JPH08177492A - Piston cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE: To enhance cooling performance of a piston by providing an injection amount decreasing means for decreasing the quantities of lubricating oil to be injected from an oil jet nozzle of an upstream side cylinder in low heat loading through a valve means. CONSTITUTION: In a cylinder block 51, a water jacket 21 for circulating engine cooling water is provided around a cylinder wall 52. Lubricating oil to be injected from an oil jet nozzle 10 collides with the back surface of a piston 20 and carries away heat of the piston 20 and the cylinder wall 52. A control unit 31 controls opening and closing of a solenoid valve 7 so that cooling performance of the piston 20 may be improved while securing workability of a variable dynamic system 18. If the piston 20 of a first cylinder in low heat loading is judged, the solenoid valve 7 is closed, and lubricating oil from the oil jet nozzle 10 of the first cylinder is stopped. The cylinder wall of the upstream side cylinder and the piston can be prevented from being excessively cooled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a piston cooling device for an internal combustion engine which injects lubricating oil into a piston.

[0002]

2. Description of the Related Art In an internal combustion engine having a high heat load such as a supercharged engine, a piston cooling device is provided in which a lubricating oil for cooling is sprayed from the rear side of the piston in order to improve the durability of the piston. Known from the past
(Japanese Utility Model Publication No. 62-56707, Japanese Utility Model Publication No. 3-1020.
23, gazette).

In this piston cooling device, the lubricating oil sent from the oil pump is guided to the oil jet nozzle protruding from the lower end of the cylinder wall, and a hydraulic valve is opened in the middle of the oil passage in response to a predetermined hydraulic pressure. Is provided. When the lubricating oil pressure introduced from the oil pump exceeds the set value, the hydraulic valve opens and the lubricating oil is injected from the oil jet nozzle. The lubricating oil sprayed from the oil jet nozzle hits the back surface of the piston and removes heat from the piston and the cylinder wall.

[0004]

However, in a water-cooled internal combustion engine having a water jacket in which cooling water flows in the cylinder row direction around each cylinder arranged in series, the most upstream side of the water jacket is provided. Since the amount of heat radiated to the cooling water by the piston of the first cylinder located is larger than that of the other cylinders, if the amount of lubricating oil injected from each oil jet nozzle is uniformly controlled for all cylinders, the piston of the first cylinder May be overcooled.

Further, in an internal combustion engine equipped with a variable valve mechanism that changes the lift characteristic of the valve in response to the discharge pressure of the oil pump, the amount of lubricating oil injected from each oil jet nozzle is controlled simultaneously in all cylinders. Then, since the discharge pressure of the oil pump greatly decreases as the lubricating oil begins to be injected from the oil jet nozzle, for example, when the lubricating oil temperature rises and the discharge pressure of the oil pump decreases, the variable operation There is a possibility that the hydraulic pressure necessary for operating the valve mechanism cannot be obtained, and the valve lift characteristics cannot be switched under the intended operating conditions.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to improve the cooling performance of a piston in a piston cooling device for an internal combustion engine while ensuring the operability of a variable valve mechanism and the like.

[0007]

A piston cooling device for an internal combustion engine according to a first aspect of the present invention is, as shown in FIG. 5, a plurality of cylinders arranged in series and cooling water around each cylinder in the cylinder row direction. A water jacket flowing along with an oil jet nozzle a for injecting lubricating oil toward the piston of each cylinder
A valve means b for controlling the supply of the lubricating oil to the oil jet nozzle a; and a low heat load determination means c for determining a low heat load when the heat load of the piston of the upstream cylinder located upstream of the water jacket is low. And an injection amount reducing device d for reducing the amount of lubricating oil injected from the oil jet nozzle a of the upstream cylinder during a low heat load via the valve device b.

According to a second aspect of the present invention, there is provided a piston cooling device for an internal combustion engine, wherein, in the first aspect of the invention, as shown in FIG. 6, a hydraulic actuator that operates in response to the discharge pressure of an oil pump, and an engine A water temperature detecting means f for detecting the cooling water temperature, a hydraulic pressure detecting means g for detecting the discharge pressure of the oil pump, and a low hydraulic pressure when the pump discharge pressure is less than a first reference value necessary for the operation of the hydraulic actuator are determined. Low hydraulic pressure determining means h, and a low thermal load that determines an operating condition in which the cooling water temperature is less than the reference value and the pump discharge pressure is the second reference value or more when the low hydraulic pressure is determined. And a time determination means c.

According to a third aspect of the invention, there is provided a piston cooling device for an internal combustion engine according to the first or second aspect, wherein the upstream cylinder is a first cylinder closest to a cooling water inlet into which the cooling water flows into the water jacket. To do.

According to a fourth aspect of the invention, there is provided a piston cooling device for an internal combustion engine according to the second or third aspect of the invention, in which the hydraulic valve actuator changes the lift characteristic of the valve in response to the discharge pressure of the oil pump. And

[0011]

In the piston cooling device for an internal combustion engine according to claim 1, the amount of heat carried away by the cooling water flowing through the water jacket from the cylinder wall and the piston is higher in the upstream cylinder near the cooling water inlet than in the downstream cylinder. Since the amount of lubricating oil injected from the oil jet nozzle a of the upstream cylinder is reduced when the thermal load of the piston of the upstream cylinder is low, the cylinder wall and piston of the upstream cylinder are excessively cooled. It is possible to prevent friction and increase in friction.

In the piston cooling device for the internal combustion engine according to the second aspect, when it is determined that the pump discharge pressure is lower than the first reference value required for the operation of the hydraulic actuator, the cooling water temperature is Less than the reference value, pump discharge pressure is determined to be a low heat load operating conditions that are greater than or equal to the second reference value,
With the configuration that reduces the amount of lubricating oil injected from the oil jet nozzle a of the upstream side cylinder, the pump discharge pressure increases,
The hydraulic actuator can be operated.

Under operating conditions in which the cooling water temperature is above the reference value or the pump discharge pressure is below the second reference value, there is a possibility that the heat load on the piston will be high, so lubrication from the oil jet nozzle a of the upstream cylinder will occur. Injects oil to secure the heat resistance of the piston with priority over the operation of the hydraulic actuator.

In the piston cooling device for an internal combustion engine according to a third aspect of the present invention, the low temperature cooling water is introduced from the cooling water inlet to the first cylinder, and the amount of heat carried away from the cylinder wall and the piston by the cooling water is higher than that of the other cylinders. This is the largest because the amount of lubricating oil injected from the oil jet nozzle of the first cylinder is reduced in operating conditions where the heat load of the piston of the first cylinder is low, and the cylinder wall and piston of the first cylinder are excessively cooled. It is possible to prevent friction and increase in friction.

In the piston cooling device for an internal combustion engine according to a fourth aspect of the present invention, the variable valve mechanism that switches the lift characteristic of the valve in response to the discharge pressure of the oil pump increases the lubricating oil temperature and discharge pressure of the oil pump. Even if the operating condition is reduced to some extent, the amount of lubricating oil injected from the oil jet nozzle in the upstream cylinder is reduced to obtain the hydraulic pressure necessary for the operation of the variable valve mechanism, and the valve operating under preset operating conditions. The lift characteristics can be switched accurately, and abrupt changes in generated torque can be suppressed.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a cross section of the first cylinder located at the front end of the in-line four-cylinder engine 5.

The cylinder block 51 has a cylinder wall 52.
A water jacket 21 that circulates engine cooling water is provided around the.

At the front end of the water jacket 21, a cooling water inlet into which cooling water discharged from a water pump (not shown) flows is formed. At the rear end of the water jacket 21, a cooling water outlet (not shown) through which cooling water flows is formed.

The cooling water flowing from the cooling water inlet flows in the water jacket 21 in the order of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder in the cylinder row direction, and removes the heat of the cylinder wall 52 of each cylinder. It is like this. The cooling water flowing out from the cooling water outlet is sucked into the water pump through a radiator or a bypass passage (not shown).

As shown in FIG. 2, the constant capacity oil pump 1 of the engine supplies the lubricating oil sucked from the oil pan 2 to each part of the engine through the oil filter 3.

A main gallery 8 is connected to the discharge side of the oil pump 1. A part of the lubricating oil discharged from the oil pump 1 is fed from the main gallery 8 to the crankshaft 11
Is supplied to each of the main bearings 12 that support.

A part of the lubricating oil supplied to each main bearing 12 is supplied to the connecting rod bearing 14 for the connecting rod 13 through a crank internal passage 15 formed inside the crankshaft 11.

A head gallery 6 is connected to the discharge side of the oil pump 1. Part of the lubricating oil discharged from the oil pump 1 passes through the head gallery 6 and the camshaft 16
It is supplied to the camshaft bearing 17 that supports the bearing and is also supplied to the sliding contact portion of the variable valve mechanism 18.

A part of the lubricating oil discharged from the oil pump 1 is guided to each oil jet nozzle 10 provided for each cylinder through the main gallery 8. The lubricating oil sprayed from the oil jet nozzle 10 hits the back surface of the piston 20 and removes the heat of the piston 20 and the cylinder wall 52.

The oil jet nozzle 10 provided in the first cylinder is connected to the main gallery 8 via an electromagnetic valve 7.

The electromagnetic valve 7 has a return spring 42 for urging the valve body 41 in the valve closing direction, and a solenoid 43 for opening the valve body 41 against the return spring 42 by an electromagnetic force.

Oil jet nozzles 10 provided in the second cylinder, the third cylinder, and the fourth cylinder are connected to the main gallery 8 via hydraulic valves 9, respectively.

The hydraulic valve 9 is provided with a main gallery 8 and an oil jet nozzle 1 by means of the urging force of a spring (not shown) in the low and middle rotation range where the discharge pressure of the oil pump 1 is below a predetermined value.
0 communication is cut off and the discharge pressure of the oil pump 1 opens against the spring in the high rotation range where it rises above a predetermined value,
The main gallery 8 and the oil jet nozzle 10 are communicated with each other, and the lubricating oil is jetted from the oil jet nozzle 10.

A hydraulic switching valve 30 for adjusting the hydraulic pressure sent to the variable valve mechanism 18 for adjusting the valve lift and valve timing is in communication with the discharge side of the oil pump 1.

The variable valve mechanism 18 has a low speed cam having a profile satisfying the valve lift characteristic required at low engine speed and a low speed cam having a profile satisfying the valve lift characteristic required at high engine speed. When the discharge pressure of the oil pump 1 is introduced through the hydraulic pressure switching valve 30, the cam involved in opening and closing the intake / exhaust valve is switched from the low speed cam to the high speed cam.

A control unit (not shown) for controlling the operation of the hydraulic pressure switching valve 30 basically inputs the detection signal of the engine speed and the load, etc., and presets a high speed cam based on the map shown in FIG. In the usage area A of
It is designed to smoothly switch from a low speed cam to a high speed cam while suppressing rapid changes in engine torque.

In FIG. 1, reference numeral 31 is a control unit for electronically controlling the opening and closing of the electromagnetic valve 7. The control unit 31 outputs a signal from an engine rotation sensor 32 that detects an engine speed NE, a signal from a cooling water temperature sensor 33 that detects a cooling water temperature TW, and a signal from a hydraulic pressure sensor 34 that detects a discharge pressure P of the oil pump 1. A signal from an opening sensor 36 for detecting the opening TH of the throttle valve 35 for adjusting the intake air amount is input.

The control unit 31 controls the opening and closing of the electromagnetic valve 7 based on these detected values so as to secure the operability of the variable valve mechanism 18 and enhance the cooling performance of the piston 20.

That is, the pump discharge pressure P is 0.2 MPa.
If the above, the temperature of the lubricating oil is not so high,
It is determined that the heat load of the piston 20 of the first cylinder is low and the heat load is low, and the electromagnetic valve 7 is closed even under the operating condition that the lubricating oil is injected from the oil jet nozzles 10 of the second, third, and fourth cylinders. Valve, oil jet nozzle 1 of the first cylinder
Lubricating oil injection is stopped from 0.

In the first cylinder, the amount of heat taken away by the cooling water from the cylinder wall 52 and the piston 20 near the cooling water inlet is larger than that of the other cylinders. Therefore, in the operating state where the heat load of the piston 20 of the first cylinder is low, By not injecting the lubricating oil from the oil jet nozzle 10 of the first cylinder, it is possible to prevent the cylinder wall 52 of the first cylinder and the piston 20 from being excessively cooled, and suppress an increase in friction.

Further, the cooling water temperature TW is lower than 90 ° C,
Under an operating condition in which the pump discharge pressure P is less than 0.3 MPa and not less than 0.2 MPa, the heat load on the piston 20 of the first cylinder is low and the hydraulic pressure required for the operation of the variable valve mechanism 18 cannot be obtained. If so, the electromagnetic valve 7 is closed and the injection of the lubricating oil from the oil jet nozzle 10 of the first cylinder is stopped.

Thus, when the heat load of the piston 20 of the first cylinder is low and the heat load is low, the lubricating oil is not injected from the oil jet nozzle 10 of the first cylinder, so that the cylinder wall 52 of the first cylinder and the piston 20 are overheated. While preventing this, the pump discharge pressure P required for the variable valve mechanism 18 to switch from the low speed cam to the high speed cam is secured. That is, the lubricating oil temperature rises and the oil pump 1
Even when the discharge pressure of the engine is reduced to some extent, the hydraulic pressure necessary for operating the variable valve mechanism 18 is obtained, and the low speed cam is switched to the high speed cam appropriately under the preset operating conditions, so that the engine torque becomes sharp. Fluctuations can be suppressed.

The flowchart of FIG. 3 shows a program executed by the control unit 31 for controlling the opening and closing of the electromagnetic valve 7, which is executed at regular intervals.

First, in step S1, the engine speed N
The signals of E, the cooling water temperature TW, and the pump discharge pressure P throttle valve opening TH are read.

Subsequently, the process proceeds to step S2 to search the operating region, and then to step S3, whether the current operating region is in the preset high speed cam use region A based on the map shown in FIG. To judge.

If it is not in the high speed cam use area A, the routine proceeds to step S4, where it is determined whether the pump discharge pressure P is 0.2 MPa or more.

When it is determined that the pump discharge pressure P is 0.2 MPa or more, the process proceeds to step S8 and the electromagnetic valve 7
Is opened, and the lubricating oil is injected from the oil jet nozzle 10 of the first cylinder in the same manner as in the other cylinders.

This prevents the lubricating oil from being jetted from the oil jet nozzles 10 of all the cylinders to remove the heat of the piston 20 and the cylinder wall 52 and overheat them even during operation in which the low speed cam is used. To do.

When it is determined that the pump discharge pressure P is less than 0.2 MPa, the process proceeds to step S7 and the electromagnetic valve 7
Is closed, and unlike other cylinders, lubricating oil is not injected from the oil jet nozzle 10 of the first cylinder.

On the other hand, if it is in the high speed cam use area A, the routine proceeds to step S5, where it is determined whether the cooling water temperature TW is 90 ° C. or higher.

In the high temperature state of the engine 5 in which it is determined that the cooling water temperature TW is 90 ° C. or higher, the process proceeds to step S8, the electromagnetic valve 7 is opened, and the oil jet nozzle 10 of the first cylinder also causes the other cylinders to open. Inject the lubricating oil in the same manner as in.

As a result, when the engine 5 is in a high temperature state,
Lubricating oil is sprayed from the oil jet nozzles 10 of all the cylinders, and the heat of the piston 20 and the cylinder wall 52 is carried away to prevent them from being overheated.

If it is determined that the cooling water temperature TW is lower than 90 ° C and the engine 5 is not in the high temperature state, step S6 is performed.
And the pump discharge pressure P is 0.3 which is the first reference value.
It is judged whether it is MPa or more.

When it is determined that the pump discharge pressure P is 0.3 MPa or more, it is determined that the operating state is such that the hydraulic pressure required for the operation of the variable valve mechanism 18 is secured, and the routine proceeds to step S8, where the electromagnetic valve is operated. The valve 7 is opened, and the lubricating oil is injected from the oil jet nozzle 10 of the first cylinder as in the other cylinders.

When it is determined that the pump discharge pressure P is less than 0.3 MPa, the process proceeds to step S9, and it is determined whether the pump discharge pressure P is 0.2 MPa or more which is the second reference value.

When it is determined that the pump discharge pressure P is 0.2 MPa or more, the process proceeds to step S7 and the electromagnetic valve 7
And the lubricating oil is not injected from the oil jet nozzle 10 of the first cylinder unlike the other cylinders. Thus, when the pump discharge pressure P is less than 0.3 MPa and not less than 0.2 MPa, the temperature of the lubricating oil is Is determined not to be so high, and the electromagnetic valve 7 is closed, so that the variable valve mechanism 18
Secures the pump discharge pressure P required to perform the switching operation from the low speed cam to the high speed cam.

If it is determined that the pump discharge pressure P is less than 0.2 MPa, it is judged that the engine 5 is in a high temperature state in which the pump discharge pressure P has decreased due to the decrease in the viscosity of the lubricating oil that has increased in temperature, and step S8 follows. Go ahead and open the solenoid valve 7,
Lubricating oil is injected from the oil jet nozzle 10 of the first cylinder in the same manner as in the other cylinders.

Thus, the pump discharge pressure P is 0.2MP.
If less than a, the oil jet nozzles 10 of all cylinders
By injecting the lubricating oil from, the heat of the piston 20 and the cylinder wall 52 is carried away, and these are prevented from being overheated. At this time, the variable valve mechanism 18 cannot switch from the low speed cam to the high speed cam due to the decrease in the pump discharge pressure P, but the heat resistance of the engine 5 is given priority.

[0055]

As described above, in the piston cooling device for an internal combustion engine according to the first aspect of the present invention, when the heat load of the piston of the upstream cylinder near the cooling water inlet is low and the heat load is low, the oil jet nozzle of the upstream cylinder is provided. The structure that reduces the amount of lubricating oil injected from the cylinder wall and piston prevents the cylinder wall and piston of the upstream cylinder, which has a large amount of heat carried away by the cooling water from the cylinder wall and piston, from being excessively cooled,
It is possible to suppress an increase in friction and improve fuel efficiency and output.

In the piston cooling device for an internal combustion engine according to a second aspect of the present invention, when it is determined that the pump discharge pressure is lower than the first reference value required for operating the hydraulic actuator, the cooling water temperature is Less than the reference value, the pump discharge pressure is determined to be a low heat load operating conditions that are equal to or higher than the second reference value, by the configuration that does not inject lubricating oil from the oil jet nozzle of the upstream cylinder, the pump discharge pressure is increased, The hydraulic actuator can be operated. Also, under operating conditions where the cooling water temperature is above the reference value or the pump discharge pressure is below the second reference value, lubricating oil is injected from the oil jet nozzle of the upstream cylinder, and the heat resistance of the piston becomes higher than the operation of the hydraulic actuator. Will be given priority.

In the piston cooling device for an internal combustion engine according to a third aspect of the present invention, the amount of lubricating oil injected from the oil jet nozzle of the first cylinder is reduced in an operating state where the heat load of the piston of the first cylinder is low. It is possible to prevent the cylinder wall of the first cylinder and the piston from being excessively cooled, suppress an increase in friction, and improve fuel consumption and output.

In the piston cooling device for an internal combustion engine according to a fourth aspect of the present invention, the variable valve mechanism that switches the lift characteristic of the valve in response to the discharge pressure of the oil pump has a lubricating oil temperature rising and a discharge pressure of the oil pump. When the operating condition is reduced to a certain extent, the amount of lubricating oil injected from the oil jet nozzle in the upstream cylinder is reduced, so that the hydraulic pressure necessary for operating the variable valve mechanism is obtained, and the valve operating under preset operating conditions. The lift characteristics can be switched appropriately, and abrupt changes in the torque generated by the engine can be suppressed.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a lubricating oil path diagram of the same.

FIG. 3 is a flowchart showing the same control contents.

FIG. 4 is a characteristic diagram similarly showing a control region.

FIG. 5 is a claim correspondence diagram showing the invention according to claim 1;

FIG. 6 is a claim correspondence diagram showing the invention according to claim 2;

[Explanation of symbols]

 1 Oil Pump 5 Engine 7 Electromagnetic Valve 8 Main Gallery 9 Hydraulic Valve 10 Oil Jet Nozzle 18 Variable Valve Mechanism 20 Piston 21 Water Jacket 30 Hydraulic Control Valve 31 Control Unit 32 Rotation Sensor 33 Water Temperature Sensor 34 Oil Temperature Sensor 36 Throttle Opening Sensor a oil jet nozzle b valve means c low heat load determination means d injection amount reduction means f water temperature detection means g oil pressure detection means h low oil pressure determination means

Claims (4)

[Claims] 1. A plurality of cylinders arranged in series, a water jacket in which cooling water flows around each cylinder along a cylinder row direction, an oil jet nozzle for injecting lubricating oil toward a piston of each cylinder, and an oil. The valve means for controlling the supply of lubricating oil to the jet nozzle, the low heat load determination means for determining the low heat load of the piston of the upstream cylinder located upstream of the water jacket, and the low heat load upstream A piston cooling device for an internal combustion engine, comprising: an injection amount reducing means for reducing an amount of lubricating oil injected from an oil jet nozzle of a side cylinder as compared with other cylinders. 2. A hydraulic actuator which operates in response to the discharge pressure of an oil pump, a water temperature detecting means for detecting the cooling water temperature of the engine, a hydraulic pressure detecting means for detecting the discharge pressure of the oil pump, and a pump discharge pressure When the low hydraulic pressure is less than the first reference value required for the operation of the hydraulic actuator, the low hydraulic pressure determination means, and when the low hydraulic pressure is determined, the cooling water temperature is below the reference value and the pump discharge The piston cooling device for an internal combustion engine according to claim 1, further comprising: a low heat load determination unit that determines an operating condition in which the pressure is equal to or higher than a second reference value as a low heat load. 3. The piston cooling device for an internal combustion engine according to claim 1, wherein the upstream side cylinder is the first cylinder closest to the cooling water inlet into which the cooling water flows into the water jacket. 4. A piston cooling device for an internal combustion engine according to claim 2, wherein the hydraulic actuator is a variable valve mechanism that switches the lift characteristic of the valve in response to the discharge pressure of the oil pump.