FIELD OF THE INVENTION

This invention relates generally to valving structures particularly useful in combination with internal combustion engines to variably control the amount of air introduced into the engine's throttle bore so as to thereby compensate for increased/decreased air demands of the engine during idling.

BACKGROUND OF THE INVENTION

Internal combustion spark ignition engines require varying amounts of air so as to .idle properly under various operating conditions. As examples, (1) an increased amount of air is required when an engine is idling "cold" as compared to the amount of air required for proper idling of a "warm" engine; (2) an extra amount of air for emission reasons is required under conditions of deceleration, and (3) the amount of air flow must be varied so as to maintain relatively constant idle speed when loads on the engine (such as air conditioning compressors, alternators, etc.) are cycled.

Internal combustion engines have become increasingly more sophisticated with the use of microprocessor-based engine control units (ECU) . For example, the ECU may typically receive data corresponding to engine temperature, engine speed,

manifold pressure, oxygen content in exhaust gases as well as other conditions, for example, closed throttle (i.e. full choke) conditions on start up and the like. This data is then assimilated by the ECU and is used for various purposes, one of which is to operate conventional idle control assemblies, such as those represented by U.S. Patent 4,539,955 issued to Robert E. Wilson et al on September 10, 1985 and U.S. Patent 4,212,272 issued to Rufus L. Hawk on July 15, 1980, each being entitled "Idle Speed Control Device for Internal Combustion Engine".

According to these prior idle control assemblies, the signals are received from the ECU in the form of- reverse polarity DC voltages so as to actuate a motor which, in turn, increases/decreases the length of a shaft having an- end in contact with the throttle valve linkage. These types of devices, therefore depend upon automatic opening and closing of the throttle valve — that is, the throttle valve itself is opened (or closed) in dependence upon the operating conditions of the engine sensed by the ECU. While this functioning may be adequate for some engine operating conditions (such as "cold" engine operation), it cannot function as a means for controlling the quantity of air introduced into a throttle bore independently of the particular throttle valve setting.

Another conventional air control valve is disclosed in U.S. Patent No. 4,369,755 issued to Masaaki Saito on January 25, 1983, entitled "Air Control Device". This prior control valve is

positioned in an air passage bypassing the throttle valve and thus operates independently thereof. A D.C. motor is connected to an inner cylindrical body in such a way that the latter can be rotated by the former. Rotation of the inner cylindrical body relative to an outer cylindrical body thus controls the amount of air flowing through the air passage bypassing the throttle. No means are disclosed in U.S. Patent No. 4,369,755 however, which mechanically "decouples" the D.C. motor and the inner cylindrical body in response to a threshold torque being exceeded. Thus, the provision of a rotation angle sensor and a motor disabling circuit appear to be requirements of the valve of U.S. Patent No. 4,369,755 during use since damage to the motor and/or inner cylindrical body could ensue without such electronic safeguards when the inner cylindrical body achieves its maximum (minimum) rotational position.

A balanced dual valve air flow regulator is disclosed in U.S. Patent 4,421,083 issued to Donald D. Stoltman on December 20, 1983, entitled "Engine Air Flow Regulator". According to this prior patent, the ECU varies the duty cycle of a solenoid so as to. correspondingly vary air flow past valve seats until pressure on one side of a diaphragm balances the diaphragm force with the bias of the solenoid. In such a manner, air flow control through a throttle bypass control may be accomplished independently of throttle position.

SUMMARY OF THE INVENTION

In accordance with the present invention, an idle control valve is described and claimed whereby the amount of air supplied to a throttle assembly of an internal combustion engine is accomplished independently of the throttle valve setting. A valve body of generally cylindrical configuration is provided having an inlet so as to admit air into the interior of the valve body and an air outlet

(preferably in the form of a generally circular array of openings) to discharge air from the valve body and into the throttle bore of a throttle assembly of an internal combustion engine. A valve spool is rotatably mounted within the valve body and includes a valve port which defines an effective area so to establish the amount of air low through the valve body between its inlet and outlet thereof. The valve spool is rotatable about an axis which is common to the spool and the body and is driven, for example, by a suitable DC motor which receives its signals in the form of reverse polarity DC voltages from an ECU so as to rotate the valve spool which, in turn, alters the effective area of the spool's valve port. In such a manner, the amount of air flowing through the valve body between its inlet and outlet is controllably altered so as to compensate during idling for varying engine operating conditions sensed by the ECU independently of the particular throttle valve setting.

Driven engagement between the motor and the valve spool is preferably effected by means of a

worm/worm gear arrangement which transmits torque to the valve spool via a clutch assembly. The clutch assembly, in a preferred form, includes a pair of spherical detent members (slidably received within a transverse bore of a male portion of the worm gear) and a splined surface on an interior adjacent portion of the valve spool. A compression spring, or other like biasing means, acts upon the pair of spherical detent members so as to urge the same into engagement with respective splines of the splined surface.

When the maximum (minimum) extent of rotation has been achieved by the valve spool so as to create the maximum (minimum) effective area of the valve port defined thereby, ^" a predetermined threshold torque level will be exceeded thereby causing the detent members to retract into the transverse bore and thus allow relative slippage to occur between "the male portion of the worm gear on the one hand, and the splined surface of the valve spool on the other hand. This relative slippage or "ratcheting" permits the motor to continue operation without damage to either the worm/worm gear arrangement or the valve spool. However, when the worm gear reverses rotation upon receipt of a DC voltage signal of a polarity reverse to that which caused the spool to rotate into its maximum (minimum) position, the detent members will again be seated within respective splines (since the transmitted torque will again be below the threshold torque) and, thus, the valve spool will be caused to rotate in an opposite direction.

The structures of the present invention,

therefore, are relatively simple in view of prior art proposals and allows the amount of air to be controllably altered ^" independently of the throttle valve of an internal combustion engine. Moreover, the structures of this invention avoid the necessity of complicated motor-disabling and/or valve spool position sensing systems typical of prior art proposals. These and other advantages of the invention will become more apparent to those skilled in this art after careful consideration is given to the detailed description of the preferred exemplary embodiment thereof which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will hereinafter be made to the accompanying drawings wherein like reference numerals throughout the various Figures denote like structural elements, and wherein:

FIGURE 1 is a schematic view of a throttle assembly for an internal combustion engine showing the idle valve of this invention operatively associated therewith;

FIGURE 2 is a cross-sectional ^* side elevational view of the idle valve of this invention taken along line 2-2 in FIGURE 3;

FIGURE 3 is a is an end elevational view of the idle valve of this invention;

FIGURE 4 is a cross-sectional view of the idle valve of this invention taken along line 4-4 in FIGURE 2;

FIGURE 5 is a cross-sectional view of the idle valve of this invention taken along line 5-5 in FIGURE 2; and

FIGURE 6 is a cross-sectional view of the idle valve of this invention taken along line 6-6 in FIGURE 2.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT

The idle valve 10 of this invention is schematically depicted in Figure 1 as being installed as part of a throttle assembly 12 of an internal combustion engine (not shown). In a well known manner, the throttle assembly defines a throttle bore 14 in which a throttle valve 16 is pivotally mounted via its shaft 18. The shaft 18 is., in turn,. connected to an acceleration pedal (not shown) on the driver's side of the vehicle via suitable linkage structures. As is notoriously well known, opening (closing) of the throttle bore by causing the throttle valve to pivot to a more (less) open position (when the driver depresses (releases) the accelerator) causes an increase (decrease) in the engine operating torque. The engine with which the idle valve 10 of this invention may be utilized can be of any well known variety, e.g., carbureted or

fuel injected (either a single point type wherein the injectors are located in the throttle assembly upstream of the throttle valve, or a multipoint type wherein a fuel injector is located near the intake valve of each engine cylinder).

In accordance with this invention, an air bypass 20 is provided in assembly 12 such that an amount of air (controlled via idle valve 10) is introduced downstream of throttle valve 16. Since no linkage between idle valve 10 and throttle valve 16 is present, the idle valve 10 is able to control the amount of air introduced into bore 14 downstream of throttle valve 16 independently of the latter. Thus, while the "idle position" of the throttle valve may remain constant, the air demands of the engine during various operating conditions during idling may be compensated for by means of the bypass 20 ^' and idle control valve 10.

The idle control valve 10 of this invention is shown more specifically in accompanying Figures 2 and

3. As is seen, the idle valve 10 includes a generally cylindrical valve body 22 having.a bearing post 24 inwardly extending along the. valve's longitudinal axis 26. An air inlet slot 28 receives air (filtered by the engine's air cleaning system) from the bypass 20 and- then discharges it into the throttle bore 14 of assembly 12 downstream of throttle valve 18 via a circular array of air outlets 30 defined in body 22.

A valve spool 32 is mounted within chamber 30 in close fitting relationship (i.e. about .001 in. (.0254 mm.) clearance) relative to valve body 22. The valve spool 32 is generally cylindrical in shape and thus establishes an interior chamber 34. Air inlet and outlet ports 36, 38, respectively, are in communication with interior chamber 34 and are registerable with the similarly configured air inlet 28 and the air outlet openings 30 defined by valve body 22. As shown in Figure 4, inlet port 36 is preferably in the form of a partial circumferential slot (i.e. similar to inlet 28) while outlet ports 38 are preferably a circular array of openings (i.e. similar to outlet openings 32).

The valve body and valve spool, 22, 32 respectively, are sealed, at least in part, by virtue of the close-fitting relationship therebetween. Also, sealing functions are provided by interdigitated finger and U-shaped flanges-33, 23, respectively, formed on valve spool 32 and valve body 22. The interdigitated flanges 33 and 23 thus from a mechanical labyrinth seal at- that end of body 22 having the outlet openings 30.

The valve spool 32 is mounted within valve body 22 for rotational motion aboxit axis 26 by spool bearings 40 and is driven by means of motor 42. Motor 42 is preferably, of a high RPM, low torque character which is operable responsive to receiving reverse polarity DC voltage signals from the ECU 44 (see Figure 1). One such motor may be ESCAP No.

16C11-205-0 Micromotor.

The drive output of motor 42 is speed-reduced by a gearing arrangement comprised of a worm 46 and a worm gear 48 housed within an enclosure 50 integrally provided as part of valve body 22. The worm gear 48 includes a male portion 52 which is mated within the valve spool 32 and is mounted for rotational motion via gear bearing 54 associated with the terminal end of bearing post 24. A transverse bore 56 extends through the male portion 52 of the worm gear 48, the purpose of which will be described later.

As is seen more clearly in accompanying Figure 5, a spool stop 60 is provided on the interior of the valve body 22 and is defined by lateral stop surfaces 62a, 62b, which respectively contact the spool ring stop surfaces 64a, 64b establishing the maximum and minimum (i.e. closed) positions of the valve spool 32. Thus, upon rotation of worm gear 48 via the driven worm 46, the valve spool will rotate in a direction dependent upon the polarity of the DC voltage signal issued by ECU 44. The valve spool will continue to rotate until reaching its maximum (minimum) position which, in turn, is determined by contact between surfaces 62a and 64a (62b and 64b).

After reaching its maximum (minimum) position, the clutch assembly 70, permits relative slippage to occur between male portion 52 and the valve spool 32. The clutch assembly 70 of this invention thus causes the male portion 58 of the worm gear 48 to be drivenly engaged with the valve spool 32 at torque

levels below a predetermined threshold while yet permitting relative slippage therebetween at torque levels in excess of the threshold.

As is shown more clearly in Figure 6, the clutch assembly 70 includes a pair of spherical detent members 72 slidably received within bore 56 at each end thereof with a compression spring 74 located therebetween. A splined surface comprised of a plurality of spline slots 76 is defined on an interior end region 78 of the valve spool 32 so that the detent members 72 are received, and thus engaged therein. Torque is thus transmitted to the valve spool 32 in response to rotation of the worm gear 48 when the detent members 72 are engaged within a corresponding pair of spline slots 76. When, however, a threshold torque level is exceeded (as by the valve spool attaining its maximum (minimum) position), the detent members 72 will be yieldably retracted into bore 56 against the bias force of the compression spring 74 so as to move away from the spline slots 76 and thus permit relative slippage to occur between the male portion 52 of the worm gear 48 and the valve spool 32. In such a manner, the motor 44 may continue to rotate in a direction even after the maximum (minimum) position of the valve spool has been achieved thereby avoiding complicated motor-disabling and/or valve spool position sensing systems and the like.

Upon a DC voltage signal of a polarity reverse of that used to move spool 32 into its maximum (minimum) position being applied to the motor 42 from

W

12

ECU 44, the torque will fall below the predetermined threshold required for relative slippage to occur between male portion 52 and valve spool 32 since the worm gear 48 is then also rotating in an opposite 5 direction. The compression spring thus urges the detent members 72 into engagement with an opposing pair of spline slots 76 defined by the valve spool 32. In such a manner, torque is again transmitted to spool 32 via detent members 76 so as to drivenly 10 rotate the former.

The threshold torque level above which relative slippage occurs between male portion 52 and valve spool 32 is predetermined, for example; by the depth 15 of spline slots 76 and/or by the force which is exerted upon detent members 72 by means of spring 74.

In operation, when a command signal 44a (see Figure 1) is issued by the ECU 44 to the DC motor 42

20 in the form of a DC voltage of a predetermined polarity, the output of the motor 42 will be transferred to the worm 46 via the motor shaft 47 (see Figure 5) which, in turn, causes the worm gear 48 to rotate in one direction about the longitudinal

25 axis 26 of the valve body 22. This rotation will continue until the ECU 44 stops sending the command signal or the spool ring stop surface 64a (64b) engages the spool stop surface 62a (62b) to establish the maximum (minimum) position of the valve spool

30 32. This rotation, in turn, controllably alters the maximum (minimum) effective area of the inlet ports 36, ^" 38, respectively, of the valve spool so as to permit a maximum (minimum) of air flow through the

valve body 22.

Upon reaching its maximum (minimum) position, the clutch assembly will sense that a predetermined threshold torque has been exceeded. Thus,- since the motor 42 will continue to operate (and attempt to further rotate spool 32 via worm/worm gear: 46/48 beyond its maximum (minimum) position), the detent members 72 will experience a force greater than that exerted upon them by compression spring 74. The detent members 72 will therefore yieldably retract within bore 56 allowing relative slippage to occur as between male portion 52 and valve spool 32. This relative slippage will continue as long as motor 42 attempts to rotate spool 32 (via worm/worm gear 46/48) beyond its. maximum (minimum) position.

Upon a DC. voltage of a polarity reverse to that previously applied being issued as a signal 44a from ECU 44, the motor 42 will responsively rotate in an opposite direction thereby transmitting this opposite rotation to the valve spool 32. Since the torque level is now less than the threshold torque encountered when the valve spool 32 is in its maximum (minimum) position, the spool 32 will rotate in the opposite direction since the detent members 72 will be urged into engagement, and will remain seated, with an opposing pair .of spline slots 76. Of course, when the threshold torque is exceeded as by spool 32 again being rotated into its maximum (minimum) position, the detent members 72 will again be yieldably retracted into the transverse bore 56 against the bias force of the compression spring 74

so that relative slippage will occur between the male portion 52 of the worm gear 48 and the valve spool 32 thereby effectively terminating or preventing further torque from being transmitted therebetween. In such a manner, the valve spool is caused to stop rotating with the advantage being that no damage occurs as between the valve spool 32 and the worm gear/worm 48/46.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included wi'thin the spirit and scope of the appended claims.