Air Pollution Preventive Device For Spark-ignition-type Internal Combustion Engines

Abstract

A device is provided for an internal combustion engine to prevent air pollution thereby and the device comprises a throttle-valve-actuating member connected to a throttle valve vacuum actuator operable by increase in intake vacuum on the downstream side of a throttle valve. The vacuum actuator is releasably connected to the valve-actuating member so as to maintain driving engagement with the actuating member only when the throttle valve is nearly closed. An operating member of the throttle valve, controlled by an accelerator pedal, is pivotably interconnected with the throttle-valve-actuating member via a lost motion connection of limited clearance so that when the throttle valve is in nearly closed condition, the actuating member is operable by the vacuum actuator upon increase in intake vacuum to open the throttle valve while allowing the operating member of the throttle valve to remain in inoperative position. With the operating member remaining in its inoperative position; a further device acts to retard the ignition timing of the engine.

Description

As known, during the idling of internal combustion engines such as for automotive vehicles, the throttle valve is fully closed and the amount of air intake is reduced so as to cause incomplete fuel combustion with the result that the engine exhaust tends to pollute the atmosphere. Also, when the throttle is rapidly closed during high-speed travel for quick retardation, the air intake is reduced to a greater extent resulting in severe pollution of the atmosphere.

The present invention has for its object to provide a simple and effective device which is designed to prevent excessive reduction in the amount of air intake with the engine idling and upon quick retardation thereby to prevent air pollution attributable to the engine exhaust and is operable on those occasions to retard the ignition timing thereby to reduce the engine power output for smooth idling and effective rapid retardation of the engine.

Another object of the present invention is to provide an air pollution preventive system of the character described which is designed particularly to prevent the throttle valve from being closed completely even for a short period of time and thus is effective to prevent air pollution otherwise resulting from such complete throttle closing.

These and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, which illustrate a few preferred embodiments of the invention and in which:

FIG. 1 is a partly schematic illustration of one embodiment of the invention;

FIG. 2 illustrates another embodiment in which the throttle valve is prevented from being closed completely when released to rapidly close;

FIG. 3 is a fragmentary illustration looking in the direction of the arrow III in FIG. 2;

FIG. 4 illustrates a modification of the device shown in FIG. 2;

FIG. 5 is an axial cross-sectional view showing a simplification of the device shown in FIG. 4.

FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5;

FIG. 7 is a partly, schematic illustration of a modification of the device shown in FIG. 1, in which the vacuum actuator is rendered ineffective at appropriate times;

FIG. 8 is an axial cross-sectional view of a form of switching means operable in association with the clutch in the engine transmission;

FIG. 9 is a view similar to FIG. 9, showing a form of switching means operable in association with the speed change gear;

FIG. 10 is a partly cutaway view showing a contact breaker unit improved over the one shown in FIG. 1;

FIG. 11 is an axial cross-sectional view of the unit;

FIG. 12 is an illustration of a further embodiment of the invention, which includes, among others, switching means operably connectable with the contact breaker unit shown in FIGS. 10 and 11;

FIG. 13 is a diagrammatic chart showing the mode of operation of the device shown in FIG. 12;

FIG. 14 is an ignition circuit diagram of the device of the invention;

FIG. 15 is a diagram illustrating the operation of the ignition circuit;

FIG. 16 illustrates a modification of the circuit shown in FIG. 14;

FIG. 17 illustrates a conventional circuit formation; and

FIG. 18 is a cross-sectional view taken along line XVIII-XVIII in FIG. 11.

Referring to the drawings and first to FIG. 1, reference numeral 1 designates an intake duct; and 2 a throttle valve with its shaft 3 pivotally supported in the intake duct 1. Numeral 4 indicates a throttle-valve-actuating member fixed to the throttle shaft 3 outside of the intake duct, with a projecting stud pin 5 and a slotted piece 6 firmly secured to the actuating member 4 at its opposite ends. An elongated slot 7 is formed in the piece 6. Pivotally mounted on the throttle shaft 3 is a throttle-valve-operating member 8, to which is connected a throttle wire 9, which is connected to accelerator pedal means (not shown). A relatively strong return spring 11 is arranged between the throttle-valve-operating member 8 and a fixed support or bracket 10 with a stop 12 adjustably threaded in and extending through the bracket 10 for abutting engagement with an abutment 8A formed on the adjacent portion of the member 8. The throttle-valve-operating member 8 is also formed with an aperture 13 to loosely receive the stud pin 5 and a relatively weak tension spring 14 is arranged between the members 4 and 8 so that, when the vacuum actuator 16 is in inoperative position, the pin 5 is held in contacting engagement with the wall of the aperture 13 at point 15 under the tension of spring 14, connecting the throttle-valve-operating member 8 integrally with the throttle-valve-actuating member 4 and throttle valve 2. In this state, it will be apparent that, when throttle wire 9 is drawn to rotate the throttle-valve-operating member 8, the throttle valve 2 is opened correspondingly and, when the wire 9 is released, the member 8 is restored under the tension of the return spring 11 into engagement with the stop 12 and the throttle valve 2 is restored to its minimum opening. It is to be understood that the stop 12 is set in advance so that even during engine idling with such minimum throttle opening, the amount of air intake is not reduced to any excessive extent.

Reference numeral 16 indicates a vacuum actuator formed with a vacuum inlet 17, which is connected with the intake duct through a vacuum takeout port 18 formed therein on the downstream side, i.e., the engine side of the throttle valve 2. Provided in the vacuum actuator 16 is a diaphragm 20 loaded with a compression spring 19 and secured to an actuator rod 21, which is loosely fitted close to its extreme end through the slot 7 in the piece 6 and carries at its extremity an enlarged engaging head 22 for releasable engagement with the throttle-valve-actuating member 4. As shown, an adjustable stop 23 is provided on the vacuum actuator 16 for limiting the movement of the actuator rod 21. With this arrangement, it will be noted that, during high-speed engine operation, when throttle wire 9 is released to allow the throttle-valve-operating member 8 to rapidly restore its inoperative position engaging stop 12, the vacuum in the intake duct is increased and, overcoming the bias of compression spring 19, causes the actuator rod 21 and hence its engaging head 22 to move upwardly, as viewed in FIG. 1. Consequently, the engaging head 22, being placed in engagement with the slotted piece 6, turns the throttle-valve-actuating member 4 counterclockwise relative to the throttle-valve-operating member 8 against the bias of tension spring 14 with the result that the opening of the throttle valve 2 is maintained above its minimum to prevent any excessive reduction in amount of air intake. On this occasion, pin 5 is moved away from the point of contacting engagement 15 against the relatively weak tension spring 14, as indicated by the chain line 5A by of the space C provided in aperture 13 for such lost motion of pin 5. On the other hand, the throttle-valve-operating member 8 remains in its released or inoperative position under the bias of return spring 11, which is stronger than tension spring 14.

It will be noted that, in this situation, when the throttle wire 9 is subsequently drawn to turn the throttle-valve-operating member 8 to a substantial extent, pin 5 is placed again in contacting engagement with the aperture 13 and the slotted piece 6 is released from the engaging head 22 of the actuator rod 21 so that the throttle valve 2 can be operated under the control of the accelerator pedal means.

Referring again to FIG. 1, reference numeral 24 indicates the casing of a contact breaker unit which includes a cam shaft 25 rotatable at a speed proportional to the engine speed with a breaker cam member 26 mounted on the cam shaft 25 for rotation therewith. The cam member 26 is also arranged in the conventional manner to rotate relative to the cam shaft 25 with variation of the engine speed, thus varying the relative angular phase between the two members 26 and 25.

Reference numeral 27 indicates a rotative disc provided in casing 24 and rotatable about the axis of cam shaft 25. Pivotally mounted on the rotative disc 27 at 29 is a first contact breaker arm or element 28 which is formed at one end with a slide finger 28A for sliding engagement with the camming surface of cam 26 and carries at the other end a movable contact 28B, which is cooperable with a fixed contact 30. Numeral 31 indicates a leaf spring provided to normally hold the movable contact 28B in pressure engagement with the fixed contact 30. The movable contact 30 and leaf spring 31 are mounted on rotatable disc 27.

Pivotally mounted in the casing 24 at 33 is a second contact breaker arm or element 32 in an angular position retarded relative to that of first contact breaker arm 28. The second breaker element 32 is formed at one end with a slide finger 32A for sliding contact with the camming surface of cam 26 and carries at the other end a movable contact 32B, which cooperates with a fixed contact 34. A leaf spring 35 is provided to normally hold the movable contact 32B in pressure contact with the fixed contact 34. A plunger or push rod 36, forming part of an appropriate vacuum actuator (not shown), is pivotally connected with the rotative disc 27 so as to rotate the rotative disc 27 under the control of vacuum led from the vicinity of throttle valve 2 in the intake duct. Thus, when the first breaker element 28 is connected in the ignition circuit, as will be described hereinafter, the ignition timing of the engine as obtained with the breaker element 28 is advanced or retarded in the conventional manner in accordance with the engine speed and also with the intake vacuum from the vicinity of throttle valve. Incidentally, the rotative disc 27 may be omitted, if desired, with the first breaker element 28 directly pivoted to the breaker casing. Also, with the provision of rotative disc 27, the second breaker element 32 can be pivotally mounted on the disc 27 together with the first breaker element 28.

Reference numeral 37 generally indicates a switching device fixed relative to the intake duct 1 and including an insulating slide pin 38 which carries a headpiece 39 and a short-circuiting ring 42. The slide pin 38 is provided with a spring 40 which acts to bias the slide pin 38 normally to hold its headpiece 39 in its outwardly extended position. Carried on the slide pin 38 is an adjustable stop 41 which serves to limit the extent of projection of the headpiece 39. The switching device 37 also includes an electrode strip 43 which is continuously in connection with short-circuiting ring 42 and further electrode strips 44 and 45 which are placed alternately in connection with short-circuiting ring 42, with conducting wires 46, 47 and 48 connected to the electrode strip 43, 45 and 44, respectively. As shown, the slide pin headpiece 39 is located opposite the abutment 8A of the throttle-valve-operating member 8 and, when the latter 8A is in abutting engagement with stop 12, the slide pin 38 is held in the shown position with the short-circuiting ring 42 placed in contact with the electrode strip 44 as well as with electrode strip 43. It will be understood that the short-circuiting ring 42 is brought into connection with the electrode strip 45 in place of the strip 44 when the abutment 8A is moved apart from stop 12 to release the slide pin 38.

Reference numeral 49 indicates the ignition circuit of the internal-combustion engine; 50 an ignition coil in the circuit; 51 a distributor; and 52 represent spark plugs of the engine. The aforesaid conducting wire 46 is connected to the ignition coil 50 and conducting wire 47 is connected to movable contact 28B of the first breaker 28 through leaf spring 31 while the remaining conducting wire 48 is connected to the movable contact 32B of the second breaker 32 through leaf spring 35. With this arrangement it will be noted that the ignition timing is retarded when the abutment 8A is in abutting engagement with stop 12, that is, when the throttle-valve-operating member 8 is in its inoperative advanced position but, when the member 8 is in operation, the ignition timing is advanced conventionally according to the engine speed.

With the inventive device constructed and arranged in the manner described, it will be appreciated that even when the internal combustion engine is idling the amount of air intake is kept relatively large, enabling relatively efficient fuel combustion and substantially eliminating rod to turn the throttle-valve-actuating danger of the engine exhaust polluting the atmosphere and that on this occasion the engine idling can be kept smooth with or abnormal rise in the engine speed since the throttle-valve-operating member 8 is in its inoperative position with the ignition timing retarded to reduce the engine power output. Also, when the throttle-valve-operating member 8 is released during high-speed engine operation to its inoperative position to rapidly close the throttle valve 2 for quick deceleration of the engine operation, the vacuum actuator 16 is immediately operated causing the engaging head 22 of the actuator rod to turn the throttle-valve-actuating member 4 to a position to hold the opening of the throttle valve 2 at a value larger than that during the engine idling. In this manner, the amount of air intake is kept from being reduced excessively and efficient fuel combustion is obtained eliminating the danger of the engine exhaust polluting the atmospheric air. Moreover, on this occasion, the lost motion provided between the throttle-valve-actuating member 4 and throttle-valve-operating member 8 allows the latter to remain in its inoperative position and maintain the retarded ignition timing and correspondingly reduced engine output, enabling rapid and smooth deceleration of the engine. Also, the arrangement of first and second contact breakers operable in association with accelerator pedal means enables rapid and accurate reduction in engine output. Further, the provision of two weak and strong springs 14 and 11 associated with the throttle-valve-actuating and operating members enables the vacuum actuator 16 to open the throttle valve 2 by tensioning only the weak tension spring 14 without tensioning the strong return spring 11 for the throttle-valve-operating member 8 thus making the action of the vacuum actuator and smooth thereof. In addition, since the tension spring 14 remains unchanged in length and hence in tension even when the throttle-valve-operating member 8 is varied in position, the vacuum actuator 16 can operate the throttle-valve-actuating member 4 at all times with a definite force and with accuracy.

With the device described above, however, when the throttle-valve-operating member 8 is rapidly operated, the throttle valve 2 may initially be fully closed, though only for a short period of time, with the result that the amount of air intake per engine cycle is reduced to such an extent as to cause incomplete fuel combustion, allowing the engine exhaust to severely pollute the atmosphere. This difficulty can be overcome by the device shown in FIGS. 2 and 4.

Referring to FIGS. 2 and 4, the shaft 3 of throttle valve 2 is formed at one end with a short arm 63 which carries a pin 5. This pin 5 is loosely fitted in an aperture 13 formed in the throttle-valve-operating member 8 as in the previously described embodiment. Throttle-valve-actuating member 64 is firmly secured to the other end of the throttle valve shaft 3. Reference numeral 62 indicates a carburetor; and 65 a first vacuum actuator with its vacuum inlet port 66 connected to the intake duct 1 at the vacuum takeout port 18. Provided in the vacuum actuator 65 is a diaphragm 68 to which an actuator rod 69 is secured. Numeral 70 indicates a biasing spring provided on the actuator to urge the actuator rod 69 outwardly thereof; and 67 indicates a vent hole. As shown in FIG. 3, an engaging piece 71 is fixed to the actuator rod 69 at its extreme end for engagement with an abutting bolt 73 threadably fitted on a support plate 72, which is fixed to the throttle-valve-operating member 64.

Reference numeral 74 generally indicates a second vacuum actuator having a vacuum inlet port 75 connected to the intake duct 1 at vacuum takeout 18. Provided in the vacuum actuator 74 is a diaphragm 78 urged in a one direction by a weak spring 76 and formed with a small aperture 77. An actuator rod 79, secured to the diaphragm, carries an adjustable engaging rod 80 threadably fitted in the actuator rod 79 for abutting engagement with support plate 72. Numerals 74A and 74B indicate air chambers formed on the opposite sides of diaphragm 78 and communicating with each other through aperture 77 formed therein; and numeral 81 indicates an adjustable stop provided to limit the extent of movement of the diaphragm 78 under vacuum.

The device described above operates as follows:

When at high engine speeds the throttle wire is released for rapid deceleration of the engine, the throttle-valve-actuating member 64 is restored under the bias of return spring 11 to rapidly close the throttle valve 2 and thus the intake vacuum in the vicinity of vacuum takeout 18 increases so that the actuator rod 69 is moved upward, as viewed in FIG. 2, through the intermediary of diaphragm 68, and thus restricts the downward pivotal movement of the throttle-valve-actuating member 64, precluding the total closure or throttle valve 2 and hence excessive reduction in the amount of air intake. In this connection, the biasing spring 70 in first vacuum actuator 65 is set to exhibit a relatively large bias so as not to be susceptible to the intake vacuum occurring during the engine idling or ordinary cruising operation. It will be noted, therefore, that, even when the throttle valve 2 is rapidly closed for rapid deceleration of the engine and the intake vacuum is increased to some extent, the first vacuum actuator 65 will not operate immediately following the throttle closing, allowing the throttle valve 2 to close completely for a brief period of time, and this might result in excessive reduction in the amount of air intake, necessarily allowing the engine exhaust to pollute the atmosphere, a difficulty which is found with the device shown in FIG. 1.

In the device shown in FIGS. 2 to 4, however, the above difficulty is effectively overcome by the provision of second vacuum actuator 74 provided with relatively weak spring 76, which is lightly deformable under intake vacuum. Thus, when the intake vacuum in the vicinity of vacuum takeout 18 is increased, the diaphragm 78 of the actuator will immediately be operated causing the actuator rod 80 to rise before the actuator rod 69 and hence engaging piece 71 of the first vacuum actuator will start to rise. In this manner, when the throttle-valve-actuating member 64 is rapidly turned downwardly, the support plate 72 is brought into collision contact with the actuator rod 80 to vigorously depress the associated diaphragm 78, and the air in chamber 74B, increasing in pressure relative to that in chamber 74A, is urged to flow into the latter through small aperture 77 formed in the diaphragm 78. It is to be recognized, however, that the airflow is restricted by the limited size of aperture 77 and this together with the increase in pressure in chamber 74B precludes any substantial descent of the throttle-valve-actuating member 64 and hence the total closing of the throttle valve 2 for a while. In the meantime, the intake vacuum increases to start operation of the first vacuum actuator 65 to raise the engaging piece 71 into abutting engagement with support plate 73 and thus preclude any further descent of throttle-valve-actuating member 64, thus preventing the throttle valve from being closed completely. After the rapid downward pivotal movement of throttle-valve-actuating member 64, the vacuum pressure is substantially balanced between the air chambers 74A and 74B and, with the limited spring rate of actuator spring 76, the second vacuum actuator 74 is rendered substantially inoperative, placing the throttle valve 2 under the control of the first vacuum actuator 65 only.

As apparent from the foregoing, this embodiment of the present invention is advantageous in that it is designed to prevent the intake throttle valve from being completely closed even in the initial period of rapid deceleration of the internal combustion engine and thus effectively prevents air pollution as caused by the engine exhaust.

Incidentally, the second vacuum actuator 74 may also be operated, for example, when the throttle valve is rapidly closed for the shifting of the speed change gear but this will cause no trouble to the engine operation as the system is restored immediately.

FIG. 4 illustrates a modification of the device shown in FIG. 2, employing instead of second vacuum actuator 74 a flow resistor 82 operable independently from the intake vacuum. The resistor 82 includes a diaphragm 84 biased by a relatively weak spring 83 and secured to an abutment rod or plunger 85. The air chamber 82B, defined on the underside of diaphragm 84, is vented by a small aperture 86 while the air chamber 82A overlying the diaphragm is vented by a large-diameter aperture 87. With this arrangement, when the throttle-valve-actuating member 64 is rapidly moved downward bringing the support plate 72 thereon into contact with the plunger 85, the diaphragm 84 is vigorously lowered and the pressure in the air chamber 82B is increased by virtue of the resistance of the small vent aperture 86 to the airflow and thus precludes any further downward movement of the throttle-valve-actuating member 64. Subsequently the air pressure is balanced between the two air chambers 82A and 82B and, with the limited spring rate of associated spring 83, the throttle-valve-actuating member 64 can be operated substantially freely despite the provision of the flow resistor 82. In this manner, it will appreciated that the device of FIG. 4 functions with the same advantageous effect as the device of FIG. 2.

A further modification of the device shown in FIG. 4 is shown in FIGS. 5 and 6, which is compact and simple in structure compared with the FIG. 4 device, including a single plunger or actuator rod corresponding in effect to a combination of the actuator rod 69 of the first vacuum actuator 65 and the plunger 85 of resistor 85 in FIG. 4.

Referring to FIGS. 5 and 6, the combined actuator-resistor unit shown therein includes a vacuum actuator section A and a dashpot-type resistor section B, and the former includes a casing 101 and a diaphragm 104, which is provided with a stop surface 102 and a return spring 103 and defines two chambers 105 and 106 on the opposite sides of the diaphragm. One of the chambers 105 is provided with a vacuum inlet port 107 to receive the intake vacuum. The dashpot section B includes a casing 108 and a diaphragm 110 arranged therein to define two chambers 111 and 112 on the opposite sides thereof and provided with a return spring 109. A vent hole 113 is formed in the dashpot B to communicate one of the chambers 111 with the atmosphere. As shown, the actuator and resistor sections A and B of the unit are arranged axially adjacent to each other and a common plunger rod 116 is slidably fitted through axial holes 117 and 118 formed in the respecting casings 101 and 108. The plunger rod 116 is arranged so as to be advanced upon closing of the throttle valve 144 under the bias of return spring 115 provided therefor. The plunger rod 116 carries a stop ring 109 for cooperation with the stop surface 102 on the actuator diaphragm 104 and, extending loosely through the latter, is secured to the resistor diaphragm 110. The shaft 120 of the throttle valve 114 carries at its extended end a lateral arm 121 fixed thereto with the outer end of the arm 121 lying opposite the adjacent extreme end of plunger rod 116 for pressure engagement therewith. Numeral 122 indicates a throttle-valve-actuating member secured to the throttle valve shaft 120 at its opposite end; 123 is a return spring provided for the member 122; 124, 125 are vent holes respectively communicating the chambers 106 and 112 to the atmosphere; and 126 is a valve provided to allow air exhaust only from chamber 111. The axial arrangement on the plunger rod 116 can be reversed, if desired.

In the operation of the device of FIGS. 5 and 6, when the throttle valve 114 is allowed to close under the bias of return spring 115, the plunger rod 116 is advanced to the right as viewed in FIG. 5 but slowly against the resistance of the dashpot B, taking more or less time to make a predetermined length of travel. Accordingly, the intake vacuum is allowed to increase with a more or less delay and subsequently causes the vacuum actuator A to operate to displace the stop surface 112 of the diaphragm therein to the left as viewed in FIG. 5. The stop ring 119 on the plunger rod 116 being advanced is thus engaged by the stop surface 112 of the diaphragm now displaced to the left and the advancing movement of the plunger rod 116 and hence the closing motion of the throttle valve 114 are hampered. In other words, the throttle valve 114 cannot be closed completely but is only brought to a slightly open position.

In use of the device shown in FIG. 1 another inconvenience is encountered as described below. In the case of no-load engine operation, as when the clutch means between the engine and its load is disengaged or when the transmission is rendered neutral, and in the case of low-output engine operation, employing lower speed transmission gear trains, the vacuum actuator may possibly be rendered operative to prevent the throttle valve from being closed completely, causing undesired increase in engine speed and thus inconvenience in the driving operation.

FIGS. 7 to 9 illustrate a device designed to overcome such inconvenience by rendering the vacuum actuator inoperative in cases such as mentioned above.

Reference will first be made to FIG. 7, in which reference numerals 1 to 36 indicate parts corresponding to the same reference numerals in FIG. 1. In FIG. 7, the push rod 36 is pivotally connected at 137 to the rotative disc 27 and secured to the diaphragm 139 of a vacuum actuator 138, which has a vacuum inlet port 140 formed thereon to receive the intake vacuum from a vacuum takeout port (not shown) provided in the vicinity of the throttle valve 2. Numeral 141 indicates a pressure spring engaging the actuator diaphragm 139. With this arrangement, the ignition timing, when the first contact breaker 28 is in connection with the ignition circuit, is advanced or retarded in accordance with the engine speed as well as with the intake vacuum in the vicinity of the throttle valve, in the same manner as described hereinbefore in connection with the device of FIG. 1, but the timer construction is different from that employed in the FIG. 1 device, as will be described hereinafter.

Reference numeral 142 indicates a switching device secured to the intake duct 1 and including two spring strips 143 and 144 with their extreme ends joined to form a type of toggle joint. Also included in the device 142 are a pin 145 provided to actuate the spring strips, a contact 146 carried on one of the spring strips 143, an electrode or terminal plate 147 engageable with contact 146, and another electrode 148 connected with spring strip 143. When the abutment 8A on the throttle-valve-operating member 8 is in engagement with stop 12 or when the member 8 is in its inoperative position, the contact 146 is closed in contact with the electrode plate 147 and, when the member 8 is operated by means of throttle wire 9, the contact 146 is opened away from the electrode 147. The electrode plate 148 is connected through conducting wire 149 and leaf spring 35 of the second breaker 32 to movable contact 32B thereof while on the other hand the conducting wire 150 connected to electrode plate 147 is also connected through wire 151 and leaf spring 35 of first breaker 28 to movable contact 28B thereof. Reference numeral 152 generally indicates the ignition circuit including an ignition coil 153, a distributor 154 and spark plugs 155. The conducting wire 150 is connected also to the ignition coil 153, as shown.

Reference numeral 156 generally indicates a vacuum switching device which includes a valve member having two valve heads 158 and 159 and biased downward as viewed in FIG. 7 by a spring 160 with an electromagnet 157 serving, when energized, to lift the valve member 158-159. Connected to the device 156 are a conduit 161 leading from the vacuum takeout port 18 of the intake duct, another conduit 162 leading to the vacuum inlet port 17 of vacuum actuator 16, and a discharge pipe 163. As will be apparent, the electromagnet 157, when energized, acts against the bias of spring 160 to lift the valve member 185-159 and thus interconnects the conduits 161 and 162. When electromagnet 157 is deenergized, the valve member 158-159 is lowered under the bias of spring 160 and thus the vacuum from conduit 161 is intercepted by the valve head 158, the vacuum in conduit 162 being released to the atmosphere through the vent hole 164 formed in the valve head 159 and through discharge pipe 163, rendering the vacuum actuator 16 inoperative. Conducting wires 165A and 165B are suitably arranged for energization of electromagnet 157 with an electric switch 166 interposed between the wires.

If the vacuum inlet port 17 of vacuum actuator 16 is continuously connected to the vacuum, the throttle valve which is rapidly closed for no-load engine operation with the clutch disengaged may at times be increased and, thus energizing the vacuum actuator 16, the opening of the throttle opening may be increased, unnecessarily increasing the engine speed. Such undesired increase of engine speed can be prevented with the provision of vacuum switching device 156 and electric switch 166 therefor by arranging appropriate means to detect the clutch state, and open the switch 166 when the clutch is in disengaged state.

FIG. 8 illustrates one example of such detecting means. In FIG. 8, reference numeral 167 indicates the master cylinder of a conventional clutching device with a piston 168 slidably arranged in the cylinder. In the conventional manner, the clutch is disengaged when the piston 168 is operated by means of a clutch pedal (not shown) and the oil pressure in the cylinder 169 is increased accordingly. In this instance, the increase in oil pressure in the cylinder 169 also serves to move another piston 170 against the action of a biasing spring 171 provided therefor so that a conducting ring 172 secured to the top of piston 170 is raised to disconnect electrode strips 173 and 174, from each other to which conducting wires 165A and 165B are connected. The conducting ring 172 and electrode strips 173 and 174 together form the above-mentioned switch 166.

Similarly, in no-load engine operation with the speed-change gear in neutral position, the speed-change operation may at times be made difficult by increase in engine speed if the vacuum inlet port 17 of vacuum actuator 16 is continually connected to the vacuum takeout port 18 of the intake duct 1. This difficulty can be overcome by employing appropriate detecting means operable upon detection of the gear shifting to close the switch 166 for energization of the vacuum switching device 156.

FIG. 9 illustrates one example of such detecting means and therein reference numeral 175 indicates an oil passage so designed that the oil pressure therein is increased upon completion of the gear shifting. As will be readily observed, the pressure increase in the oil passage 175 causes a piston 176 to move against the bias of a return spring 177 and, as a result, a conducting ring 178 fixed to the top end of the piston 176 is carried into a position to interconnect electrode strips 179 and 180, to which conducting wires 165A and 165B are connected, respectively. It will be apparent that the conducting ring 178 and electrode strips 179, 180 together form the electric switch 166 mentioned hereinbefore.

Another difficulty which may possibly occur if the vacuum inlet port 17 is continuously in connection with the vacuum takeout port 18 is that the vacuum actuator 16 may again inadvertently operate during cruising to make the car speed control difficult. In general, the cruising period of the car drive employing the high-speed gear train is longer than that employing lower speed gear trains and this fact makes it more important to prevent air pollution during high-speed cruising than during low-speed drive. Accordingly, the vacuum actuator 16 is usually set to operate smoothly by the increase in intake vacuum occuring upon deceleration during high-speed cruising.

Accordingly, during low-output low-speed cruising, which requires only a limited throttle opening, the intake vacuum tends to acquire a value higher than the value for the vacuum actuator setting referred to above, causing the actuator 16 to operate to increase the throttle opening. This results in the inconvenience that the car speed can hardly be controlled in the manner desired by the driver. Such inconvenience can be avoided by employing appropriate means for detecting completion of the high-speed gear train thereby to close the switch 166 and render the vacuum switching device 156 effective, thus precluding operation of the vacuum actuator 16 during the drive with any low-speed gear train completed.

It is to be noted that as such detecting means use can be made of the device shown in FIG. 9 as long as it is adapted so that the oil pressure in passage 175 is increased only with the high-speed gear train completed.

Although the description has been made here assuming that the electric switch 166 is operable by oil hydraulic means, it will be apparent that the switch may be provided with any other type of operating mechanism or be made manually operable, as desired.

Furthermore, with the device shown in FIG. 1 or FIG. 7, if the throttle valve 2 is opened wide when the second contact breaker element 32 is in operation with a small throttle opening, the second breaker element 32 is quickly replaced by the first breaker element 28 with the result that the ignition timing is substantially instantaneously to rapidly increase the engine power output exerting shock and other undesirable effects upon the engine and the passengers in the vehicle.

FIGS. 10 to 13 illustrate a device modified to overcome the deficiency described above and in which, when the throttle valve is operated from small to large opening, the first breaker initially remains ineffective, the second breaker continuing to operate but with its ignition timing advanced at the instant of throttle operation, and subsequently the first breaker is put into action taking the place of the second breaker.

Referring to FIGS. 10, 11, and 18, which illustrate the breaker unit of the device, reference numeral 201 indicates the casing of the unit; 202 a breaker cam shaft rotatable at a speed proportional to the engine speed; 203 a second breaker cam sleeve mounted on the cam shaft; and 204 a first breaker cam sleeve mounted on the second cam sleeve 203. As shown in FIGS. 11 and 18, cam plates 205 and 206 are secured to respective cam sleeves 203 and 204 and a support plate 207 is fixed to cam shaft 202 with centrifugal advancing weights 208 and 209 pivotally mounted on the support plate 207 and carrying respective pins 208A and 209A for engagement with cam plates 205 and 206, respectively. Fixed in the casing 201 are base plates 210 and 211 on which respective annular rotative discs 212 and 213 are journaled. First and second breaker arms or elements 215 and 214 are pivotally mounted on the rotative discs 213 and 212 at 213A and 212A, respectively.

As shown in FIG. 10, the first breaker element 215 is formed at one end with a slide finger 215A for sliding engagement with the camming surface of the first cam sleeve 204 and carries at the other end a movable contact 215B for cooperation with a fixed contact 216. A leaf spring 217 is provided normally to hold the movable contact 215B in pressure contact with the fixed contact 216. Similarly, the second breaker element 214 is formed at one end with a slide finger 214A for sliding engagement with the camming surface of second cam sleeve 203 and carries at the other end a movable contact 214B for cooperation with a fixed contact 218. A leaf spring 219 is provided normally to hold the movable contact 214B in pressure contact with the fixed contact 218. It is to be understood that the second breaker 214 is retarded in ignition timing relative to the first breaker 215.

Reference numeral 220 indicates an appropriate vacuum actuator operable under the control of intake vacuum fed from the vicinity 18 of throttle valve 2 as shown in FIG. 12. The actuator 220 is operably connected with the rotative disc 213 carrying first breaker element 215 by way of an actuator rod 221 but this is not always necessary.

Reference numeral 222 indicates a connecting rod pivotally secured to the rotative disc 212, which carries the second breaker element 214. A tubular member 224 is provided to receive the extreme end portion of the connecting rod 222 in sliding relation to the enlarged head 223 thereof with a compression spring 225 arranged between the head 223 and the bottom of the tubular member 224, as shown. Connected to the tubular member 224 is a wire 226 which is operable upon depression of the accelerator pedal (not shown). Arranged between an abutment piece 227 extending laterally from the connecting rod 222 and a fixed part 228 is a return tension spring 229 which is weaker than spring 225. The connecting rod 222 also carries another abutment piece 230 which is normally held in abutting engagement with said fixed part 228. Another fixed part 228A serves to limit the travel of the first-mentioned abutment piece 227, as will be described below.

With this arrangement, it will be readily observed that when the accelerator pedal is depressed, the connecting rod 222 is drawn against the bias of spring 229 until the abutment piece 227 comes into abutment against the fixed part 228A and with this motion of the connecting rod 222, the annular rotative disc 212 is turned carrying the second breaker 214 angularly relative to the associated cam sleeve 203 to advance the ignition timing of the breaker. Continued drawing of the wire 226 after the engagement of abutment piece 227 with the fixed part 228A is only effective to further compress the spring 225. In this situation, releasing the accelerator pedal first allows the spring 225 to expand, subsequently allowing the spring 229 to contract until the abutment piece 230 is restored into engagement with fixed part 228 and in this manner the second breaker 214 is restored to its initial retarded position.

In FIG. 12, reference numerals 1 to 23 correspond to those in FIGS. 1 and 7. In the device of FIG. 12, however, the elongated aperture 13 is slightly enlarged in the direction of the point of contacting engagement 15 as indicated by the chain line 243A, and an adjustable stop 242A is provided for abutting engagement with the throttle-valve-actuating member 4 against the bias of spring 14. The adjustable stop 242A is set so as to provide a slight gap or distance between the pin 5 and the wall 243A of the enlarged aperture portion when the throttle-valve-actuating member 4 is in engagement with the stop 242A. It will be apparent that this stop device is effective to moderate the shock occurring when the throttle-valve-operating member 8 is operated.

Referring again to FIG. 12, reference numeral 254 generally indicates an electric switch fixed relative to the intake duct 1. The switch 254 includes an insulating slide pin 255 having an extended head 256 and biased by a spring 257 toward the abutment 8A carried on throttle-valve-operating member 8 with the pin head 256 normally held in engagement with the abutment 8A under the spring bias. As shown, the slide pin 255 carries a short-circuiting ring 259 and a stop 258. Reference numerals 260 and 261 indicate respective electrode strips which are in contact with short-circuiting ring 259 only when the throttle-valve-operating member 8 is in abutting engagement with stop 12 or is spaced therefrom by a small distance. This distance is determined by the axial length Y of that portion of the short-circuiting ring 259 which extends from the point of contact 262 with the electrode strips 260 and 261 toward the spring 257. Reference numeral 263 generally indicates the ignition circuit including an ignition coil 264, a distributor 265, spark plugs 266, and a voltage source 267. As shown, one of the electrode strips 261 is connected through a conducting wire 268 to the ignition coil 264. Another conducting wire 269 connected at one end to the other electrode strip 260 is connected at the other end to leaf spring 219, which is connected to the movable contact 214B of second contact breaker 214. A further conducting wire 270 connected at one end to the conducting wire 268 is connected at the other end to the leaf spring 217 connected to the movable contact 215B of the first contact breaker 215. It will be obvious that short circuiting of electrode strips 260 and 261 made by the short circuit ring 259 renders the second circuit breaker 214 effective to make spark ignition at plugs 266. On this occasion, the first contact breaker 215 remains ineffective even when its contacts 215B and 216 are opened since the primary current of ignition coil 264 is not interrupted.

With the embodiment arranged as described above, it will be observed that, when the accelerator pedal is released to place the throttle-valve-operating member 8 in engagement with stop 12, the electrode strips 260 and 261 are short circuited by the short-circuiting ring 259 to render the second contact breaker 214 effective and thus the ignition timing is retarded. In addition on this occasion the throttle opening is held at an appropriate level by the provision of stop 242A and is properly increased with intake vacuum. In this situation, it will be readily appreciated that discharge of any engine exhaust tending to pollute the atmospheric air is effectively prevented and the engine output is effectively reduced intensifying the engine brake effect. Subsequently, if the accelerator pedal is operated to turn the member 8 and correspondingly increase the throttle opening, the second contact breaker 214 will initially continue to operate until the slide pin 255 has been moved over a distance corresponding to the partial length Y of the short circuiting ring 259 and the ignition timing of the second contact breaker 214 will be advanced by means of the wire means 226 and connecting rod 222 to approach the ignition timing of the first contact breaker 215. Subsequently, as the throttle-valve-operating member 8 continues its turning motion, the electrode strips 260 and 261 will be separated from the short-circuiting ring 259, coming into engagement with the rear nonconducting portion 271 of slide pin 255 extending adjacent to the short-circuiting ring 259, and thus render the first breaker 215 effective in the place of the second breaker 214. The amount of ignition advance effected under this switching action is reduced by an amount corresponding to the advancement of the second breaker 214 previously effected by the connecting rod 222 and associated means and accordingly, the rapid increase otherwise occurring in engine power output is relieved.

The above variation of ignition timing is graphically illustrated in FIG. 13, in which the abscissa represents the r.p.m. of the engine and the ordinate represents the ignition timing, D denoting the top dead center. Line 272 represents the spark-advance characteristic of the first contact breaker 215; line 273 represents the basic spark-advance characteristic of the second contact breaker 214; and line 273A represents the spark-advance characteristic of the second breaker 214 in case the connecting rod 222 is drawn to the extreme extent by the accelerator pedal and thus the second breaker is advanced to the extreme extent. It is assumed that the device of the invention is put into operation when the engine is running at low speed with the ignition timing lying at point a on the characteristic line 273. The timing initially lying on line 273 will move first to a point on line 273A, such as a.sub.1, a.sub.2 or a.sub.3 and then to an adjacent point on line 272 or to the very proximity thereto and subsequently onto line 272. Whether point a moves to point a.sub.1, a.sub.2 or a.sub.3 is determined by the speed of operation of the accelerator pedal. In case the operating speed is extremely high, the variation in engine speed during the pedal operation will be negligible and point a will move, for example, to point a.sub.1. Further, if the device of the invention is put into operation when the engine is in high-speed operation with the point of ignition timing lying at point b on line 273, the point b will first move to a point on line 273A such as b.sub.1 or b.sub.2 and then immediately to a point c.sub.1 or c.sub.2 on line 272. This increase in spark advance or the distance between points b.sub.1 and c.sub.1 or between b.sub.2 and c.sub.2 is still appreciable, it is apparently reduced to a remarkable extent compared with that obtainable if the ignition timing be varied from point b on the characteristic line 273 directly to a point on line 272 such as point c.sub.1.

With the device according to the invention it will be appreciated that such marked reduction in variation of ignition timing at the instant when the second breaker 214 is replaced by the first breaker 215 realizes substantial reduction in the shock otherwise exerted upon the engine and its supports.

As has already been described, the first and second contact breakers 215 and 214 provided for ignition of spark plugs 266 are switchable between themselves by electric switch 254. The wiring connection associated with this is schematically illustrated in FIG. 14.

If the switch 254 is arranged as indicated at 254A in FIG. 17, for selective connection of the two breakers 215 and 214 to the primary side 264A of ignition coil 264, the ground circuit including the primary side 264A will be opened at the instant when the switch 254A is transferred, and spark ignition will be effected at this instant with an ignition timing differing from that intended and, depending upon the timing of such premature ignition, misfiring may occur as described below. For example, in switching over from the first breaker 215 to the second 214, if ignition is effected upon operation of the switch 254A immediately before the switching is actually completed, so-called misfiring tends to occur since, subsequently when the second breaker 214 acts to interrupt the primary current of coil 264, the electric charge accumulated in the time is insufficient to effect actual ignition.

The ignition system schematically shown in FIG. 14 is designed to overcome the difficulty described above. Referring to FIG. 14, a parallel arrangement of first and second breakers 215 and 214 is provided in the primary side 264A of ignition coil 264 with a switch 254 inserted in the circuit of second breaker 214. As shown, the first breaker 215 remains connected to the ignition coil 264 when the switch 254 is opened, both breakers being connected to the ignition coil 264 with the switch closed.

The operation of the system of FIG. 14 will next be described. When switch 254 is opened to select first breaker 215, spark ignition is placed under the control of the breaker 215 alone and will be effected each time the contacts thereof are opened. Such ignition is shown in the chart of FIG. 15 at point A and the ignition timing is advanced. Subsequently, when switch 254 is closed, first and second breakers 215 and 214 are both connected to ignition coils, as described above, but in this state, ignition is not effected at the instant when the contacts of first breaker 215 are opened since the ignition coil 264 is grounded through the second breaker 214 as long as the contacts thereof are closed and the grounding of coil 264 is broken only when subsequently the contacts of second breaker 214 are opened. Thus, in this case the second breaker 214 is selected and ignition is effected each time the contacts of second breaker 214 are opened with a retarded timing as indicated by point B in FIG. 15.

Though with the arrangement of FIG. 17 spark ignition is made even at the instant when the switch 254A is operated, as described hereinbefore, and thus cause various inconveniences, it will be recognized that such inconveniences can be effectively avoided with the arrangement of FIG. 14 since opening the switch 254 causes no spark ignition except when such switch opening is effected by chance within the desirable range of ignition timing. More specifically, as long as the contacts of the first breaker 215 are closed, the ignition coil 264 is grounded through the first breaker circuit 270 and such grounding is in no way affected by the opening of switch 254, prohibiting occurrence of any spark ignition with such switch opening. Similarly, when the contacts of first breaker 215 are open, ignition coil 264 is ungrounded as long as the contacts of second breaker are open, and under such condition the opening of switch 254 will exert no effect upon the ungrounded state of the ignition coil and thus causes no spark ignition. On the other hand, if the switch 254 is opened when the first breaker contacts are open with the second breaker contacts remaining closed, it will be apparent that the grounding of ignition coil 264 is broken to cause spark ignition but such ignition will have no adverse effect upon engine operation as it is timed intermediate the point of advanced ignition A and that of retarded ignition B in FIG. 15.

Again with the arrangement of FIG. 14, there is a danger that ignition is unduly advanced if the resistance of the circuit of second breaker 214 be increased, for example, with some damage to its contacts since in this case the closing of switch 254 causes a relatively large current to flow through the circuit of first breaker 215. This apparently means that the opening of the contacts of first breaker 215 will have a larger influence upon the coil 264 than the opening of the contacts of the second breaker, and spark ignition will thus be effected each time the contacts of first breaker 215 are opened.

One arrangement designed to overcome this difficulty is shown in FIG. 16, in which reference numeral 274 indicates a resistance element inserted in the first breaker circuit 270 to make the latter relatively high in resistance in order to avoid passage of any relatively large current through the first breaker circuit 270 when both breaker circuits are employed. Further, it is desirable to provide means for bypassing the resistance element 274 when switch 254 is operated to select the first breaker 215 since otherwise the resistance 274 will cause loss in power consumption. In the arrangement shown, the switch 254 is operable between two switch contact 276A and 276B, and one of these contacts 276B is inserted in a circuit 275 bypassing the resistance element 274 when the switch 254 is thrown to select first breaker 215. The other switch contact 276A is inserted in the second breaker circuit 269, as shown.

Although several embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the spirit of the invention or from the scope of the appended claims.

Claims

We claim:

1. An air pollution preventive device for a spark-ignition-type internal combustion engine, comprising a throttle-valve-actuating member connected to a throttle valve vacuum actuator means operable by increase in intake vacuum on the downstream side of a throttle valve and releasably connected with said throttle-valve-actuating member so as to maintain driving engagement therewith only when the throttle valve is nearly closed, a throttle-valve-operating member operable by an accelerator pedal control and pivotally interconnected with said throttle-valve-actuating member by lost motion means of limited clearance, when the throttle valve is in nearly closed position, said throttle-valve-actuating member being operable by said vacuum actuator means with increase in intake vacuum to open the throttle valve while allowing said throttle-valve-operating member to remain in inoperative position when the throttle valve is in nearly closed position, and means for retarding the ignition timing of the engine relative to the normal ignition timing thereof when said throttle-valve-operating member is in inoperative position.

2. A device as claimed in claim 1, comprising first contact breaker means adapted to advance the ignition timing with increase in engine speed when the engine is in the state of normal drive, second contact breaker means arranged for ignition timing retarded relative to that of said first contact breaker means, and electric switch means arranged between said first and second contact breaker means and operable in association with the accelerator pedal control to render said first and second contact breaker means alternately effective.

3. A device as claimed in claim 1, in which said throttle-valve-actuating and operating members are not only operably interconnected by lost motion means of limited clearance but are also interconnected by a tension spring that is weaker than a return spring provided for said throttle-valve-operating member.

4. A device as claimed in claim 1, further comprising a means to resist initial returning movement of said throttle-valve-actuating member when the throttle valve is allowed to return quickly to the vicinity of its fully closed position.

5. A device as claimed in claim 1, comprising a combined vacuum actuator and dashpot assembly including: a vacuum actuator section including a spring-loaded diaphragm formed with a stop surface and a vacuum inlet formed on one side thereof to receive intake vacuum of the engine; a dashpot section arranged in axially adjacent relation to said vacuum actuator section and including a spring-loaded diaphragm; and a plunger rod slidably arranged on a common axis of said sections and secured to the dashpot diaphragm, said plunger rod being adapted to advance with closing movement of the throttle valve and carrying a stop member for abutting engagement with said stop surface on said actuator diaphragm.

6. A device for automotive use as claimed in claim 1, further comprising vacuum switching means inserted in the line of intake vacuum leading to said vacuum actuator means and operable at appropriate times to render said vacuum actuator means ineffective.

7. A device as claimed in claim 6, further comprising means for detecting load on the engine, said detecting means being operably connected with said vacuum switching means in a manner such that said vacuum actuator means remains inoperative as long as the engine is not loaded.

8. A device as claimed in claim 2 further comprising: means for maintaining the operation of said second contact breaker means for an initial period of movement of the throttle valve from small to wide opening and then rendering said first contact breaker means effective in the place of said second contact breaker means; and means for advancing the ignition timing of said second contact breaker means as the opening of the throttle valve increases in said initial period.

9. A device as claimed in claim 2, comprising a parallel arrangement of said first and second contact breaker means in the primary side of the ignition coil, said second contact breaker means being adapted to break later than said first contact breaker means while the latter is open, said electric switch means being inserted in the circuit of said second contact breaker means so as to connect only said first contact breaker means to the ignition coil when thrown open and to connect both said first and second contact breaker means to the ignition coil when closed.