US3478729A

US3478729A - Apparatus for controlling ignition time of automobile engine

Info

Publication number: US3478729A
Application number: US684332A
Authority: US
Inventors: Yasuo Tada
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1966-11-24
Filing date: 1967-11-20
Publication date: 1969-11-18
Anticipated expiration: 1986-11-18

Description

Nov. 18, 1969 Y suo TADA 3,478,729

APPARATUS FOR CONTROLLING IGNITION TIME OF AUTOMOBILE ENGINE Filed Nov. 20, 1967 United States Patent US. Cl. 123117 8 Claims ABSTRACT OF THE DISCLOSURE The ignition timing of an internal combustion engine having a throttle valve in a fuel intake passage is controlled by a pressure responsive device to which negative pressure is supplied through a single control valve comprising a cylinder having chambers, at opposite ends connected with the intake passage on opposite sides of the throttle valve and a floating piston having two passageways communicating respectively with said chambers. According to the running condition of the engine the piston is movable by fluid pressure to bring one or the other of said passageways into communication with a line leading the pressure responsive device.

This invention relates in general to an apparatus for controlling a time point at which an internal combustion engine equipped on an automobile is to be ignited, in accordance with a fuel pressure within a feed fuel line to the engine, and more particularly to improvements in a control valve for use with such an apparatus.

It is Well known that the exhaust gas exhausted from any automobile engine during its idling operation and deceleration operation of applying a braking action to automobile wheels, generally contains large amounts of harmful ingredients such as hydrocarbons, carbon monoxide gas, etc., resulting in contamination of the air. It has been reported and sustained by the results of experiments that such harmful ingredients contained in the exhaust gas can reduce in amounts by adjusting an ignition time of an engine to a time point corresponding to a position of the associated piston behind to its upper dead point, for example its position lagging the upper dead point by approximately 10 degrees in terms of the crank angle for the idling operation. For a deceleration operation, the ignition time of the engine has been adjusted to a time point corresponding to a position of the piston sufliciently leading its upper dead point, for example its position in advance of the upper dead point thereof by approximately degrees in terms of the crank angle.

One of apparatus for controlling an ignition time of an automobile engine during its deceleration operation on the basis of the adjustment just described is described and claimed in the corresponding US. application Ser. No. 656,580 Apparatus for Controlling Ignition Time of Automobile Engine filed on July 27, 1966 by H. Miyazaki et al. and assigned to the same assignee as the present application. According to the above cited application, the apparatus comprises a throttle valve disposed in a feed fuel line to the associated engine, first pressure sensing means communicating with that side of the throttle valve as in its minimum open position remote from the engine to sense a fuel pressure in the feed fuel line on the said throttle side, and second pres sure sensing means communicating with that side of the throttle valve as in its minimum open position near to the engine to sense a fuel pressure in the feed fuel line on the last-mentioned throttle side. The arrangement is such that in a deceleration operation of the engine with the throttle valve maintained at its minimum open position the fuel pressure sensed by the first pressure sensing means is effectively for sufficiently putting an ignition time in advance of the upper dead point of the associated piston and that in the normal or an acceleration operation during which a degree of opening the throttle valve is increasing beyond its minimum open position a fuel pressure sensed by the second pressure sensing means is effective for controlling the ignition time to provide an angle of advance in accordance with the open position of the throttle valve and therefore with loading on the engine.

The apparatus just outlined comprises a single pressure responsive device including a single flexible diaphragm to define a single negative pressure chamber along with a housing for the device, and a separate duct connecting each of the pressure sensing means to the negative pressure chamber. This leads to the necessity of disposing one control valve in each of the ducts in order to selectively introduce the pressure sensed by both pressure sensing means into the negative pressure chamber. In other words, a pair of independent control valves are separately disposed in the ducts respectively. Therefore it is necessary to mount a pair of individual control valves to the pressure responsive device in predetermined different positions resulting in both a complicated construction and also an assemblage requiring labor and time.

Accordingly it is an object of the invention to provide an improved apparatus for controlling an ignition time of an automobile engine to decrease amounts of harmful ingredients contained in the exhaust gas from the engine during its deceleration operation which is simple in construction and easily assembled.

It is another object of the invention to provide a new and improved control valve of simple construction for use with the apparatus of the type described in the preceding paragraph.

Briefly, the invention accomplishes the above cited objects by the provision of a control valve structure for use with the apparatus as previously outlined, comprising a cylindrical valve chamber, a valve body in the form of a piston slidably fitted into the valve chamber. The valve body is provided with a pair of independent passageways communicating with the first and second pressure sensing means as previously described respectively and having a first stable operative position where one of the passageways communicates with the abovementioned negative pressure chamber and a second stable operative position where the other passageway communicates with the negative pressure chamber.

The invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a schematic sectional view, partly in elevation of a control apparatus constructed in the teachings of the invention; and

FIGURE 2 is a schematic sectional view of a control valve shown in FIGURE 1 and illustrated in its operative position different from in FIGURE 1.

Referring now to the drawing and FIGURE 1 in particular, it is seen that within a distribution housing 10 there are disposed a cam 12 rigidly secured on a distributor shaft (not shown), and an apertured support plate 14 surrounding the cam 12 and rotatable in one or the other direction about the axis of the latter. The distributor shaft is adapted to be driven in the direction of the arrow by the associated internal combustion engine through a gearing though they are not illustrated in FIGURE 1. Mounted on the support plate 14- is a contact breaker 16 including a cam follower 18 engaging the cam 12 and a movable contact controlled by the cam 12 through the cam follower 18 to be contacted by and separated away from a stationary contact 22. When the movable contact 20 contacts the stationary contact 22 a primary winding of an ignition coil (not shown) is permitted to be energized by a battery (not shown) while upon the movable contact disengaging from the stationary contact 22, an ignition voltage is generated across a secondary ignition winding (not shown) to ignite one of combustion chambers in the engine. The above-mentioned components are of the conventional construction and need not be further described.

As shown in FIGURE 1, a pressure responsive device generally designated by the reference numeral 24 is disposed externally of the distributor housing 10. The pressure responsive device 24 comprises a pair of hollow, frusto-

conical housings

26 and 28 connected together into a unitary structure as by caulking with the enlarged open ends facing each other and with a flexible diaphragm 30 sandwiched between those enlarged open ends to divide the interior of the

housings

26 and 28 into an atmospheric chamber 32 and a negative pressure chamber 34 sealed from the air. A control rod 36 extends from the center of the diaphragm 30 through the atmospheric chamber 32 into the distributor housing 10 for limited longitudinal movement. The control rod 36 has the other end pivotably connected to the support plate 14 at the periphery and serves to rotate the support plate 14 about the axis of the cam 12 for the purpose as will be apparent hereinafter. The control rod 36 has one portion of enlarged diameter extending through the atmospheric chamber 32 and a shoulder 36a formed on one end of that enlarged portion to normally abutting against the reduced end face of the atmospheric chamber 32 by the action of a compression spring 38 disposed within the negative pressure chamber 34.

According to the teachings of the invention a single control valve of transfer type generally designated by the reference numeral 40 is operatively connected to the negative pressure chamber 34 for the purpose of selectively introducing a fuel pressure on either side of a throttle valve disposed in a feed fuel line to the engine, into the negative pressure chamber 34 dependent upon the operating condition of the engine. The control valve 40 includes a hollow cylindrical housing 42 suitably secured on that side of the pressure response device 24 remote from the distributor housing 10 or on the reduced end face of the negative pressure chamber 34 and defining a valve chamber in the form of a cylinder generally designated by the reference numeral 44. The cylinder 44 has an outlet port 46 disposed on the middle portion of the cylindrical peripheral wall and aligned with an inlet port 34a formed on the reduced end face of the negative pressure chamber 34 to communicate with the interior of the latter chamber. The cylinder 44 further has a pair of

inlet ports

48 and 50 disposed on the opposite end faces thereof and communicating with a feed fuel line to the engine as will be described hereinafter.

4 shoulders 44b and 0 respectively serving as stoppers for limiting movement of the valve body 52. The valve body 52 has disposed therein a pair of passageways 58 and not communicating with each other and opening at one end into the

operating spaces

54 and 56 respectively and at the other ends into the peripheral wall surface thereof in such positions that, when the valve body 52 abuts against one of the shoulders 44]) or 0 one of the passageways opening toward that shoulder abutting against the valve body communicates with the outlet port 46. More specifically, with the valve body 52 abutting against the shoulder 44b as shown in FIGURE 1, the passageway 58 communicates with the port 46 to permit the operating space 54 to communicate with the interior of the negative pressure chamber 34 through the passageway 58, the outlet port 46 and the inlet port 34a. On the other hand, if the valve body 52 abuts against the shoulder 440 the other space 56 communicates with the interior of the chamber 34 through the passageway 60, the ports 46 and 34a.

A compressing spring 62 is disposed within the operating space 56 in order to force the valve body 52 to normally abut against the shoulder 44b in the opposite space 54. The position of the valve body 52 where it abuts against the shoulder 44b is called a first stable operative position whereas its position where the valve body abuts against the shoulder 44c is called a second stable operative position.

In FIGURE 1 the reference numeral generally designates a carburetor schematically shown as a section of pipe and serving to vaporize a fuel to be supplied to the engine (not shown). The carburetor 70 includes a passageway 72 for flowing air through its interior, a Venturi portion 74 where a nozzle 76 for injecting fuel is open and a throttle valve 78 controlled by an accelerator pedal (not shown). The fuel injected from the nozzle 76 is mixed with air passing through the passageway 72 and flows around the throttle valve 78 and through suction pipe 80 to the engine.

The carburetor 70 is further provided with a first and a second pressure sensing unit preferably in the form of apertures extending through its wall on both sides of the throttle valve 78 as in its minimum open position. More specifically, the first pressure sensing unit or aperture 82 opens upstream of the throttle valve 78 with respect to a flow of fuel or on that side thereof as in its minimum position as shown in FIGURE 1, remote from the associated engine (not shown) while the second pressure sensing unit or aperture 84 is downstream of the throttle valve 78 or on that side thereof as in its minimum open position, near to the engine. The second aperture 84 is shown as being provided on the suction pipe 80. The first and

second apertures

82 and 84 communicate with the

inlet ports

48 and 50 of the control valve 40 through the respective connecting

conduit

86 and 88.

Pressures of fuel predominating in the first and second

pressure sensing units

82 and 84 respectively depend upon loading on the associated engine and may generally be in ranges listed in the following Table I.

TABLE I.-FUEL PRESSURE UNDER VARIOUS OPERATING CONDITIONS OF ENGINE Operating Condition- First Apcrature 82" Second Aperature 84.

. Idling Declaration Normal.

0 i 0 0400 mm. Hg 400 mm. H 500-700 mm. Hg 0-350 mm. Hg.

The term Normal means the operating conditions of the engine other than its idling and deceleration operation.

From the above Table I it is seen that during the normal operation including an acceleration operation a negative pressure of fuel predominating in the first pressure sensing unit or aperture 82 is higher than that in the secder 44 provided adjacent both ends with a pair of annular 0nd pressure sensing unit or aperture 84. Under these circumstances, the valve body 52 is held in its first stable operative-position as illustrated in FIGURE 1 by the action ofvthe compression spring 62. This permits the pressure of fuel in the first aperture 82 to be transmitted through the conduit 86, the inlet valve port 48 to the operating space 54 and thence to the negative pressure chamber 34 of the pressure responsive device 24 through the passageway 58, the outlet port 46 and the inlet port 34a. Thus a suction force dependent upon the particular loading on the engine exerts upon the flexible diaphragm 30 against the action of the compression spring 38 to be operated through the control rod 36 and the support plate 14 to advance the operating position of the contact breaker 16 and hence an ignition position of the engine to a predetermined magnitude.

During the idling operation, a pressure the second pressure sensing aperture 84 is higher than that in the first aperture 82. Under these circumstances, the valve body 52 is held in its first stable operative position by the action of the compression spring 62. In other words, the compression spring 62 is designed to have an initial resiliencegwithstanding a negative pressure in the order of 400 mm. Hg.

If the engine is in a deceleration operation a negative pressure predominating in the second pressure sensing aperture 84 becomes high as compared with the idling operation. This permits the valve body 52 to move to its second stable operative position as illustrated in FIG- URE 2 against the action of the compression spring 62 where the operating space 56 communicates with the negative pressure chamber 34. Therefore the negative pressure in the second aperture 84 is similarly transmitted to the chamber 34 to advance the ignition position of the engine in .the similar manner as described for the normal operation. It is to be noted that as a negative pressure in the second aperture 84 is higher in a deceleration operation than in the normal or an acceleration operation that an angle of advance in the deceleration operation can be substantially equal to or greater than that in the normal or acceleration operation. For example such an angle may reach the order of 20 degrees in advance of the upper dead point of the associated piston.

From the foregoing it will be apparent that without imparting the angle advance characteristics in the normal or an acceleration operation the aperture as previously described can sufiiciently advance the ignition time of the engine during a deceleration operation with the result that the fuel is prevented from incompletely burning during such deceleration operation leading to a great decrease in contents of hydrocarbons, carbon monoxide in the exhaust gas.

Further, as compared with the use of two separate control valves the present apparatus is simple in construction and easily assembled because the conventional type of devices for controlling ignition times is operatively coupled to a single control valve including a single valve body movable between its first stable operative position where a negative pressure of fuel in a first pressure sensing unit is transmitted to a negative pressure chamber and its second stable operative position where a negative pressure of fuel in a second pressure sensing unit is transmitted to the negative pressure chamber. Particularly a valve housing having disposed therein the valve body is secured to a housing defining the negative pressure chamber to eliminate any conduit connecting in fluid communication relationship the valve to the negative pressure chamber.

The valve body has provided therein a pair of passageways opening into its opposed end faces to continuously communicate with the first and second pressure sensing units. Thus the pressures of fuel in both units are always applied to both end faces of the valve body to control the position of the latter to selectively communicate both units with the negative pressure chamber in simple manner. This causes simplification of the valve construction.

While the invention has been illustrated and described in conjunction with a single preferred embodiment thereof it is to be understood that various changes and modifications in the details of construction and the combination and arrangement of parts and elements may be resorted to without departing from the spirit and scope of the invention. For example, if the passageway 58 in the valve body 52 may communicate 'with the first pressure unit 82 through another connection means, the atmospheric chamber 32 may open directly into the surrounding air. In this case only the pressure of fuel in the second pressure sensing aperture 84 controls the position of the valve body 52.

What I claim is:

1. An apparatus for controlling an ignition time of an automobile engine, comprising (1) a pressure responsive device including a negative pressure chamber and operative to control an ignition time of the engine in accordance with a pressure predominating in said negative pressure chamber,

(2) a throttle valve disposed in a feed fuel line to the engine,

(3) a first pressure sensing unit communicating with said feed fuel line on that side of said throttle valve remote from the engine to sense a pressure of fuel on said side of said throttle valve,

(4) a second pressure sensing unit communicating with said feed fuel line on that side of said throttle valve near to the engine to sense a pressure of fuel on the last-mentioned side of said throttle valve, and

(5) a control valve device operatively coupled to said pressure responsive device and including a cylindrical valve chamber, and a spring biased cylindrical valve body movably disposed with said valve chamber and having a first and a second stable operative position,

(6) a communicating port provided on said valve chamber communicating with the said negative pressure chamber,

(7) a first passageway extending through said valve body continuously communicating with said first pressure sensing unit and capable of communicating with said communicating port when said valve body is in said first stable operative position, and

(8) a second passageway extending through said valve body so as not to communicate with said first passageway, and continuously communicating with said second pressure sensing unit, said second passageway being capable of communicating with said communicating port when said valve body is in said second stable operative position.

2. An apparatus for controlling an ignition time of an automobile engine as claimed in claim 1, comprising a flexible diaphragm in said pressure responsive device responsive to a pressure predominating in said negative pressure chamber,

a cam driven by the engine,

a support plate rotatable about the axis of said cam,

a contact breaker mounted on said support plate and controlled by said cam, and

a control member connecting said diaphragm to said support plate.

3. An apparatus for controlling an ignition time of an automobile engine as claimed in claim 1, further comprising a housing defining said negative pressure chamber, said control valve device rigidly secured to said housing, and an inlet port formed on said housing so as to be aligned and communicate with said communicating port on said valve chamber.

4. An apparatus for controlling an ignition time of an automobile engine as claimed in claim 1, wherein said valve body is responsive to a pressure in said second pressure sensing unit such that said valve body occupies said first stable operative position during an acceleration operation of the engine and said second stable operative position during a deceleration operation of the engine.

5. An apparatus for controlling an ignition time of an automobile engine comprising (1) a pressure responsive device including a negative pressure chamber and operative to control an ignition time of the engine in accordance with a pressure predominating in said negative pressure chamher,

(2) a throttle valve disposed in a feed fuel line to the engine,

(4) a second pressure sensing unit communicating with said feed fuel line on that side of said throttle valve near to the engine to sense a pressure of fuel on the last-mentioned side of said throttle valve,

(5) a control valve device operatively coupled to said pressure responsive device and including a cylindrical valve chamber, and a valve body movably disposed within said valve chamber and having a first and a second stable operative position, said valve body having a pair of opposed end faces bearing pressure in said first and second pressure sensing units respectively such that said valve body occupies said first stable operative position during an acceleration operation of the engine and said second stable operative position during a deceleration operation of the engine,

(6) a communicating port provided on said valve chamber to communicate with said negative pressure chamber, v

(7) a first passageway extending through said valve body between the peripheral surface and one of said end faces thereof to continuously communicate with said first pressure sensing unit, said first passageway being capable of communicating with said communicating port when said valve body is in said first stable operative position, and

(8) a second passageway extending through said valve body between the peripheral surface and the other end face but not communicating with said first passageway, said second passageway continuously communicating with said second pressure sensing unit and also being capable of communicating with said communicating port when said valve body is in said second stable operative position.

6. An apparatus for controlling an ignition time of an automobile engine as claimed in claim 5, further comprising a compression spring tending to normally force said valve body to said first stable operative position, said valve body being movable to said second stable position against the action of said compression spring, said compression spring preventing said valve body from moving to said second stable position under the pressures in the respective pressure sensing units during the idling operation of the engine.

7. An apparatus for controlling an ignition time of an automobile engine as claimed in claim 5, further comprising a flexible diaphragm in said pressure responsive device responsive to a pressure predominating in said negative pressure chamber,

a cam driven by the engine,

a support plate rotatable about the axis of said cam,

a contactbreaker mounted on said support plate and controlled by said cam, and

a control member connecting said diaphragm to said support plate.

8. An apparatus for controlling an ignition time of an automobile engine as claimed in claim 5, further comprising a housing defining said negative pressure chamber, said control valve device rigidly secured to said housing, and an inlet port formed on said housing to be aligned and communicate with said communicating port on said valve chamber.

References Cited UNITED STATES PATENTS 3,014,974 12/1961 McDuffie et a1. 123--l17.l 3,157,168 11/1964 Sterner et a1. 123-117.1 3,252,451 5/1966 Sarto 123117.1 3,329,136 7/1967 Cadiou 123-1171 3,353,524 11/1967 Sarto 123--l17.1 3,356,083 12/1967 Clark et al 123-117.1

WENDELL E. BURNS, Primary Examiner US. Cl. X.R.