DE102011053664A1 - Low-pressure EGR device Umführ - Google Patents

Abstract

A low-pressure bypass EGR apparatus (1) has a mechanical stopper (14) for regulating a driven arm (11) of a link mechanism (7) for driving an intake throttle valve (5) by changing the output characteristic of an electric actuator (6) , An angle (Aθ) of the driven arm of the drive arm (11) is always set larger than 0 °, while a cam plate (9) has a rotation and has a variation range defined between 0 ° and a predetermined value (Aθ0). The mechanical stopper (14) regulates the driven arm (11) in a travel range between 0 ° and the predetermined value (Aθ0).

Description

The present invention relates to a low-pressure bypass EGR apparatus in which a part of the exhaust gas emitted from an internal combustion engine from a low outlet pressure region (where the outlet pressure is low) of the exhaust passage to a low intake negative pressure region (where the negative pressure of the intake air less produced) of the intake passage is returned.

A high-pressure bypass EGR apparatus is known in which a combustion temperature of an engine combustion chamber is suppressed so that nitrogen oxides (NOx) in the exhaust gas are hardly generated (or the knock is hardly generated).

Such a high-pressure bypass EGR apparatus is basically referred to as an EGR apparatus in which a part of the exhaust gas flowing through an exhaust passage to an intake passage downstream of a throttle valve (in a region where a negative pressure the intake air is strongly generated) is returned as EGR gas. The EGR gas, which is a non-flammable gas, is mixed with intake air, whereby the combustion temperature of the engine is suppressed.

A high pressure bypass EGR regulating valve is provided in a high pressure bypass EGR passage of the high pressure bypass EGR apparatus via which EGR gas flows to the inlet port. The high pressure bypass EGR regulating valve adjusts the flow channel area of the high pressure bypass EGR passage. An electronic control unit (ECU) controls the high-pressure bypass EGR regulating valve so that the EGR amount (exhaust gas flow rate per unit time) is obtained in accordance with a motor drive state such as engine speed or engine load.

In contrast, recently, in addition to the high pressure bypass EGR device, a low pressure bypass EGR device (e.g. JP-2008-150955A referred) as a technology designed to suppress the combustion temperature of the engine in a wide operating range.

In the low-pressure bypass EGR apparatus, a part of the low-pressure exhaust gas in the exhaust passage is returned to an area where the negative pressure of the intake air is less generated in an intake passage, so that a small amount of the EGR gas is returned to the intake passage of the internal combustion engine ,

Thus, a low-concentration EGR gas may be supplied to a motor driving region where the engine load is high, which can not be realized by the high-pressure bypass EGR device.

A low pressure bypass EGR regulating valve is provided in a low pressure bypass EGR passage of the low pressure bypass EGR device through which EGR gas flows to the inlet port. The low pressure bypass EGR regulating valve adjusts the flow channel area of the low pressure bypass EGR passage. An ECU controls the low pressure bypass EGR regulating valve so that the EGR amount corresponding to a motor driving state similar to the high pressure bypass EGR regulating valve is obtained.

In the low-pressure bypass EGR apparatus, a part of the low-pressure exhaust gas in the exhaust passage is returned to the region where the negative pressure of the intake air is less generated in the intake passage.

Although it is necessary to recycle a large amount of EGR gas to the internal combustion engine using the low-pressure bypass EGR apparatus, such a requirement is hardly achieved.

It is conceivable that an intake throttle valve, which may generate an intake negative pressure, is located in the intake passage to which EGR gas is returned. When it is required that a large amount of EGR gas is returned to the engine, the intake throttle valve is closed to generate an intake negative pressure.

That is, in a motor drive state in which a large amount of EGR gas is required to be used using the low-pressure bypass EGR device, the intake throttle valve generates an intake negative pressure, so that a large amount of EGR gas is used Motor is returned.

However, as described above, the low-pressure bypass EGR regulating valve is controlled according to an engine speed, an engine load, and the like.

Meanwhile, the intake throttle valve is closed by the ECU only when a large amount of EGR gas is required.

The low pressure bypass EGR regulating valve and the intake throttle valve are controlled based on different driving factors, so that the low pressure bypass EGR regulating valve and the intake throttle valve are individually operated.

Therefore, an exclusive actuator for driving the low-pressure bypass EGR regulating valve and another exclusive actuator for driving the intake throttle valve are necessary, which increases the manufacturing cost, the size thereof, and the weight thereof.

It is required that the low-pressure bypass EGR regulating valve and the intake throttle valve are driven by a single electric actuator constituted by an electric motor and a reduction mechanism so as to reduce the size, cost and weight thereof.

It is suggested that a single electric actuator drive the low pressure bypass EGR regulating valve and then transfer its output to the intake throttle valve via a linkage mechanism.

With reference to 5 An example of the connection mechanism will be specifically described. The connection mechanism 7 who in 5 is shown, indicates:
a cam plate 9 with a cam groove 8th that deals with a low-pressure bypass EGR regulating valve 4 turns, and
a powered arm 11 with a cam engagement section 10 , with the cam groove 8th is mated with and engages with, and that engages with an intake throttle 5 rotates.

The cam engagement section 10 is by a roll 10a and a wave 10b educated.

Only the low pressure bypass EGR regulating valve 4 that by an electric motor 44 and a reduction mechanism 45 is formed by the electric actuator 6 in an area where the valve 4 has a fully closed position θ0, turned to a middle position θ1, and an opening degree of the intake throttle valve 5 is maintained as maximum.

While the low-pressure bypass EGR regulating valve 4 by the electrical actuator 6 is rotated from the middle position θ1 to a fully open position θ2, the opening degree of the intake throttle valve 5 changed.

A variation range of an angle Aθ of the driven arm is always set larger than 0 °, so that the link mechanism 7 evenly the cam engagement section 10 in accordance with a rotation of the cam plate 9 can move. That is, in a design stage, the angle Aθ of the driven arm is set as 0 ° <Aθ.

The angle Aθ of the driven arm is an angle that is a rotational position of the driven arm 11 and corresponds to an angle defined between a reference line L0 and a rotation line L1. The reference line L0 is defined to be a rotation center of the low-pressure bypass EGR regulating valve 4 and a rotation center of the intake throttle valve 5 connect to. The rotation line L1 is defined to be the center of rotation of the low-pressure bypass EGR regulating valve 4 and a rotation center of the roll 10a connect to.

However, in a real situation, an external force such as intake pulsation or misfire becomes the intake throttle valve 5 applied and becomes the driven arm 11 set in rotation so that an actual angle Aθ of the driven arm can become smaller than 0 °.

That is, at the angle Aθ of the driven arm, there is a probability that Aθ <0 ° exists even though it has been designed as 0 ° <Aθ at the design stage.

More precisely, as it is in 5 is shown, a gap (for example, manufacturing tolerances) between the cam groove 8th and the role 10a in front. Furthermore, the wave 10b that the role 10a supported, deformed by external forces.

Therefore, turning in a state of 5 (a) where the low pressure bypass EGR regulating valve 4 has the fully closed position θ0 when an external force on the intake throttle valve 5 is applied in a clockwise direction, as it is in 5 (b) shown is the driven arm 11 also in a clockwise direction while the cam plate 9 not moved. While the rotation line L1 is configured in a manner that the low-pressure bypass EGR regulating valve 4 has the fully closed position θ0, the designed rotation line L1 is changed to a rotation line L1 'so that an actual angle Aθ of the driven arm becomes smaller than 0 °. That is, in the real situation, the angle Aθ of the driven arm Aθ becomes <0 °.

When the actual angle Aθ of the driven arm becomes smaller than 0 ° (Aθ <0 °), the cam engagement portion operates 10 as a bolt or rod with respect to the cam groove 8th so the cam plate 9 can be blocked.

That means the cam plate 9 can be blocked when the situation of Aθ <0 ° is generated. The cam plate 9 can not turn, even if the electric actuator 6 is energized, so that the low-pressure bypass EGR regulating valve 4 and the intake throttle valve 5 can get out of control.

The present invention has been made in view of the above objects, and it is an object of the present invention to provide a low-pressure bypass EGR device in which a cam plate is prevented from being blocked.

According to an example of the low-pressure bypass EGR apparatus, due to a mechanical stopper for restricting a rotation range of a driven arm, a minimum angle of the driven arm has been regulated to 0 ° or more. More specifically, the minimum angle of the driven arm is regulated to an angle range between 0 ° and a minimum angle Aθ0 of the arm.

Thereby, the actual angle Aθ of the driven arm does not become smaller than 0 ° even when a rotational force is applied to the driven arm by an external force such as an intake pulsation or a misfire applied to an intake throttle valve.

As a result, even if the external force is applied to the intake throttle valve, a cam engagement portion can be prevented from acting as a rod with respect to a cam groove, so that a cam plate can be prevented from being blocked. Thus, the reliability of a low-pressure bypass EGR regulating valve can be increased.

The cam engagement portion has a roller fitted in the cam groove and a shaft fixed to a rotating end of the driven arm. The shaft rotatably supports the rotor.

Thus, even if a gap is generated between the cam groove and the roller or even when the shaft is deformed, the minimum angle of the actual angle Aθ of the driven arm is regulated to 0 ° or more.

For example, a first member constituting the mechanical stopper is the driven arm that rotates outside of a valve housing, and a second member that constitutes the mechanical stopper is a protrusion defined on an outer wall of the valve housing. The driven arm contacts the projection to regulate a substantial minimum angle of the driven arm to 0 ° or more.

For example, a first member constituting the mechanical stopper is an intake throttle valve, and a second member constituting the mechanical stopper is a protrusion defined on an inner wall of an intake port. The intake throttle valve contacts the protrusion to regulate a substantially minimum angle of the driven arm to 0 ° or more.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

is 1 12 is a schematic view showing a low-pressure bypass EGR regulating valve and an intake throttle valve according to an embodiment;

is 2 FIG. 2 is a schematic view showing an engine intake / exhaust system according to an embodiment; FIG.

is 3 10 is a graph showing a relationship between the EGR gas flow rate, the intake air flow rate, and a rotational position of the low pressure bypass EGR regulating valve;

is 4 12 is a diagram for explaining EGR control according to a high pressure / low pressure EGR control program according to an embodiment; and FIG

is 5 12 is a schematic view showing a low-pressure bypass EGR regulating valve and an intake throttle valve for comparison.

• – ein Niederdruck-Umführ-AGR-Regulierventil 4, das einen Strömungskanalbereich eines Niederdruck-Umführ-AGR-Kanals 3 einstellt, durch den das AGR-Gas in einem Einlasskanal 2 eingeführt wird,
• – ein Einlassdrosselventil 5 zum Erzeugen eines Einlassunterdrucks an einem Zusammenflussabschnitt des Einlasskanals 2 und des Niederdruck-Umführ-AGR-Kanals 3,
• – eine einzige elektrische Betätigungseinrichtung 6, die das Niederdruck-Umführ-AGR-Regulierventil 4 antreibt, und
• – einen Verbindungsmechanismus 7 zum Antreiben des Einlassdrosselventils 5 durch das Ändern einer Ausgabecharakteristik einer elektrischen Betätigungseinrichtung 6.

As it is in 1 shows a low pressure bypass EGR device 1 on:

• A low pressure bypass EGR regulating valve 4 comprising a flow channel region of a low pressure bypass EGR passage 3 through which the EGR gas in an intake passage 2 is introduced
• - An inlet throttle valve 5 for generating an intake negative pressure at a confluence portion of the intake passage 2 and the low pressure bypass EGR channel 3 .
• A single electrical actuator 6 holding the low pressure bypass EGR regulating valve 4 drives, and
• - a connection mechanism 7 for driving the intake throttle valve 5 by changing an output characteristic of an electric actuator 6 ,

• – eine Nockenplatte 9 mit einer Nockennut 8, die sich mit dem Niederdruck-Umführ-AGR-Regulierventil 4 dreht, und
• – einen getriebenen Arm 11, der einen Nockeneingriffsabschnitt 10 in Eingriff mit der Nockennut 8 hat und der sich mit dem Einlassdrosselventil 5 dreht.

The connection mechanism 7 indicates:

• - a cam plate 9 with a cam groove 8th that deals with the low-pressure bypass EGR regulating valve 4 turns, and
• - a driven arm 11 , the one cam engagement section 10 in engagement with the cam groove 8th and that deals with the intake throttle valve 5 rotates.

In a case where the angle Aθ of the driven arm 11 is represented by an angle defined between a reference line L0 and a rotation line L1, a variation range of the angle Aθ of the driven arm is always made larger than 0 ° when the cam plate 9 is turned. The reference line L0 is defined to be a rotation center of the low-pressure bypass EGR regulating valve 4 and a rotation center of the intake throttle valve 5 connect to. The rotation line L1 is defined to be the center of rotation of the valve 4 and the cam engaging portion 10 connect to.

The angle Aθ of the driven arm has a minimum angle Aθ0 of the arm in the designed variation range.

The low pressure bypass EGR device 1 has a mechanical stop device 14 on that a minimal angle of the driven arm 11 regulated to become 0 ° or greater than 0 °. More specifically, the minimum angle of the driven arm 11 limited within an angular range between 0 ° and the minimum angle Aθ0 of the arm. The limitation is, for example, a contact between the driven arm 11 and a lead 13 a valve housing 12 receive.

With reference to the figures, an embodiment will be described specifically below. The embodiment discloses only a specific example, and the present invention is not limited to the embodiment.

With reference to the 2 to 4 An engine intake / exhaust system will be explained. The engine intake / exhaust system is with a high pressure bypass EGR device 21 and a low pressure bypass EGR device 1 Mistake.

In the high pressure bypass exhaust gas recirculation (EGR) device 21 is a high pressure section in an exhaust passage 23 (upstream of a DPF 22 where outlet high pressure is generated) with a portion of high vacuum in the inlet channel 2 (downstream of a throttle valve 24 , where a strong inlet vacuum is generated) connected. A large amount of EGR gas is emitted from the exhaust duct 23 to the inlet channel 2 via a high pressure bypass EGR channel 25 recycled.

More precisely, it is an end of the channel 25 from 2 with an exhaust manifold in the exhaust duct 23 connected and is the other end with a surge tank 26 an intake manifold in the intake passage 2 connected.

The high pressure bypass EGR device 21 from 2 has a high pressure bypass EGR regulating valve 27 , which has a flow channel area of the channel 25 adjusts a high pressure bypass EGR cooler 28 Cooling EGR gas to the intake port 2 returns, a high pressure bypass EGR cooler bypass 29 that the cooling device 28 bypasses, and a high pressure bypass EGR cooler switch valve 30 that is between the cooling device 28 and the bypass 29 turns on. It should be noted that 2 an example shows. The cooling device 28 , the bypass or the bypass 29 and the switching valve 30 are not always necessary.

In the low pressure bypass exhaust gas recirculation (EGR) device 1 is a low pressure section in the exhaust duct 23 (downstream of the DPF 22 where the outlet pressure is low) with a low vacuum section in the inlet channel 2 (upstream of the throttle valve 24 where the intake vacuum is low) via a low pressure bypass EGR passage 3 connected. A small amount of EGR gas is emitted from the exhaust duct 23 to the inlet channel 2 recycled.

More precisely, it is an end of the channel 3 from 2 with an outlet tube downstream of the DPF 22 in the outlet channel 23 connected and is the other end with the inlet channel 2 upstream of a compressor 31 a turbocharger in the inlet duct 2 connected.

The low pressure bypass EGR device 1 has a low pressure bypass EGR regulating valve 4 , which is the flow channel area of the channel 3 and a low pressure bypass EGR cooler 32 that cools the EGR gas to the intake port 2 is attributed to.

Further, the low pressure bypass EGR device has 1 an intake throttle valve 5 at a confluence portion of the intake passage 2 and the low pressure bypass EGR channel 3 ,

Even if the intake throttle valve 5 the inlet channel 2 completely throttles, is part of the intake duct 2 open. More specifically, even if the intake throttle valve 5 the inlet channel 2 completely throttles, about 10% of the flow channel area of the inlet channel 2 open (it is referred to a minimum gas flow rate indicated by a solid line Y in FIG 3 is displayed).

• (i) ein Hochdruck-Umführ-AGR-Kühleinrichtungsschaltprogramm, in dem das Hochdruck-Umführ-AGR-Kühleinrichtungsschaltventil 30 auf der Grundlage eines Motorerwärmungszustandes (beispielsweise einer Motorkühlmitteltemperatur) geschaltet wird, und
• (ii) ein Hochdruck/Niederdruck-AGR-Mengensteuerprogramm, in dem das Hochdruck-Umführ-AGR-Regulierventil 27, das Niederdruck-Umführ-AGR-Regulierventil 4 und das Einlassdrosselventil 5 entsprechend einer Motordrehzahl und einer Motorlast (Motorlastdrehmoment) gesteuert werden.

Then, an electronic control unit (ECU, not shown) incorporating the high-pressure bypass EGR apparatus will be described 21 and the low pressure bypass EGR device 1 controls. An EGR control program stored in the ECU has:

• (i) a high pressure bypass EGR cooler switch program in which the high pressure bypass EGR cooler switch valve 30 is switched on the basis of an engine warming condition (for example, an engine coolant temperature), and
• (ii) a high pressure / low pressure EGR flow control program in which the high pressure bypass EGR control valve 27 , the low pressure bypass EGR regulating valve 4 and the intake throttle valve 5 in accordance with an engine speed and an engine load (engine load torque).

With reference to 4 an overview of the high pressure / low pressure EGR quantity control program is described.

• (i) wird, wenn die Motordrehzahl und das Motorlastdrehmoment nicht mehr als eine Volllinie α in 4 sind, die Niederdruck-Umführ-AGR-Vorrichtung 1 gestoppt und wird die AGR-Steuerung nur durch das Hochdruck-Umführ-AGR-Regulierventil 27 der Hochdruck-Umführ-AGR-Vorrichtung 21 ausgeführt. Genauer gesagt wird der Kanal 3 durch das Regulierventil 4 geschlossen und wird eine Position des Regulierventils 27 entsprechend der Motordrehzahl und dem Motorlastdrehmoment gesteuert.
• (ii) wird, wenn die Motordrehzahl und das Motorlastdrehmoment zwischen der Volllinie α und einer Volllinie β in 4 sind, die AGR-Steuerung durch das Regulierventil 27, das Regulierventil 4 und das Einlassdrosselventil 5 ausgeführt. Genauer gesagt wird eine Position des Regulierventils 27 entsprechend der Motordrehzahl und dem Motorlastdrehmoment gesteuert und werden Positionen des Regulierventils 4 und des Einlassdrosselventils 5 entsprechend der Motordrehzahl und dem Motorlastdrehmoment gesteuert.
• (iii) wird, wenn die Motordrehzahl und das Motorlastdrehmoment größer als die Volllinie β in 4 sind, die Hochdruck-Umführ-AGR-Vorrichtung 21 gestoppt und die AGR-Steuerung nur durch das Niederdruck-Umführ-AGR-Regulierventil 4 und das Einlassdrosselventil 5 der Niederdruck-Umführ-AGR-Vorrichtung 1 ausgeführt. Genauer gesagt wird der Kanal 25 durch das Regulierventil 27 geschlossen und werden Positionen des Niederdruck-Umführ-AGR-Regulierventils 4 und des Einlassdrosselventils 5 entsprechend der Motordrehzahl und des Motorlastdrehmoments gesteuert.

According to the high pressure / low pressure EGR quantity control program

• (i) when the engine speed and the engine load torque are not more than one full line α in 4 are the low pressure bypass EGR device 1 the EGR control is stopped only by the high pressure bypass EGR regulating valve 27 the high pressure bypass EGR device 21 executed. More precisely, the channel becomes 3 through the regulating valve 4 closed and becomes a position of the regulating valve 27 controlled according to the engine speed and the engine load torque.
• (ii) when the engine speed and the engine load torque between the full line α and a solid line β in 4 are the EGR control through the regulating valve 27 , the regulating valve 4 and the intake throttle valve 5 executed. More specifically, a position of the regulating valve 27 controlled in accordance with the engine speed and the engine load torque and become positions of the regulating valve 4 and the intake throttle valve 5 controlled according to the engine speed and the engine load torque.
• (iii) becomes when the engine speed and the engine load torque is greater than the full line β in 4 are the high pressure bypass EGR device 21 stopped and the EGR control only by the low pressure bypass EGR regulating valve 4 and the intake throttle valve 5 the low pressure bypass EGR device 1 executed. More precisely, the channel becomes 25 through the regulating valve 27 closed and become positions of the low pressure bypass EGR regulating valve 4 and the intake throttle valve 5 controlled according to the engine speed and the engine load torque.

In the low pressure bypass EGR device 1 For example, since EGR gas in the low outlet pressure region is returned to the low intake negative pressure region, a small amount of EGR gas is returned to the engine. However, even in a case where it is necessary that a large amount of EGR gas is returned to the engine, it is difficult to control the large amount of EGR gas by the low-pressure bypass EGR apparatus 1 due.

According to the present embodiment, the low-pressure bypass EGR device 1 the inlet throttle valve 5 on, which has an intake vacuum in the intake passage 2 generated. In a motor drive state in which the large amount of EGR gas in the low pressure bypass EGR device 1 is required, the inlet throttle valve 5 controlled to be closed, whereby the large amount of EGR gas can be returned to the engine.

However, (i) in a low concentration control state where a small amount of EGR gas is supplied to the engine using the low pressure bypass EGR device 1 is returned, the intake throttle valve 5 fixed in a fully open position so as not to generate negative pressure, and becomes only the low-pressure bypass EGR regulating valve 4 controlled.

(ii) becomes, in a high-concentration control state, where a large amount of EGR gas to the engine using the low-pressure bypass EGR device 1 is returned, the opening degree of the regulating valve 4 increases and becomes the opening degree of the intake throttle valve 5 lowered to increase the intake vacuum.

Thus, in the low-concentration control state, the intake throttle valve becomes 5 fixed in the fully open position and will only the regulating valve 4 controlled. In the high-concentration control state, the opening degree of the intake throttle valve becomes 5 according to the opening degree of the regulating valve 4 changed.

Therefore, an exclusive actuator for driving the regulating valve 4 and another exclusive actuator for driving the intake throttle valve 5 necessary, which increases the manufacturing cost, size and weight.

According to the present embodiment, as this in 1 shows the low pressure bypass EGR apparatus 1 the only electrical actuator 6 that the regulating valve 4 drives, and the connection mechanism 7 on to the intake throttle valve 5 by changing the output characteristic of the electric actuator 6 drive. The valve 5 is by the output of the electric actuator 6 powered by the connection mechanism 7 is transmitted.

The connection mechanism 7 has a characteristic conversion section that determines the output characteristic of the electric actuator 6 changes and this to the intake throttle valve 5 transfers. After the opening degree of the valve 4 becomes larger than a predetermined value, the opening degree of the intake throttle valve becomes 5 designed smaller when the opening degree of the valve 4 bigger (it will be on 3 based).

In 3 A solid line X represents a change in the EGR gas flow rate with respect to the opening degree of the regulating valve 4 and a solid line Y represents a change in the intake air flow rate due to the intake throttle valve 5 with respect to the opening degree of the regulating valve 4 represents.

As described above, the regulating valve 4 and the intake throttle valve 5 over the connection mechanism 7 connected and these by the common electrical actuator 6 driven. As it is in 1 is shown, are the regulating valve 4 and the intake throttle valve 5 as a single low pressure bypass EGR valve unit 40 assembled.

The valve unit 40 has a valve housing 12 which includes a confluence section of the low pressure bypass EGR channel 3 and the inlet channel 2 Are defined. The regulating valve 4 , the inlet throttle valve 5 , the electrical actuator 6 and the connection mechanism 7 are on the valve body 12 assembled.

Below are the regulating valve 4 , the inlet throttle valve 5 , the electrical actuator 6 and the connection mechanism 7 described schematically in this order.

The regulating valve 4 is a throttle valve that is in the duct 3 is arranged, and is using a low-pressure bypass EGR shaft 42 turned in one piece, attached to the valve body 12 is rotatably supported or stored.

The intake throttle valve 5 is a throttle valve that is in the intake passage 2 is arranged, and is provided with an intake throttle shaft 43 turned in one piece, attached to the valve body 12 is rotatably supported or stored. The AGR wave 42 and the intake throttle shaft 43 are arranged parallel to each other.

The electrical actuator 6 has an electric motor 44 , such as a DC motor, and a reduction gear mechanism 45 , The motor 44 generates a rotation output by the excitement. The reduction gear mechanism 45 reduces an output speed of the motor 44 to the output torque of the motor 44 to increase. An output of the reduction gear mechanism 45 drives the regulating valve 4 and drives the input throttle valve 5 over the connection mechanism 7 at.

The connection mechanism 7 is outside of the valve body 12 arranged. The connection mechanism 7 changes the output characteristic of the electric actuator 6 to the intake throttle valve 5 drive. The connection mechanism 7 has a cam plate 9 , which together with the regulating valve 5 turns, and a driven arm 11 that joins together with the intake throttle valve 5 rotates.

The cam plate 9 is plate-shaped and made of a material having high anti-abrasion quality, such as nylon-based resin. The cam plate 12 is with one end of the shaft 42 connected vertically.

The driven arm 11 is plate-shaped and made of a material having a high anti-abrasion quality, such as nylon-based resin. The driven arm 11 is perpendicular to one end of the intake throttle shaft 43 connected in a way that a rotation end of the arm 11 the cam plate 9 covered over a predetermined gap.

The characteristic conversion section of the link mechanism 7 , the output characteristic of the electric actuator 6 has a cam groove 8th from the center of rotation of the cam plate 9 is spaced, and a cam engaging portion 10 , the center of rotation of the arm 11 is spaced. The cam engagement section 10 stands with the cam groove 8th engaged.

The cam engagement section 10 has a cylindrical roller 10a (a rotation difference absorbing means) connected to the cam groove 8th matched, and a wave 10b attached to a rotating end portion of the driven arm 11 is attached. The role 10a is by wave 10b rotatably supported or stored. The wave 10b and the driven arm 11 can be formed integrally from a single integral piece. Alternatively, the wave 10b be formed individually and then on the driven arm 11 be attached.

A cam profile of the cam groove 8th including the cam engaging portion 10 drives, is defined, by a valve position holding cam groove 8a and an intake throttle cam groove 8b get connected.

The valve position holding cam groove 8a is an arcuate groove with the same center as the cam plate 9 and is formed in such a manner that the intake throttle valve 5 held in the fully open position while the regulating valve 4 in a rotation range (θ0-θ1) from a fully closed position θ0 (in FIG 3 EGR valve angle = 0 °) is rotated to a specified center position θ1.

The intake throttle cam groove 8b is from one end of the valve position holding cam groove 8a formed continuously and has an angular shape which changes with a predetermined angle with respect to the arc groove, which is the same center as the cam plate 9 Has. The regulating valve 4 turns the driven arm 11 in a rotation range (θ1-θ2) from the middle position (θ1) to a fully opened position (θ2: in 3 , EGR valve angle = 90 °) and turns the intake throttle valve 5 from a fully open position in one direction, which is the inlet channel 2 closes.

If the cam plate 9 by the actuator 6 over the valve 4 is rotated, the cam engaging portion shifts 10 along the cam groove 8th so that the angle Aθ of the driven arm is changed.

The angle Aθ of the driven arm is an angle that is a rotational position of the driven arm 11 and corresponds to an angle defined between a reference line L0 and a rotation line L1. The reference line L0 is defined to be a center of rotation of the valve 4 and a rotation center of the valve 5 connect to. The rotation line L1 is defined to be the center of rotation of the valve 4 and a rotation center of the roll 10a of the cam engagement portion 10 connect to.

A variation range of a shaped angle Aθ of the driven arm corresponding to a rotation of the cam plate 9 is always set larger than 0 ° (0 ° <Aθ) to shift the cam engagement portion 10 uniform. That means, even if the valve 4 is rotated in the entire rotation range (θ0-θ2), a rotation change of the angle Aθ of the driven arm is made larger than 0 ° (0 ° <Aθ).

More specifically, the driven arm 11 stopped at a position (0 ° <Aθ) in a manner that the angle Aθ of the driven arm is near 0 ° when the valve 4 is rotated between the fully closed position θ0 and the middle position θ1. Furthermore, the driven arm 11 moves in a direction that the angle Aθ of the driven arm becomes larger than 0 ° (0 ° <Aθ) when the valve 4 between the middle position θ1 and the fully opened position θ2.

When the angle Aθ of the driven arm is near 0 ° (when the valve 4 has a range between the fully closed position θ0 and the middle position θ1: for example, the valve is located 4 at the fully closed position θ0 as shown in FIG 1 shown), a rotational force in the driven arm 11 be generated so that a real angle Aθ of the driven arm is less than 0 ° due to the external force (intake pulsation or misfire) acting on the intake throttle valve 5 is applied is.

A mechanical stop device 14 is in the valve unit 40 provided to prevent the actual angle Aθ of the driven arm is less than 0 °. The mechanical stop device 14 Regulates a substantial angle Aθ of the driven arm to 0 ° or more due to contact between an element and an element when the angle Aθ becomes minimum with a rotation line L1 '. That is, the mechanical stop device 14 regulates the minimum value of the angle Aθ of the driven arm to a range between 0 ° and the minimum arm angle Aθ due to the contact between the element and the element.

More specifically, the mechanical stop device 14 of the embodiment by the driven arm 11 that is outside the valve body 12 turns, and a lead 13 attached to an outer wall of the valve body 12 is defined, constructed. As it is in a dashed line in 1 is shown, the driven arm touches 11 the lead 13 , whereby the substantially minimal angle of the driven arm 11 is regulated to 0 ° or more.

That is, even if a gap (including manufacturing tolerances) between the cam groove 8th and the role 10a present, or even if the wave 10b that the role 10a Supports, is deformed, the minimum actual value of the angle Aθ of the driven arm is regulated to 0 ° or more.

The lead 13 can with the valve body 12 be made from a single one-piece piece. Alternatively, the projection 13 individually and then on the valve body 12 be attached.

According to the low pressure bypass EGR device 1 of the embodiment as described above, the minimum actual angle of Angle Aθ of the driven arm is regulated to 0 ° or more by the mechanical stop device 14 is provided. Thereby, the actual angle Aθ of the driven arm does not become smaller than 0 °, even if a force is applied to the driven arm 11 rotates, by the external force, such as an intake pulsation or misfire, on the intake throttle valve 5 is applied is generated.

Therefore, when the external force works on the valve 5 is applied, the cam engaging portion 10 not as bolts or screws with respect to the cam groove 8th , so that prevents the cam plate 9 is blocked. Thus, the reliability of the low pressure bypass EGR regulating valve 4 increase.

Furthermore, the above advantage can only be obtained by the projection 13 on the outer wall of the valve body 12 is provided. That is, the advantage of the present invention can be obtained by a simple structure without increasing its cost.

In the embodiment, as an example of the mechanical stopper, the projection is 13 provided to the driven arm 11 to touch, so that the opening is regulated. Alternatively, the position of the driven arm 11 by a contact between a stopper and the intake throttle valve 5 be regulated.

More specifically, the mechanical stop device 14 through the valve 5 and a protrusion formed on an inner wall of the intake passage 2 is defined. The valve 5 contacts the protrusion projecting into the inlet channel, thus minimizing the substantially minimal angle of the driven arm 11 is regulated to 0 ° or more.

In the embodiment, the present invention is applied to an engine intake / exhaust system with a turbocharger. Alternatively, the present invention may be applied to an engine intake / exhaust system having another intake charge direction (such as a supercharger) different from the turbocharger, or may be applied to an engine intake / exhaust system without an intake charging device.

In the exemplary embodiment, the present invention is applied to an intake / exhaust system for a diesel engine that is driven by the DPF 22 can be known. Alternatively, the present invention may be applied to an intake / exhaust system for another type of internal combustion engine (for example, gasoline engine).

In the above description, NOx is reduced by decreasing the combustion temperature by returning EGR gas to the intake side. Alternatively, the knocking can be reduced by reducing the combustion temperature by returning EGR gas to the inlet side.

A maximum value of the variation range of an angle Aθ of the driven arm is set as a predetermined value Aθ0 and the mechanical stop means 14 Regulates the driven arm 11 in such a manner that the angle Aθ of the driven arm has an angle range between 0 ° and the predetermined value Aθ0.

The angle Aθ of the driven arm is defined to be greater than 0 ° when the rotation line L1 is opposite to the mechanical stop means 14 with respect to the reference line L0 in 1 what is contrary to 5 (b) stands.

Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.

A low pressure bypass EGR device ( 1 ) thus has a mechanical stop device ( 14 ) for regulating a driven arm ( 11 ) a connection mechanism ( 7 ) for driving an intake throttle valve ( 5 ) by changing the output characteristic of an electric actuator ( 6 ) on. An angle (Aθ) of the driven arm of the drive arm ( 11 ) is always set greater than 0 °, while a cam plate ( 9 ) has a rotation and has a variation range defined between 0 ° and a predetermined value (Aθ0). The mechanical stop device ( 14 ) regulates the driven arm ( 11 ) in a travel range between 0 ° and the predetermined value (Aθ0).

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• JP 2008-150955 A [0005]

Claims (6)

A low pressure bypass EGR device ( 1 ) comprising: a low pressure bypass EGR regulating valve ( 4 ) comprising a flow channel region of a low pressure bypass EGR channel ( 3 ) via the EGR gas into an intake passage ( 2 ), an intake throttle valve ( 5 ) for generating intake negative pressure at a confluence portion of the intake passage (Fig. 2 ) and the low pressure bypass EGR channel ( 3 ), a single electrical actuator ( 6 ), the low pressure bypass EGR regulating valve ( 4 ) drives a connection mechanism ( 7 ) for driving the intake throttle valve ( 5 ) by changing an output characteristic of the electric actuator ( 6 ), whereby the connection mechanism ( 7 ): a cam plate ( 9 ) with a cam groove ( 8th ), which deals with the low-pressure bypass EGR regulating valve ( 4 ) and a driven arm ( 11 ) with a cam engagement portion ( 10 ), which interacts with the intake throttle valve ( 5 ), wherein the cam engagement portion (FIG. 10 ) with the cam groove ( 8th ) and a mechanical stop device ( 14 ) for regulating the driven arm ( 11 ), whereby the driven arm ( 11 ) has an angle (Aθ) of the driven arm represented by an angle formed between a reference line (L0) which is a center of rotation of the low-pressure bypass EGR regulating valve (10). 4 ) and a rotation center of the intake throttle valve ( 5 ) and a rotation line (L1) defining the center of rotation of the low pressure bypass EGR regulating valve (12) 4 ) and the cam engagement portion ( 10 ), and the angle Aθ of the driven arm has a variation range which is always set larger than 0 °, while the cam plate (FIG. 9 ) describes a rotation. The low-pressure bypass EGR device according to claim 1, wherein said cam engagement portion (16) 10 ) has a role ( 10a ) in the cam groove ( 8th ) and a wave ( 10b ), which at one end of rotation of the driven arm ( 11 ), and wherein the shaft ( 10b ) the rotor ( 10a ) rotatably supports. The low-pressure bypass EGR apparatus of claim 1 or 2, further comprising: a valve housing ( 12 ), in which the low-pressure bypass EGR regulating valve ( 4 ) and the intake throttle valve ( 5 ), whereby the driven arm ( 11 ) outside of the valve housing ( 12 ), the mechanical stop device ( 14 ) a lead ( 13 ), which on an outer wall of the valve housing ( 12 ) and the driven arm ( 11 ) the lead ( 13 ) to a substantially minimum angle of the driven arm ( 11 ) to 0 ° or more. The low pressure bypass EGR apparatus of claim 1 or 2, wherein said mechanical stop means (16) 14 ) through the inlet throttle valve ( 5 ) and a projection formed on an inner wall of the inlet channel ( 12 ), and the intake throttle valve ( 5 ) touches the projection to a substantially minimum angle of the driven arm ( 11 ) to 0 ° or more. The low-pressure bypass EGR apparatus according to any one of claims 1 to 4, wherein a minimum value of the variation range is set as a predetermined value (Aθ0), and the mechanical stop device (16) 14 ) regulates a minimum value of the angle (Aθ) of the driven arm to an angle range between 0 ° and the predetermined value (Aθ0). The low-pressure bypass EGR apparatus according to any one of claims 1 to 4, wherein a maximum value of the variation range is set as a predetermined value (Aθ0), and the mechanical stop means (A) 14 ) the driven arm ( 11 ) in such a manner that the angle (Aθ) of the driven arm has an angle range between 0 ° and the predetermined value (Aθ0).

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