JPS6018606Y2 - Air-fuel ratio control device for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an internal combustion engine having an exhaust gas purification device.

A three-way catalyst (NOx reduction, CO, H) is installed in the exhaust system of an internal combustion engine.
When installing a catalyst that also has an oxidizing function (C) to purify automobile exhaust, the conversion efficiency of the catalyst will drop significantly unless the air-fuel ratio is controlled within a narrow range of the stoichiometric air-fuel ratio. The opening area of the bypass air valve provided in the bypass air passage leading from the fuel valve or air cleaner to the downstream side of the throttle valve is controlled by a pulse motor that is directly connected to the bypass air passage and rotated by the output of an oxygen sensor, or an oxygen sensor and electronic fuel injection are used. Feedback control of the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine was performed using a combination of devices to maintain the stoichiometric air-fuel ratio. The disadvantage is that the degree of control is self-limited, and the latter has the disadvantage of having a large number of parts and high cost.

The purpose is to remove the air-fuel ratio control device and to make it easier to adjust the initial position of the air-fuel ratio control device.It is threaded onto the shaft of the motor, which rotates in response to the output of the oxygen sensor, and is prevented from rotating by a locking member. a bushing rod, a control shaft that faces a fuel or air control valve moved by the bushing rod directly or via a rocker arm, and adjustment means for adjusting the initial position of the bushing rod; A plurality of axial grooves are formed on the circumferential surface, and the locking means engages with one of the grooves when the bushing rod is engaged with the control shaft adjusted to the initial position, either directly or via a rocker arm. It comes together.

FIGS. 1 and 2 of the fuel engine show a fuel valve control device in an air-fuel ratio control device according to an embodiment of the present invention.

1 is a carburetor, 2 is a throttle valve, 3 is a carburetor float chamber containing fuel, and below it there is a main jet 5 and a control valve 6 that communicate with the main fuel passage 4 opened by the carburetor 1. A valve body 15 is fixed to a set plate 7 with machine screws 8, and a fuel valve control device comprising a pulse motor 10, a bushing rod 11, a rocker arm 12, a control shaft 13, etc. is provided on the upper part.

The control valve 6 is shaped like a bullet so that the air-fuel ratio changes linearly from 12.5 to 16.5 with respect to the valve stroke, and its root is shaped like a control jet 14.
It has a tapered shape so as to block and close the air-fuel ratio, and is incorporated into the valve body 15 and the control jet 14, which are divided into two parts, so as to be seated by a spring 16 when the air-fuel ratio is at the maximum lean state.

A gear 19 and a screw 20 are provided on the shaft 18 of the pulse motor 10 attached to the base 17, and a gear 22 having a plurality of teeth, for example, two to three times the number of teeth, is screwed into the gear 19. The protrusion 23 provided on this gear 22 engages with an arcuate groove 24 formed in the base body 17 so that the motor 10 rotates multiple times, for example, 2 to 3 times, and stops at the maximum lean state or the maximum rich state, respectively. do.

The screw 20 is a bushing rod 1 that fits into the inner cavity of the base 17.
A locking member, such as a pin 27, fitted to the base body 17 is fitted into a plurality of axial grooves 26, for example, equal parts of 8 to m, provided on the outer periphery of the bushing rod 11.

A rotary arm 12 in contact with one end of a bushing rod 11 that moves in the axial direction by the rotation of the motor 10 is pivotally supported at the center, and the other end is a collar of a control shaft 13 that is pushed upward by a spring 29 within a guide 28. 13a.

The initial position of the control shaft 13 is adjusted by adjusting means 30 consisting of a screw mechanism so that in the maximum lean state, the lower end of the control shaft 13 faces the control valve 6 with a minute gap of □ (0.1 to 0.3 mm).
This adjustment is made to prevent the control valve 6 and control shaft 13 from opening at high temperatures due to thermal expansion.

At this time, a bushing rod 1 is attached to the other end of the rocker arm 12 that engages with G13a of the control shaft 13.
The bushing rod 11 is rotated to advance and retreat so that the tips of the bushing rods 1 and 1 are in contact with each other, and in this state, the pin 27, which is a locking member, is inserted through the hole drilled in the base body 17, and the bushing rod 11 is moved in a plurality of axial directions on the outer circumferential surface of the bushing rod 11. The bushing rod 11 is fitted into one of the grooves 26 to set the initial position of the bushing rod 11.

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

Now, when the oxygen sensor detects that the air-fuel ratio of the exhaust gas in the exhaust manifold is lower than the stoichiometric air-fuel ratio (rich state), the pulse motor rotates in one direction via the control circuit, and the bushing rod 11 is moved to the left in the figure. Then, control is performed in the direction of moving the control shaft 13 upward to decrease the opening area of the control valve 6 and increase the air-fuel ratio.

In addition, when the oxygen sensor detects that the air-fuel ratio of exhaust gas is higher than the stoichiometric air-fuel ratio (lean state), the pulse motor 1
0 rotates in the opposite direction, the bushing rod 11 is moved to the right in the drawing, and the control shaft 13 is moved downward to increase the opening area of the control valve 6 and to decrease the air-fuel ratio.

In this air-fuel ratio control, the pulse motor 10 continues until the protrusion 23 of the gear 22 hits the groove 24 from one end of the base body 17 to the other end and stops, until the air-fuel ratio changes from the maximum lean state to the maximum rich state. Rotate multiple times, e.g. 2 to 3 times, until
Since it can rotate, the rotation can be converted into a minute movement of the control valve 6 in the axial direction, and therefore, this device can finely control the air-fuel ratio.

In this embodiment, a case has been described in which a fuel valve is controlled, but an air valve can also be controlled in the same way, and the control valve can be directly controlled with a bushing rod without a rocker arm.

As described above, according to the present invention, there is a bushing rod that is threadedly engaged with the shaft of the motor that rotates in response to the output of the oxygen sensor and is prevented from rotating by a locking member, and a bushing rod that is moved directly or via a rocker arm by the bushing rod. a control shaft facing a fuel or air control valve, and adjustment means for adjusting the initial position of the control shaft; a plurality of axial grooves are formed on the circumferential surface of the bushing rod; The stop means is engaged with one of the grooves when the bushing rod is engaged with the control shaft adjusted to the initial position, either directly or through a rocker arm, so it is more effective than conventional air-fuel ratio control devices for internal combustion engines. It is possible to make fine air-fuel ratio control by using the control valve, dramatically reduce the release of harmful components into the atmosphere, and reduce costs due to the small number of parts. It is easy to adjust the initial position of the control shafts so that they face each other at an interval, which has the effect of preventing the valve from opening at high temperatures due to thermal expansion of the control valve and control shaft.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, with FIG. 1 being a sectional view and FIG.
The figure is an exploded view of the main parts. 6...◆Control valve, 10...
Pulse motor, 11...Butsch rod, 12
...Rocker arm, 13 ... Control shaft, 14 ... Control jet, 20 ... Screw, 22 ... Gear, 23
...Protrusion, 24...Circular groove, 25.
...Female thread, 26...Groove, 27...
... Pin, 30 ... Adjustment means.

Claims (1)

[Scope of utility model registration request] A bushing rod that is threadedly engaged with the shaft of a motor that rotates in response to the output of an oxygen sensor and is prevented from rotating by a locking portion, and a fuel or air control valve that is moved by the bushing rod directly or via a rocker arm. The bushing rod has a plurality of axial grooves formed on the circumferential surface of the bushing rod, and the locking means is arranged so that the bushing rod is in the initial position. An air-fuel ratio control device for an internal combustion engine, which engages one of the grooves in engagement with an adjusted control shaft, either directly or via a rocker arm.