JP2009264154A - Egr valve device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EGR valve device capable of preventing generation of black smoke caused by supply of excessive EGR gas to a gas supply side and generation of chattering by structural features of device elements constituting the EGR valve device. <P>SOLUTION: In the EGR valve device 10, by the movement of an EGR valve 30 to the axial direction of a shaft 32, a valve element 31 opens/closes a valve hole 28 in order to recirculate and cut off exhaust gas on an EGR passage 17. A housing 22 of the EGR valve device 10 has a liquid filling chamber 27 filled with liquid, and a volume chamber 36 which is communicated with the liquid filling chamber 27 and to which the shaft 32 is inserted is formed within a guide hole 28. A throttle passage 37 for interconnecting the liquid filling chamber 27 and the volume chamber 36 is formed. The cross section of the throttle passage 37 is set smaller than the flow passage cross section of the volume chamber 36, and by the reciprocation of the shaft 32, the volume of the volume chamber 36 is fluctuated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an EGR device in which a part of exhaust gas discharged from an engine body of an internal combustion engine to an exhaust passage is recirculated to an intake passage through an EGR passage and is supplied again into a combustion chamber. The present invention relates to an EGR valve device that controls opening and closing.

Conventionally, in a diesel engine, for the purpose of reducing nitrogen oxides (hereinafter referred to as “NOx”) generated in a combustion chamber, a part of exhaust gas discharged from the engine body to the exhaust passage is removed from the EGR passage. In some cases, an exhaust gas recirculation (hereinafter referred to as “EGR”) device that recirculates air to the intake passage is provided.
Note that the main component of the recirculated EGR gas is an inert gas. If the supply amount of EGR gas is excessively increased, the amount of intake air supplied to the combustion chamber becomes excessively small, resulting in insufficient oxygen. Since black smoke may be generated, it is preferable to adjust the supply amount of EGR gas in accordance with the diesel engine operation state.
Therefore, an EGR valve device that adjusts the amount of EGR gas is installed in the EGR passage that connects the exhaust passage and the intake passage.
Normally, the opening adjustment of the EGR valve in the EGR valve device is performed by controlling an actuator that is a drive source of the valve.

The amount of EGR gas passing through the EGR passage varies depending on the EGR valve opening degree in the EGR valve device and the differential pressure between the upstream side and the downstream side of the EGR valve.
In the EGR valve device, a target opening degree of the EGR valve corresponding to the operating state of the engine is set in advance.
An electronic control unit (ECU) mounted on the vehicle determines whether or not EGR gas is necessary, and when it is determined that EGR gas needs to be passed, opens the EGR valve at the target opening degree. .

However, if the operating state rapidly changes in a short time, the differential pressure between the upstream side and the downstream side of the EGR valve becomes excessive, and the EGR valve may be opened from the closed state to the target opening degree.
At this time, the differential pressure between the upstream side and the downstream side of the EGR valve is a large value, and after opening the EGR gas is excessively supplied to the intake passage until the differential pressure becomes a steady state. Black smoke may be generated.
In addition, when the opening of the EGR valve is small, there is a problem that chattering occurs when the pressure in the exhaust passage fluctuates due to pulsation, and abnormal noise is generated and the durability of the EGR valve is impaired.

In order to solve this problem, for example, an EGR control device for an internal combustion engine disclosed in Patent Document 1 is known.
The EGR control device includes an EGR device that includes an EGR valve that adjusts the amount of EGR that is recirculated through an exhaust circulation passage that communicates the exhaust passage and the intake passage, and a control unit that controls the opening of the EGR valve. It has been.
The control means controls the EGR valve to a target opening degree according to the operation state at that time, and performs EGR return control when the EGR valve is opened from the fully closed state. In EGR return control, the EGR valve is set as a target. After holding for a set time at a set opening smaller than the opening, the target opening is returned.
The EGR return control in Patent Document 1 means that when the EGR is turned on from off, the EGR valve is not immediately opened to the target opening, but the timing to open to the target opening is the exhaust pressure even if a severe accelerator operation is performed. In this control, the pressure difference between the intake pressure and the intake pressure is waited and delayed for a set time that is expected to sufficiently converge to the steady state value.
JP 2004-36413 A

Although the EGR control device disclosed in Patent Literature 1 can solve the problem of black smoke due to supply of excess EGR gas to the supply side and chattering when the opening of the EGR valve is small, The EGR return control for preventing the EGR valve from being immediately opened to the target opening when the EGR is turned on is based on program control using an electronic control unit.
In other words, in the prior art, in order to solve the problem of excessive EGR gas supply to the supply side and the problem of chattering, the EGR valve is held at a set opening smaller than the target opening for a set time, and then the target opening is performed. A control program that restores each time and a control system that executes the program are required.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to provide a black color by supplying excess EGR gas to the supply side due to the structural features of the apparatus elements constituting the EGR valve apparatus. The present invention provides an EGR valve device that can prevent the generation of smoke and chattering.

In order to achieve the above object, the present invention includes a valve housing having a valve hole disposed in an EGR passage of an internal combustion engine and disposed in a gas passage, a shaft and a valve body, and opens and closes the valve hole. An EGR valve device having an EGR valve and an actuator connected to the shaft for driving to open and close the EGR valve, wherein a part of the shaft is inserted and a liquid filling chamber having a liquid therein; A throttle passage that is defined by the shaft and the valve housing, is formed by the shaft and the valve housing, communicates the volume chamber and the liquid filling chamber, and changes the flow path cross-sectional area by the movement of the EGR valve. And at least in a state where the EGR valve is in the closed position, the flow passage cross-sectional area of the throttle passage is small.
The throttle passage may have the same flow area as the volume chamber depending on the opening of the EGR valve. In this case, there is no distinction between the throttle passage and the volume chamber.

According to the present invention, when the EGR valve is opened from the closed position, since the flow passage cross-sectional area of the throttle passage is small, rapid movement of the EGR valve is limited by the flow of liquid flowing through the throttle passage, Excessive EGR gas supply to the intake side is suppressed.
Therefore, in the present invention, rapid movement of the EGR valve can be suppressed, and generation of black smoke and chattering can be prevented.

  Further, according to the present invention, in the EGR valve device, the flow passage cross-sectional area of the throttle passage is in a small state in a range from the valve closing position of the EGR valve to a predetermined valve opening position, and is fully opened from the predetermined valve opening position. It is good also as a large state in the range which reaches a valve position.

In this case, sudden movement of the EGR valve is suppressed in the lift range from the closed position where the flow passage cross-sectional area of the throttle passage is set to a small state to the fully opened position in the total lift range of the EGR valve. In the lift range from the predetermined valve opening position where the flow passage cross-sectional area of the passage is set to a large state to the fully valve opening position, the EGR valve can be moved rapidly with respect to the operation of the actuator.
For this reason, when the EGR valve is opened from the closed position to the predetermined open position, excessive EGR gas is supplied to the supply side by a throttle action that restricts the movement of the EGR valve by the flow of liquid flowing through the throttle passage. By suppressing it, generation of black smoke and chattering can be prevented, and when the EGR valve is opened from the predetermined valve opening position to the fully opened position, the valve body can be quickly moved to the target opening degree.

  In the present invention, in the above EGR valve device, the volume chamber may be formed over the entire circumference of the shaft.

  In this case, since the volume chamber is formed over the entire circumference of the shaft, the shaft does not slide in contact with the housing in the volume chamber, and uneven wear does not occur in the shaft.

  According to the present invention, in the above EGR valve device, the throttle passage is formed by the shaft and the liquid filling chamber wall surface, and the liquid filling chamber wall surface in the throttle passage is in the direction perpendicular to the shaft axis. You may provide the reduced diameter wall part with the cross-sectional area diameter-reduced from the area.

In this case, the throttle passage is formed by the filling chamber side wall surface of the shaft and the reduced diameter wall portion in which the guide hole is formed.
Since the reduced diameter wall portion forms a part of the throttle passage, conditions such as processing surface restrictions for providing the filling chamber side wall surface on the shaft are relaxed, and the degree of freedom in setting the throttle passage is high. Become.

  According to the present invention, the EGR valve device can prevent the generation of black smoke and chattering due to the supply of excessive EGR gas to the supply side due to the structural features of the device elements constituting the EGR valve device. Can be provided.

Hereinafter, an EGR valve device according to an embodiment of the present invention will be described with reference to FIGS.
In this embodiment, an EGR valve device provided in an EGR (exhaust gas recirculation) device in a diesel engine as an internal combustion engine will be described.
FIG. 1 is a schematic view showing an EGR valve device and its periphery according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing a main part of the EGR valve device, and shows a state when the EGR valve is closed. 3 is an enlarged vertical cross-sectional view showing the main part of the EGR valve device shown in FIG. 2, and FIG. 4 is a vertical cross-sectional view showing the main part of the EGR valve device, when the EGR valve is open. Indicates the state.
An engine 11 as an internal combustion engine shown in FIG. 1 includes a cylinder bore (not shown) into which a reciprocating piston (not shown) is inserted.
The engine 11 is formed with a cooling water passage 12 through which cooling water for cooling each part of the engine 11 is passed.

The engine 11 has an intake pipe 14 that constitutes an intake passage 13 and an exhaust pipe 16 that constitutes an exhaust passage 15.
The intake passage 13 has a throttle valve (not shown) further upstream of the intake pipe 14.
The intake air FA is supplied into the combustion chamber via the intake passage 13 and burned together with the fuel injected from the fuel injection valve in the combustion chamber, and the exhaust gas EG after combustion is discharged to the outside through the exhaust pipe 16.

The engine 11 has an EGR passage 17 that connects the exhaust passage 15 and the intake passage 13.
The EGR passage 17 is a passage for returning a part of the exhaust gas EG discharged from the combustion chamber as the EGR gas RG from the exhaust passage 15 to the intake pipe 14.
The EGR gas RG that has passed through the EGR passage 17 is mixed with the intake air FA in the intake passage 13 and supplied to the combustion chamber as a mixed gas MG.
An EGR cooler 18 and an EGR valve device 20 are installed in the middle of the EGR passage 17.
The EGR cooler 18 is for cooling the EGR gas RG passing through the EGR passage 17 so as to have an appropriate temperature.
The EGR cooler 18 is disposed on the upstream side of the EGR valve device 20, and the cooling medium of the EGR cooler 18 is engine cooling water.

The EGR valve device 20 is a valve device for adjusting the amount of EGR gas passing through the EGR passage 17.
As shown in FIG. 1, the EGR valve device 20 includes a valve housing 22 disposed in the middle of the EGR passage 17.
An actuator 21 (in this embodiment, a diaphragm that operates with negative pressure) is provided on the upper portion of the valve housing 22.
An EGR valve 30 that is actuated by an actuator 21 is provided inside the valve housing 22.
The actuator 21 according to this embodiment includes a diaphragm mechanism (not shown).
In addition to being disposed in the middle of the EGR passage 17, the valve housing 22 is disposed in the middle of the cooling water circulation passage 19 connected to the cooling water passage 12.

As shown in FIG. 2, two space portions are formed vertically in the valve housing 22.
The lower space portion forms a gas passage 23 through which EGR gas passes.
As shown in FIG. 1, the upstream end of the gas passage 23 is connected to an upstream EGR passage 17 </ b> A communicating with the EGR cooler 18 and the exhaust passage 15.
The downstream end of the gas passage 23 is connected to a downstream EGR passage 17 </ b> B connected to the intake pipe 14.
A valve seat 24 having a valve hole 25 and a seat surface 26 is provided in the middle of the gas passage 23.
In this embodiment, the valve seat 24 is mounted on the valve housing 22 in a horizontal state so that the valve hole 25 faces up and down.

The upper space in the valve housing 22 is a cooling water filling chamber 27 as a liquid filling chamber, and the cooling water filling chamber 27 is filled with cooling water as a liquid.
As shown in FIG. 2, the cooling water filling chamber 27 has an introduction passage 27 a and a discharge passage 27 b, and the introduction passage 27 a is connected to the upstream side of the cooling water circulation passage 19.
The outlet passage 27 b is connected to the downstream side of the cooling water circulation passage 19.
The cooling water filling chamber 27 is configured to receive the supply of cooling water from the introduction passage 27a through the cooling water circulation passage 19, and the cooling water used in the cooling water circulation passage 19 is led out from the outlet passage 27b.

A through hole is formed between the gas passage 23 and the cooling water filling chamber 27, and this through hole is a first guide hole 28 for guiding the EGR valve 30.
The hole wall of the valve housing 22 forming the first guide hole 28 has a reduced diameter wall portion 22a having a reduced diameter hole 28a on the cooling water filling chamber 27 side.
The diameter-reduced hole 28 a formed by the diameter-reduced wall portion 22 a has a diameter that is smaller than the diameter of the first guide hole 28.
The reduced diameter wall portion 22a includes an annular wall surface 22b that faces the first guide hole 28 and is formed in the radial direction.
Another through hole is formed in the upper part of the cooling water filling chamber 27 in the valve housing 22, and this through hole is a second guide hole 29 for guiding the EGR valve 30.
In this embodiment, the centers of the valve hole 25 of the gas passage 23, the first guide hole 28, and the second guide hole 29 coincide with each other.

Here, the EGR valve 30 will be described.
The EGR valve 30 includes a valve body 31 that is attached to and detached from the valve seat 24, and a shaft 32 that includes the valve body 31 at an end.
The valve body 31 has a shape that expands in a bowl shape from the lower end of the shaft 32 in the radial direction of the shaft 32.
The outer peripheral surface 31 a of the valve body 31 is reduced in diameter downward, and the outer peripheral surface 31 a is in surface contact with the seat surface 26 when the valve body 31 is seated on the valve seat 24.
The shaft 32 is inserted through the first guide hole 28 and the second guide hole 29 and penetrates the gas passage 23 and the cooling water filling chamber 27.
The upper end of the shaft 32 is connected to the actuator 21.

The shaft 32 has a sliding shaft portion 33 that slides with the first guide hole 28, an intermediate shaft portion 34 formed by reducing the shaft diameter from the sliding shaft portion 33, and a shaft diameter that extends from the intermediate shaft portion 34. And a diameter-expanding shaft portion 35 formed by expanding the diameter.
The cross section of each axial part 33, 34, 35 in the direction perpendicular to the axial direction is circular.
First, the sliding shaft portion 33 will be described. The sliding shaft portion 33 is the shaft portion closest to the valve body 31 side.
The shaft diameter of the sliding shaft portion 33 is set so that the sliding shaft portion 33 and the first guide hole 28 are in sliding contact with each other.
The sliding shaft portion 33 is provided with a sliding portion (a portion set in the range of R1 in FIG. 2) inserted into the first guide hole 28 in the axial direction.

Next, the intermediate shaft portion 34 will be described.
The intermediate shaft portion 34 is a shaft portion that is formed continuously from the sliding shaft portion 33.
The shaft diameter of the intermediate shaft portion 34 is set to be smaller than the hole diameter of the first guide hole 28 and the shaft diameter of the sliding shaft portion 33.
A radial surface connecting the outer diameter surface of the sliding shaft portion 33 and the outer diameter surface of the intermediate shaft portion 34 is a passage side wall surface 33a.
When the EGR valve 30 is closed, all of the intermediate shaft portion 34 is inserted into the first guide hole 28, and when the EGR valve 30 is fully opened (100% open), the upper half of the intermediate shaft portion 34 is about The axial length of the intermediate shaft portion 34 is set so as to leave the first guide hole 28 to the cooling water filling chamber 27.

Next, the diameter-expanded shaft portion 35 will be described. The diameter-expanded shaft portion 35 is a shaft portion formed continuously from the intermediate shaft portion 34.
The shaft diameter of the diameter-expanded shaft portion 35 is set larger than the shaft diameter of the intermediate shaft portion 34 and smaller than the inner diameter of the diameter-reduced hole 28a formed by the diameter-reduced wall portion 22a.
A radially extending surface that connects the outer diameter surface of the intermediate shaft portion 34 and the outer diameter surface of the enlarged diameter shaft portion 35 is a filling chamber side wall surface 35b.
The lower part of the diameter-expanded shaft part 35 is mainly located in the cooling water filling chamber 27, and the upper part is mainly inserted into the second guide hole 29.
The upper end of the diameter expansion shaft portion 35 is connected to the actuator 21.
A part of the lower portion of the diameter-expanded shaft portion 35 is referred to as a portion 35a to be inserted into the first guide hole 28 when the EGR valve 30 is closed (for convenience of description, “insertable portion 35a”. R2 in FIG. 2). It is a part set by the range).

Since the shaft diameter of the intermediate shaft portion 34 is smaller than the shaft diameter of the sliding shaft portion 33, a cylindrical volume chamber 36 as a volume chamber is formed in the first guide hole 28.
In the state where the insertable portion 35a is inserted into the first guide hole 28, the cylindrical volume chamber 36 has an outer surface formed by the valve housing 22 and an intermediate shaft portion 34 as shown in FIGS. And an end surface on the gas passage 23 side formed by the passage side wall surface 33a, and an end surface on the cooling water filling chamber 27 side formed by the filling chamber side wall surface 35b and the annular wall surface 22b. Yes.
Accordingly, the cylindrical volume chamber 36 is mainly formed over the entire circumference of the intermediate shaft portion 34 of the shaft 36.
Cooling water is introduced into the cylindrical volume chamber 36 from the cooling water filling chamber 27.
In the passage side wall surface 33 a and the annular wall surface 22 b, the region S set in the radial direction is a region that overlaps each other when viewed from the axial direction, and is a region that moves away from and close to each other by the reciprocating motion of the shaft 32.
In other words, the end surface on the cooling water filling chamber 27 side and the end surface on the gas passage 23 side in the cylindrical volume chamber 36 have an overlap region that moves away from each other by the reciprocating motion of the shaft 32.
Since the overlap region exists, the volume of the cylindrical volume chamber 36 varies due to the reciprocation of the shaft 32.
The volume of the cylindrical volume chamber 36 becomes the maximum volume when the EGR valve 30 is closed, and becomes the minimum volume when the EGR valve 30 is 100% opened.

In a state where the insertable portion 35a is inserted into the first guide hole 28, the area obtained by adding the areas of the filling chamber side wall surface 35b and the annular wall surface 22b is set smaller than the area of the passage side wall surface 33a.
For this reason, a gap is formed between the reduced diameter wall portion 22 a and the insertable portion 35 a or the intermediate shaft portion 34 of the shaft 32.
This gap constitutes a throttle passage 37 between the cooling water filling chamber 27 and the cylindrical volume chamber 36.
In a state where the insertable portion 35a is inserted into the first guide hole 28, the flow passage cross-sectional area of the throttle passage 37 is formed small, and the insertable portion 35a is inserted into the first guide hole 28. In a state where it is not, the flow passage cross-sectional area of the throttle passage 37 is formed to be large.
In this embodiment, the axial length of the insertable portion 35a is set smaller than the axial length of the reduced diameter wall portion 22a.

The range in which the flow passage cross-sectional area of the throttle passage 37 is small corresponds to the lift range of the EGR valve 30.
The range in which the flow passage cross-sectional area of the throttle passage 37 is small is such that the insertable portion 35a is disengaged from the first guide hole 28 from the closed position where insertion of the insertable portion 35a into the first guide hole 28 is maximized. This corresponds to the lift range of the EGR valve 30 up to the valve opening position.
Of the entire lift range of the EGR valve 30, the insertable portion 35 a is located in the cooling water filling chamber 27 in the lift range from the valve opening position where the insertable portion 35 a is separated from the first guide hole 28 to the fully open position. .
That is, the lift range of the EGR valve 30 in which the insertable portion 35a is detached from the first guide hole 28 corresponds to a range where the flow passage cross-sectional area of the throttle passage 37 is in a large state.
As shown in FIG. 4, the flow path cross-sectional area between the reduced diameter wall portion 22 a and the intermediate shaft portion 34 is within the range of the cylindrical volume chamber 36 in the range where the flow path cross-sectional area of the throttle passage 37 is large. The area of the overlap region becomes larger, and the throttle passage 37 at this time does not function as a throttle.

The range in which the flow passage cross-sectional area of the throttle passage 37 is small corresponds to the lift range of the EGR valve in which chattering is likely to occur in the conventional EGR valve device.
In the EGR valve device 20, the flow passage cross-sectional area of the throttle passage 37 is made small in this range, so that when the opening degree of the EGR valve 30 is relatively small, the EGR valve 30 reciprocates in a very small range. Repetitive chattering is suppressed by the throttling action.
On the other hand, in the range in which the flow passage cross-sectional area of the throttle passage 37 is in a large state, the throttle action does not function so that the cooling water is smoothly passed between the cooling water filling chamber 27 and the cylindrical volume chamber 36, and the actuator The responsiveness of the EGR valve 30 based on the operation of 21 is not impaired.
For example, as shown in FIG. 4, when the flow passage cross-sectional area of the throttle passage 37 is large, the end surface of the cylindrical volume chamber 36 on the cooling water filling chamber 27 side is only the annular wall surface 22b in the reduced diameter wall portion 22a. It is formed by.

An annular seal member 38 is attached to the valve housing 22 at a position facing the gas passage 23 of the first guide hole 28.
The sliding shaft portion 33 existing below the cylindrical volume chamber 36 prevents the cooling water from entering the gas passage 23 from the first guide hole 28, but the annular seal member 38 enters the cooling water gas passage 23. Is more reliably prevented.
An annular seal member 39 is attached to the valve housing 22 at a position facing the cooling water filling chamber 27 of the second guide hole 29, and the annular seal member 39 moves toward the actuator 21 side of the coolant through the second guide hole 29. Prevent the intrusion.

Next, the operation of the EGR valve device 20 of this embodiment will be described.
When the engine 11 is in a predetermined operation state, a part of the exhaust gas EG of the engine 11 is recirculated to the intake passage 13 through the EGR cooler 18 and the EGR valve device 20.
The opening degree of the EGR valve 30 is adjusted according to the operating state of the engine 11, and the recirculation amount of the exhaust gas EG to the intake passage 13 is determined according to the opening degree of the valve body 31.
The degree of opening and closing of the EGR valve 30 is set on the assumption that the differential pressure between the upstream EGR passage 17A and the downstream EGR passage 17B is a steady differential pressure.
That is, the target opening degree of the EGR valve 30 based on the steady differential pressure is set, and the actuator 21 operates to reach the target opening degree according to the operating state of the engine 11.

The enlarged diameter shaft portion 35 formed on the shaft 32 of the EGR valve 30 is inserted into and removed from the first guide hole 28 according to the degree of opening and closing of the EGR valve 30.
As shown in FIGS. 2 and 3, when the diameter-expanded shaft portion 35 is inserted into the first guide hole 28, the reduced-diameter wall portion 22 a and the insertable portion 35 a of the diameter-expanded shaft portion 35 are opposed to each other to form a cylindrical shape. The end surface of the volume chamber 36 on the cooling water filling chamber 27 side is formed by a filling chamber side wall surface 35b and an annular wall surface 22b.
Therefore, the flow passage cross-sectional area of the throttle passage 37 is formed small between the cylindrical volume chamber 36 and the cooling water filling chamber 27 in the first guide hole 28.
By setting the flow passage cross-sectional area of the throttle passage 37 to a small state, the flow of cooling water between the cylindrical volume chamber 36 and the cooling water filling chamber 27 is throttled by receiving a throttle action.
For example, when the shaft 32 rises (forwards) in a state where the diameter-expanded shaft portion 35 is inserted into the first guide hole 28, the passage side wall surface 33a approaches the annular wall surface 22b, and the volume of the cylindrical volume chamber 36 is increased. Decrease.
At this time, the pressure in the cylindrical volume chamber 36 increases due to the throttling action of the throttling passage 37, and the rapid opening operation of the EGR valve 30 is suppressed.
When the shaft 32 is lowered while the diameter-expanded shaft portion 35 is inserted into the first guide hole 28, the volume of the cylindrical volume chamber 36 increases. The pressure of 36 falls, and the rapid valve closing operation of the EGR valve 30 is suppressed.
For this reason, when the diameter-expanded shaft portion 35 is inserted into the first guide hole 28, the rapid movement of the EGR valve 30 is suppressed by the action of the restriction of the restriction passage 37, and the movement of the EGR valve 30 becomes gentle.
When the flow passage cross-sectional area of the throttle passage 37 is small, the pressure in the cylindrical volume chamber 36 varies according to the degree of volume variation of the cylindrical volume chamber 36 due to the reciprocating motion of the shaft 32.

As shown in FIG. 4, when the EGR valve 30 is in a valve opening state greater than or equal to a predetermined value, the insertable portion 35 a is detached from the first guide hole 28 and the end surface of the cylindrical volume chamber 36 on the cooling water filling chamber 27 side. Is formed only by the annular wall surface 22b.
Accordingly, the flow passage cross-sectional area of the throttle passage 37 is formed large between the cylindrical volume chamber 36 and the cooling water filling chamber 27.
At this time, the cooling water entering and exiting between the cylindrical volume chamber 36 and the cooling water filling chamber 27 has a weak throttling action, so the cooling water between the cooling water in the cylindrical volume chamber 36 and the cooling water filling chamber 27 is Going in and out is smooth.
Therefore, the EGR valve 30 can be moved suddenly.
Conversely, when the EGR valve 30 moves from the fully open position to the closed position, when the insertable portion 35a is inserted from the coolant filling chamber 27 into the first guide hole 28, the flow passage cross-sectional area of the throttle passage 37 is increased. Is formed small.
When the EGR valve 30 moves from the fully open position to the closed position by the lowering (return) of the shaft 32, the passage side wall surface 33a is separated from the annular wall surface 22b.
For this reason, in the lift range of the EGR valve 30 from the timing of insertion of the insertable portion 35a into the first guide hole 28 to the valve closing, the volume increase of the cylindrical volume chamber 36 becomes gentle due to the throttling action, and the EGR valve The rapid movement of 30 is suppressed.

A specific operation state will be described. For example, in general, the EGR valve 30 is controlled to be closed during a high load such as during rapid acceleration. In this case, the rotational speed of the engine 11 increases while the EGR valve 30 is closed, and the differential pressure between the upstream EGR passage 17A and the downstream EGR passage 17B of the EGR valve device 20 becomes excessive.
Thereafter, at the timing when the EGR valve is opened due to a medium to low load, the EGR valve 30 tends to open suddenly from the closed state to the fully opened state due to the influence of an excessive differential pressure.
In this case, the sliding shaft portion 33 is further inserted into the first guide hole 28 and attempts to rapidly reduce the volume of the cylindrical volume chamber 36, but the flow passage cross-sectional area of the throttle passage 37 is formed small. In the lift range of the EGR valve 30, the rapid reduction of the cylindrical volume chamber 36 is hindered by the throttle action, and the volume of the cylindrical volume chamber 36 gradually decreases according to the flow rate through the throttle passage 37.

For this reason, the EGR valve 30 is opened by a gradual movement, but in a range where the insertable portion 35a faces the reduced diameter wall portion 22a, the gradual movement of the EGR valve 30 is maintained due to a throttling action.
When the insertable portion 35a is detached from the first guide hole 28 to the cooling water filling chamber 27, the flow passage cross-sectional area of the throttle passage 37 is formed large as shown in FIG. The volume is allowed to rapidly decrease, and the EGR valve 30 is quickly opened to the target opening degree by the operation of the actuator 21.
In the EGR valve device 20, the EGR valve 30 is moved gently at the initial stage of valve opening, and is allowed to move quickly when a predetermined opening is exceeded, so that black smoke is not generated in the exhaust gas while NOx is generated. The reduction effect is maintained.

Furthermore, another driving situation will be described.
If the EGR valve 30 is in the open position less than the predetermined opening, the EGR valve 30 may try to generate chattering due to a differential pressure fluctuation between the intake passage 13 and the exhaust passage 15.
When the EGR valve 30 is in the open position less than a predetermined opening, the insertable portion 35a in the diameter-expanded shaft portion 35 is located between the cooling water filling chamber 27 and the cylindrical volume chamber 36 together with the diameter-reduced wall portion 22a. The flow passage cross-sectional area of the throttle passage 37 is formed small.
Therefore, when the volume of the cylindrical volume chamber 36 decreases due to the throttling action of the throttling passage 37, the EGR valve 30 moves slowly, so that chattering that repeats the reciprocating motion in a minute range of the EGR valve 30 is repeated. Is prevented.

This embodiment has the following effects.
(1) When the insertable portion 35a of the enlarged diameter shaft portion 35 is inserted into the first guide hole 28, the filling chamber side wall surface 35b exists in the first guide hole 28, and the flow passage cross-sectional area of the throttle passage 37 Therefore, the rapid movement of the EGR valve 30 is suppressed by the throttle action of the throttle passage 37, and the EGR valve 30 moves slowly. When the insertable portion 35 a is detached from the first guide hole 28 and a flow passage cross-sectional area of the throttle passage 37 is formed between the cylindrical volume chamber 36 and the cooling water filling chamber 27, Compared with the case where the flow path cross-sectional area is small, the throttle action is weak, so that the EGR valve 30 can be moved rapidly. Therefore, after the EGR valve 30 is held at a set opening smaller than the target opening for a set time, the EGR valve 30 can be returned to the target opening and chattering can be prevented. Thus, in this embodiment, rapid valve opening and chattering of the EGR valve 30 can be prevented based only on the structural features of the valve housing 22 and the shaft 32 that constitute a part of the EGR valve device 20.

(2) When the shaft 32 reciprocates and the volume of the cylindrical volume chamber 36 fluctuates in a lift range from a predetermined valve opening position to a fully valve opening position where the flow passage cross-sectional area of the throttle passage 37 is set small, The rapid movement of the EGR valve 30 is suppressed, and in the lift range from a predetermined valve opening position where the flow passage cross-sectional area of the throttle passage 37 is set to a fully opened position, the EGR valve 30 suddenly moves with respect to the operation of the actuator 21. It can be moved. For this reason, while not generating the black smoke by supply of the excess EGR gas RG to the supply side, the NOx reduction effect can be maintained and chattering can be prevented.
(3) When the flow passage cross-sectional area of the throttle passage 37 is set to be small, it is formed by the insertable portion 35 a and the reduced diameter wall portion 22 a, but the reduced diameter wall portion 22 a forms part of the throttle passage 37. Since it is an element, conditions such as restrictions on the processing surface in providing the diameter-expanded shaft portion 35 on the shaft 32 are relaxed, and the setting of the flow passage cross-sectional area and passage length in setting the throttle passage 37 is reduced. The degree of freedom increases.

(4) Since the cooling water is introduced into the cylindrical volume chamber 36 in the first guide hole 28, the shaft 32 of the EGR valve 30 is cooled in a wide range, and overheating of the EGR valve 30 can be suppressed. Therefore, the exhaust gas EG having a temperature higher than that of the conventional one can be used as the EGR gas RG.
(5) Since the cylindrical volume chamber 36 is mainly formed over the entire circumference of the intermediate shaft portion 34, the intermediate shaft portion 34 does not come into sliding contact with the valve housing 22 in the cylindrical volume chamber 36, and the intermediate shaft Uneven wear does not occur in the portion 34.

(Example 1)
Next, an EGR valve device according to another example of the above embodiment will be described.
An EGR valve device according to another example 1 is shown in FIG.
The EGR valve device 40 according to this alternative example 1 is an example in which the reduced diameter wall portion 22a described in the previous embodiment is not provided.
For convenience of explanation, common or similar constituent elements are used in common with the previous embodiment, and the explanation is used.
In this example, the EGR valve 50 includes a valve body 51 and a shaft 52, and the shaft 52 includes a sliding shaft portion 53, an intermediate shaft portion 54, and an enlarged diameter shaft portion 55.
A radial surface connecting the outer diameter surface of the intermediate shaft portion 54 and the outer diameter surface of the enlarged diameter shaft portion 55 is a filling chamber side wall surface 55b.
In this example, the sliding shaft portion 53 and the intermediate shaft portion 54 are set to the same shaft diameter.

In this example, the first guide hole 43 is formed by the valve housing 42, but the first guide hole 43 includes a slide hole portion 44 into which the slide shaft portion 53 is inserted, and cooling of the slide hole portion 44. A diameter-enlarged hole portion 45 formed on the water filling chamber 27 side and having a hole diameter set larger than the hole diameter of the sliding hole portion 44 is provided.
A radial surface connecting the inner peripheral surface of the sliding hole portion 44 and the inner peripheral surface of the enlarged diameter hole portion 45 is a passage side wall surface 46.
In FIG. 5, the intermediate shaft portion 54 is mainly inserted through the diameter-expanded hole portion 45, but the diameter-expanded hole portion 45 is inserted through part of the sliding shaft portion 53 and part of the diameter-expanded shaft portion 55. Is done.

In this other example 1, the shaft diameter of the diameter-expanded shaft portion 55 is set larger than that of the previous embodiment.
An insertable portion 55 a to be inserted into the enlarged diameter hole 45 is formed in the enlarged diameter shaft portion 55.
In a state where the insertable portion 55a is inserted into the diameter-expanded hole 45, the insertable portion 55a forms a throttle passage 57 that functions sufficiently with the hole wall.
Therefore, a throttle passage 57 is formed between the cylindrical volume chamber 56 as a volume chamber formed over the entire circumference of the intermediate shaft portion 54 in the diameter-expanded hole portion 45 and the cooling water filling chamber 27.
The cross-sectional area of the throttle passage 57 is set smaller than the cross-sectional area of the cylindrical volume chamber 56.
The cylindrical volume chamber 56 includes an outer surface formed by the valve housing 42, an inner surface formed by the intermediate shaft portion 54, an end surface on the gas passage 23 side formed by the passage side wall surface 46, and a filling chamber side wall surface. And an end surface on the cooling water filling chamber 27 side formed by 55b.
Therefore, the cylindrical volume chamber 56 is mainly formed over the entire circumference of the intermediate shaft portion 54 of the shaft 52.

In the passage side wall surface 46 and the filling chamber side wall surface 55 b, the region S set in the radial direction is a region that overlaps each other when viewed from the axial direction, and is a region that moves away from and close to each other by the reciprocating motion of the shaft 32.
That is, the end surface on the cooling water filling chamber 27 side and the end surface on the gas passage 23 side in the cylindrical volume chamber 56 have an overlap region that moves away from each other by the reciprocating motion of the shaft 52.
Since there is an overlap region, the volume of the cylindrical volume chamber 56 fluctuates due to the reciprocating motion of the shaft 52, and in a state where the flow passage cross-sectional area of the throttle passage 57 is formed small, depending on the degree of volume fluctuation. The pressure in the cylindrical volume chamber 56 varies.
The volume of the cylindrical volume chamber 56 becomes the minimum volume when the EGR valve 50 is closed, and becomes the maximum volume when the EGR valve 50 is 100% opened.
Since the throttle passage 57 is formed, the area of the filling chamber side wall surface 55 b is smaller than the area of the passage side wall surface 46.
In this other example, when the EGR valve 50 moves from the closed position to the fully closed position due to the rising (forward movement) of the shaft 52, the filling chamber side wall surface 55 b is separated from the passage side wall surface 46, and the shaft 52 In the downward movement (return), the filling chamber side wall surface 55 b approaches the passage side wall surface 46.

In the state where the insertable portion 55a is not inserted into the first guide hole 43, the throttle passage 57 and the cylindrical volume chamber 56 are not distinguished.
At this time, the end surface on the cooling water filling chamber 27 side is not formed in the cylindrical volume chamber 56.
According to this alternative example 1, since the diameter-expanded hole 45 in the first guide hole 43 is formed with a constant diameter, it is not necessary to form a reduced-diameter wall in the valve housing 42.

(Example 2)
Next, an EGR valve device according to another example 2 will be described with reference to FIG.
An EGR valve device 60 according to another example 2 shown in FIG. 6 is another example in which the reduced-diameter wall portion 22a described in the previous embodiment is not provided.
For convenience of explanation, common or similar constituent elements are used in common with the previous embodiment, and the explanation is used.
In this example, the EGR valve 70 includes a valve body 71 and a shaft 72, and the shaft 72 is formed by a sliding shaft portion 73 and an intermediate shaft portion 74.
Accordingly, the shaft 72 is not formed with the diameter-expanded shaft portions 35 and 45 in the previous embodiment and the other example 1.
In this example, the sliding shaft portion 73 and the intermediate shaft portion 74 are set to the same shaft diameter, and both the shaft portions 73 and 74 are the same as in the first example.

In this example, the first guide hole 63 formed by the valve housing 62 is formed. The first guide hole 63 includes a slide hole portion 64 into which the slide shaft portion 73 is inserted, and a slide hole portion. 64 is provided on the cooling water filling chamber 27 side, and has an enlarged hole portion 65 having a hole diameter set larger than the hole diameter of the sliding hole portion 64.
A radial surface connecting the inner peripheral surface of the sliding hole portion 64 and the inner peripheral surface of the enlarged diameter hole portion 65 is a passage side wall surface 66.
An intermediate shaft portion 74 is inserted through the diameter-expanded hole portion 65.

A disc body 75, which is a separate member, is fixed to the intermediate shaft portion 74.
The disc body 75 includes a shaft hole 76 into which the intermediate shaft portion 74 is inserted, and a large number of through holes 77 are formed around the shaft hole 76.
A surface of the disk body 75 that faces the passage side wall surface 66 is a filling chamber side wall surface 78.
The disc body 75 is inserted into the first guide hole 63 at the valve closing position of the EGR valve 70, and in this state, the outer peripheral surface of the disc body 75 faces the first guide hole 63 with a slight gap.
Therefore, a cylindrical volume chamber 79 as a volume chamber is formed over the entire circumference of the intermediate shaft portion 54 in the diameter expansion hole portion 65.
The cylindrical volume chamber 79 includes an outer surface formed by the valve housing 62, an inner surface formed by the intermediate shaft portion 74, an end surface on the gas passage 23 side formed by the passage side wall surface 66, and a filling chamber side wall surface. And an end surface on the cooling water filling chamber 27 side formed by 78.

The region where the filling chamber side wall surface 78 is projected on the passage side wall surface 66 is a region that overlaps each other in the axial direction, and is a region that approaches and separates from each other by the reciprocating motion of the shaft 72.
That is, the end surface on the cooling water filling chamber 27 side and the end surface on the gas passage 23 side in the cylindrical volume chamber 79 have an overlap region that is separated from each other by the reciprocating motion of the shaft 72.
Since there is an overlap region, the volume of the cylindrical volume chamber 79 varies as the shaft 72 reciprocates.
In this other example, when the EGR valve 70 moves from the closed position to the fully closed position due to the rising (forward movement) of the shaft 72, the filling chamber side wall surface 78 is separated from the passage side wall surface 66, and the shaft 72 In the downward movement (return), the filling chamber side wall surface 78 approaches the passage side wall surface 66.

Since the through hole 77 is formed in the disc body 75, the area of the filling chamber side wall surface 78 is smaller than the area of the passage side wall surface 66.
The volume of the cylindrical volume chamber 79 fluctuates due to the reciprocating motion of the shaft 72. The volume of the cylindrical volume chamber 79 is the minimum volume when the EGR valve 70 is closed, and the maximum volume when the EGR valve 70 is 100% open. Become.
In this other example, the through hole 77 of the disc body 75 functions as a throttle passage. When all the cross-sectional areas of these through holes 77 are added, the flow of the throttle passages 37 and 57 in the previous embodiment and the different example 1 is added. It becomes equal to the road crossing area.
The total cross-sectional area of the communication hole 77 is set smaller than the cross-sectional area of the cylindrical volume chamber 79.

Therefore, when the disc body 75 is inserted into the enlarged diameter hole portion 65, the through hole 77 functions as a throttle passage between the cylindrical volume chamber 79 and the cooling water filling chamber 27.
In a state where the through-hole 77 functions as a throttle passage, the pressure in the cylindrical volume chamber 79 varies depending on the degree of volume variation of the cylindrical volume chamber 79.
In the state where the disc body 75 is not inserted into the enlarged diameter hole portion 65, the cylindrical volume chamber 79 and the throttle passage are not distinguished.
At this time, the end surface on the cooling water filling chamber 27 side is not formed in the cylindrical volume chamber 79.
In the lift range of the EGR valve 70, the range where the through-hole 77 functions as a throttle passage and the range where it does not function are the same as the range set in the lift range of the EGR valve 30 in the previous embodiment.
According to the second example, in addition to the effect of the first example in which it is not necessary to form the reduced diameter wall portion in the valve housing 62, it is not necessary to form the enlarged diameter shaft portion in the shaft 72. The shaft 72 can be easily formed as compared with the case where the enlarged diameter shaft portion is formed.

  The EGR valve device according to the above-described embodiment (including Examples 1 and 2) shows one embodiment of the present invention, and the present invention is not limited to the above-described third embodiment. Various modifications can be made within the scope of the gist of the invention as described below.

In the above embodiment (including Examples 1 and 2), the case where the internal combustion engine is a diesel engine has been described. However, the internal combustion engine may be, for example, a gasoline engine, and the types of the internal combustion engine are particularly limited. Not.
In the above embodiment (including Examples 1 and 2), the liquid filling chamber is provided in the valve housing. However, the valve housing is a member that supports the EGR valve, and the gas passage side structure and the liquid filling chamber side structure are Alternatively, it may be formed of a separate member.
In the above embodiment (including Examples 1 and 2), the liquid filled in the liquid filling chamber is the cooling water, but in an oil-cooled engine, lubricating oil may be used as the liquid.
○ In the above embodiment (including Examples 1 and 2), the cooling water filling chamber as the liquid filling chamber is connected to the cooling water circulation passage and supplied with cooling water, but the liquid filling chamber is filled with liquid. In this case, it is necessary to devise a device for absorbing the volume in the closed space that fluctuates due to the movement of the valve.For example, after filling the liquid filling chamber with a sufficient amount of liquid, Gas may be enclosed in the liquid filling chamber to absorb.
In the above embodiment, the hole diameter of the first guide hole is set to the same diameter in the axial direction except for the reduced diameter wall portion, but the axial direction corresponding to the cylindrical volume chamber formed in the first guide hole About the range, you may enlarge the hole diameter of a 1st guide hole. In this case, the end surface on the gas passage side and the end surface on the liquid filling chamber side of the cylindrical volume chamber to be formed may have an overlap region in which they are separated from each other by reciprocation of the shaft, and the volume may be changed.
In the above embodiment, the volume chamber formed in the guide hole is cylindrical. However, the volume chamber is not limited to the cylinder shape. For example, a plurality of volume chambers are formed in the guide hole around the shaft. The cross-sectional shape of the hole wall forming the volume chamber may be an arbitrary shape such as a polygon other than a circle or an ellipse.
In the above embodiment, the volume chamber and the liquid filling chamber are provided in the valve housing, but the volume chamber and the liquid filling chamber may be provided in a range in contact with the shaft.

It is the schematic which shows the EGR valve apparatus which concerns on embodiment of this invention, and its periphery. It is a longitudinal cross-sectional view which shows the principal part of the EGR valve apparatus which concerns on embodiment of this invention, and shows the state at the time of valve closing of the EGR valve in which a throttle passage is formed. FIG. 3 is an enlarged longitudinal sectional view showing an essential part of the EGR valve device shown in FIG. It is a longitudinal cross-sectional view which shows the principal part of an EGR valve apparatus, and shows the state at the time of valve opening of the EGR valve in which a throttle passage is not formed. 6 is a longitudinal sectional view showing a main part of an EGR valve device according to another example 1. FIG. 10 is a longitudinal sectional view showing a main part of an EGR valve device according to another example 2. FIG.

Explanation of symbols

17 (17A, 17B) EGR gas passages 20, 40, 60 EGR valve device 21 Actuator 22, 42, 62 Valve housing 22a Reduced diameter wall portion 23 Gas passage 24 Valve seat 27 Cooling water filling chamber (as liquid filling chamber)
28, 43, 63 First guide hole 28a Reduced diameter hole 29 Second guide hole 30, 50, 70 EGR valve 31, 51, 71 Valve body 32, 52, 72 Shaft 33, 53, 73 Sliding shaft portion 33a, 46 , 66 Passage side wall surface 34, 54, 74 Intermediate shaft portion 35, 55 Expanded diameter shaft portion 35b, 55b, 78 Filling chamber side wall surface 35a Insertable portion 36, 56, 79 Cylindrical volume chamber 37, 57 Restricted passage 44, 64 Sliding hole portions 45, 65 Expanded diameter hole portion 75 Disc body 77 Through hole RG EGR gas

Claims (4)

A valve housing provided with a valve hole arranged in the gas passage of the internal combustion engine, a shaft and a valve body, connected to the shaft; and an EGR valve that opens and closes the valve hole; An EGR valve device having an actuator for opening and closing the EGR valve,
A part of the shaft is inserted, and is defined by a liquid filling chamber having liquid inside, the shaft and the valve housing,
A throttle passage that is formed by the shaft and the valve housing, communicates the volume chamber and the liquid filling chamber, and has a flow passage cross-sectional area that is changed by movement of the EGR valve;
The EGR valve device, wherein the flow passage cross-sectional area of the throttle passage is small at least when the EGR valve is in the closed position. The flow passage cross-sectional area of the throttle passage is in a small state in a range from a valve closing position of the EGR valve to a predetermined valve opening position, and is in a large state in a range from a predetermined valve opening position to a full valve opening position. The EGR valve device according to claim 1. 3. The EGR valve device according to claim 1, wherein the volume chamber is formed over the entire circumference of the shaft. The throttle passage is formed from the shaft and the liquid filling chamber wall surface, and the liquid filling chamber wall surface in the throttle passage has a reduced diameter wall having a cross-sectional area reduced in diameter from the volume chamber sectional area in a direction perpendicular to the shaft axis. The EGR valve device according to claim 1, further comprising a portion.

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