JP2013199868A - Control system of exhaust gas recirculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To circulate exhaust gas with high accuracy in a desired flow rate, even if a seat member with a valve body seated thereon wears in an exhaust gas recirculation device.SOLUTION: In a control system 10 of an exhaust gas recirculation device, an angle when the valve 22 is fully closed is detected by an opening sensor 28, and an angle difference Δθ is calculated by comparing the same with the fully closed angle when starting an engine in a previous time. A determination is made that a ware is generated in a valve seat 24 on which the valve 22 sits when the angle difference Δθ exceeds an allowable range, and a flow rate map is corrected so as to add a turning angle of the valve corresponding to a flow rate increase of exhaust gas increasing due to the wear.

Description

  The present invention relates to a control system for controlling an exhaust gas recirculation device provided in an exhaust gas recirculation means that connects an intake system and an exhaust system in an internal combustion engine.

  Conventionally, for example, an exhaust gas recirculation device has been used to remove harmful components discharged from an internal combustion engine. The exhaust gas recirculation device recirculates exhaust gas discharged from an internal combustion engine to an intake system, and reduces harmful components such as NOx contained in the exhaust gas to reduce the harmful components such as NOx. Has the function of communicating with the system.

  The present applicant has proposed a flow path opening / closing valve provided in an exhaust gas recirculation path that connects an intake passage and an exhaust passage of an internal combustion engine (see Patent Document 1). The flow path opening / closing valve has a body main body connected to the exhaust gas recirculation path, and a spherical ball valve is rotatably disposed inside the body main body. Then, the ball valve connected to the rotational drive source via the shaft rotates by a predetermined angle to switch the communication state between the exhaust gas inlet and the exhaust gas outlet formed in the body body, and the exhaust gas The flow state of the exhaust gas in the reflux path is controlled.

JP 2010-236686 A

  The present invention has been made in connection with the above-mentioned proposal. Even when the seat member on which the valve body is seated is worn, the exhaust gas recirculation capable of circulating the exhaust gas at a desired flow rate with high accuracy is provided. An object is to provide a control system for a circulation device.

In order to achieve the above-mentioned object, the present invention is provided in an exhaust gas recirculation passage connecting an intake system and an exhaust system of an internal combustion engine, and by communicating the intake system and the exhaust system, Exhaust gas having an exhaust gas recirculation valve for recirculating a part of the exhaust gas exhausted from the exhaust system to the intake system through the exhaust gas recirculation passage, and a control unit for driving and controlling the exhaust gas recirculation valve In the control system of the recirculation device,
The exhaust gas recirculation device includes a body and a rotatable inside of the body, and at least a part of the outer surface is formed in a spherical shape, and the center of rotation is eccentric with respect to the center of curvature of the outer surface. A valve member, and a seat member that is provided in the body and that shuts off the flow of exhaust gas by seating the valve,
The control system includes a storage unit that stores a flow rate map indicating the flow rate of the exhaust gas corresponding to the opening of the valve body in the control unit;
An opening degree detecting means for detecting an opening degree of the valve body with respect to the seat member;
From the fully closed angle of the valve body in the fully closed state in which the valve body is seated on the seat member, and the fully closed set angle preset in the control unit, which is detected by the opening degree detection means, Wear amount calculating means for calculating the wear amount;
Arithmetic means for changing a flow map of the exhaust gas in the control unit based on the wear amount;
It is characterized by having.

  According to the present invention, in the control system of the exhaust gas recirculation device, the fully closed angle in the fully closed state in which the valve body is seated on the seat member is detected by the opening degree detecting means capable of detecting the opening degree of the valve body, The wear amount of the seat member is calculated by the wear amount calculating means by comparing with the set fully closed set angle. And the flow map of the exhaust gas in a control part is changed by a calculation means based on the amount of wear.

  Therefore, even when the seat member on which the valve body is seated is worn, the exhaust gas flow map is changed based on the exhaust gas flow rate change that increases due to the wear, so that the exhaust gas can be accurately and accurately supplied at a desired flow rate. It becomes possible to distribute to.

  The calculating means may calculate the flow rate of the exhaust gas that increases in accordance with the wear amount of the seat member, and update the flow rate map in accordance with the increase in the flow rate.

  Furthermore, it is preferable to set the fully open state in which the valve body is separated from the seat member as a zero point, and to perform drive control of the valve body. Thereby, the complicated calculation of map conversion can be avoided.

  Furthermore, the fully closed set angle is an opening detected by the opening detection means when the internal combustion engine was operated last time, and may be stored in the storage means.

  According to the present invention, the following effects can be obtained.

  That is, in the control system of the exhaust gas recirculation device, the fully closed angle in the fully closed state in which the valve body is seated on the seat member is detected by the opening degree detecting means capable of detecting the opening degree of the valve body. The wear amount of the seat member is calculated by the wear amount calculation means by comparing with the closed set angle. Then, by changing the exhaust gas flow rate map in the control unit by the calculation means based on the wear amount, for example, even when the seat member on which the valve body is seated wears, the exhaust gas flow rate change that increases due to the wear Since the flow map of the exhaust gas can be changed based on the above, the exhaust gas can be circulated at a desired flow rate with high accuracy.

It is a schematic block diagram of the control system of the exhaust-gas recirculation apparatus which concerns on embodiment of this invention. It is an expanded sectional view of the exhaust gas recirculation valve which comprises the control system of FIG. It is a flowchart for correct | amending the opening degree of a valve corresponding to abrasion of a valve seat. It is the 1st and 2nd characteristic curve figure which shows the relationship between the opening degree of a valve | bulb, and the flow volume of exhaust gas.

  A preferred embodiment of a control system for an exhaust gas recirculation apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. In FIG. 1, reference numeral 10 indicates a control system for an exhaust gas recirculation device according to an embodiment of the present invention.

  As shown in FIG. 1, the control system 10 for the exhaust gas recirculation device includes a controller 12 (for example, ECU) mounted on a vehicle (not shown) and an exhaust gas based on a control signal output from the controller 12. The controller 12 includes a calculation unit (calculation unit) 16 that performs calculation and a memory (storage unit) 18 that stores various data to be described later. .

  Next, the configuration of the exhaust gas recirculation valve 14 described above will be briefly described with reference to FIGS.

  The exhaust gas recirculation valve 14 is provided between an intake device and an exhaust device constituting the engine, and is provided rotatably in the body main body 20 and the body main body 20 as shown in FIG. A valve (valve element) 22, a valve seat (seat member) 24 that abuts on the outer peripheral surface of the valve 22, and a drive source that provides a rotational driving force to the valve 22 provided on the body body 20. 26 and an opening degree sensor (opening degree detecting means) 28 (see FIG. 1) for detecting the rotation angle of the valve 22.

  The body main body 20 is provided with a gas inlet 30 to which exhaust gas is supplied and a gas outlet (not shown) provided on the opposite side to lead out the exhaust gas. In the communication chamber 32 provided between the gas outlet and the gas outlet, a substantially spherical valve 22 is rotatably provided.

  In addition, a mounting hole 34 is formed in the body main body 20 between the communication chamber 32 and the gas inlet 30, and a valve seat 24 that slides on the outer peripheral surface of the valve 22 is provided in the mounting hole 34. The valve seat 24 has a seat portion 36 that is formed on the side of the communication chamber 32 and contacts the valve 22.

  On the other hand, as shown in FIG. 2, a shaft hole (not shown) penetrating vertically upward from the communication chamber 32 is formed in a substantially central portion of the body main body 20, and a shaft of a driving force transmission mechanism described later is formed. 38 is rotatably inserted.

  The bulb 22 has an outer circumferential surface formed at least partially in a spherical shape, and a shaft 38 is inserted at a position eccentric from the center of curvature of the bulb 22 by a predetermined distance in the radially outward direction. For this reason, the valve 22 is installed in the communication chamber 32 so as to rotate (swing) about the axis A2 of the shaft 38 set at a position eccentric from the axis A1 of the valve 22.

  The drive source 26 is, for example, a stepping motor or a rotary actuator that is electrically connected to the controller 12 and that rotationally drives the shaft 38 and the valve 22 based on a control signal from the controller 12. Then, the rotational driving force of the drive source 26 is transmitted to the shaft 38, so that the valve 22 connected to the shaft 38 opens the valve 22 in the valve opening direction (in FIG. Rotate by a predetermined angle in the direction of arrow B).

  The opening sensor 28 is composed of, for example, an encoder, is arranged coaxially with the shaft 38 and the drive source 26, and detects the rotation amount (rotation angle) of the drive source 26 and the shaft 38. Then, the detected rotation amount of the shaft 38 is output to the controller 12 as a detection signal, and is stored as data in the memory 18, for example. That is, the opening angle sensor 28 can detect the rotation angle of the valve 22 based on the rotation amount of the shaft 38.

  The control system 10 of the exhaust gas recirculation apparatus according to the embodiment of the present invention is basically configured as described above. Next, the operation of the control system 10 will be described with reference to FIG. .

  First, the driver turns on the ignition switch in the vehicle and starts the engine (step S1). Thereafter, in step S2, a flow rate map for setting the flow rate of the exhaust gas is read based on the relationship between the engine speed NE and the negative pressure PB.

  Next, in step S3, a control signal is output from the controller 12 to the drive source 26, and the valve 22 is rotated by a predetermined angle so that it is seated on the valve seat 24 and fully closed (in the direction of arrow C in FIG. 2). ). In step S <b> 4, the opening degree sensor 28 determines whether or not the valve 22 is in a fully closed state in which the valve 22 is seated on the valve seat 24. After confirming that the valve 22 is fully closed, the engine is started (step S5), and it is determined in step S6 whether the engine has been started.

  Then, after engine start is confirmed in step S6 (step S6: YES), in step S7, the angle in the fully closed state of the valve 22 seated on the valve seat 24 is detected by the opening sensor 28, and the detection is performed. The fully closed angle θcl of the valve 22 is output to the controller 12 and stored in the memory 18. Thereafter, in step S8, the calculation unit 16 of the controller 12 compares the fully closed set angle θorg of the valve 22 that is detected when the engine is started last time and is previously stored in the memory 18, with the fully closed angle θcl. Then, an angle difference Δθ which is the difference is calculated (step S9). That is, in this step S9, the amount of wear of the valve seat 24 is calculated as the rotation angle of the valve 22. In this case, the angle of the valve 22 is detected as an angle (for example, 85 °) with the valve 22 being fully opened (a two-dot chain line shape in FIG. 2) as a zero point.

  Next, it is determined in step S10 whether or not the angle difference Δθ is within a preset allowable range (α1 ≦ Δθ ≦ α2). If it is determined that the angle difference Δθ is within the allowable range, In the case where the angle of the valve 22 at the time of closing (full closing angle θcl) hardly changes with respect to the previous angle (full closing set angle θorg) and the amount of wear of the valve seat 24 has hardly increased, in step S11 The duty corresponding to the engine speed NE and the negative pressure PB of the intake air sucked into the combustion chamber from the intake device is set with reference to the flow map, and a control signal based on the duty is sent to the drive source 26. Is output. As a result, the valve 22 rotates by a predetermined angle from the fully closed state, and the exhaust gas flows from the gas inlet 30 to the gas outlet through the communication chamber 32 at a predetermined flow rate and is recirculated to the intake system of the engine. .

  That is, when the angle difference Δθ is within the allowable range, the flow rate map stored in advance in the controller 12 is referred to, and the valve 22 of the exhaust gas recirculation valve 14 is rotated at an opening based on the map. Let

  On the other hand, if it is determined in step S10 that the angle difference Δθ is outside the preset allowable range, it is determined in step S12 whether the angle difference Δθ is smaller than the allowable range. If it is determined that the angle is less than the allowable range (Δθ <α1), the rotation angle of the valve 22 is abnormal. For example, a foreign object or the like is caught between the valve 22 and the valve seat 24. It is judged that Therefore, in step S13, for example, a warning signal indicating the occurrence of a failure is output to the failure warning lamp, and a series of processing is stopped.

  Next, when it is determined in step S12 that the angle difference Δθ exceeds the allowable range (α2 <Δθ), the exhaust of the valve seat 24 progresses and the exhaust gas is exhausted when the valve 22 is fully closed. There is a concern that a leak will occur. Therefore, in step S14, in order to correct the opening degree of the valve 22, the arithmetic opening part 16 of the controller 12 corrects the instruction opening degree θcmd output from the controller 12 to the drive source 26.

  In order to correct the indicated opening degree θcmd, first, based on the angle difference Δθ, the seat portion 36 of the valve seat 24 and the seat portion 36a of the current valve seat 24 during the previous engine operation (two-dot chain line in FIG. 2). 4), that is, the wear amount ΔG (see FIG. 2) of the seat portion 36, and then the flow rate increase amount ΔQ of the exhaust gas flowing through the wear amount ΔG is calculated. The correction angle Δθ ′ of the valve 22 for circulating the flow rate increase amount ΔQ is calculated based on the flow rate map shown in FIG. Note that the flow rate increase amount ΔQ with respect to the wear amount ΔG is measured in advance by experiments or the like and stored in the memory of the controller 12 as a flow rate map (not shown).

  That is, the correction angle Δθ ′ is a rotation angle of the valve 22 corresponding to an increase in the flow rate of the exhaust gas that increases due to wear of the valve seat 24.

  Then, based on the calculated correction angle Δθ ′, the flow rate map shown in FIG. 4 is changed from the first characteristic curve L1 to the second characteristic curve L2. More specifically, since the rotation angle of the valve 22 in the fully closed direction (the direction of arrow C in FIG. 2) is increased due to wear of the valve seat 24, the fully closed side (FIG. 4) corresponds to the correction angle Δθ ′. The characteristic curve is shifted in the middle (to the left of the page). In this case, the second characteristic curve L2 is moved in parallel by the correction angle Δθ ′ as it is without changing the linearity of the first characteristic curve L1, and the indicated opening degree θcmd is corrected.

  Finally, in step S11, referring to the flow rate map updated in step S14, the instruction opening degree θcmd corresponding to the engine speed NE and the negative pressure PB of the intake air sucked into the combustion chamber from the intake device is set. Then, a control signal (for example, a duty signal) based on the indicated opening degree θcmd is output to the drive source 26. As a result, the valve 22 rotates by a predetermined angle from the fully closed state, and the exhaust gas flows from the gas inlet 30 to the gas outlet through the communication chamber 32 at a predetermined flow rate and is recirculated to the intake system of the engine. .

  As described above, in the present embodiment, in the exhaust gas recirculation valve 14 in which the axis A2 of the shaft 38 and the axis A1 of the valve 22 are eccentric, the seat portion 36 of the valve seat 24 is worn by the opening / closing operation of the valve 22. In this case, an angle difference Δθ between an angle when the valve 22 is fully closed (fully closed set angle) θorg and an angle when the valve 22 is fully closed when the engine is started (θcl) is calculated, A correction angle Δθ ′ of the valve 22 corresponding to the flow rate increase amount ΔQ corresponding to the increase in the exhaust gas flow rate when the angle Δθ occurs is calculated. Thus, the exhaust gas flow rate can be controlled with high accuracy in accordance with the wear of the valve seat 24 by changing the rotation angle of the valve 22 to the fully closed side by the correction angle Δθ ′ in the flow rate map. Is possible.

  In other words, the flow rate map is changed based not only on the angle difference Δθ of the rotation angle of the valve 22 when the valve seat 24 is worn, but also on the flow rate increase amount ΔQ caused by the angle difference Δθ. It becomes possible to control the gas flow rate with higher accuracy.

  Further, in the flow map having the flow characteristic of the exhaust gas, the valve opening degree is set so that the valve opening degree becomes zero when the valve 22 is fully opened (see FIG. 4). A new flow rate map can be easily set by simply adding 22 opening increments (Δθ) to the flow rate map. As a result, it is possible to suppress the calculation amount in the calculation unit 16 of the controller 12 as compared with the case of creating another new flow rate map.

  For calculating the angle difference Δθ, the fully closed set angle θorg of the valve 22 detected when the engine was started last time was used. Instead, for example, the first (initial) total of the valve 22 is used. A closed set angle may be used. In this case, for example, it is possible to construct a flow rate map that takes into account the increase in flow rate due to the total amount of wear from the time of product shipment to the time when the engine is started this time, so that accurate exhaust gas flow rate control can be achieved.

  The control system for the exhaust gas recirculation device according to the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Control system 12 of exhaust gas recirculation apparatus ... Controller 14 ... Exhaust gas recirculation valve 16 ... Calculation part 18 ... Memory 20 ... Body main body 22 ... Valve 24 ... Valve seat 26 ... Drive source 28 ... Opening sensor 36 ... Seat Part 38 ... Shaft

Claims (4)

An exhaust gas recirculation passage connecting an intake system and an exhaust system of the internal combustion engine is provided, and a part of the exhaust gas discharged from the internal combustion engine is removed from the exhaust system by communicating the intake system and the exhaust system. In an exhaust gas recirculation control system comprising an exhaust gas recirculation valve that recirculates to the intake system through the exhaust gas recirculation passage, and a control unit that drives and controls the exhaust gas recirculation valve;
The exhaust gas recirculation device includes a body and a rotatable inside of the body, and at least a part of the outer surface is formed in a spherical shape, and the center of rotation is eccentric with respect to the center of curvature of the outer surface. A valve member, and a seat member that is provided in the body and that shuts off the flow of exhaust gas by seating the valve,
The control system includes a storage unit that stores a flow rate map indicating the flow rate of the exhaust gas corresponding to the opening of the valve body in the control unit;
An opening degree detecting means for detecting an opening degree of the valve body with respect to the seat member;
From the fully closed angle of the valve body in the fully closed state in which the valve body is seated on the seat member, and the fully closed set angle preset in the control unit, which is detected by the opening degree detection means, Wear amount calculating means for calculating the wear amount;
Arithmetic means for changing a flow map of the exhaust gas in the control unit based on the wear amount;
A control system for an exhaust gas recirculation device. The control system according to claim 1,
The control means calculates the flow rate of the exhaust gas that increases in accordance with the amount of wear of the seat member, and updates the flow rate map in response to the increase in the flow rate. system. The control system according to claim 1 or 2,
A control system for an exhaust gas recirculation device, wherein the valve body is driven and controlled by setting a fully open state in which the valve body is separated from the seat member as a zero point. The control system according to any one of claims 1 to 3,
The fully closed set angle is an opening detected by the opening detecting means when the internal combustion engine was operated last time, and is stored in the storage means. system.

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