JP2667317B2 - Engine cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for a vehicle engine. More particularly, the present invention relates to an engine cooling device suitable for a cab-over type truck.

[0002]

2. Description of the Related Art As a cooling device of this type, the present applicant has provided a radiator in communication with a cooling water system of an engine, and a header tank for storing supplementary cooling water at a position higher than a cooling water level in the engine. A reservoir that is provided in communication with the cooling water system, has a closed airtight pressure lid in the upper part of the header tank, and further stores reserve cooling water that is at the same level or higher as the header tank and can be supplied into the header tank. Patent application for a cooling device for an engine in which a tank is provided in communication with a pressure lid of a header tank.
-91411). In this device, a part of the cooling water expanded when the cooling water temperature rises at the time of starting the engine and steam generated in the cooling water system are condensed and stored in the reservoir tank, so that the cooling water hardly decreases.

However, in the above-described device, the pressure of the cooling water system of the engine rapidly increases due to the expansion of the cooling water accompanying the rise of the temperature of the cooling water at the time of starting the engine. there were. Further, during operation of the engine, there is a possibility that the components constituting the cooling water system of the engine may be deteriorated due to pressure fluctuations caused by a temperature change of the cooling water system. Furthermore, since the cooling water repeatedly expands and contracts due to the change in the cooling water temperature during operation of the engine,
There has been a problem that the frequency of valve opening of the pressure lid increases, humid air is discharged from the reservoir tank, and pre-cooling water gradually decreases.

In order to solve these problems, an air chamber protruding above the pressure lid is provided at an upper part of a tank body having a pressure lid at an upper part, and a water supply pipe and an air escape pipe are provided at a lower part of the tank body. The disclosed reserve tank is disclosed (Japanese Utility Model Application Laid-Open No. 61-94).
232). In this tank, the increase in the pressure of the cooling water system of the engine due to the expansion of the cooling water accompanying the rise in the temperature of the cooling water at the time of engine start is moderated by the air in the air chamber being compressed and serving as a cushion, and A sudden increase in pressure in the cooling water system can be prevented. Further, the width of the pressure fluctuation due to the change in the temperature of the cooling water system of the engine during operation of the engine can be suppressed within a range smaller than that of the air in the air chamber.

[0005]

However, in the above-mentioned tank, the air chamber protrudes upward from the tank body and the total height of the tank increases, so that the tank is installed in a place where the height is restricted such as under the floor of a cab of a truck. There was an inability to do so. Further, since the cooling water in the tank and the air in the chamber are in contact with each other over a wide area, the temperature of the air in the chamber rapidly changes with the temperature of the cooling water in the tank. For this reason, the temperature of the air in the air chamber rises as the temperature of the cooling water rises when the engine is started, so that not only the cooling water but also the air in the air chamber expands, and the air in the air chamber functions as a cushion. There was a problem that cannot fully be exhibited.

SUMMARY OF THE INVENTION It is an object of the present invention to moderate the rise in pressure of a cooling water system at the time of engine start, to reduce the range of pressure fluctuations in the cooling water system during operation of the engine, and to reduce the frequency of valve opening of a pressure lid. To provide an engine cooling device capable of extending a replenishment interval of preliminary cooling water to the engine.

[0007]

A configuration of the present invention for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment. The engine cooling device of the present invention stores a radiator 14 provided in communication with the cooling water system of the engine 13, a supplementary cooling water, and is located at a position higher than the cooling water level in the engine 13, and A header tank 19 provided in communication with a pressure lid 22 that is closed and airtight at the top, and stores pre-cooling water and is at the same level or higher as the header tank 19;
9 is a cooling device for an engine, comprising a reservoir tank 38 which communicates with the inside of the pressure lid 22 and is capable of supplying pre-cooling water into the header tank 19, and which expands on the bottom surface of the header tank 19 via the communication passage 20a. The bottom surface of the space tank 20 is provided at a location where the space is communicated.

[0008]

When the engine 13 is started, the cooling water expands with an increase in the temperature of the cooling water, and the pressure of the cooling water system of the engine 13 tends to increase rapidly, but the expanded cooling water communicates with the header tank 19. By compressing the air in the space tank 20, the pressure rise in the cooling water system of the engine 13 becomes gentle. Further, during operation of the engine 13, pressure fluctuations due to temperature changes of the cooling water system of the engine 13 are absorbed by the air in the expansion space tank 20, the pressure fluctuations are suppressed within a small range, and the pressure lid 22 is hardly opened.

[0009]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 1 to 5, an engine 13 and a radiator 14 are mounted on a chassis frame 12 below a floor panel 11 of a cab-over type truck 10. The lower part of the radiator 14 communicates with the jacket of the engine 13 via a water pump 16 and the radiator 14
Communicates with the jacket of the engine 13 via the thermostat 17. The pump 16 is connected to the thermostat 17 via the bypass line 15 (FIG. 1).

A header tank 19 for storing makeup water is provided at a position higher than the cooling water level in the jacket of the engine 13. In this example, the header tank 19 is formed flat in the horizontal direction, and the floor panel 1 close to the back panel 18 is formed.
1 bracket 12 erected from the frame 12 below
a. A supply port 19a for supplying makeup water to the cooling water system is provided at the bottom of the header tank 19, and the supply port 19a is connected to the pump 16 via a water supply pipe 21 (FIG. 1). A pressure lid 22 is attached to a lid attachment portion 19b formed on the upper part of the header tank 19 (FIGS. 2, 4 and 5). In addition, the header tank 19 is provided with inlets 19c and 19d for introducing bubble-containing water containing bubbles generated in the cooling water system of the engine 13, and the upper end of the thermostat 17 and the radiator through air escape pipes 23 and 24, respectively. 14 (FIG. 1). The header tank 19 includes a tank lower member 26 and a tank upper member 27 each formed of a synthetic resin. A plurality of lower baffle plates 2 are provided inside the tank lower member 26 and the tank upper member 27.
8a and the upper baffle plate 28b are respectively provided integrally. The tank lower member 26 and the tank upper member 27 are joined by hot plate welding with the openings facing each other, and the header tank 19 is formed by welding the edges of the openings and the edges of the plates 28a and 28b (FIG. 2 and FIG. 2). (Fig. 3).

A characteristic configuration of the present embodiment is that the bottom surface of the expansion space tank 20 is provided to communicate with the bottom surface of the header tank 19 via the communication passage 20a. As shown in detail in FIGS. 2 and 3, the expansion space tank 20 has an air chamber 20g formed therein and a tank lower member 20b.
And a tank upper member 20c. Tank lower member 2
0b is the rib 2 on the tank lower member 26 of the header tank 19.
0d, the tank upper member 20c
Is formed integrally with the tank upper member 27 via the rib 20e. The communication passage 20a is connected to the tank lower member 20b.
And a connecting portion 20f integrally formed between the bottom surfaces of the tank lower member 26.

In the header tank 19, a bubble-containing water introduction chamber 29, 30, a buffer chamber 31, and a makeup water supply chamber 32 are sequentially formed by a baffle plate 28 from the front to the rear in the traveling direction of the truck 10. The inlets 19c and 19d are located in the introduction chambers 29 and 30, respectively, and the supply port 19a is located in the supply chamber 32. At the upper and lower portions of the plate 28, small-diameter vent holes 28c communicating the four chambers 29 to 32 are provided.
And a large-diameter water passage hole 28d. A slope is provided on the top surface of the tank upper member 27, and the volume of the introduction chamber 29 located on the front side in the traveling direction of the truck 10 is the smallest, and the volume increases toward the rear.
2 is formed the largest. Tank lower member 26
Before joining the tank upper member 27 with the auxiliary pipe 3
The base ends of the members 4 and 35 are inserted into the introduction ports 19c and 19d, respectively, and are bent so that their ends are located near the top surface of the upper member 27, respectively. Further pipe 3
4, 35 are ribs 29a, 30 formed on the lower member 26.
The pipes 34 and 35 are fixed by inserting these grooves into the grooves at the end of a and closing the grooves with the ribs 29b and 30b formed on the upper member 27 (FIGS. 2 and 3).

At the bottom of the buffer chamber 31, a water level alarm sensor 36 which is activated when the amount of cooling water falls below a predetermined amount is mounted (FIG. 2). The sensor 36 is connected to a water level alarm circuit (not shown) provided in the cab. The supply port 19a provided at the bottom of the supply chamber 32 is formed at a predetermined angle with respect to the bottom surface of the header tank 19, in this example, at an angle of 25 ° with respect to the bottom surface of the header tank 19, so as to protrude tubularly from the bottom surface of the header tank 19. Then, the opening area of the supply port 19a facing the bottom surface of the header tank 19 is formed large in an elliptical shape (FIGS. 2 and 3). As described above, the lid mounting portion 19 formed at the upper part of the supply chamber 32, that is, at the highest top of the header tank 19
A pressure lid 22 is attached to b (FIGS. 2, 4 and 5). The lid 22 is moved by the elastic force of the spring 22a.
pressure valve 2 that can be in close contact with lower seat 19e
2b. A through hole 22c is provided in the center of the valve 22b, and a vacuum valve 22e that can be in close contact with the bottom surface of the valve 22b is inserted into the through hole 22c by the elastic force of a spring 22d. When the lid 22 is closed, the top seal 22f of the lid 22 is attached to the top sheet 19f of the lid mounting portion 19b.
, So that the gas in the header tank 19 does not leak from the lid 22.

A front lid 3 is provided on the front of the cab 10a.
7 is provided to be openable and closable. Inside the lid 37, a reservoir tank 38 is housed and installed at the same level as the header tank 19. Preliminary cooling water is stored in the reservoir tank 38, and the reservoir tank 38 is connected to the lid mounting portion 19b via a hose 39 so as to be connected thereto. An overflow tube 38a communicating with the atmosphere and a water supply lid 38b are provided above the reservoir tank 38. Further, a rear body 41 is provided close to the rear surface of the back panel 18 (FIG. 1).

The operation of the engine cooling apparatus thus configured will be described. When the engine 13 is started, the temperature of the cooling water in the cooling water system of the engine 13 rises, and the cooling water expands. The expanded cooling water enters the air chamber 20g in the expansion space tank 20 connected to the header tank 19 via the communication passage 20a, and compresses the air in the air chamber 20g. At this time, the pressure of the cooling water system of the engine 13 is
Since the pressure is lower than the pressure at which the second pressure valve 22b is opened, the pressure valve 22b is not opened. As a result, the pressure rise generated by the expansion of the cooling water of the incompressible fluid does not immediately act on the cooling water system of the engine 13, and the air chamber 2
0 g of air acts as a cushion to moderate the pressure rise in the cooling water system of the engine 13.
Each component constituting the cooling water system does not deteriorate.

While the engine 13 is running, the thermostat 17
Detects that the cooling water temperature has become higher than a predetermined water temperature, a cooling fan (not shown) operates to lower the cooling water temperature and contract the cooling water. The contraction of the cooling water is absorbed by the expansion of the air in the air chamber 20g. At this time, since the pressure of the cooling water system of the engine 13 does not become a negative pressure, the vacuum valve 22e of the pressure lid 22 does not open. When the thermostat 17 detects that the cooling water temperature is lower than the predetermined water temperature, the cooling fan stops, the cooling water temperature rises, the cooling water expands, and the cooling water expands. The expansion of the cooling water is absorbed by compressing the air in the air chamber 20g. At this time, since the pressure of the cooling water system of the engine 13 is smaller than the pressure at which the pressure valve 22b of the pressure lid 22 opens, the pressure valve 22b does not open. As a result, the pressure fluctuation of the cooling water of the incompressible fluid does not immediately act on the cooling water system of the engine 13, and the range of the pressure fluctuation of the cooling water system of the engine 13 can be suppressed within a small range. The components constituting the cooling water system do not deteriorate. Further, since the frequency of opening the pressure valve 22b and the vacuum valve 22e of the pressure lid 22 is extremely small, the evaporation of the cooling water can be minimized, and the frequency of the operation of replenishing the cooling water can be greatly reduced. it can.

In the embodiment, the expansion space tank is formed integrally with the header tank. However, this is merely an example, and the expansion space tank is formed of a separate member from the header tank, and a communication passage is formed inside. The connection member may be connected so that the bottom surface of the header tank and the bottom surface of the expansion space tank communicate with each other. In the embodiment, the expansion space tank is provided at substantially the same level as the header tank. However, the expansion space tank may be provided at a position higher or lower than the header tank. In the embodiment, the header tank is divided into four chambers by the baffle plate. However, the header tank may be divided into three or less chambers or five or more chambers by the baffle plate.
Alternatively, the entire inside of the header tank may be formed in one chamber without using a baffle plate. Further, although the capacity of the expansion space tank is made constant in the embodiment, the capacity of the expansion space tank may be changed. In this case, the pressure of the cooling water system and the temperature of the cooling water can be kept constant, so that the combustion efficiency of fuel in the cylinder of the engine can be improved, and the cavitation of the water pump can be prevented. Further, although the cooling device for the engine of the truck is described in the embodiment, the cooling device for the engine of a passenger car, another vehicle, or an industrial machine may be used.

[0018]

As described above, according to the present invention, a radiator is provided in communication with the cooling water system of the engine, and the header tank which stores the supply cooling water at a position higher than the cooling water level in the engine is provided. Provided in communication with the cooling water system,
An airtight pressure lid is provided in the upper part of the header tank in a closed state, and a reservoir tank that is at the same level or higher as the header tank and stores preliminary cooling water that can be supplied to the header tank is communicated with the header tank pressure lid. And the bottom of the expansion tank is connected to the bottom of the header tank via a communication passage, so that the sudden increase in pressure of the cooling water system when the engine starts is absorbed by the air in the expansion tank. Thus, it is possible to prevent the components constituting the cooling water system of the engine from deteriorating. Further, during the operation of the engine, the air in the expansion space tank suppresses the pressure fluctuation of the cooling water system of the engine within a small range, so that it is possible to prevent the components constituting the cooling water system of the engine from deteriorating. Further, since the air in the expansion space tank absorbs pressure fluctuations due to the expansion and contraction of the cooling water and the frequency of opening the pressure lid decreases, the interval of replenishment of the preparatory cooling water to the reservoir tank can be extended.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of a truck including an engine cooling device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an expansion space tank and a header tank.

FIG. 3 is a perspective view showing a state before a hot plate is welded to an expansion space tank and a header tank.

FIG. 4 is an enlarged cross-sectional view of a pressure lid showing a state where a pressure in a header tank is increased and a pressure valve is opened.

FIG. 5 is a cross-sectional view corresponding to FIG. 4, showing a state in which the pressure in the header tank decreases and the pressure valve is closed.

[Explanation of symbols]

 13 engine 14 radiator 19 header tank 20 expansion space tank 20a communication passage 22 pressure lid 38 reservoir tank

Claims (1)

(57) [Claims] A radiator (14) provided in communication with a cooling water system of an engine (13), and a replenishing cooling water is stored therein and is located at a position higher than a cooling water level in the engine (13). 13) A pressure lid which is provided in communication with the cooling water system and has a closed
(22) provided with a header tank (19), which stores preliminary cooling water, is at the same level or higher as the header tank (19), and communicates with the inside of the pressure lid (22) of the header tank (19). A cooling tank for the engine, comprising a reservoir tank (38) capable of supplying the preliminary cooling water into the header tank (19), and a communication passage (20a) formed on a bottom surface of the header tank (19). The cooling device for an engine, wherein a bottom surface of the expansion space tank (20) is provided so as to communicate therewith.