JPH0979094A - Flow control valve for recirculating exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate mounting and reduce a cost, by providing a helical groove along a outer peripheral surface of a tubular part receiving a valve housing connection part, and screwing a cooling pipe into close contact to be matched with the helical groove, so that a functional part of a flow control valve is effectively protected from a high temperature transmitted from exhaust gas. SOLUTION: A valve housing 10 of a valve functional part 3, valve shaft 11 and a valve unit 12 provided in an end part of the valve shaft 11 are provided. The valve housing 10 is constituted by an exhaust passage part 10A and a tubular part 10B positioned in an upper part of the exhaust passage part 10A to hold a shaft connection part 13 in the inside also to have a helical groove part 13A in the outside. A coil-shaped cooling pipe 14, mounted so as to be screwed along the helical groove 13A, is provided. In order to protect the cooling pipe 14, a collar member 16 is held between above/below this pipe. In this way, in an operation mechanism part, in the case of using motors of step motor or the like particularly in the operation mechanism part, decrease in the function due to a high temperature can be effectively prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation flow control valve, and more particularly, to an exhaust gas recirculation control device which is controlled so as to recirculate a part of exhaust gas to an intake system in accordance with an operating state of an engine. The present invention relates to a flow control valve used in.

[0002]

2. Description of the Related Art In a vehicle engine, the amount of nitrogen oxides (NO _x ) contained in exhaust gas increases as the combustion gas temperature increases and the oxygen concentration remaining after combustion increases. Are known. When such NO _x is released into the atmosphere, it causes the generation of harmful substances due to photochemical reactions and causes pollution. Therefore, in order to suppress the NO _x and to keep the fuel economy and drivability in the optimum state, a part of the exhaust gas is exhausted. An exhaust gas recirculation (EGR) control device that recirculates from an exhaust system to an intake system according to an operating state of an engine has been widely adopted so far.

A flow rate control valve for such an EGR control device is disclosed in, for example, Japanese Patent Laid-Open No. 2-33459 and Japanese Patent Laid-Open No. 4-34359.
No. 276166 is disclosed.

In the former example, a housing provided with an exhaust gas recirculation passage that connects an intake system and an exhaust system of an engine,
A pipe, which is integrally provided in this housing and is curved in a U shape in advance in a lower case manufactured by casting, and has both ends thereof curved downward, is embedded as a cooling water passage. By circulating the cooling water through the cooling water passage, the heat transferred from the housing to the diaphragm via the lower case is effectively cut off.

Further, in the latter example, a control valve case provided with an exhaust gas recirculation passage for connecting an intake system and an exhaust system of an engine is used as a flow rate control valve of an EGR control device in which driving of a step motor is controlled. , A joint case interposed between the step motor and the control valve case, and a cooling water passage (cooling water pipe) is embedded in a thick portion of the joint case, and the cooling water passage is provided in the cooling water passage. By circulating the cooling water, the heat transmitted from the control valve case to the step motor of the flow control valve via the joint case is shut off.

[0006]

However, in each of the above-mentioned conventional examples, a cooling water pipe is provided in the lower thick portion of the lower case in the former case and in the thick portion of the joint case in the latter case. Since the casting is performed integrally by casting, the structure of the casting mold for forming the cooling water passage becomes complicated, resulting in a decrease in manufacturing work efficiency and an increase in cost. Further, since the diaphragm is cooled through the lower case and the step motor is cooled through the joint case, both are indirect and the formation area of the cooling water passage is limited. No cooling effect.

The object of the present invention is to pay attention to the above-mentioned conventional problems and to solve them, it is possible to effectively protect the functional part of the flow control valve from the high temperature transmitted from the exhaust gas. It is an object of the present invention to provide a flow rate control valve for exhaust gas recirculation, which is provided with cooling means which is arranged as described above and which can be easily mounted and reduced in cost.

[0008]

In order to achieve the above object, the present invention provides a valve member for recirculating exhaust gas to the intake side, and an operating shaft of an operating mechanism section involved in the opening / closing operation of the valve member. And a connecting portion that connects the valve shaft of the valve member to an integral valve housing, and a spiral groove is provided along an outer peripheral surface of a cylindrical portion of the valve housing in which the connecting portion is received. It is characterized in that a cooling pipe wound in a coil shape is closely screwed in accordance with the above.

According to the present invention, although the high temperature of the exhaust gas is transmitted to the valve housing, the outer circumference of the connecting portion of the tubular valve housing in which the valve shaft of the valve member and the operating shaft of the operating mechanism portion are connected to each other. By providing a spiral groove along the surface and screwing a cooling tube wound in a coil shape so as to be in close contact with the spiral groove, it is effective from the valve housing through such a cooling tube. In addition to being able to take away heat to the outside, it can also radiate heat from the coiled outer peripheral part of the cooling pipe itself that comes into contact with the atmosphere, so that it is possible to suppress not only the operating mechanism becoming hot but its function decline, but also easy cooling. The tube can be mounted in the housing.

[0010]

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

FIG. 1 shows a first embodiment of the present invention. Here, 1 is a flow rate control valve according to the present invention, 2 is a step motor section (operation mechanism section) thereof, and 3 is a valve function section.
The step motor unit 2 has an electromagnetic coil 6 as a stator held between a motor housing 4 and a coil casing 5 and a rotor 8 rotatably held by a bearing 7. Further, a female screw 8A is formed in the shaft hole of the rotating rotor 8, and the male screw portion 9A of the motor shaft (actuating shaft) 9 is screwed into the female screw 8A to rotate the rotor 8 in a straight line of the motor shaft 9. Converted into movement.

Reference numeral 10 denotes a valve housing of the valve function section 3, 1
Reference numeral 1 is a valve shaft, and 12 is a valve element provided at an end of the valve shaft 11. In addition, the valve housing 10 includes the exhaust passage portion 1.
0A, and a cylindrical portion 10B located above the exhaust passage portion 10A, which holds the shaft connecting portion 13 inside and has a spiral groove 13A outside. Reference numeral 14 is a coil-shaped cooling pipe attached so as to be screwed along the spiral groove 13A. The valve housing 1
In the final assembly step of the flow control valve 1 with and without the cooling pipe 14 attached to the tubular portion 10B of 0, the step motor portion 2 and the valve function portion 3 are fixed by bolts 15 as shown in FIG. The fixing member 16 is a collar member that is held between the upper and lower sides of the cooling pipe 14 to protect it.

Further, an exhaust passage portion 10A of the valve housing 10 has an exhaust inlet port 17A communicating with an exhaust system (not shown) of the engine, and an exhaust outlet port 1 communicating with an intake system.
7B is provided, and the valve seat 18 on which the valve body 12 is seated is attached therebetween. In this example, a male screw portion 11A and a female screw portion 12A are formed on the end portion of the valve shaft 11 and the valve body 12 so that the valve closing position can be adjusted. Reference numeral 19 denotes a shaft guide portion that keeps the valve shaft 11 slidable and keeps the space between the shaft connecting portion 13 and the exhaust passage 20 airtight.

In the flow rate control valve 1 having such a structure, the rotor 8 is rotated by energizing the electromagnetic coil 6 when a valve opening request is set in advance according to the operating condition of the engine, and the valve is passed through the motor shaft 9. By the downward valve opening operation by the shaft 11, the valve body 12 separates from the valve seat 18, and the exhaust inlet port 17A and the exhaust outlet port 17B communicate with each other. Thus, an EGR operation is performed in which a part of the exhaust gas introduced to the exhaust inlet port 17A from the exhaust system side via the bypass not shown is returned from the exhaust outlet port 17B to the intake system.

Here, the valve housing 10 is always in contact with the high-temperature exhaust gas via the exhaust inlet port 17A, so that the temperature becomes high. However, the spiral groove 13A around the cylindrical portion 10B of the valve housing 10 is provided. The coil-shaped cooling pipe 14 that keeps a sufficient contact area along the pipe can effectively cool the valve housing 10. Therefore, the high temperature transmitted to the step motor unit 2 through the motor housing 4 is radiated by the tubular portion 10B provided with the cooling pipe 14,
Furthermore, the high temperature transmitted to the chamber around the shaft connecting portion 13 via the valve shaft 11 can also be cooled. Note that, here, the member that houses the electromagnetic coil 6 such as the motor housing 4 and the coil casing 5 is made of a material having a high thermal conductivity such as aluminum or an aluminum alloy, so that the temperature generated from the step motor unit 2 itself is suppressed. The effect is obtained.

Further, since the cooling pipe 14 is formed in conformity with the shape of the spiral groove 13A, the coil-shaped cooling pipe 14 is screwed into the groove 13A so that the cooling pipe 14 can be extremely easily tubular. Not only can it be mounted in close contact with the outer peripheral surface of the portion 10B, but the outer peripheral side of the cooling pipe 14 is kept in direct contact with the atmosphere, so the heat dissipation effect is enhanced.

FIG. 2 shows a second embodiment of the present invention. In this example, in the motor housing 4 of the step motor portion 2, a male screw portion 4A is provided in a portion to be fitted with the tubular portion 10B of the valve housing 10, and a female screw is provided on the inner peripheral portion of the fitted tubular portion 10B. The portion 10C is provided, and the step motor portion 2 and the valve function portion 3 are integrally assembled by screwing the female screw portion 10C and the male screw portion 4A. If there is a risk that loosening will occur after the two are connected by screwing, known pin striking or spot welding may be used to prevent this. Other configurations are the same as those of the first embodiment described above. According to the present embodiment, the bolt 15 and the collar member 16 as shown in FIG. 1A are not required in the first embodiment, Further, the final assembling process can be further facilitated.

In the above-mentioned embodiments, an example of application to a flow control valve in which a step motor section is used as the actuator has been described, but it goes without saying that the present invention can also be applied to a system in which a DC motor is used instead of the step motor. Is. Furthermore, as an actuator, for example, Japanese Patent Laid-Open No. 2-3345 does not rely on the motor.
As in the example disclosed in No. 9, a flow rate control valve configured so as to drive the valve by utilizing the negative pressure of the intake system introduced into the diaphragm chamber is driven by a solenoid. It can be widely applied to control valves and the like.

[0019]

As described above, according to the present invention, a valve member for recirculating exhaust gas to the intake side,
A tubular portion in which a connecting portion that connects an operating shaft of an operating mechanism portion related to opening and closing of the valve member to a valve shaft of the valve member is housed in an integral valve housing, and the connecting portion of the valve housing is housed. Since a spiral groove is provided along the outer peripheral surface of the coil and the cooling pipe wound in a coil shape is closely screwed to the spiral groove, a motor such as a step motor is attached to the operating mechanism, particularly the operating mechanism. In the case of using a number, it is possible to effectively prevent the deterioration of its function due to high temperature.

Further, since the coiled cooling pipe is mounted so as to be screwed into the spiral groove on the outer peripheral surface of the tubular portion of the valve housing, the cooling passage is formed in the cast valve housing as in the conventional case. Not only can the mold for forming the valve housing be simplified, but also the assembly process does not require much labor for mounting the cooling pipe, which contributes to reduction in manufacturing cost.

Furthermore, the tubular portion and the motor housing containing the actuating mechanism portion are fastened together via the screw portion with the cooling pipe mounted on the outer peripheral surface of the tubular portion of the valve housing containing the connecting portion. By configuring, the assembly can be further facilitated and the cost can be further reduced.

[Brief description of drawings]

FIG. 1 is a side view of a configuration according to a first embodiment of the present invention (A).
It is explanatory drawing shown by the sectional view on the AA line of (A) and (B).

FIG. 2 is a side view of the configuration according to the second embodiment of the present invention (A).
It is explanatory drawing shown by the BB sectional drawing of (A) and (A).

[Explanation of symbols]

 1 Flow Control Valve 2 Step Motor Section (Operating Mechanism Section) 3 Valve Function Section 4 Motor Housing 5 Coil Casing 6 Electromagnetic Coil 7 Bearing 8 Rotor 8A Female Thread 9 Motor Shaft (Operating Shaft) 9A Male Thread Section 10 Valve Housing 10A Exhaust Passage Section 10B Cylindrical portion 10C Female screw portion 11 Valve shaft 12 Valve body 13A Spiral groove 14 Cooling pipe 15 Bolt 16 Color member 17A Exhaust inlet port 17B Exhaust outlet port 18 Valve seat 19 Shaft guide portion 20 Exhaust passage

Claims (2)

[Claims] 1. A valve member for recirculating exhaust gas to the intake side, and a connecting portion for connecting an operating shaft of an operating mechanism portion involved in opening / closing operation of the valve member to a valve shaft of the valve member are integrated. A spiral groove is provided along an outer peripheral surface of a cylindrical portion that is housed in the valve housing and that accommodates the connecting portion of the valve housing, and a cooling pipe wound in a coil shape is closely screwed to the spiral groove. A flow control valve for exhaust gas recirculation, characterized in that 2. The housing for accommodating the actuating mechanism portion and the tubular portion of the valve housing, to which the cooling pipe is closely screwed, are fastened to each other via a screw portion. The flow control valve for exhaust gas recirculation described.