JPH06137220A - Exhaust gas recirculation control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance control accuracy over the entire operating range, and also to stabilize the characteristics in performance for a long period of service. CONSTITUTION:An exhaust gas recirculation control device is provided both with a pump part 10 having an intake port 101 communicated with an exhaust passage 3 and a discharge port 102 communicated with an intake passage 2, and with a motor part 12 for driving the pump part. The motor part 12 is controlled by a control signal responding to the operating condition that is obtained by a control unit 7 on the basis of the detection signals from respective sensors 5, 6.

Description

Detailed Description of the Invention

[0001]

The present invention is used in an internal combustion engine,
The exhaust gas to reduce harmful components such as NO _X was set to be recirculated to the intake system to an exhaust recirculation control system.

[0002]

2. Description of the Related Art Conventionally, as such an exhaust gas recirculation control device, for example, one described in Japanese Patent Publication No. 55-42258 is known.

In this conventional example, exhaust gas recirculation (hereinafter,
A control device (referred to as EGR) has a negative pressure signal chamber communicating with an EGR port in which a negative pressure is generated according to the rotation of the throttle valve, and a diaphragm that operates in response to the negative pressure of the negative pressure signal chamber. The valve body is driven by the diaphragm to control the effective cross-sectional area of the return passage, and the diaphragm and the valve body are integrally connected by a rod.

[0004]

However, in such a conventional example, the structure is such that it is operated by the negative pressure generated according to the rotation of the throttle valve, and the negative pressure signal sensing portion is a diaphragm. Since it is configured, it can accurately and reliably respond to engine operating conditions.
It is difficult to control the R amount, the operating characteristics are likely to vary, and it takes time to transfer the negative pressure from the EGR port to the negative pressure signal chamber, so that the responsiveness of the operation is deteriorated. Further, when the throttle is fully opened, a negative pressure signal of a sufficient level for properly controlling the EGR control device cannot be obtained, and there is a problem that it is difficult to perform EGR properly over the entire operating range.

Further, since the physical characteristics of the diaphragm change over time, there has been a problem that the performance characteristics of the diaphragm change when used for a long period of time.

The object of the present invention is to solve the problems of the prior art, to improve the control accuracy over the entire operating range, and to recirculate the exhaust gas of an internal combustion engine in which the performance characteristics do not change even after long-term use. It is to provide a control device.

[0007]

In order to achieve the above object, the present invention drives a pump means having an intake port communicating with an exhaust passage and a discharge port communicating with an intake passage, and the pump means. And motor means.

[0008]

According to the present invention, when the pump means is driven by the motor means, the pump means sucks the exhaust gas from the suction port communicated with the exhaust passage and passes it through the discharge port communicated with the suction passage. And send it to the inhalation passage.

Therefore, a desired amount of exhaust gas can be recirculated to the intake passage by controlling the motor means.

[0010]

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

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

First, the structure will be described. 1 is an engine, 2 is an intake passage, and 3 is an exhaust passage. A throttle valve 4 and an air flow meter 5 are provided in the intake passage 2, and a detection signal of the throttle sensor 6 for detecting the opening degree of the throttle valve 4 and the air flow meter 5 is sent to a control unit 7 including a microcomputer or the like. Sent.

Reference numeral 8 is an EGR passage for returning a part of the exhaust gas in the exhaust passage 3 of the engine 1 to the intake passage 2, and 9 is the above EG.
An exhaust gas recirculation control device arranged in the middle of the R passage 8, the exhaust gas recirculation control device 9 sucks the exhaust gas in the exhaust passage 3 through the intake port 10 ₁ , and discharges it into the intake passage 2. It is composed of a pump unit 10 for discharging via 10 ₂ and a motor unit 12 for driving the pump unit 10.

FIG. 2 shows details of the exhaust gas recirculation control device 9.
The pump unit 10 is a vane pump in this embodiment, and the vane 10B movable in the radial direction from the center of the pump shaft.
Has a rotor 10A that holds a shaft 10C that is connected to an output shaft 12A of the drive motor unit 12
It is integrated with. Therefore, the rotor 10A also rotates in association with the rotation of the drive motor unit 12, and the vane 10B moves in the radial direction by the centrifugal force of the rotation. At that time, the moving position of the vane 10B is regulated along the shape of the elliptical hole of the cam ring 10D, so that the exhaust gas is sucked from the EGR passage 8 communicating with the exhaust passage 3 and discharged to the intake passage 2, as shown in FIG. Will be done. The exhaust gas discharge flow rate of the exhaust gas recirculation control device 9 is determined by controlling the rotation speed of the drive motor unit 12 according to the operating conditions of the engine 1 by the magnitude of the output signal from the control unit 7. That is, the control unit 7 includes a crank angle sensor that detects the engine speed in addition to the detection signals from the air flow meter 5 and the throttle sensor 6 of the throttle valve 4.
Detection from various sensors such as a negative pressure sensor that detects the pressure in the intake passage 2 downstream of the throttle valve 4, an exhaust pressure sensor that detects the pressure in the exhaust passage 3, and a cooling water temperature sensor that detects the temperature of engine cooling water. A signal is sent and the current engine operating state is calculated based on these detected values. Therefore, NO for this engine operating state
By changing the output signal (current value) to the drive motor unit 12 so that the optimum amount of exhaust gas for reducing _X etc. is sent from the pump unit 10 to the intake passage 2, Thus, the exhaust gas recirculation amount is arbitrarily selected.

As described above, the control unit 7 which obtains the current engine operating state based on the detection signals from various sensors controls the rotation speed of the motor 12 by the output signal to control the intake and discharge amounts of the pump 10. Since variable control is possible, it becomes possible to control the exhaust gas recirculation amount with high accuracy according to the engine operating state. Needless to say, the model of the pump is not limited to the model of the vane pump described above, and the model of the gear pump or the axial flow pump may be used.

In the above embodiment, the pump portion 10 and the drive motor portion 12 are integrated, but when the operating temperature is high and it is difficult to secure the durability of the motor, the motor 12 is driven. It is also possible to separate the pump unit 10 and the drive motor unit 12 by transmitting the force to the pump unit 10 via a belt or the like.

[0017]

As described above, according to the present invention, the exhaust gas recirculation control device has the pump means having the intake port communicated with the exhaust passage and the discharge port communicated with the intake passage, and the pump means. Since it is equipped with a motor means for driving the engine, the exhaust gas recirculation amount is not restricted by the lack of a negative pressure source unlike the diaphragm method, and the exhaust gas recirculation amount is accurately and appropriately set in the entire engine rotation range. The performance characteristics do not change even after long-term use.

Further, even in the region where the negative pressure on the intake side of the internal combustion engine is insufficient, the exhaust gas can be recirculated by pressurizing because of the pump system. Therefore, there is an effect that it is possible to set the diesel engine without using the throttle valve.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an exhaust gas recirculation control device according to an embodiment of the present invention.

FIG. 3 is an explanatory view showing a cross section taken along line AA of FIG. 2 together with piping.

[Explanation of symbols]

 2 Intake passage 3 Exhaust passage 7 Control unit 10 Pump section 12 Motor section

Claims (2)

[Claims] 1. Pump means having an intake port communicating with an exhaust passage and a discharge port communicating with an intake passage,
An exhaust gas recirculation control device for an internal combustion engine, comprising: a motor unit that drives the pump unit. 2. The exhaust gas recirculation control device for an internal combustion engine, wherein the motor means controls the rotational speed thereof according to the operating state of the internal combustion engine.