JPH0598964A - Cooling device for engine - Google Patents

Abstract

PURPOSE:To loosen a pressure rise in a cooling system at the time of engine starting by providing an expansion space tank, to reduce amplitude of pressure change of the cooling water during operation of the engine, and to prolong supplementary intervals of preservation cooling water to a reservoir tank by decreasing valve-opening frequency of a pressure cover. CONSTITUTION:A radiator 14 is communicated with a cooling water system of an engine 13. A header tank 19 is communicated with the cooling water system of the engine 13, which tank 19 is arranged on a position higher than a cooling water level inside the engine 13 and stores supplementary cooling water. A pressure cover 22, having air-tightness in a closing condition is provided on an upper portion of the header tank 19. A reservoir tank 38 is communicated with the pressure cover 22 of the header tank 19, which tank 38 is arranged on a portion as high as the header tank 19 or higher and stores preservation cooling water capable of being sent into the header tank 19. A bottom surface of an expansion space tank 20 is communicated with a bottom surface of the header tank 19 through a communication passage 20a.

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 specifically, it 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 applicant of the present invention is provided with a radiator in communication with a cooling water system of an engine, and a header tank at a position higher than the cooling water level in the engine for storing makeup cooling water A reservoir that is provided in communication with the cooling water system, has a pressure lid that is airtight in a closed state at the top of the header tank, and that is at the same level as the header tank or above and that stores preliminary cooling water that can be sent to the header tank. An application for an engine cooling device in which a tank is provided in communication with the pressure lid of a header tank (Japanese Patent Application No. 2)
-91411). In this device, a part of the cooling water expanded when the temperature of the cooling water 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 is hardly reduced.

However, in the above apparatus, 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 cooling water temperature at the time of starting the engine, so that there is a risk of deteriorating the respective parts constituting the cooling water system of the engine. there were. Further, during engine operation, pressure fluctuations associated with temperature changes of the cooling water system may cause deterioration of each component forming the cooling water system of the engine. Furthermore, because the cooling water repeats expansion and contraction due to changes in the cooling water temperature during engine operation,
There has been a problem that the frequency of opening the pressure lid increases and humid air is discharged from the reservoir tank, and the amount of precooling water gradually decreases.

In order to solve these problems, an air chamber projecting above the pressure lid is provided above the tank body having a pressure lid at the top, and a water supply pipe and an air escape pipe are provided below the tank body. A reserve tank is disclosed (Shokaisho 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 increase in the cooling water temperature at the time of engine start is moderated by the air in the air chamber being compressed and acting as a cushion. It is designed to prevent a sudden pressure rise in the cooling water system. Further, the width of the pressure fluctuation due to the change in the temperature of the cooling water system of the engine during the 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 tank, since the air chamber projects upward from the tank body to increase the overall height of the tank, the tank is installed in a place where the height is limited, such as under the floor of the cab of a truck. There was a problem that could not be done. 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 changes abruptly as the temperature of the cooling water in the tank changes. Therefore, when the engine starts, the temperature of the air in the air chamber rises as the cooling water temperature rises, so not only the cooling water but also the air in the air chamber expands, and the air in the air chamber serves as a cushion. There was a problem that could not be fully utilized.

An object of the present invention is to slow down the pressure rise of the cooling water system at the time of engine start, to reduce the width of pressure fluctuation of the cooling water system during engine operation, and to reduce the frequency of opening the pressure lid to reduce the frequency of opening the reservoir tank. An object of the present invention is to provide an engine cooling device that can extend the interval for supplying 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 supplementary cooling water and a radiator 14 provided in communication with the cooling water system of the engine 13, and is located at a position higher than the cooling water level in the engine 13 and is connected to the cooling water system of the engine 13. A header tank 19 which is provided in communication and has a pressure lid 22 having airtightness in a closed state at the upper part, and precooling water are stored, and the header tank 19 is at the same level as or higher than the header tank 1.
9 is a cooling device for an engine including a reservoir tank 38 that communicates with the inside of the pressure lid 22 of FIG. 9 and that can supply preliminary cooling water into the header tank 19, and expands the bottom surface of the header tank 19 through a communication passage 20 a. It is where the bottom surface of the space tank 20 is provided in communication.

[0008]

When the engine 13 is started, the cooling water expands as the cooling water temperature rises, and the pressure of the cooling water system of the engine 13 tries to rise rapidly. However, the expanded cooling water communicates with the header tank 19 and expands. By compressing the air in the space tank 20, the pressure rise of the cooling water system of the engine 13 becomes slow. Further, the air in the expansion space tank 20 absorbs the pressure fluctuation caused by the temperature change of the cooling water system of the engine 13 during the operation of the engine 13, the width of the pressure fluctuation is suppressed within a small range, and the pressure lid 22 is hardly opened.

[0009]

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 portion of the radiator 14 communicates with the jacket of the engine 13 via the water pump 16,
The upper part of the engine 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 horizontally flat, and is adjacent to the back panel 18.
Bracket 12 erected from a frame 12 below 1.
It is attached to 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). The pressure lid 22 is attached to the lid attachment portion 19b formed on the upper portion of the header tank 19 (FIGS. 2, 4, and 5). Further, 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 via the air escape pipes 23 and 24, respectively. It is connected to the upper end of 14 (FIG. 1). The header tank 19 is composed of a tank lower member 26 and a tank upper member 27, each of which is molded of 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 integrally provided. Further, the tank lower member 26 and the tank upper member 27 have their openings opposed to each other, and the peripheral edge of the openings and the edges of the plates 28a and 28b are joined by hot plate welding to form the header tank 19 (FIG. 2 and FIG. 2). (Figure 3).

The characteristic structure of this embodiment is that the bottom surface of the expansion tank 20 is provided in communication with the bottom surface of the header tank 19 via a 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. Lower tank member 2
0b is a rib 2 on the tank lower member 26 of the header tank 19.
Tank upper member 20c which is integrally formed through 0d.
Is integrally formed with the tank upper member 27 via the rib 20e. Further, the communication passage 20a is a tank lower member 20b.
And the tank lower member 26 is integrally formed between the bottom surfaces of the connecting portion 20f.

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

At the bottom of the buffer chamber 31 is attached a water level alarm sensor 36 which operates when the amount of cooling water falls below a predetermined level (FIG. 2). This 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, and in this example, is inclined at an angle of 25 ° with respect to the bottom surface of the header tank 19 and projects in a tubular shape from the bottom surface of the header tank 19. As a result, the opening area of the supply port 19a facing the bottom surface of the header tank 19 is formed in a large elliptical shape (FIGS. 2 and 3). As described above, the lid mounting portion 19 formed on the upper portion of the supply chamber 32, that is, the highest top portion of the header tank 19.
A pressure lid 22 is attached to b (FIGS. 2, 4, and 5). The lid 22 is attached to the lid 22 by the elastic force of the spring 22a.
Pressure valve 2 that can be attached to the lower seat 19e of b
2b. A through hole 22c is provided at the center of the valve 22b, and a vacuum valve 22e that can be brought into close contact with the bottom surface of the valve 22b by the elastic force of a spring 22d is inserted into the through hole 22c. 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.
It is configured so that the gas inside the header tank 19 does not leak from the lid 22.

A front lid 3 is provided on the front surface of the cab 10a.
7 is provided so that it can be opened and closed. 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. An overflow tube 38a communicating with the atmosphere and a water supply lid 38b are arranged above the reservoir tank 38. Further, a rear body 41 is provided close to the back surface of the back panel 18 (FIG. 1).

The operation of the engine cooling device 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 through 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 changed to the pressure lid 2.
The pressure valve 22b does not open because it is lower than the pressure for opening the second pressure valve 22b. As a result, the pressure rise generated by the expansion of the cooling water of the incompressible fluid does not act immediately on the cooling water system of the engine 13, and the air chamber 2
Since 0 g of air acts as a cushion and moderates the pressure rise of the cooling water system of the engine 13, the engine 13
The components that make up the cooling water system do not deteriorate.

The thermostat 17 while the engine 13 is operating
When detecting that the cooling water temperature is higher than the predetermined water temperature, a cooling fan (not shown) operates to lower the cooling water temperature and the cooling water contracts. This contraction of the cooling water is absorbed by the expansion of the air in the air chamber 20g. At this time, the pressure of the cooling water system of the engine 13 does not become a negative pressure, so that 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. This expansion of the cooling water is absorbed by compressing the air in the air chamber 20g. At this time, the pressure of the cooling water system of the engine 13 is lower than the pressure for opening the pressure valve 22b of the pressure lid 22, so 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 width of the pressure fluctuation of the cooling water system of the engine 13 can be suppressed within a small range. It does not deteriorate the components of the cooling water system. Further, since the frequency of opening the pressure valve 22b and the vacuum valve 22e of the pressure lid 22 is extremely low, the evaporation of the cooling water can be suppressed to the minimum, and the frequency of the replenishing work of the cooling water can be greatly reduced. it can.

In the embodiment, the expansion space tank is formed integrally with the header tank, but this is an example, and the expansion space tank is formed as a separate member from the header tank, and the communication passage is formed inside. The bottom surface of the header tank and the bottom surface of the expansion space tank may be connected by a connecting member so as to communicate with each other. Further, although the expansion space tank is provided at substantially the same level as the header tank in the embodiment, the expansion space tank may be provided at a position higher or lower than the header tank. Further, in the embodiment, the inside of the header tank is divided into 4 chambers by the baffle plate, but it may be divided into 3 chambers or less or 5 chambers or more by the baffle plate,
Alternatively, the entire header tank may be formed as one chamber without using the baffle plate. Further, in the embodiment, the capacity of the expansion space tank is made constant, but 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 made constant, so that the combustion efficiency of the 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 mentioned in the embodiment, it may be a cooling device for the engine of a passenger car, other vehicles or industrial machines.

[0018]

As described above, according to the present invention, the radiator is provided in communication with the cooling water system of the engine, and the header tank at the position higher than the cooling water level in the engine for storing the supplementary cooling water is provided in the engine. Provided in communication with the cooling water system,
A pressure lid that is closed and airtight is provided above the header tank, and a reservoir tank that is at the same level as the header tank or above and that stores pre-cooling water that can be fed into the header tank is connected to the header tank pressure lid. Since the bottom surface of the expansion tank is connected to the bottom surface of the header tank through a communication passage, the air in the expansion space tank absorbs a sudden increase in pressure of the cooling water system at engine startup. Therefore, it is possible to prevent deterioration of each component constituting the cooling water system of the engine. 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 deterioration of each component constituting the cooling water system of the engine. Further, the air in the expansion space tank absorbs the pressure fluctuation due to the expansion and contraction of the cooling water, and the valve opening frequency of the pressure lid is reduced, so that the supply interval of the preliminary cooling water to the reservoir tank can be extended.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part 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 hot plate welding of the expansion space tank and the header tank.

FIG. 4 is an enlarged cross-sectional view of the pressure lid showing a state in which the pressure in the header tank rises and the pressure valve opens.

FIG. 5 is a cross-sectional view corresponding to FIG. 4, showing a state in which the pressure in the header tank is lowered 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)

[Claims] 1. A radiator (14) provided so as to communicate with a cooling water system of an engine (13), and a makeup cooling water is stored in the radiator (14) at a position higher than a cooling water level in the engine (13). A pressure lid installed in communication with the cooling water system of 13) and airtight in the closed state at the top.
A header tank (19) provided with (22) and precooling water are stored and are at the same level or higher as the header tank (19) and communicate with the pressure lid (22) of the header tank (19). A cooling device for an engine comprising a reservoir tank (38) capable of sending the preliminary cooling water into the header tank (19), wherein a communication passage (20a) is provided on the bottom surface of the header tank (19). The cooling device for the engine, wherein the bottom surface of the expansion space tank (20) is provided so as to communicate with each other.