of the piston portion at the time of starting the cold machine can be prevented. (B) An excessive increase in oil temperature can be suppressed, and a decrease in oil pressure during steady operation can be prevented. According to the third aspect of the invention, in order to prevent seizure of the piston portion, the oil can be concentratedly supplied to a portion of the piston which is preferable for cooling the piston portion, and the cooling performance can be improved. Has an effect.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing a configuration of a piston cooling device for an engine according to the present invention. The engine E to which the piston cooling device shown in FIG. 1 is applied is configured as follows. That is, the oil 3 is stored in an oil pan 2 attached to a lower position of the crankcase 1,
The oil strainer 4 is immersed in the oil 3, and the oil through the oil strainer 4 is sent out to the first oil passage 6 by the oil pump 5. First oil passage 6
An oil cleaner 7 is connected to the end of the oil cleaner 7, and an outlet 7a of the oil cleaner 7 communicates with a second oil passage 8.

The first oil passage 7 is provided with a hydraulic switch 9 as detecting means 32 for detecting that the engine is in a cold state, and a safety hydraulic adjusting device 10 (regulating valve). This hydraulic adjustment device 1
Although 0 is provided to prevent the oil pressure from rising too high, the oil pressure at which the oil starts to leak is set to be larger than the set pressure of the oil pressure switch 9. The second oil passage 8 is provided with a branch passage 12 for supplying lubricating oil to the crankshaft 11 and the like, and an injection passage 14 for injecting cooling oil to the piston 13. An electromagnetic valve 15 as valve means 31 is provided in the injection passage 14, and the tip of the injection passage 14 is an injection nozzle 16. The injection nozzle 16 is shown as an example of the oil supply unit 33.

The hydraulic switch 9 is configured to open the valve of the solenoid valve 15 when the hydraulic pressure of the first oil passage 6 exceeds 5.0 kgf / cm ² .
For example, when the hydraulic switch 9 is turned on, a current flows through the electromagnetic coil of the electromagnetic valve 15, and the valve body directly connected to the movable iron core is opened. When the solenoid valve 15 is not in the open state, the supply of oil from the second oil passage 8 to the injection nozzle 16 of the injection passage 14 is shut off, and no oil is injected from the injection nozzle 16. Although only one piston is shown in FIG. 1 for simplicity, the injection passage 14 is actually branched corresponding to each piston position, and each injection nozzle 16 is provided at the tip of the branch passage. ing.

The oil pump 5 is, for example, a gear pump, and pumps the oil 3 in the oil pan 2 to the first oil passage 6 by a driving force of a camshaft or an intermediate shaft. The operation of the piston cooling device having the above configuration will be briefly described. After the engine is started and before the warm-up operation is completed, for example, when the engine E is suddenly operated at a high load and a high rotation speed, the thermal expansion speed of the piston portion 13 is higher than the thermal expansion speed of the cylinder 17, Piston part 1
The resistance between cylinder 3 and cylinder 17 increases,
No. 3 burning occurs.

This embodiment solves the above problem.
When cold, oil viscosity is high and oil pressure is high
Utilizing that the hydraulic pressure is at a set boundary hydraulic pressure, for example,
5.0 kgf / cm described^TwoIf the state exceeds
A state in which the piston 13 of the engine is easily burned
Is determined, the solenoid valve 15 is opened, and the injection nozzle 16 is turned off.
Is injected into the piston portion 13 so that the temperature of the piston portion 13
That the temperature is significantly higher than the temperature of the cylinder 17.
To prevent. And the oil pressure is 5.0kgf / cm ^Twoless than
If it does, the piston 13 of the engine will burn
Judge that the pan has been removed, close the solenoid valve 15 and inject
The injection of oil from the nozzle 16 is stopped. That is,
A state in which the piston 13 of the engine is easily burned
It is determined whether the hydraulic pressure detected by the hydraulic switch 9 is a predetermined value.
Is determined by whether it exceeds the boundary oil pressure
It is. With this configuration, it is easy
It is possible to prevent seizure of the piston part 13 with a cheap structure.
Can be.

[0015] Incidentally, in the normal engine, the oil pressure at the time of warm-up start 3~4kgf / cm ² or so, the oil pressure at the time of high-speed full-load state operation oil is about 3 kgf / cm ^2. When the cold start is performed, the hydraulic pressure becomes 7 to 8 kgf / cm ² . Therefore, the hydraulic switch is set to 5.0 kgf / c.
By setting the solenoid valve 15 to be in the open state only when the pressure is equal to or more than m ^{2, the} cooling oil can be supplied to the piston portion 13 only at the time of cooling.

[0016]

Second Embodiment FIG. 2 is a schematic configuration diagram showing a second embodiment of the piston cooling device for an engine according to the present invention. The feature of the second embodiment is that a relief valve 20 as a valve means 31 is provided in the middle of the injection passage 14, and the relief valve 20 is opened when the oil pressure of the injection passage 14 exceeds a set boundary oil pressure. When the oil is supplied to the injection nozzle 16 and the oil pressure in the injection passage 14 is equal to or lower than the set boundary oil pressure, the injection nozzle 16 is closed so that the oil is not injected from the injection nozzle 16. In this embodiment, for example, if the set boundary oil pressure of the relief valve 20 is set to 5.0 kgf / cm ² , the cooling oil can be supplied to the piston portion 13 only when the cold start is performed.

According to the second embodiment, the same operation and effect as those of the first embodiment can be obtained, and only the relatively inexpensive relief valve 20 is used instead of the hydraulic switch 9 and the solenoid valve 15. There is an advantage that it can be configured and the manufacturing cost can be reduced.

[0018]

Third Embodiment FIG. 3 is a schematic structural view showing a third embodiment of a piston cooling device for an engine according to the present invention. First, a feature of the third embodiment is that an oil temperature switch 21 for detecting the temperature of the oil 3 in the oil pan 2 or the oil in the predetermined oil passages 6 and 8 is provided. When the oil temperature is equal to or lower than the set oil temperature (for example, 50 ° C.), the solenoid valve 15 is opened and lubricating oil is injected from the injection nozzle 16 into the piston portion 13.
The solenoid valve 15 is closed when the temperature exceeds a set oil temperature (for example, 50 ° C.).

According to the third embodiment, when the engine is cold started, the temperature of the lubricating oil of the engine is low. Only in such a case, a large amount of lubricating oil is supplied around the piston to prevent the seizure of the piston. Can be prevented. In the third embodiment, the oil pump 5
Irrespective of the rotation speed of the engine related to the oil pressure, the amount of oil injected to the piston portion 13 can be increased when the temperature of the oil is low, so that the engine is operated without being affected by the rotation speed of the engine. Even if the surrounding environment is extremely low and the difference between the temperature of the cylinder block of the engine and the temperature of the piston is likely to be large, seizure of the engine can be prevented.

In the third embodiment, the oil temperature switch 21 is set to a water temperature for detecting a water temperature related to the operation of the engine such as cooling water, for example, a cooling water temperature switch 22.
It can also be implemented in place of. In this case as well, the solenoid valve 15 may be opened when the cooling water temperature switch 22 is, for example, 60 ° C. or lower, and may be closed when the temperature exceeds 60 ° C.

[0021]

Fourth Embodiment FIGS. 4A and 4B are main part configuration diagrams showing a fourth embodiment of a piston cooling device for an engine according to the present invention. The feature of the fourth embodiment is that at least two detections of oil pressure, oil temperature, and cooling water temperature are performed,
The point is that the opening and closing operation of the solenoid valve 15 is performed based on the two detected values. 4A, a cooling water temperature sensor 28 and a hydraulic pressure sensor 29 are provided, and their detection values are input to the logic circuit unit 24, and after a predetermined calculation is performed, the electromagnetic valve 15 is opened and closed. It is like that. The predetermined calculation is appropriately performed according to the use purpose and use conditions of the engine,
Just set it. The configuration shown in FIG.
And the cooling water temperature switch 22 are connected in series, and the solenoid valve 15 is opened and injected only when the hydraulic pressure switch 9 is turned on beyond a predetermined oil pressure and the cooling water temperature switch 22 is turned on below the set temperature. In this configuration, oil is injected from the nozzle 16. In FIG. 4B, reference numeral 24 denotes a logic circuit unit serving as the valve control means 30, and reference numeral 25 denotes the solenoid valve 1
Reference numeral 26 denotes a movable iron core, and reference numeral 27 denotes a valve body directly connected to the movable iron core 26.

In the configuration shown in FIG. 4B, by appropriately setting the boundary cooling water temperature and the boundary oil pressure, the condition of the boundary for supplying oil to the piston portion 13 is changed to the cooling water set temperature. Can be finely set according to the temperature of the cylinder block and the oil pressure of the oil. For example, since the oil pressure of the oil is affected by the rotation speed of the engine, unnecessary oil injection can be reduced by considering the temperature of the cylinder block. As another configuration, a configuration in which the hydraulic switch 9 and the coolant temperature switch 22 (or the oil temperature switch 21) are simply connected to the solenoid valve 15 in parallel is also conceivable.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the present invention. Hereinafter, such an embodiment will be described. (1) In the above-described embodiment, the case where the oil supply unit 33 is constituted by the injection nozzle 16 that injects oil is illustrated, but the oil for cooling is supplied to the portion of the piston unit that can cool the piston unit 13. Then, the supply form is not particularly limited. (2) It goes without saying that the route through which the oil is supplied to the oil supply unit 33 can be appropriately designed according to the configuration of the engine. (3) In the present invention, the hydraulic switch 9 and the hydraulic sensor 29
The position of the oil passage provided with can be appropriately set according to the engine.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the present invention.

FIGS. 4A and 4B are main part configuration diagrams showing a fourth embodiment of the present invention.

[Explanation of symbols]

13: piston part, 16: injection nozzle, 20: relief valve, 30: valve control means, 31: valve means, 32: detection means, 33: oil supply part, E: engine.

Claims (3)

[Claims] 1. A piston cooling device for an engine (E), comprising an oil supply section (33) for supplying oil for cooling to a piston section (13) of the engine (E). Detecting means (32) for detecting a cold state;
An oil passage (1) for supplying oil to the oil supply section (33)
4) a valve means (31) for selecting between a state in which oil is supplied to the oil supply section (33) and a state in which supply is stopped.
Valve control means (32) for bringing the valve means (32) into a state of supplying oil to the oil supply unit (33) for a time during which the detection means (32) detects that the engine (E) is in a cold state. 30) A piston cooling device for an engine, comprising: 2. A piston cooling device for an engine, comprising an oil supply unit (33) for supplying cooling oil to a piston unit (13) of the engine (E), wherein oil is supplied to the oil supply unit (33). Oil passage (1)
4) A relief valve (20) is provided, and the relief valve (20) is provided.
Is configured to supply oil to the oil supply section (33) only when a predetermined oil pressure when the engine (E) is in a cold state is exceeded. 3. The oil supply section (33) is constituted by an injection nozzle (16) for injecting oil, and the oil is injected toward a position of the piston section (13) which is preferable for cooling the piston section (13). 3. The piston cooling device for an engine according to claim 1, wherein the piston cooling device is configured to perform the following operations.