JP4085752B2 - Exhaust pressure control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for controlling the exhaust pressure of an engine, and more particularly to an exhaust pressure control apparatus suitable for use in efficiently purifying exhaust gas at the time of cold start.
[0002]
[Prior art]
As shown in FIG. 5, conventionally, an exhaust gas purification catalyst that purifies harmful substances (carbon monoxide CO, hydrocarbon HC, nitrogen oxides NOx, etc.) discharged from a gasoline engine and converts them into more harmless substances (hereinafter referred to as “exhaust gas purification catalyst”). 33 (referred to as a catalyst) is interposed in an exhaust pipe 31 constituting an exhaust passage 32 of the engine 30.
[0003]
By the way, since the catalyst 33 is not activated unless the temperature becomes high, the catalyst 33 is not activated when the engine 30 is cold-started, and the above-mentioned harmful substances may be discharged without being purified. In particular, since unburned HC is discharged in large quantities from the engine 30 when the engine 30 is cold-started, it is required to reduce the discharge amount of the unburned HC.
[0004]
Therefore, as shown in FIG. 5, an exhaust throttle valve 34a that controls the exhaust flow between the catalyst 33 and a silencer (muffler) 35, and an actuator 36 (see FIG. 6) that drives the exhaust throttle valve 34a to open and close. The exhaust pressure control device 34 is provided, and when the engine 30 is started, the exhaust throttle valve 34a is fully closed to increase the pressure upstream of the exhaust throttle valve 34a, and in the exhaust passage 32 upstream of the exhaust throttle valve 34a. A technology for purifying unburned HC by reacting unburned HC with excess air has been developed.
[0005]
In such a conventional technique, in order to efficiently purify the unburned HC, it is necessary to accurately control the exhaust pressure when the exhaust throttle valve 34a is closed to a predetermined pressure (for example, atmospheric pressure +93.3 kPa).
For this reason, as shown in FIGS. 6A and 6B, the conventional exhaust pressure control device 34 is provided with a relief valve 34b for exhaust pressure control.
[0006]
The relief valve 34b is normally urged in a closing direction (downward in FIG. 6B) by a spring (not shown). When the exhaust pressure exceeds the predetermined pressure, the relief valve 34b is opened (in FIG. 6B). It functions so as to adjust the exhaust pressure to the predetermined pressure by moving the exhaust gas upward and passing the exhaust gas downstream of the exhaust throttle valve 34a via the bypass passage 34c.
[0007]
[Problems to be solved by the invention]
By the way, as shown in FIG. 6A, the actuator 36 that rotationally drives the exhaust throttle valve 34a is provided on the outer peripheral portion of the exhaust pipe 31, but the vehicle under floor (not shown) in which the exhaust pipe 31 is disposed. ) Has a restriction on the minimum ground clearance, and therefore the actuator 36 is generally arranged on either the left or right side of the exhaust pipe 31.
[0008]
On the other hand, the relief valve 34b is arranged at the upper part or the lower part of the exhaust pipe 31 so as not to interfere with the actuator 36 and the shaft support part of the exhaust throttle valve 34a opposite to the actuator 36. However, since the relief valve 34b is operated only when the engine 30 is started, if the relief valve 34b is disposed below the exhaust pipe 31, as shown in FIG. Therefore, the relief valve 34b is installed on the upper side of the exhaust pipe 31. In this case, the bypass passage 34c is inevitably provided on the upper side of the exhaust pipe 31.
[0009]
For example, as shown in FIG. 7, Japanese Patent Laid-Open No. 2001-59428 discloses a valve body 82 that performs opening / closing control of an inlet port 81 in a bypass passage 80 and urges the valve body 82 toward the inlet port 81. A technology is disclosed in which a relief valve 84 including a compression spring 83 is disposed on the upper side of the exhaust pipe 22 and the relief valve 84 is opened when the back pressure in the exhaust pipe 22 upstream of the exhaust control valve 24 exceeds a target value. Has been.
Also in this technique, the relief valve 84 and the bypass passage 80 are provided so as to protrude above the exhaust pipe 22.
[0010]
However, as described above, the vehicle underfloor generally has a minimum ground clearance. Therefore, in the case of the exhaust pressure control device 34 in which the relief valve 34b and the bypass passage 34c protrude above the exhaust pipe 31, it is installed. The place is limited. For this reason, the installation of such an exhaust pressure control device 34 imposes great restrictions on the design of the under floor.
For these reasons, it is desired to reduce the overall height of the exhaust pressure control device 34 as much as possible.
[0011]
The present invention has been devised in view of the above-described problems, and an object of the present invention is to provide an exhaust pressure control device that can be easily installed in a vehicle by reducing the overall height of the device.
[0012]
[Means for Solving the Problems]
For this reason, an exhaust pressure control device according to the present invention (Claim 1) is provided in an exhaust passage of an engine, and is disposed concentrically with an exhaust throttle valve having a hollow shaft and inside the hollow shaft. A main shaft, a first passage formed through the main shaft in the diametrical direction, a second passage formed through the hollow shaft in the diametric direction, and the main shaft, An integrally rotating arm, a return spring that urges the exhaust throttle valve in the valve closing direction, a stopper that contacts the arm and restricts the rotation of the exhaust throttle valve by the urging force of the return spring, and a pressure chamber A pressure upstream of the exhaust throttle valve is introduced into the chamber, a negative pressure is introduced into the chamber facing the pressure chamber, and the rod connected to the arm is moved in the axial direction to rotationally drive the arm. And a fluid pressure actuator A fluid pressure actuator comprising: a pressure introduction path for introducing the upstream pressure and the negative pressure into a rotor; an electromagnetic valve for opening and closing the pressure introduction path; and a control means for controlling opening and closing of the electromagnetic valve. When the negative pressure is introduced into the chamber facing the pressure chamber, the main shaft is rotated in the valve closing direction of the exhaust throttle valve by the fluid pressure actuator, and the stopper comes into contact with the arm. In this state, the exhaust throttle valve is rotated in conjunction with the main shaft to be closed, and when the exhaust throttle valve is closed , pressure upstream from the exhaust throttle valve is introduced into the pressure chamber. When, that only the main shaft is further rotated in the closing direction, in communication with the first passageway and the second passageway with each other, the bypass flow path opened between upstream and downstream of the exhaust throttle valve is formed It is characterized by.
[0013]
Further, when the exhaust throttle valve is in a closed state , the fluid pressure actuator rotates the main shaft according to the pressure upstream of the exhaust throttle valve, and the upstream pressure exceeds a predetermined value. , it is preferred to communicate the said first passage and said second passage (claim 2).
[0016]
Further, the control means controls the electromagnetic valve to introduce the negative pressure in the chamber opposite to the pressure chamber when the engine is started, after satisfying the Jo Tokoro conditions, blocking the introduction negative pressure (Claim 3 ).
And an exhaust gas purification catalyst that is interposed in the exhaust passage of the engine and purifies harmful substances discharged from the engine and converts them into harmless substances. The control means includes the exhaust gas purification catalyst. When the predetermined condition can be estimated as that activity is established, it is preferable to open the exhaust throttle valve (claim 4).
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show an exhaust pressure control apparatus according to an embodiment of the present invention. FIGS. 1 and 2 show an exhaust throttle valve and a main shaft during normal operation of the engine (that is, after completion of engine warm-up). FIG. 3 is a schematic cross-sectional view of the exhaust pipe, and FIG. 4 is a schematic view showing the relationship between the exhaust throttle valve and the main shaft when the exhaust pressure control device is operated. It is.
[0018]
As shown in FIG. 1, the exhaust pressure control device according to the present embodiment is provided between a catalyst 33 and a muffler 35 (see FIG. 5), for example, in an exhaust pipe 16 of an engine (not shown). The exhaust throttle valve 1 for adjusting the flow rate of exhaust gas flowing through the exhaust passage 17, the main shaft 6, and drive means 19 for rotationally driving the main shaft 6 and the exhaust throttle valve 1 are provided.
[0019]
The exhaust throttle valve 1 includes a hollow shaft 2 provided perpendicularly to the axial direction of the exhaust pipe 16 in the exhaust passage 17 of the exhaust pipe 16, and a valve body protruding in the outer circumferential direction of the hollow shaft 2. The hollow shaft 2 is formed with a second passage 4 penetrating in the diameter direction of the hollow shaft 2.
2 and 3, both end portions of the hollow shaft 2 protrude from the exhaust pipe 16 and are pivotally supported. By rotating one end portion 2a of the hollow shaft 2, the exhaust throttle valve is rotated. 1 can be rotated in the exhaust pipe 16.
[0020]
Further, a return spring 15 that urges the exhaust throttle valve 1 in the valve closing direction is interposed between the outer periphery of the exhaust pipe 16 and the outer periphery of the one end portion 2 a of the hollow shaft 2. Here, the return spring 15 is constituted by a spiral spring that applies a biasing force in the axial rotation direction of the hollow shaft 2 (that is, the valve closing direction of the exhaust throttle valve 1 indicated by the arrow X2 in FIG. 1). However, the present invention is not limited to this, and other types of springs may be used.
[0021]
Further, a stopper 5 that abuts on an arm 7 to be described later is provided at one end portion 2a of the hollow shaft 2 in a radial direction. The urging force of the return spring 15 acts so that the stopper 5 contacts the arm 7. When the exhaust throttle valve 1 is within the rotation range, when the arm 7 rotates, the exhaust throttle valve 1 moves to the arm 7. It follows the rotation (linked).
[0022]
As shown in FIG. 1, the main shaft 6 is inserted into the hollow shaft 2 and is concentrically disposed with the hollow shaft 2. The main shaft 6 includes a first shaft penetrating in the diameter direction of the main shaft 6. A passage 3 is formed.
2 and 3, when the main shaft 6 rotates with respect to the exhaust throttle valve 1, the first passage 3 of the main shaft 6 and the second passage 4 of the exhaust throttle valve 1 communicate with each other. As described later, even when the exhaust throttle valve 1 is closed, one passage (bypass passage) 20 that minutely communicates the upstream and downstream of the exhaust throttle valve 1 is formed.
[0023]
Further, both ends of the main shaft 6 are projected and supported outside the exhaust pipe 16 in the same manner as the exhaust throttle valve 1, and in particular, one end (the end on the side where the return spring 15 is disposed) is a hollow shaft. The main shaft 6 can be driven to rotate by rotating one end portion 6 a of the main shaft 6 by the driving means 19.
The drive means 19 includes an arm 7 coupled to one end 6a of the main shaft 6, a rod 9 pin-connected to the arm 7, a fluid pressure actuator (here, an air cylinder) 10 that moves the rod 9 in the axial direction, and Is configured.
[0024]
A hole 8 is formed in the arm 7, one end 9 a of the rod 9 is rotatably attached to the hole 8, and the other end 9 b is coupled to a movable partition wall 10 a of the actuator 10 described later. Has been. Accordingly, the partition wall 10a is moved by the operation of the actuator 10 and the rod 9 is moved so as to protrude in the axial direction, whereby the main shaft 6 is rotated in the direction indicated by the arrow X1 in FIG.
[0025]
Further, since the rod 9 is provided on the side of the exhaust pipe 16 substantially in parallel with the exhaust pipe 16, even if the rod 9 moves in the axial direction indicated by the arrow X3 in FIGS. It does not protrude upward and does not affect the overall height of the device.
The actuator 10 is constituted by an air cylinder fixed to the exhaust pipe 16 by a bracket 18, and the inside of the actuator 10 is divided into a first pressure chamber (A chamber) 11 and a second pressure chamber (B chamber) by a partition wall 10a. It is divided into 12.
[0026]
The A chamber 11 is connected to, for example, a negative pressure tank (not shown) connected to an intake manifold of an engine (not shown) and a pipe 13 for introducing atmospheric pressure. By switching the electromagnetic valve 11a, the negative pressure tank 11 Negative pressure and atmospheric pressure are selectively input to the A chamber 11.
The B chamber 12 is connected to an exhaust pipe 16 upstream of the exhaust throttle valve 1 and a pipe 13 for introducing atmospheric pressure. By switching the electromagnetic valve 12a, the upstream pressure and the atmospheric pressure are changed. Are selectively input to the B chamber 12.
The solenoid valves 11a and 12a are each configured to introduce atmospheric pressure into the pressure chambers 11 and 12 when not energized.
[0027]
Further, the partition wall 10a is biased by the spring 14 in the direction in which the B chamber 12 is compressed (that is, the direction in which the rod 9 is retracted). Accordingly, when the pressure input to the B chamber 12 increases, the partition wall 10a moves against the urging force of the spring 14, and the rod 9 protrudes in the direction indicated by the arrow X3 in FIG. 1 or FIG. Thus, the main shaft 6 is rotationally driven.
[0028]
Since the exhaust pressure control apparatus according to an embodiment of the present invention is configured as described above, the control means before the engine is started (or after the engine is warmed up) as shown in FIG. The solenoid valves 11a and 12a are deenergized, atmospheric pressure is input to the A chamber 11 and the B chamber 12, and the actuator 10 is deactivated. That is, the rod 9 is in a retracted state drawn into the actuator 10, and the main shaft 6 is stopped at the position shown in the figure. Accordingly, the stopper 5 of the exhaust throttle valve 1 contacts the arm 7 of the main shaft 6, and the exhaust throttle valve 1 is held in the fully opened state through the rod 9 and the stopper 5.
[0029]
Then, as shown in FIG. 4A, when the engine is started (specifically, when the engine starts), the electromagnetic valve 11a is energized to introduce negative pressure into the A chamber 11 and into the B chamber 12. Leave atmospheric pressure input. Thereby, the partition wall 10a moves in the direction in which the A chamber 11 is compressed, and the rod 9 projects from the air cylinder 10 to rotationally drive the main shaft 6. The exhaust throttle valve 1 is forcibly closed by rotating the hollow shaft 2 in conjunction with the rotation of the main shaft 6.
[0030]
As shown in FIG. 4 (b), after closing the exhaust throttle valve 1, the solenoid valve 12 a is energized to introduce upstream pressure into the B chamber 12. After the engine is started, the pressure on the upstream side of the exhaust throttle valve 1 increases, so the pressure input to the B chamber 12 increases, and the rod 9 further protrudes from the actuator 10, so that the main shaft 6 further rotates. At this time, since the exhaust throttle valve 1 is already closed, it does not rotate any further. Therefore, after the exhaust throttle valve 1 is closed, only the main shaft 6 continues to rotate according to the upstream pressure.
[0031]
When the pressure input to the B chamber 12 reaches a predetermined pressure P (here, atmospheric pressure + 93.3 kPa), the first passage 3 and the second passage 4 communicate with each other to bypass the bypass passage 20. As shown by an arrow F in FIG. 3B, the exhaust on the upstream side of the exhaust throttle valve 1 is bypassed to the downstream side.
Thus, when the bypass passage 20 is opened, the upstream pressure decreases. However, if the upstream pressure input to the B chamber 12 becomes smaller than the predetermined pressure P, the rod 9 returns and the main shaft 6 also returns. The relative phase between the first passage 3 and the second passage 4 changes, and the bypass passage 20 is blocked. Thereby, when the upstream pressure rises again and exceeds the predetermined pressure P, the bypass passage 20 is opened. In this way, the communication area between the first passage 3 and the second passage 4 is appropriately adjusted so that the pressure upstream of the exhaust throttle valve 1 maintains the predetermined pressure P. Can be maintained at a predetermined pressure P.
[0032]
Then, when a predetermined condition, that is, a condition that can be estimated that the catalyst is activated, is established, the solenoid valves 11a and 12a are deenergized and the exhaust throttle valve 1 is opened. Whether or not the catalyst in this case has been activated can be determined, for example, by directly measuring the temperature of the catalyst using a high-temperature sensor or by estimating the elapsed time after starting the engine or the total fuel injection amount.
[0033]
As described above, in this exhaust pressure control device, the relief function (bypass passage 20) is provided in the shaft portion of the exhaust throttle valve 1, that is, in the exhaust pipe 16, so that the overall height of the device can be reduced. Therefore, since the installation location of the exhaust pressure control device is not limited, it is easy to design the underfloor and install the device.
Further, since the exhaust throttle valve 1 and the main shaft 6 are driven by one actuator 10, the configuration is simplified and the manufacturing cost can be suppressed.
[0034]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the exhaust pressure control device of the present invention, when the exhaust throttle valve 1 is closed, the first passage 3 of the main shaft 6 and the hollow shaft 2 are set so that the pressure upstream of the exhaust throttle valve 1 becomes a predetermined pressure. It is only necessary that the bypass passage 20 can be formed by adjusting the communication area with the second passage 4, and the opening area or the opening shape of the first passage 3 or the second passage 4 is not particularly limited. A plurality of first passages 3 may be formed along the axial direction of the main shaft 6, and a plurality of second passages 4 may be formed along the axial direction of the hollow shaft 2.
[0035]
【The invention's effect】
As described in detail above, according to the exhaust pressure control device of the present invention, the bypass passage (relief function) can be provided in the shaft portion of the exhaust throttle valve, that is, in the exhaust pipe. The total height of the apparatus can be lowered. Therefore, since the installation location of the exhaust pressure control device is not limited, it is easy to design the under floor and install the device.
[0036]
According to the exhaust pressure control device of the present invention as set forth in claim 2, the exhaust is bypassed by communicating the first passage and the second passage according to the pressure on the upstream side of the exhaust throttle valve. The upstream pressure can be maintained at a predetermined pressure.
According to the exhaust pressure control device of the present invention, the main shaft can be rotationally driven by moving the rod in the axial direction.
[0037]
According to the exhaust pressure control device of the present invention, the exhaust throttle valve rotates in conjunction with the rotation of the main shaft in the rotation range of the exhaust throttle valve, so that the main shaft is rotated by the driving means. The exhaust throttle valve can be rotated with a simple structure.
According to the exhaust pressure control device of the present invention, the exhaust throttle valve can be easily controlled to open and close by opening and closing the electromagnetic valve.
[0038]
According to the exhaust pressure control apparatus of the present invention as set forth in claim 6, the opening / closing control of the exhaust throttle valve can be performed based on whether or not a predetermined condition is satisfied.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a relationship between an exhaust throttle valve before starting an engine and a main shaft according to an exhaust pressure control apparatus as an embodiment of the present invention, and a longitudinal section of the exhaust pipe (FIG. 2). FIG. 3 is a cross-sectional view taken along the line AA in FIG.
FIG. 2 is a schematic configuration diagram showing an exhaust pressure control device as one embodiment of the present invention, and shows an exhaust pipe in a longitudinal section (a section taken along line BB in FIGS. 1 and 3); A longitudinal section is also shown for the cylinder.
FIG. 3 is a cross-sectional view of the exhaust pipe (cross-sectional view taken along the line CC in FIGS. 1 and 2) showing an embodiment of the present invention.
FIG. 4 is a configuration diagram showing the open / close state of the bypass in a vertical cross section of the exhaust pipe when the exhaust throttle valve is closed when the exhaust pressure control device according to the embodiment of the present invention is operated; The closed state is shown, and (b) shows the bypass open state.
FIG. 5 is an overall configuration diagram schematically showing an exhaust system of an engine to which a conventional exhaust pressure control device is applied.
6A and 6B show a conventional exhaust pressure control device, in which FIG. 6A is a cross-sectional view of the exhaust pipe, and FIG. 6B is a longitudinal cross-sectional view of the exhaust pipe [a cross-sectional view taken along line DD in FIG. ].
FIG. 7 is a configuration diagram of an exhaust system schematically showing a conventional exhaust pressure control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Exhaust throttle valve 1a Valve body 2 Hollow shaft 2a End 1 of hollow shaft 3 First passage 4 Second passage 5 Stopper 6 Main shaft 6a End 1 of main shaft 7 Arm 8 Hole 9 Rod 9a End 1b of rod 9b The other end 10 Air cylinder (fluid pressure actuator)
10a Partition wall 11 First pressure chamber (A chamber)
11a Solenoid valve in chamber A 12 Second pressure chamber (B chamber)
12a B chamber solenoid valve 13 Pipe 14 Spring 15 Return springs 16, 22, 31 Exhaust pipes 17, 32 Exhaust passage 18 Bracket 19 Drive means 20 Bypass passage 24 Exhaust control valve 30 Engine 33 Catalyst 34 Exhaust pressure control device 34a Valve 34b Relief Valve 34c Bypass passage 35 Silencer 36 Actuator 80 Bypass passage 81 Inlet port 82 Valve body 83 Compression spring 84 Relief valve

Claims (4)

An exhaust throttle valve provided in the exhaust passage of the engine and having a hollow shaft;
A main shaft disposed concentrically with the hollow shaft inside the hollow shaft ;
A first passage formed therethrough in the diametrical direction of the main shaft,
A second passage formed through the diameter of the hollow shaft ;
An arm coupled to the main shaft and rotating integrally with the main shaft;
A return spring that urges the exhaust throttle valve in the valve closing direction;
A stopper that contacts the arm and restricts the rotation of the exhaust throttle valve by the urging force of the return spring;
A pressure upstream of the exhaust throttle valve is introduced into the pressure chamber, a negative pressure is introduced into the chamber facing the pressure chamber, and a rod connected to the arm is moved in the axial direction to move the arm. A fluid pressure actuator for rotational driving;
A pressure introduction path for introducing the upstream pressure and the negative pressure into the fluid pressure actuator;
A solenoid valve for opening and closing the pressure introduction path;
Control means for controlling opening and closing of the solenoid valve,
When the negative pressure is introduced into a chamber facing the pressure chamber of the fluid pressure actuator, the main shaft is rotated in the valve closing direction of the exhaust throttle valve by the fluid pressure actuator, and the stopper is moved to the arm. The exhaust throttle valve is rotated in conjunction with the main shaft while being in contact with the main shaft to be closed, and when the exhaust throttle valve is closed , the pressure chamber has a pressure upstream of the exhaust throttle valve. When There is introduced, only the main shaft is further rotated in the closing direction, in communication with the first passageway and the second passageway with each other, the bypass flow path opened between upstream and downstream of the exhaust throttle valve An exhaust pressure control device characterized by being formed. When the exhaust throttle valve is closed , the fluid pressure actuator rotationally drives the main shaft according to the pressure upstream of the exhaust throttle valve, and when the upstream pressure exceeds a predetermined pressure , exhaust pressure control system according to claim 1, wherein the communicating with said first passage and the second passage. Wherein the control means controls the electromagnetic valve, the negative pressure introduced into the chamber opposite to the pressure chamber when the engine is started, after satisfying the Jo Tokoro conditions, blocking the introduction negative pressure <br / The exhaust pressure control device according to claim 1 or 2, wherein: The exhaust gas purification catalyst is disposed in the exhaust passage of the engine and purifies harmful substances discharged from the engine and converts them into harmless substances, and the control means is activated by the exhaust gas purification catalyst. The exhaust pressure control device according to any one of claims 1 to 3, wherein the exhaust throttle valve is opened when a predetermined condition that can be estimated is established.

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