JPS60108556A - Intake heating apparatus for diesel engine - Google Patents

Abstract

PURPOSE:To effectively avoid the diesel knock in low speed and low load by supplying the coolant vapor supplied from a boiling cooling apparatus into a heating chamber in low speed and low loading and heating the intake by the coolant vapor having the high heat radiation performance and high temperature. CONSTITUTION:A heating chamber 64 having a circular section is formed midway in a bypass passage 60 which detours a condenser 23, and heat exchange with the intake in an intake pipe 61 is performed. A switching means is constituted of a control unit 50 and a solenoid valve 70. Since the bypass passage 60 is allowed to communicate by the valve opening of the solenoid valve 70 in low- speed and low-load, the coolant vapor in a gaseous space 22a is supplied into the heating chamber 64 through the bypass passage 60. Then, the intake gas is heated by the coolant vapor which has high heat radiation performance and high temperature, and the diesel knock in low-speed and low-load can be effectively avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an intake air heating device for a diesel engine that includes a boiling cooling device that cools the engine based on boiling vaporization of a liquid phase refrigerant.

(Technical background) A water-cooled cooling system that circulates cooling water between the engine water jacket and the radiator has to meet the required amount of heat dissipation due to efficiency and dimensional limitations of the radiator and the heat capacity of the water. It is necessary to circulate a large amount of cooling water, which causes a large drive loss in the water pump, and it is difficult to variably control the cooling water to an appropriate temperature depending on the engine operating state.

10,000, Special Publication No. 57-57608 and U.S. Patent No. 43676
In No. 99, a cooling system was proposed that utilizes the latent heat of vaporization of water to cool the engine with a small amount of circulating water. These systems use a cycle in which the cooling water stored in the water jacket is boiled using the heat generated by the engine, and the generated steam is liquefied in a radiator and returned to the water jacket. The structure is such that the path through which the water flows is communicated with the atmosphere to avoid pressure fluctuations, which not only causes maintenance problems such as easy cooling water consumption, but also fixes the engine temperature to the boiling point of the cooling water at atmospheric pressure. Therefore, there was a problem in that it was difficult to apply it to automobile engines, etc., where the required amount of heat radiation fluctuated greatly.

On the other hand, the present applicant, in Japanese Patent Application No. 58-145467, etc., sealed a liquid phase refrigerant in a closed loop cooling circuit and controlled the boiling point A by changing the pressure of the liquid refrigerant, thereby controlling the engine operating state. We are proposing a boiling cooling system that can perform efficient cooling according to the conditions.

To explain all this with reference to FIG. 1, in the figure, 21 is the engine (main body), 22 is a water jacket filled mostly with liquid phase refrigerant such as water, and 23 is water jacket 2.
24 is a tank that stores the liquefied refrigerant from the condenser 23; 25 is a supply pump that returns the refrigerant stored in the tank 24 to the water jacket 22; and 26 is a supply pump that supplies forced cooling air to the condenser 23. It is a cooling fan that supplies

The water jacket 22 is formed over the cylinder block 21a and the cylinder head 21b so as to surround the cylinders and combustion chambers of the engine 21, and has a predetermined amount of liquid phase refrigerant sealed therein. The upper part of the water jacket 22 is a gas phase space 22aK filled with refrigerant vapor.
It has become.

In addition, in a multi-cylinder engine, the gas phase space 22a is communicated with each other between each cylinder section.

Water jacket 22II: 1' its gas phase space 22a
Refrigerant injection pipe (steam manifold) 29 connected facing the
and communicates with the -C condenser inlet section 30 via the steam passage 27. The refrigerant injection pipe 29 is located at the top of the path through which the refrigerant circulates, and the upwardly rising injection port 29a is sealed with a cap 29b.

The lower tank 24 of the condenser 23 communicates with the water jacket 22 via a refrigerant passage 28, forming a closed circuit in which refrigerant circulates between the water jacket 22 and the condenser 23.

In the case of an automobile, the condenser 23 is installed in a position where the wind flows through the vehicle, and the cooling fan 26 is positioned on the front or rear side of the vehicle to supply forced cooling K to the condenser 23. Also,
The supply pump 25 is located in the middle of the refrigerant passage 28 and pumps the liquid phase refrigerant stored in the tank 24 to the water jacket 22 based on a command from a control system to be described later. In addition,
Both the cooling fan 26 and the supply pump 2511''1. are electric.

50 is a control circuit that controls the operation of the supply pump 25 and the cooling fan;
Like the liquid level sensor 31 provided, a control system is formed together with a temperature sensor 32 and other means (not shown) for detecting the engine operating state.

The liquid level sensor 31 is a single-point switch that turns on and off depending on the position of the refrigerant liquid level with respect to the detection part. Based on this change in output, the control circuit 5o drives the supply pump 25 when the refrigerant liquid level falls below a predetermined value depending on the position of the liquid level adjuster 31 until it reaches the predetermined liquid level again. All of the refrigerant stored in the tank 24 is replenished into the water jacket 22. Therefore, a predetermined amount or more of refrigerant liquid is always secured in the water jacket 22.

Note that the package (standard amount) of liquid phase refrigerant sealed in this cooling system is such that the inside of the condenser 23 is air-filled with the refrigerant being secured to the predetermined liquid level in the water jacket 22 as described above. It is set to such a degree that it is in a phase state.

The temperature sensor 32Fi detects the engine temperature from the temperature or pressure of the refrigerant, and provides an output corresponding to the engine temperature to the control circuit 50 as an actual temperature signal.

The control circuit 50 detects the actual temperature detected by the temperature sensor 32 as well as engine rotation, throttle opening, fuel supply amount, etc. through well-known sensors, determines the operating state of the engine, and determines the actual temperature. Based on the comparison, the cooling fan 26 is controlled to operate or stop so that the engine temperature reaches a predetermined temperature depending on the operating state at that time.

It goes without saying that the relationship between the engine operating state and the control temperature value can be set freely depending on the engine specifications, purpose, and application, but generally speaking, when driving in a city, the relationship between the engine operating state and the control temperature value can be set freely. The system is designed to maintain a relatively high temperature in low operating ranges, and to lower the temperature in high-speed, high-load ranges.

To explain the basic function of the cooling system based on the above configuration, when the liquid phase refrigerant in the water jacket 22 is heated by the engine combustion heat, it reaches a boiling point according to the pressure in the system at that time. When the temperature reaches that point, it starts boiling, takes away the latent heat of vaporization, and evaporates.

At this time, the refrigerant boils vigorously in the high-temperature parts of the engine 21 and cools the part corresponding to the latent heat of vaporization, so that the combustion chamber and the cylinder wall are kept at a substantially uniform temperature. This makes it possible to raise the temperature of the entire combustion chamber to near the limit temperature that does not cause problems such as abnormal combustion.

The refrigerant vapor generated as a result of the boiling cooling action is transferred to the steam passage 2.
7 from the water jacket 22Ω gas phase space 22a to the condenser 23, where it is cooled by heat exchange with outside air, condensed and liquefied, and then stored in the tank 24.

In this case, as described above, the inside of the condenser 230 is in a gas phase, and the high-temperature refrigerant vapor is cooled by the outside air with a large temperature difference under a good heat transfer state with the metal surface that constitutes the condenser 23. As a result, the heat dissipation efficiency is significantly increased compared to when heat is dissipated in the liquid phase. Incidentally, for this reason, the condenser 23 and the cooling fan 26 can be significantly smaller than those in the past.

The refrigerant liquefied in the condenser 23 and stored in the tank 24 is returned to the water jacket 22 again by the operation of the supply pump 25 as the refrigerant level in the water jacket 22 decreases, and the above process is repeated to perform boiling cooling. can continue.

- In such a closed-circuit boiling cooling system, the pressure inside the system always becomes negative when the engine is stopped. Therefore, as a measure against this negative pressure, the gas phase space 22a'tri is replaced with a liquid phase refrigerant from an auxiliary tank 41 provided outside.

The auxiliary tank 41 stores liquid phase refrigerant at least as large in capacity as the gas phase space 22a, and the inside thereof is provided with a cap 41. Atmospheric pressure is introduced via IK.

This auxiliary tank 41 communicates with the water jacket 22 via an auxiliary passage 37 having a solenoid valve 34 interposed therebetween.

When the solenoid valve 34't- is opened after the engine is stopped, the refrigerant stored in the auxiliary tank 41 is introduced into the system based on the decrease in pressure accompanying the temperature drop, and eventually the space in the system is mostly filled with liquid phase refrigerant. It will be replaced.

This reliably prevents harmful air from entering the cooling system when the engine is stopped. Note that when the engine is started in the above state, the liquid phase refrigerant in the system is pushed back into the auxiliary passage 37 and the auxiliary tank 41 by the pressure of the refrigerant vapor that has been boiled and vaporized by the combustion heat. water jacket 2
Since the refrigerant liquid amount in No. 2 is maintained at a predetermined value by the replenishment operation of the supply pump 25, apparently only the liquid amount in the condenser 23 decreases and the liquid level thereof decreases.

Eventually, when the inside of the capacitor 23 becomes a gas phase, the tank 2
The electromagnetic valve 34 closes based on a signal from the liquid level sensor 39 which detects this from the liquid level of 4, and thereafter the boiling cooling described above is performed.

As mentioned above, this boiling cooling system can quickly control the amount of heat dissipated according to the operating condition of the engine, and therefore the engine can always be operated under optimal temperature conditions, which greatly contributes to improving fuel efficiency and increasing output. Air infiltration into the cooling system, which has an adverse effect on heat dissipation efficiency, is self-managed and prevented by liquid replacement of the refrigerant, so it is characterized by extremely high practicality.

In a diesel engine, only air is taken in and compressed, and fuel is injected into the cylinder, which has become sufficiently hot due to the compression, to cause self-ignition.

However, unlike premixed gasoline engines that use a carburetor, the intake air is not forcibly heated, and the combustion chamber and cylinder temperatures are low at low speeds and low loads, such as when idling. The gas temperature at the end of the compression stroke is low, and the injected fuel does not immediately self-ignite.

For this reason, there is a problem in that the fuel heated by the high-temperature compressed air combusts explosively after a while, resulting in a so-called diesel knock in which the pressure rapidly increases.

(Objective of the Invention) An object of the present invention is to provide an intake air heating device that reduces diesel knock at low speeds and low loads by heating intake air using refrigerant vapor generated by evaporative cooling.

(Structure and operation of the invention) The present invention is based on a diesel engine equipped with an evaporative cooling device.

In other words, the evaporative cooling system connects the engine water jacket, which is mostly filled with liquid-phase refrigerant, and the condenser, which maintains the interior in the vapor phase, through a vapor passage that flows the refrigerant vapor from the upper part, and a pump that supplies the liquefied refrigerant from the condenser. A cooling 7a/ is provided which communicates with the refrigerant passage that returns via the refrigerant passage to form a closed circuit in which the refrigerant circulates, and supplies forced cooling air to the condenser, and an auxiliary tank storing liquid phase refrigerant is connected to the condenser via a valve means. and is connected to the closed circuit.

Further, in the present invention, the above-mentioned device is provided with a bypass passage that bypasses the condenser, and a heating means that is interposed in the bypass passage and exchanges heat with the intake air in the intake pipe.
A switching means is provided for connecting the bypass passage and supplying all of the refrigerant vapor to the heating means at low speed and low load.

Therefore, since the medium for heat exchange with the intake air is high-temperature refrigerant vapor, the heat exchange rate is high, and the intake air is quickly heated at low speeds and low loads.

(Example) The following description will be given based on the illustrated embodiment.

FIG. 2 is a schematic diagram of a first embodiment of the invention.

In the figure, as a bypass passage that detours around the capacitor 23,
A bypass passage 60 is formed from the upper part of the gas phase space 22a, passing through the cylinder head 21b, branching off, and merging upstream of the supply pump 25.

In the middle of this bypass passage 60, a heating means for heating by heat exchange with intake air is formed in the intake pipe 61.

Specifically, the intake pipe 61 has a collector section 62 and a branch pipe 63.
Therefore, the heating means includes a heating chamber 64 having an arc shape extending over the entire lower part of each branch pipe 63 and separating the branch pipe wall.
(See Figure 3).

Therefore, the high temperature refrigerant vapor supplied to the heating chamber 64 via the bypass passage 60 exchanges heat with the low temperature intake air in the branch pipe 63. In this case, the heat-radiated refrigerant vapor is condensed and liquefied and stored in the lower part of the heating chamber 64, so the lower part of the heating chamber 64 is inclined so that the stored liquefied refrigerant is returned to the refrigerant passage 28 via the bypass passage 60. The lowest part of the slope is connected to the bypass passage 60.

- 10,000, the switching means for communicating the bypass passage 60 at low speed and low load is composed of the operating state detection means and the control unit 5.
0 and a solenoid valve 70.

The operating state detection means includes, for example, a rotation speed sensor 66 that detects the engine rotation speed and a load sensor 67 that detects the opening degree of the control lever of the injection pump. determines the low speed and low load region, and the solenoid valve 7 installed in the pass passage 60 downstream of the outlet of the heating chamber 64
0 Fully open the valve.

Since the other constituent parts are the same as those in FIG. 1, the same parts are given the same reference numerals and detailed explanations will be omitted.

With the above configuration, at low speed and low load,
The control unit 50 opens the solenoid valve 70 based on a signal from the operating state detection means that detects this.

At low speeds and low loads, the temperature of the cylinder and combustion chamber is low, but the opening of the electromagnetic valve 70 opens the binoculars passage 60, so the refrigerant vapor in the gas phase space 22a flows through the bypass passage 60 to the heating chamber 64. supplied to

Since the partition wall of the branch pipe 63 that separates the intake air and the refrigerant vapor is made of metal, the heat transfer coefficient from the refrigerant vapor to the metal surface is more than three times larger than the heat transfer coefficient from hot water to the metal surface, and Since the temperature is higher than hot water, the intake air is heated efficiently.

As in the past, if the intake air is not heated at low speeds and low loads, as shown by the broken line in Figure 4, self-ignition is slow and combustion occurs rapidly after this layer ignition delay, resulting in a large pressure rise and resulting in diesel knock. . However, if the intake air is preheated at low speed and low load as in the present invention, the gas temperature at the end of the compression stroke will rise to the extent that it induces self-ignition, so self-ignition is likely to occur, and after ignition, the gas temperature will rise close to where the fuel is injected. Since the fuel is combusted, the pressure does not rise suddenly as shown by the solid line in FIG. 4, but instead follows a gradual curve, and as a result, diesel knock is avoided. Note that the one-point dotted line in FIG. 4 shows the case of motoring.

Further, in an operating range other than at low speed and low load, the drive current to the solenoid valve 70 is cut off and the valve is closed, and the bypass passage 60 is cut off. Therefore, the liquefied refrigerant does not circulate, and the supply of refrigerant vapor is stopped.

For example, when the load is high, the temperature of the combustion chamber is already high, so there is no need to heat the intake air, and therefore the solenoid valve 70 is closed.

FIG. 5 is a schematic diagram of a second embodiment of the invention.

In this example, an intake air temperature sensor 71 for detecting the intake air temperature is further attached to the branch pipe 61LZ in the first embodiment, and the intake air temperature is determined to be below a predetermined value based on the signal from this intake air temperature sensor 71 and the above-mentioned operating state detection means. The solenoid valve 70 is opened only at low speed and low load to heat the intake air.

The intake air is heated by refrigerant vapor when the temperature is low, and its temperature rises completely, contributing to maintaining the gas temperature at the end of the compression stroke.
Excessive heating lowers the filling efficiency and reduces the excess air ratio, causing smoke to occur. Therefore, when the intake air temperature exceeds a predetermined value, heating of the intake air is completely stopped.

Therefore, in this example, the diesel knock prevention operation range is further expanded, and the diesel knock prevention effect is further enhanced.

Further, in both the first embodiment and the second embodiment, the steam passage 29 leading to the condenser 23 may be provided with a solenoid valve that completely eliminates the opening cross-sectional area of the steam passage 29 at the same time as the solenoid valve 70 is opened. .

In this case, for example, when the amount of refrigerant vapor generated is small, such as immediately after startup, the amount of refrigerant vapor flowing to the condenser 23 is reduced, and the amount of refrigerant vapor supplied to the heating chamber 64 is increased accordingly. Therefore, the heating effect of the intake air is further improved.

(Effects of the Invention) As described above, according to the present invention, refrigerant vapor from the boiling cooling device is preferentially supplied to the heating chamber at low speed and low load, and intake air is converted into high-temperature refrigerant vapor with high heat dissipation. Since the heating is performed at a low speed and a low load, it is possible to effectively avoid diesel knocking at low speeds and low loads.

Drivability and fuel efficiency can be improved by avoiding diesel knock.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional example. FIG. 2 is a schematic diagram of the first embodiment of the present invention, FIG. 3 is a sectional view taken along the line AA in FIG. 2, and FIG. 4 is a characteristic diagram of the cylinder internal pressure. ' FIG. 5 is a schematic diagram of a second embodiment of the invention. 21... Engine (main body), 22... Water jacket, 22a... Gas phase space, 23... Condenser, 24... Tank, 25... Supply pump, 26...
- Cooling fan, 27... Steam passage, 28... Refrigerant passage, 31... Liquid level sensor, 32... Temperature sensor, 3
4... Solenoid valve, 37... Auxiliary passage, 41... Auxiliary tank, 5o... Control circuit, 60... Bypass passage, 61... Intake pipe, 63... Branch pipe, 64 ... Heating chamber, 66... Rotation speed sensor, 67... Load sensor, 7o... Solenoid valve, 71... Temperature sensor. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] The engine water jacket, which is mostly filled with liquid-phase refrigerant, and the condenser, which maintains the interior in a gas phase, are connected by a vapor passage in the upper part through which the refrigerant vapor flows, and a refrigerant passage, in which the liquefied refrigerant from the condenser is returned via a supply pump. A boiling cooling device that has a closed circuit that communicates with the refrigerant to circulate, is provided with a cooling fan that supplies forced cooling air to the condenser, and has an auxiliary tank storing liquid phase refrigerant connected to the closed circuit via a valve means. A diesel engine comprising: a bypass passage that bypasses the condenser; a heating means that is interposed in the bypass passage and exchanges heat with the intake air in the intake pipe; An intake air heating device for a diesel engine, characterized in that it is provided with a switching means for supplying air to the air.