JPS6120267Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust gas recirculation control device for a diesel engine.

Exhaust gas recirculation (EGR) is generally used in diesel engines to recirculate part of the exhaust gas back into the intake air in order to reduce the generation of NOx emitted from the engine.
Equipped with equipment.

Conventionally, there is an EGR device as shown in FIG. 1, for example. (References JP-A-1973-
111015) This is because the intake throttle valve 4 installed in the intake pipe 3 that supplies air from the air cleaner 2 to the engine 1 is interlocked with the control lever 7 of the fuel injection pump 6 via the link mechanism 5. The control lever 7 is linked to an accelerator pedal (not shown).

The other end of an EGR passage 9 whose one end opens into an exhaust pipe 8 is connected to the intake pipe 3 downstream of the throttle valve 4 .

The interlock between the control lever 7 and the intake throttle valve 4 is generally configured such that as the opening degree of the control lever 7 increases, that is, as the fuel injection amount increases, the opening degree of the intake throttle valve 4 also increases.

Therefore, a negative pressure proportional to the opening degree of the intake throttle valve 4 is generated downstream of the intake throttle valve 4. At this time, a negative pressure is generated from the EGR passage 9 to the intake pipe 3 according to the differential pressure between the intake negative pressure and the exhaust pressure. A portion of the exhaust gas is recirculated.

As a result, the EGR amount is controlled so that it increases in the lower load range and decreases as the load increases.

However, in this device, the EGR amount is controlled only by the differential pressure between the suction negative pressure and the exhaust pressure. In this case, even if the suction negative pressure decreases in the high-speed, high-load range, the exhaust pressure (positive pressure) develops, so the differential pressure does not become much smaller, resulting in excessive EGR, which worsens combustion and increases the production of HC, CO, etc. The problem was that a large amount of unburned components and black smoke were emitted.

This invention was proposed in view of these points,
A piston-type intake throttle valve is provided that responds to the control lever of the injection pump.
The purpose of the present invention is to solve the above problems by configuring the EGR amount to be controlled through a valve that opens and closes the EGR passage.

Hereinafter, embodiments of the present invention will be described based on the drawings.

Figure 2 shows the entirety of the present invention.
11 is the diesel engine body, 11 is the air cleaner, 12 is the intake pipe, 13 is the exhaust pipe, and upstream of the intake pipe 12 is a piston-type exhaust recirculation amount control device 1.
4, and an EGR passage (pipe) 15 branched from the exhaust pipe 13 is connected to the lower part of the control device 14.

16 is an interlocking device provided in the intake pipe 12, which includes an accelerator wire 19 connected to the lever 18 of the accelerator pedal 17, and an EGR connected to the control device 14.
A control wire 20 and a control wire 21 connected to a control lever of a fuel injection pump (not shown) are connected, respectively.

This interlocking device 16 synchronizes the fuel injection pump and the control device 14 and interlocks them with the accelerator pedal 17. At the same time, a negative pressure actuator 22 attached to the intake pipe 12 independently controls the control device 14 (that is, the accelerator pedal 17). It also allows driving (independently of the pedal 17).

As shown in FIG. 3, the piston type exhaust recirculation amount control device 14 includes a cylindrical piston type intake throttle valve 2 mounted on a housing 25 fixed to the intake pipe 12 with bolts or the like.
6 is housed in a freely sliding manner, and its main body 26A moves forward and backward in a direction perpendicular to the axis of the intake pipe 12, thereby making the passage area of the intake pipe 12 variable.

The maximum approach position at this time is regulated by the piston portion 27 of the intake throttle valve 26 having an upwardly expanded diameter coming into contact with the tip of the guide tube portion 28 of the intake pipe 12 .

A weight 29 is fixed to the piston portion 27 so as to partition the internal space 26B of the intake throttle valve 26.
A cylindrical stopper 31 is provided in this internal space 26B and is biased toward the weight 29 by a spring 30.
is mounted to be movable up and down in the figure.

The base end of a valve shaft 32 is fixed to the center of this stopper 31, and the other end freely slides through a guide 33 at the lower wall of the intake throttle valve 26 and opens directly below the intake throttle valve 26. A poppet-shaped valve exits through the EGR gas inlet 34, reaches the lower part of the valve seat 35 press-fitted into the inlet 34, and at its end connects and separates from the valve seat 35 to communicate and block the EGR passage 15. 36 is fixed.

The EGR passage 15 is connected to the intake pipe 12 via a valve housing 37.

In other words, the valve housing 37 is the EGR passage 1
5 and branched from the exhaust pipe 13.
The EGR passage 15 is connected to a housing 37 via a connector 38, and the housing 37 is fixed to the intake pipe 12 with bolts or the like so as to surround the valve seat 35 and valve 36.

The inside of the housing 25 of the intake throttle valve 26 is
A negative pressure chamber 40 and an atmospheric chamber 41 are created by the piston part 27.
In the negative pressure chamber 40, the negative pressure of the bench lily part 42 formed by the main body part 26A of the intake throttle valve 26 and the inner wall protrusion 12A of the intake pipe 12 opposing thereto is applied to the negative pressure chamber 40. 26, negative pressure holes 43a and 43b formed in the stopper 31 and the weight 29, respectively;
43c, and the atmospheric chamber 41 is open to the atmosphere upstream of the throttle valve 26 through a vent 44 formed in the intake pipe 12.

Further, a return spring 45 is interposed in the negative pressure chamber 40 to always urge the intake throttle valve 26 toward the intake pipe 12 side.

The return spring 45 is made of a spring constant that is stronger than the force that pushes up the intake throttle valve 26 due to the pressure difference even under engine operating conditions where the pressure difference between the atmospheric chamber 41 and the negative pressure chamber 40 is maximum. It is composed of

One end of the rod 47 is connected to the center of the weight 29 fixed to the piston portion 27.
The leading end of the housing 25 passes through the upper wall of the housing 25 upwardly through the guide 48, and the connecting bracket 4 is connected to this terminal.
9 and the cylindrical mooring stopper 50 described above.
An EGR control wire 20 is connected.

This EGR control wire 20 is protected by an outer casing 51, and the terminal of the outer casing 51 is connected to a screw 52 and a nut 5.
3 and 53 to the upper wall of a protective cover 54 which is fixed to the upper part of the housing 25 with bolts or the like.

And the above-mentioned screw 52, rod 47,
Intake throttle valve 26, valve shaft 32, valve seat 35
(EGR gas outlet 34) and valve 36 are all arranged concentrically.

FIG. 4 shows a detailed configuration of the interlocking device 16 that interlocks the piston-type exhaust gas recirculation amount control device 14 configured as described above and the control lever of the fuel injection pump (not shown).

The interlocking device 16 has a fan-shaped first drum 56 and a second drum 57 that are slightly different in height and are arranged in parallel on the same axis at a predetermined interval, and are formed at the base end of each drum. Stays 58a and 58b are provided opposite to the intake pipe 12 via a fulcrum hole (not shown).
It is supported rotatably in the direction of the arrow in the figure by a bolt 59 that passes through it.

Guide grooves 60a and 60b are formed on both upper sides of the first drum 56, and the aforementioned accelerator wire 19 and the control wire 21 of the fuel injection pump are inserted into the notches 61a and 61b of the guide grooves 60a and 60b. Connecting mooring stopper pins 62a and 62b are respectively locked.

A guide groove portion 63 is similarly formed on the upper side of the second drum 57, and the EGR control wire 20 of the aforementioned control device 14 (piston type intake throttle valve 26) is connected to the notch portion 64. The mooring stopper pin 65 is locked.

The second drum 57 is operated by a return spring 66 interposed between the second drum 57 and the first drum 56.
It is always energized so as to come into contact with a stopper 67 formed on the first drum 56.

Therefore, whenever the first drum 56 rotates, the second drum 57 also rotates following it, but the second drum 57 can rotate independently in the direction away from the stopper 67.

A negative pressure actuator 22 that independently drives the second drum 57 is attached to a predetermined position of the intake pipe 12 via a bracket 68.

The negative pressure actuator 22 is a general actuator consisting of a diaphragm, a diaphragm disk, a compression coil spring, etc. (not shown), and atmospheric pressure or negative pressure is selectively introduced into the negative pressure hole 69 from a pressure source (not shown) via a three-way solenoid valve, etc. The rod 70 is expanded and contracted by being moved.

The tip of the rod 70 is bent at a substantially right angle and is slidably engaged with an arcuate slit 71 formed in the middle of the second drum 57.

Next, the operation of the present invention will be explained.

In a low engine load range, the amount of depression of the accelerator pedal 17 is small, so the interlocking device 16 is positioned to the left in FIGS. 2 and 4.

Therefore, the control wire 21 and
Since the amount of rightward tension of the EGR control wire 20 is small, the opening degree of the control lever is small in the fuel injection pump (not shown) and the fuel injection amount is controlled to a small amount, and the piston-type intake throttle valve in the control device 14 is controlled to a small amount. 26 is also pressed toward the intake pipe 12 by the return spring 45, causing its main body portion 26A to protrude into the intake pipe 12 to the maximum extent.

A stopper 31 is integrated with this intake throttle valve 26.
Since the valve shaft 32 also moves downward, the valve 36 is opened to its maximum extent.

As a result, the negative pressure in the bench lily portion 42 is maximized, and at the same time, the passage area of the EGR gas inlet 34 is also maximized, so a large amount of EGR gas flows into the EGR passage 1.
5 to the intake pipe 12.

As a result, the generation of NOx in the low engine load range is effectively reduced.

Then, as the engine load increases, the first drum 56 in the interlocking device 16 and the second drum 57 that follows the first drum 56 via the stopper 67 are rotated clockwise by the accelerator wire 19.

As a result, the control wire 21 and
Since the EGR control wire 20 is pulled to the right, the opening degree of the control lever is increased and the amount of fuel injection is increased.
is pulled upward against the return spring 45, and the stopper 31, which is biased by the spring 30 so as to come into contact with the weight 29 of the intake throttle valve 26, is simultaneously moved upward.

As a result, the valve 36 integrated with the stopper 31 also moves upward as shown in FIG. 5A, reducing the passage area of the EGR gas inlet 34. Therefore, the EGR amount is reduced in the medium load range.

Further, in a high load range, the amount of depression of the accelerator pedal 17 also increases, and the interlocking device 16 is rotated significantly clockwise.

As a result, the fuel injection amount is further increased, and the intake throttle valve 26 is also pulled upward as shown in FIG. 5B, increasing the passage area of the intake pipe 12. The EGR gas outlet 34 is completely blocked.

Furthermore, in the full load range, the valve 36 is prevented from moving upward by the valve seat 35, as shown in FIG. to increase the passage area of the intake pipe 12.

As a result, in the high and full load range, EGR passage 1
5 will be completely shut off, and during this operation
EGR is not performed.

Therefore, only the differential pressure between suction negative pressure and exhaust pressure
As in the conventional example where the amount of EGR was controlled, the amount of EGR could not be reduced completely during operation due to the exhaust pressure developing in the high and full load range, resulting in excessive EGR and worsening of combustion, resulting in HC, This prevents a large amount of unburned components such as CO and black smoke from being discharged, and also prevents deterioration of engine performance.

Furthermore, in the present invention, during cold start and warm-up operation where the best combustion conditions are required without EGR, if the operation is detected by a water temperature switch (not shown) or the like and the negative pressure actuator 22 is activated, The control device 14 (piston type intake throttle valve 26) can be driven independently without being linked to the fuel injection pump,
EGR can be cut during this operation.

In other words, during the above operation, the negative pressure actuator 2
Atmosphere is introduced into 2, and the rod 70 is made to protrude outward.

As a result, a slit 71 is formed at the tip of the rod 70.
The second drum 57 engaged through the second drum 57 is moved independently against the return spring 66 in a direction away from the stopper 67 of the first drum 56 .

As a result, the EGR control wire 20 is pulled to the right, controlling the control device 14 to the above-mentioned high or full load range state (FIGS. 5B and 5C) and stopping EGR.

Therefore, combustion conditions during the above operation become favorable, and startability and engine performance are improved.

As explained above, according to the present invention, since the EGR amount can be optimally controlled according to the engine operating condition,
It has the effect of effectively reducing NOx emissions in all operating ranges of the engine, and in particular, in high load ranges, EGR can be reliably stopped, resulting in better combustion during these operations and reducing unburned HC, CO, etc. This has the advantage of reducing emissions of components and black smoke and improving output.

[Brief explanation of the drawing]

FIG. 1 is a front view of the conventional device, FIG. 2 is a schematic overall view of the present invention, FIG. 3 is a sectional view of the piston-type exhaust recirculation control device, and FIG. 4 is a perspective view of the interlocking device.
5A, B, and C are sectional views showing the operating state of the control device of FIG. 3, respectively. 12... Intake pipe, 14... Piston type exhaust recirculation amount control device, 15... EGR passage, 16... Interlocking device, 26... Piston type intake throttle valve, 34...
EGR gas inlet, 36... Valve, 21... Control wire, 56... First drum, 20
...EGR control wire, 57...2nd
Drum, 66... Return spring, 22...
Negative pressure actuator.

Claims (1)

[Scope of utility model registration request] An intake throttle valve that is linked to the control lever of the fuel injection pump is installed in the intake passage, and a
In a diesel engine exhaust recirculation control device that connects the EGR passage and controls the amount of EGR according to the opening degree of the intake throttle valve, the intake throttle valve that is interlocked with the control lever via the interlocking device is connected to the intake passage. It is formed by a piston body that moves forward and backward to increase and decrease the passage area, and has an EGR gas inlet facing the intake throttle valve, and a valve that moves up and down together with the intake throttle valve to open and close the EGR passage. An exhaust recirculation control device for a diesel engine, characterized in that the amount of EGR is reduced or cut off as the load increases.