GB2163214A

GB2163214A - Controlling i.c. engine throttle valve

Info

Publication number: GB2163214A
Application number: GB08520538A
Authority: GB
Inventors: Peter Gordon Green
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-08-18
Filing date: 1985-08-16
Publication date: 1986-02-19
Also published as: AU4679285A; EP0189475A1; WO1986001256A1; GB8421061D0; GB8520538D0

Abstract

A control means for a throttle valve of an induction system of an internal combustion engine comprising a manually operable member (29), a control device (23) operable to interconnect the manually operable member (29) and the throttle valve, the control device (23) having an input means (26) connected to the manually operable member, an output means (25) connected to the throttle valve, first fluid pressure means operable to interconnect said output and input means, means responsive to the pressure, of a second fluid separate from the first fluid, in the induction system of the engine to control said first fluid pressure means to move the throttle valve in a direction to close the throttle valve to oppose increase in pressure in the induction system.

Description

SPECIFICATION Control means for IC engine This invention relates to a control means for a throttle valve of an induction system of an internal combustion engine.

According to one aspect of the invention, we provide a control means for a throttle valve of an induction system of an internal combustion engine comprising a manually operable member, a control device operably to connect the manually operable member to the throttle valve, the control device having an input means connected to the manually operable member, an output means connected to the throttle valve, first fluid pressure means operably to interconnect said output and input means, means responsive to the pressure, of a second fluid separate from the first fluid, in the induction system of the engine to control said first fluid pressure means to move the throttle valve in a direction to close the throttle valve to oppose increase in pressure in the induction system.

Preferably the control device includes mode defining means to provide a plurality of desired modes of interconnection between the input and output means by the first fluid pressure means and mode control means responsive to an engine parameter to control the mode defining means to select a desired one of said modes.

According to another aspect of the invention, we provide a control means for a throttle valve of an induction system of an internal combustion engine comprising a manually operable member, a control device operably to interconnect the manually operable member and the throttle valve, the control device having mode defining means to provide a plurality of desired modes of interconnection between the manually operable member and the throttle valve and mode control means responsive to an engine parameter to control said mode defining means to select a desired one of said modes.

The control device may have an input means connected to the manually operable member, an output means connected to the throttle valve, and fluid pressure means operable to interconnect said input and output means.

In both aspects of the invention, a first of said modes may comprise interconnection of the manually operable member and throttle valve to permit of movement of the throttle valve in a direction to open and close the throttle in response to corresponding movement of the manually operable member, and a second mode comprises disconnection of the throttle valve and manually operable member to prevent opening of the throttle valve in response to movement of the manually operable member.

In the first aspect of the invention, the first mode may further comprise providing connection between the throttle valve and said means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

The first mode may also inhibit movement of the throttle valve in a direction to close the throttle valve in consequence of increase in induction system pressure.

In the second aspect of the invention, the first mode may further comprise providing connection between the throttle valve and means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

In the first aspect of the invention, the second mode may further comprise connection between the throttle valve and said means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in pressure in the induction system and to permit of movement of the throttle valve in the direction to close the throttle valve in consequence of increase of pressure in the induction system.

In the second aspect of the invention, the second mode may further comprise connection between the throttle valve and means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in pressure in the induction system and to permit of movement of the throttle valve in a direction to close the throttle valve in consequence of increase of pressure in the induction system.

In the first aspect of the invention, the modes may include a third mode in which the throttle valve and manually operable member are disconnected to inhibit movement of the throttle valve in a direction to open or close the throttle valve in response to corresponding movement of the manually operable member and to connect the throttle valve to said means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

The third mode may also inhibit movement of the throttle valve in a direction to close the throttle valve in consequence of increase in induction system pressure.

In the second aspect of the invention, the modes may include a third mode in which the throttle valve and manually operable member are disconnected to- inhibit reciprocation of the throttle valve in a direction to open or close the throttle valve in response to corresponding movement of the manually operable member and to connect the throttle valve to means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

In the first aspect of the invention, the first mode may comprises providing a flow path for said first fluid between the input and output means to permit of reciprocation of the output means in directions to open and close the throttle valve in response to reciprocation of the input means, and a flow path for the first fluid between the output member and the means to control the first fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

The first mode may also prevent flow of fluid in the reverse direction to thereby inhibit movement of the output member in a direction to close the throttle valve in consequence of increase in induction system pressure.

In the second aspect of the invention, the first mode may comprise providing a flow path for said fluid between the input and output means to permit of reciprocation of the output means in directions to open and close the throttle valve in response to reciprocation of the input member, and a flow path for the fluid between the output member and the means to control the fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

In the first aspect of the invention, the second mode may comprise providing no flow path for said first fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the first fluid between the output means and the means to control the first fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure, and to permit of movement of the output means in a direction to close the throttle valve in consequence of increase in induction system pressure.

In the second aspect of the invention, the second mode may comprise providing no flow path for said fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the fluid between the output means and the means to control the fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure, and to permit of movement of the output means in a direction to close the throttle valve in consequence of increase in induction system pressure.

In the first aspect of the invention, the third mode may comprise providing no flow path for said first fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the first fluid between the output means and the means to control the first fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

The third mode may also prevent flow of fluid in the reverse direction to thereby inhibit movement of the output member in a direction to close the throttle valve in consequence of increase in induction system pressure.

In the second aspect of the invention, the third mode may comprise providing no flow path for said fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the fluid between the output means and the means to control the fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

The input means may comprise an input member connected to an input element, movable within an input chamber.

The output means may comprise an output member connected to an output element, movable within an output chamber.

The elements may comprise a piston and/or a flexible skirt or diaphragm, having a part fixed relative to the chamber and a part fixed relative to the input or output elements respectively.

The means responsive to the pressure of a second fluid separate from the first fluid may comprise an element movable in a chamber, the element dividing the chamber into two regions on opposite sides of the element, one region being in communication with said first fluid and the second region being in communication with the second fluid.

The second region may be connected by a conduit to the induction system of the engine so that the pressure of the fluid in the induction system of the engine is communicated to the second region.

The first fluid may be hydraulic fluid.

The second fluid may be induction fluid.

The mode defining means may comprise a multi-position valve disposed in the flow path of fluid between the input and output means and the means responsive to the fluid pressure in the induction system.

The valve may be positionable in a first position corresponding to said first mode in which flow of fluid is permitted in either direction between the input and output means, and to permit flow of fluid from the output means to the means responsive to fluid pressure in the induction system.

Flow of fluid in the reverse direction may be prevented.

The valve may be positionable in a second position, corresponding to said second mode, in which flow of fluid between said input and output means is prevented, and flow of fluid in either direction between the output means and the means responsive to fluid pressure in the induction system is permitted.

The valve may be positionable in a third mode in which flow of fluid between the input and output means is prevented, flow of fluid from the output means to the means responsive to fluid pressure in the induction system is permitted.

Flow of fluid in the reverse direction may be prevented.

The control means may be provided with means to permit of movement of the throttle valve in a direction towards a closed position as a result of corresponding movement of the manually operable member independently of said means responsive to fluid pressure in the induction system and said mode defining means.

The control means may be provided with overriding means operable when the manually operable member is moved against an override pressure to cause said throttle valve to move in a direction towards an open position independently of said means responsive to fluid pressure in the induction system and said mode defining means.

The overriding means may comprise a valve to permit passage of fluid from the output means to the input means independently of the means responsive to pressure in the induction system and said mode defining means when the manually operable member is moved against said override pressure.

The overriding valve may be a pressure sensitive valve which remains closed when pressure acting thereon is below a predetermined value and opens when pressure acting therein is above a predetermined value, the pressure acting on the valve rising above said predetermined value as a result of movement of the manually operable member against said override pressure.

One embodiment of the invention will now be described by way of example, with reference to the accompanying drawings, wherein: Figure 1 is a cross-sectional view through a control means embodying the invention: Figure 2 is a section on the line 2-2 of Fig.

1; Figure 3 is a fragmentary cross-sectional view, to an enlarged scale, on the line 3-3 of Fig. 1; and Figure 4 is a diagrammatic illustration of a pressure responsive valve.

Referring to the drawings, a throttle valve of a carburettor of an internal combustion engine (not shown) is mounted on a spindle 10. Fixed to the spindle 10 is an arm 11 engaged with one end of a coil tension spring 12, the other end of which is anchored to a part 1 3 fixed relative to the engine. Also fixed to the spindle 10 is an arm 14 connected to one end 1 5 of the internal member 1 6 of a flexible cable 1 7 of the "Bowden" type. The outer member 1 8 of the cable 1 7 abuts at one end 1 9 an abutment member 20 fixed relative to the engine whilst at its other end 21, the outer member 18 is fixed to a sleeve 22 of a control device 23.The inner member 1 6 of the cable 1 7 is fixed, at its opposite end 24, to an output member 25 of the control device 23.

The control device 23 on the opposite side thereof to the output member 25 is provided with an input member 26 connected to an inner member 27 of a flexible Bowden type cable 28, the other end of the inner member 27 being connected to a manually operable member 29 in the form of a foot pedal pivoted about an axis 30. The cable 28, like the cable 17, has an outer member 31 in engagement at one end with an abutment 32 fixed relative to the axis of pivot 30 of the pedal 29 and at the other end in abutment with a sleeve 33 fixed relative to the control device 23.

The control device 23 comprises an input chamber 40 in which an input element comprising a piston 41, connected to the input member 26, can reciprocate with a flexible skirt 42 being connected between the piston 41 and the wall 43 of the chamber 40 to provide a fluid-tight seal therebetween.

Within the chamber 40, the sleeve 33 is provided with a head 44 which serves as an abutment to retain a slider 45 in sliding engagement with the sleeve 33 and a coil compression spring 46 is engaged between a base part 47 of the chamber 40 and an outturned flange 48 on the slider 45 so as normally to bias the slider 45 to the right in Fig. 1 into abutment with the head 44.

The control device 23 is provided with an output chamber 50 in which an output element comprising a piston 51, connected to the output member 25, can reciprocate with a flexible skirt 52 connected between the piston 51 and the wall 53 of the chamber 50 to provide a fluid-tight seal therebetween.

The chambers 40, 50 are provided on opposite sides of a valve block 60, hereinafter to be described, having a valve 70 which provides a mode defining means which controls the passage of hydraulic fluid between the chambers 40 and 50 from regions 40a, 50a thereof respectively on one side of the pistons 41 and 51. The pistons 41, 51 being connected to their associated input and output members 26, 25 respectively on the opposite side of the pistons. The valve block 60 is provided with two passages 61, 62 which extend between opposite walls 63, 64 of the valve block 60 to communicate with the regions 40a, 50a of the chambers 40, 50. As best shown in Fig. 2, the passage 61, which is shown in chain dotted line in Fig. 1, is behind the plane of the section on which Fig.

1 is taken, whilst the passage 62, which is shown in dotted line in Fig. 1, is in front of the section line.

The passage 61 is provided with a one-way valve 65 at the end thereof adjacent the face 64 of the valve block to prevent passage of hydraulic fluid from the region 40a towards the region 50a, whilst the passage 62 is provided with a similar one-way valve 66 at the end thereof adjacent to face 63 of the valve block 60 to prevent passage of hydraulic fluid from the region 50a towards the region 40a.

The passages 61, 62 communicate with the valve 70, best shown in Fig. 3, adjacent their mid-points.

The valve 70 is provided within a bore 71 of the valve block 60 and comprises a sleeve 72 provided with O-ring seals 73 to provide a fluid-tight seal with the wall of the bore 71.

Adjacent the intersection of the passage 61 with the bore 70, the sleeve 72 is provided with an annular 'in section' recess 74 whilst adjacent the intersection of the passage 62 with the bote 71 the sleeve 72 is provided with an annular 'in section' recess 75 so that fluid in the passages 61 and 62 respectively can flow around the space provided by the recesses 74, 75.

A plurality, in the present example four, of radial openings 76 are provided through the wall of the sleeve 72 in the base of the recess 74 and similar radial passages 77 are provided in the sleeve in the base of the recess 75.

Axially reciprocable within the sleeve 72 is a valve member 80 provided with O-ring seals 81 which press PTFE sleeves 82 against the internal surface 72a of the sleeve 72 to provide a fluid-tight, low friction, seal therewith. The valve member 80 adjacent its lower end is provided with an annular, in section, recess 83 in the base of which is provided a plurality, in the present example two, of radial passages 84 which communicate with a counterbore 85 provided in the lower end surface 86 of the valve member 80.

A one-way valve member 87 is provided at the end 86 of the valve member 80 to permit of flow of hydraulic fluid from within the counterbore 85 but to prevent passage of hydraulic fluid in the opposite direction. The valve member 87 comprises a head 88 having a stem 89 biased by a coil tension spring 90 normally into sealing engagement with the end surface 86 of the valve member 80. The stem 89 is an interference fit within one end of the spring 90 whilst the other end of the spring 90 is an interference fit on a spigot 91 which has a reduced diameter part on which the spring 90 can move freely.

The valve member 80, as best shown in Fig. 1, is provided with a counterbore 95 at its upper end in which is received a coil compression spring 96, the lower end of which engages an end surface 97 of the counterbore 95, and the upper end of which engages on abutment 98 such as a shoulder provided an a manually operable adjustment member 99 threadedly engaged in a boss 100 provided on a chamber 101 provided on the top of the valve block 60. Rotation of the member 99 causes longitudinal movement thereof and hence adjusts the force imposed by the spring 95 on the surface 97 of the valve member 80 thus permitting of adjustment of the force normally biasing the valve member 80 downwardly.

At its upper end, the valve member 80 is connected to a flexible skirt 102 anchored at its lower end 103 to the upper surface 104 of the valve block 60. The chamber 101 has a port 105 connected by a conduit 106 to the induction system of the engine. The chamber 101, skirt 102 and conduit 106 comprise a mode control means.

Referring again to Fig. 3, at its lower end, the sleeve 72 is provided with a plurality, in the present example four, of slots 78 to permit passage of hydraulic fluid therethrough into and out of a chamber 110 provided on the undersurface 111 of the valve block 60.

The housing 110 is provided by an assembly of two pressings clamped together by suitable means, with a flexible skirt or diaphragm 11 2 trapped therebetween, as indicated at 11 3.

One side of the skirt or diaphragm abuts a plate 114 having a stem 11 5 threadedly engaged with a thread 11 6 provided in a boss 11 7 of the chamber 110. Thus rotation of the stem permits of adjustment of the maximum volume of the region of the chamber 110 between the diaphragm 11 2 and the valve block 60 which is designated 11 0a in the Figures, and the minimum volume of the region of the region of the chamber 110 on the opposite side of the diaphragm 11 2 which is designated 11 Ob. This region 11 Ob is connected by a port 118 and a conduit 119 to the induction system of the engine.

The piston chambers and valve members described above are all of generally circular configuration in cross-section. The piston 41 has a diameter in relation to the diameter of the piston 51 such that its surface area is approximately twice that of the piston 51 and hence for a given linear movement of the piston 41 under the influence of the throttle pedal 19, and the absence of any other influence hereinafter described, the piston 51 will be caused to move through approximately twice the linear distance because the piston 41 displaces approximately twice the volume of hydraulic fluid than does the piston 51.

The filled volume of the region 11 Oa of the chamber 110, i.e. when the diaphragm 112 is in the position shown in Fig. 1, is approximately equal to the filled volume of the region 50a of the chamber 50, i.e. the volume of that region when the piston 51 is in the extreme right-hand position opposite to that shown in Fig. 1, and the filled volume of the region 40a of the chamber 40, i.e. when the piston is moved fully to the left in Fig. 1 is approximately equal to the combined filled volumes of the region 50a and 11 Oa.

The valve block 60 also contains an overriding valve to permit of rapid movement of fluid from the region 50a into the region 40a thus by-passing the valve 70 to permit of rapid acceleration of the engine when this is desired. The override valve is arranged to be sensitive to the pressure exerted thereon as a result of movement of the piston 41 to the left in Fig. 1, and is arranged to open when the force applied to the pedal 29 is such as to create a predetermined "override" pressure differential between the regions 40a and 50a.

The override valve is set so that the "override" pressure differential corresponds to a desired force to be applied to the pedal which is convenient for a user to apply when override is required. It is to be noted that the force required to be applied to the pedal 29 is increased when the piston 41 engages the slider 45 so that the driver senses an increased resistance to movement of the pedal 29 due to the need to compress the spring 46 to permit of movement of the piston 41 further to the left. The driver is therefore warned of the situation where the pedal is depressed to a large extent. The overriding valve may be provided with manual adjustment means to permit of adjustment of the "override" pressure at which the valve opens.

When the engine is stopped, the piston 51 is fully to the right under the influence of the spring 1 2 and the throttle is closed. The diaphragm 11 2 may be in any position between its two extreme positions depending upon the pressure conditions in the engine induction system immediately prior to the engine stopping. For example, if the pressure was low, the diaphragm will be in a "down" position as shown in Fig. 1, and the piston 41 will be fully to the right in Fig. 1. Alternatively, if the pressure was high, the diaphragm will be in an "up" position and the piston 41 will be in the position shown in full lines in Fig. 1. With intermediate pressure in the engine induction system, the diaphragm and piston 41 will be in corresponding intermediate positions.

If the pressure conditions when the engine was stopped were such that the diaphragm 112 is in the position shown in Fig. 1, then both the pistons 41 and 51 will be in their extreme right hand positions. If the pressure conditions were such that the diaphragm 11 2 is not in its fully down position, then whilst the piston 51 will be in its fully right hand position with the throttle closed, the piston 41 will be displaced from its fully right hand position so that the pedal 29 will also not be fully up.

However, under such circumstances when the engine is started, there will be a pressure reduction in the engine induction system which causes the diaphragm 11 2 to move downwardly to the position shown in Fig. 1, so drawing fluid into region 11 Oa from region 40a through the one-way valve 87 thus moving the piston 41 to its fully right hand position and the pedal 29 to its fully up position; flow of fluid from the region 50a is resisted by the force of the spring 1 2 so that the throttle valve remains closed.

The operation of the control means will now be described. In the present example, the control means is applied to an internal combustion engine installed in a road vehicle. For the purpose of this example, it is assumed that the vehicle in proceeding along a level road at steady speed with the throttle pedal 29 in such a position that the piston 41 is in the position shown in dotted lines in Fig. 1, i.e. near to its fully right-hand position, corresponding to a closed throttle.

In these circumstances, the pressure in the engine induction system will be relatively low because the engine will be rotating at a relatively high speed with a relatively small throttle valve opening, thereby restricting the flow of induction mixture causing a relatively low pressure to exist in the induction system. The strength of the spring 1 2 is arranged so that the moment applied to the spindle 10 by the spring 1 2 is less than the moment applied to the spindle 10 by the force imposed on the piston 51 due to the pressure of the hydraulic fluid in the chamber 50a arising from the pressure of the fluid in the region 11 Oa of the chamber 110 due to the position of the diaphragm 112.Therefore, neglecting for the present the effect of the piston 41, under such circumstances the force imposed upon the diaphragm 11 2 by the relatively low pressure in the induction system which is communicated to the diaphragm 11 2 through the conduit 119, would be sufficient to cause fluid to flow into the region 11 Oa from the region 50a and thus to cause movement of the piston 51 fully to the left in Fig. 1, it being remembered that the filled volume of the regions 11 ova and 50a are substantially equal. Resistance to movement of the piston 51 by the spring 12 is not sufficient to prevent movement of the piston 51 under the influence of the pressure acting thereon in the region 50a created by the above described pressure conditions in the engine induction system.

In order that the spring 1 2 can effect such movement of the piston 51, the strength of the spring 1 2 is, in certain circumstances, such that there is an unacceptably high resistance to movement of the foot pedal 29 during normal operation of the device. Accordingly, a vacuum release valve is preferably provided in the conduit 11 9 extending to the induction system of the engine. One such vacuum release valve is illustrated diagrammatically in Fig. 4 and comprises a valve body 1 30 having a passage 1 31 connected to the conduit 11 9 and a further passage 1 32 connected to the induction system of the engine.

Slidably mounted within the body is a piston 1 33 sealed to the body by a suitable flexible diaphragm 1 35. Fixed to the piston 1 33 is a valve stem 1 34 which carries a valve member 1 36 arranged to connect the passage 1 30 alternately to be in communication with, or sealed from, a passage 1 37 extending to atmosphere and a passage 1 38 extending to the one side of the piston 1 33 which is connected to the induction system of the engine by the passage 1 32.

In use, as the pressure in the induction system of the engine rises to, for example, 6 p.s.i., the piston 1 33 is permitted to move downwardly under the bias of a spring 1 39 to disconnect the conduit 11 9 from the induction system of the engine and connect it to atmosphere so that the vacuum acting on the underside of the diaphragm 11 2 no longer opposes the action of the spring 1 2 so that the spring 1 2 can consequently be of less strength than would be the case if the vacuum release valve were not provided.

When the pressure in the induction system subsequently falls to below 6 p.s.i., then the low pressure is communicated to the one side of the piston 1 33 to cause it to move upwardly against the bias of the spring 1 39, thus disconnecting the underside of the diaphragm 11 2 from atmosphere and reconnecting it to the induction system of the engine.

It is preferred that a conventional vacuum release valve is provided in the conduit 11 9 between the device shown in Fig. 4 and the diaphragm 11 2 operative to prevent a pressure below 4 p.s.i., for example, to be applied to the diaphragm 11 2 to protect the diaphragm from undue stress.

Of course, in the circumstances referred to above, when the vehicle is proceeding along a level road at constant speed, the driver will have little or no pressure on the pedal 29 and so the spring 1 2 will move the piston 51 to the right to, or nearly to, a closed throttle position, thus drawing fluid from the region 40a to move the piston 41 to, or nearly to, the extreme right hand position, the diaphragm 11 2 remaining in its fully "down" position.

In addition, under such circumstances because the pressure in the engine induction system is relatively low, pressure communicated to the chamber 101 through the conduit 106 acts upon the skirt 102 and hence upon the valve member 80 to cause the valve member 80 to move upwardly to a first position against the effect of the coil compression spring 95, the strength of which is again arranged to permit such movement under such conditions. The valve member 80 therefore provides a first mode of the interconnection between the input and output means 26, 25.

When the valve member 80 is in said first position, the recess 83 thereof provides communication between the passages 76 and 77 in the sleeve 72 and also permits of passage of fluid through the passages 84 into the counterbore 85 and hence into the region 11 Oa of the chamber 110 through the oneway valve 87. Thus, the above described pressure in the chamber 50a is permitted to act upon the piston 51 due to passage of hydraulic fluid from the region 50a through the passage 61, passages 76, counterbore 85 and oneway valve 87 into the region 11 Oa.

Movement of fluid in the reverse direction is not permitted. In addition, fluid flows from the passage 61 through the passages 76, recess 83 and passages 77 into the passage 62 and hence into the region 40a of the chamber 40.

Therefore, in such first mode, if the driver of the vehicle presses further on the throttle pedal 29 to move the piston 41 further to the left, this will cause fluid to pass through the passages 61 and 62 and hence to move the piston 51 further to the left.

If the driver wishes to decelerate, he will lift his foot from the throttle pedal 29 which will permit the piston 41 to move to the right under the influence of pressure imposed ther eon via the valve 70 and passages 61 and 62 as a result of movement of the piston 51 to the right under the influence of the spring 1 2.

The one-way valve 66 need not operate in this first mode since fluid can pass via the valve 70.

If the pressure in the induction system rises, for example as a result of the vehicle encountering an upward incline so that the engine speed falls, this would tend to permit the diaphragm 11 2 to move upwardly in Fig.

1 when the pressure rises such that it would not counter the moment applied to the spindle 10 by the spring 1 2. But such movement which would close the throttle and hence cause the pressure to again fall, is inhibited due to the presence of the one-way valve 87.

The one-way valve 87 is provided so that when the driver requires maximum torque from the engine, for example to overtake, he depresses the pedal 29, to open the throttle, which causes the override valve 1 20 to open.

However, in the absence of one-way valve 87, flow would occur not only from region 50a, which opens the throttle, but also from region 11 or which would hamper, to some extent, movement of the piston 51 to the left to open the throttle. The one-way valve 87 is therefore provided to prevent such flow of fluid from the region 11 ova. It is to be noted that even with the provision of the one-way valve 87, the sudden opening of the throttle can cause the valve member 80 to move to the second mode position which allows flow of fluid from region 11 Os into region 40a via the slot 78 etc and the override valve 120, but such flow is comparatively small, however, and does not greatly interefere with the rapidity of throttle opening.

It is possible not to provide the one-way valve 87 but with consequent inhibition on the obtaining of maximum torque from the engine rapidly on depression of the pedal 29.

When the pressure in the engine induction system rises above a predetermined pressure, the effect of the spring 98 on the valve member 80 is such as to apply a force to the valve member 80 urging it downwardly which is greater than the force urging the valve member upwardly imposed by the application of induction pressure to the chamber 101, and thus the valve member 80 moves to an intermediate position in which the recess 83 is moved downwardly out of alignment with the passages 77 aligned with the passage 62, such intermediate position being shown in Fig. 3.Therefore, in this mode, herein referred to as a third mode, fluid from the region 50a of the chamber 50 can pass along the passage 61 and through the radial passages 76 into the recess 83 of the valve member 80 but cannot pass through the radial passages 77 into the passage 62 and thus cannot communicate with the region 40a of the chamber 40 associated with the throttle pedal. The fluid can however still pass through the radial passages 84 in the valve member into the counterbore 85 and pass the one-way valve 87 into the region 11 ova.

Therefore under such conditions, i.e. when the vehicle is slowing due to encountering an upward incline so that the induction pressure in the engine has risen, the natural tendency of the driver to press further on the throttle pedal to open the throttle valve is caused to have no effect on the opening of the throttle due to the inhibition of connection between the region 40a and the region 50a by virtue of the intermediate position of the valve member 80.

The piston 51 is therefore caused to remain in the same position as it occupied immediate prior to the valve member 90 moving into intermediate position and again, as mentioned above, a rise in pressure in the induction system does not cause the valve member 51 to move in a direction to close the throttle valve due to the one-way valve 87 inhibiting passage of fluid from the region 11 Oa to the region 50a which flow would otherwise occur due to the higher pressure permitting the diaphragm 11 2 to move upwardly under the influence of pressure imposed thereon from the piston 51 due to the spring 12.

The third mode is provided to permit the engine to provide an increased torque for hill climbing before the second mode, hereinafter to be described, permits the throttle to move to its closed position.

As the pressure in the induction system increases further due to continued slowing of the engine, the resultant of the forces imposed upon the valve member 80 by the spring 96 and the pressure applied to the skirt 102 causes the valve member 80 to move fully downwardly. In this mode, herein referred to as the second mode, the recess 83 of the valve member becomes aligned with the radial passages 76 and the radial slots 78 thereby providing a direct connection, bypassing the one-way valve 87 between the region 11 Oa of the chamber 110 and, via the passage 61, the region 50a of the chamber 50.Therefore, in this mode the spring 1 2 is permitted to rotate the throttle spindle 10 in the direction to close the throttle because the moment imposed on the spindle 10 by the spring 1 2 is greater than the moment imposed on the spindle 10 by the piston 51 because the diaphragm 11 2 is permitted to move upwardly resulting in flow of fluid from the region 11 Oa into the region 50a through the radial slots 78, recess 83, radial slots 76 and passage 61.

Thus, normal variations in the power requirements of the engine which cause a consequential rise and fall of the pressure in the engine induction system are reflected by variation in the force acting upon the diaphragm 11 2 and this tends to, providing that the piston 41 is held at a constant position.

Transfer of fluid between the regions 110 and SOs at a rate such that sudden variations in the engine induction system pressure are normally prevented, thereby saving fuel.

It is to be noted that in all modes a decrease in pressure in the induction system tends to cause fluid to be drawn from the region 50a into the region 11 ova via the oneway valve 87 irrespective of the position of the valve member 80 and hence the mode of the valve 70 and irrespective of the position of the throttle pedal 29. Thus, if at any time the pressure in the induction system falls below a predetermined pressure which creates a moment on the spindle 10 greater than that imposed by the spring 12, the throttle valve is moved towards its fully open position, assuming the pedal 29 is not moved, thereby permitting increase in engine speed.

If pressure on the pedal 29 is relaxed, the rate of fluid flow from the region 40a into region 50a via the one-way valves 65 and 66 is always greater than fluid flow from region 50a into region 11 ova due to the low pressure in the engine induction system. A situation can therefore occur, for example when driving steadily down a slight incline, whereby the region 11 Oa would be full and so further flow into region 11 Oa could not occur regardless of any further fall in engine induction system pressure.

The practical effect of the above is as follows. As the vehicle encounters resistance to travel at constant speed, for example an upwardly inclined hill, the vehicle speed and hence the engine speed drops. Initially the effect of the resultant increase in fluid pressure acting upon the diaphragm 11 2 is inhibited and hence there is no tendency for the throttle valve to be closed by this means. If the driver desires to increase the throttle valve opening by pressing further on the throttle pedal 29 this is permitted because at this stage the valve member 80 is in its fully up position, i.e. first mode, thereby providing communication between the regions 50a and 40a via the valve 70.

As the engine speed continues to fall and the pressure rises further, the valve member moves to its intermediate position, i.e. third mode, inhibiting communication between the regions 40a and 50a so that the first effect that the driver notices is that further pressing of the throttle pedal 1 9 has no effect on opening the throttle valve.

Of course, at this stage if the driver wishes to decelerate and lifts his foot from the throttle pedal, the piston 41 is permitted to move to the right under the influence of pressure imposed thereon by the piston 51 under the influence of the spring 12, by virtue of the one-way valves 65 and 66 which thus bypasses the valve 70.

In this "intermediate" mode, again a rise in pressure and its potential effect upon the diaphragm 11 2 is inhibited by the one-way valve 87.

As the pressure increases further due to further slowing of the engine, the valve member 80 moves to its fully down position, i.e.

second mode, to maintain inhibition of connection between the passages 40a and 50a so that further pressing of the throttle pedal has no effect, and in addition communication is permitted between the region 11 Oa and the region 50a thus permitting the piston 51 to move to the right under the influence of the piston 1 2 to close the throttle valve to decrease the pressure in the induction manifold.

In terms of unit fuel consumed per unit power output, a decrease in the engine induction system pressure does not necessary save fuel.

The device is designed to even out as much as is practicable torque output to within a band of optimum economy.

As the pressure in the induction system is reduced, the above described sequence of operations occurs in reverse and the vehicle is returned to a normal control mode of operation in which movement of the throttle pedal controls the throttle valve.

If at any time the driver wishes to override the fuel saving effect of the control device, he can press further on the throttle pedal to move to a position which effects opening the overriding valve described previously to permit direct connection between the regions 50a and 40a by-passing the valve 70 to permit the throttle valve to be fully opened independently of variation in pressure in the induction system.

Such further movement of the throttle pedal draws more fluid into the region 40a from the regions 11 ova and 50a so as to inhibit normal transfer of fluid between the regions 11 Oa to 50a.

The limit of movement of the piston 41 under the influence of the throttle pedal 29 past the position at which increased resistance to movement of the pedal 29 is encountered, is arranged so that, as mentioned heretofore the volume of the region 40a when the piston is in such extreme left-hand position in Fig. 1 is substantially equal to the combined maximum possible volumes of the regions 11 Oa and 50a. The result is that the piston 51 is moved fully to the left in Fig. 1 to give a potential for maximum acceleration of the engine regardless of variation in engine induction pressure or other engine factors which are used to control the valve 70.

Although in the above example, the input and output members 26, 25 respectively comprise mechanical means in the form of piston rods which are connected by flexible cables to the throttle pedal and throttle spindle, the input and output members may comprise another form of input and output means.

For example, movement of the pistons 41 and/or 51 may be communicated hydraulically, pneumatically or electrically to the throttle pedal and/or throttle spindle. Moreover, although diaphragms/pistons moving in chambers have been described as the means for moving the input and output members and to communicate the effect of induction pressure thereto, if desired, any other pressure sensitive transducer may be used.

Although in the above example the valve 70 has been described as being actuated directly as a result of pressure variations in the induction system, it, or other mode defining means, such as an appropriately programmed computer, may be operated by other mode control means such as mechanical, electrical or hydraulic means which are responsive to one or more variations in engine parameters such as induction system pressure, torque, r.p.m., temperature and the like.

The features disclosed in the foregoing description, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed results, or the class or group of substances or compositions, as appropriate, may, separately or any combination of such features, be utilized for realising the invention in diverse forms thereof.

Claims

1. A control means for a throttle valve of an induction system of an internal combustion engine comprising a manually operable member, a control device operable to interconnect the manually operable member and the throttle valve, the control device having an input means connected to the manually operable member, an output means connected to the throttle valve, first fluid pressure means operable to interconnect said output and input means, means responsive to the pressure, of a second fluid separate from the first fluid, in the induction system of the engine to control said first fluid pressure means to move the throttle valve in a direction to close the throttle valve to oppose increase in pressure in the induction system.

2. A control means according to claim 1 wherein the control device includes mode defining means to provide a plurality of desired modes of interconnection between the input and output means by the first fluid pressure means and mode control means responsive to an engine parameter to control the mode defining means to select a desired one of said modes.

3. A control means according to claim 3 wherein a first of said modes comprises interconnection of the manually operable member and throttle valve to permit of movement of the throttle valve in a direction to open and close the throttle in response to corresponding movement of the manually operable member, and a second mode comprises disconnection of the throttle valve and manually operable member to prevent opening of the throttle valve in response to movement of the manually operable member.

4. A control means according to claim 3 wherein the first mode further comprises providing connection between the throttle valve and said means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

5. A control means according to claim 4 wherein the first mode also inhibits movement of the throttle valve in a direction to close the throttle valve in consequence of increase in induction system pressure.

6. A control means according to any one of claims 3 to 5 wherein the second mode further comprises connection between the throttle valve and said means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in pressure in the induction system and to permit of movement of the throttle valve in the direction to close the throttle valve in consequence of increase of pressure in the induction system.

7. A control means according to any one of claims 3 to 6 wherein the modes include a third mode in which the throttle valve and manually operable member are disconnected to inhibit movement of the throttle valve in a direction to open or close the throttle valve in response to corresponding movement of the manually operable member and to connect the throttle valve to said means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

8. A control means according to claim 7 wherein the third mode also inhibits movement of the throttle valve in a direction to close the throttle valve in consequence of increase in induction system pressure.

9. A control means according to any one of claims 3 to 8 wherein the first mode comprises providing a flow path for said first fluid between the input and output means to permit of reciprocation of the output means in directions to open and close the throttle valve in response to reciprocation of the input means, and a flow path for the first fluid between the output member and the means to control the first fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

10. A control means according to claim 9 wherein the first mode also prevents flow of fluid in the reverse direction to thereby inhibit movement of the output member in a direction to close the throttle valve in consequence of increase in induction system pressure.

11. A control means according to any one of claims 3 to 10 wherein the second mode comprises providing no flow path for said first fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the first fluid between the output means and the means to control the first fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure, and to permit of movement of the output means in a direction to close the throttle valve in consequence of increase in induction system pressure.

1 2. A control means according to claim 7 or any one of claims 8 to 11 when dependent directly or indirectly on claim 7 wherein the third mode comprises providing no flow path for said first fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the first fluid between the output means and the means to control the first fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

1 3. A control means according to claim 1 2 wherein the third mode also prevents flow of fluid in the reverse direction to thereby inhibit movement of the output member in a direction to close the throttle valve in consequence of increase in induction system pressure.

14. A control means according to any one of the preceding claims wherein the input means comprises an input member connected to an input element, movable within an input chamber.

15. A control means according to any one of the preceding claims wherein the output means comprises an output member connected to an output element, movable within an output chamber.

16. A control means according to claim 1 5 when dependent on claim 14 wherein the or each element comprises a piston and/or a flexible skirt or diaphragm, having a part fixed relative to the chamber and a part fixed relative to the input or output element respectively.

1 7. A control means according to any one of the preceding claims wherein the means responsive to the pressure of a second fluid separate from the first fluid comprises an element movable in a chamber, the element dividing the chamber into two regions on opposite sides of the element, one region being in communication with said first fluid and the second region being in communication with the second fluid.

18. A control means according to claim 1 7 wherein the second region is connected by a conduit to the induction system of the engine so that the pressure of the fluid in the induction system of the engine is communicated to the second region.

1 9. A control means according to claim 18 wherein the second region is connected to the induction system of the engine via a pressure responsive valve which is operative when the pressure in the induction system rises above a predetermined pressure to disconnect the second region from the induction system.

20. A control means according to any one of the preceding claims wherein the first fluid is hydraulic fluid.

21. A control means according to any one of the preceding claims wherein the second fluid is induction fluid.

22. A control means according to claim 2 or any one of claims 3 to 21 when dependent on claim 2 wherein the mode defining means comprises a multiposition valve disposed in the flow path of fluid between the input and output means and the means responsive to the fluid pressure in the induction system.

23. A control means according to claim 22 when dependent on claim 3 or any one of claims 4 to 22, when directly or indirectly dependent on claim 3, wherein the valve is positionable in a first position corresponding to said first mode in which flow of fluid is permitted in either direction between the input and output means, and to permit flow of fluid from the output means to the means responsive to fluid pressure in the induction system.

24. A control means according to claim 23 wherein flow of fluid in the reverse direction is prevented.

25. A control means according to claim 23 or claim 24 when dependent on claim 6 or any one of claims 7 to 22, when dependent directly or indirectly on claim 6, wherein the valve is positionable in a second position, corresponding to said second mode, in which flow of fltiid between said input and output means is prevented, and flow of fluid in either direction between the output means and the means responsive to fluid pressure in the induction system is permitted.

26. A control means according to any one of claims 22 to 25 when dependent on claim 7 or any one of claims 8 to 22, when dependent directly or indirectly on claim 7, wherein the valve is positionable in a third mode in which flow of fluid between the input and output means is prevented and flow of fluid from the output means to the means responsive to fluid pressure in the induction system is permitted.

27. A control means according to claim 25 wherein flow of fluid in the reverse direction is prevented.

28. A control means according to any one of the preceding claims wherein the control means is provided with means to permit of movement of the throttle valve in a direction towards a closed position as a result of corresponding movement of the manually operable member independently of said means responsive to fluid pressure in the induction system and said mode defining means when present.

29. A control means according to any one of the preceding claims wherein the control means is provided with overriding means operable when the manually operable member is moved against an override pressure to cause said throttle valve to move in a direction towards an open position independently of said means responsive to fluid pressure in the induction system and said mode defining means when present.

30. A control means according to claim 29 wherein the overriding means comprises a valve to permit passage of fluid from the output means to the input means independently of the means responsive to pressure in the induction system and said mode defining means, when present, when the manually operable member is moved against said override pressure.

31. A control means according to claim 30 wherein the overriding valve is a pressure sensitive valve which remains closed when pressure acting thereon is below a predetermined value and opens when pressure acting therein is above a predetermined value, the pressure acting on the valve rising above said predetermined value as a result of movement of the manually operable member against said override pressure.

32. A control means for a throttle valve of an induction system of an internal combustion engine comprising a manually operable member, a control device operable to interconnect the manually operable member and the throttle valve, the control device having mode defining means to provide a plurality of desired modes of interconnection between the manually operable member and the throttle valve and mode control means responsive to an engine parameter to control said mode defining means to select a desired one of said modes.

33. A control means according to claim 32 wherein the control device has an input means connected to the manually operable member, an output means connected to the throttle valve, and fluid pressure means operable to interconnect said input and output means.

34. A control means according to claim 32 or claim 33 wherein a first of said modes comprises interconnection of the manually operable member and throttle valve to permit of movement of the throttle valve in a direction to open and close the throttle in response to corresponding movement of the manually operable member, and a second mode comprises disconnection of the throttle valve and manually operable member to prevent opening of the throttle valve in response to movement of the manually operable member.

35. A control means according to claim 34 wherein the first mode further comprises providing connection between the throttle valve and means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

36. A control means according to claim 35 wherein the first mode also inhibits movement of the throttle valve in a direction to close the throttle valve in consequence of increase in induction system pressure.

37. A control means according to any one of claims 34 to 36 wherein the second mode further comprises connection between the throttle valve and means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in pressure in the induction system and to permit of movement of the throttle valve in a direction to close the throttle valve in consequence of increase of pressure in the induction system.

38. A control means according to any one of claims 34 to 37 wherein the modes include a third mode in which the throttle valve and manually operable member are disconnected to inhibit reciprocation of the throttle valve in a direction to open or close the throttle valve in response to corresponding movement of the manually operable member and to connect the throttle valve to means responsive to fluid pressure in the induction system of the engine to permit of movement of the throttle valve in a direction to open the throttle valve in consequence of decrease in induction system pressure.

39. A control means according to claim 38 wherein the third mode also inhibits movement of the throttle valve in a direction to close the throttle valve in consequence of increase in induction system pressure.

40. A control means according to any one of claims 34 to 39 when directly or indirectly dependent on claim 32, wherein the first mode comprises providing a flow path for said fluid between the input and output means to permit of reciprocation of the output means in directions to open and close the throttle valve in response to reciprocation of the input member, and a flow path for the fluid between the output member and the means to control the fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

41. A control means according to claim 40 wherein the first mode also prevents flow of fluid in the reverse direction to thereby inhibit movement of the output member in a direction to close the throttle valve in consequence of increase in induction system pressure.

42. A control means according to any one of claims 34 to 41 when dependent directly or indirectly on claim 33 wherein the second mode may comprise providing no flow path for said fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the fluid between the output means and the means to control the fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure, and to permit of movement of the output means in a direction to close the throttle valve in consequence of increase in induction system pressure.

43. A control means according to claim 38, when directly or indirectly dependent on claim 33, or any one of claims 37 to 42, when dependent directly or indirectly on claim 38, when directly or indirectly dependent on claim 33, wherein the third mode comprises providing no flow path for said fluid between the input and output means to prevent movement of the output means in a direction to open the throttle valve in response to movement of the input means, and to provide a flow path for the fluid between the output means and the means to control the fluid pressure to permit of movement of the output means in a direction to open the throttle valve in consequence of decrease in induction system pressure.

44. A control means according to claim 43 wherein the third mode also prevents flow of fluid in the reverse direction to thereby inhibit movement of the output member in a direction to close the throttle valve in consequence of increase in induction system pressure.

45. A control means according to claim 33 or any one of claims 34 to 45 when directly or indirectly dependent on claim 33, wherein the input means comprises an input member connected to an input element, movable within an input chamber.

46. A control means according to claim 33 or any one of claims 34 to 45 when directly or indirectly dependent on claim 33, wherein the output means comprises an output member connected to an output element, movable within an output chamber.

47. A control means according to claim 46 when dependent on claim 45 wherein the or each element comprises a piston and/or a flexible skirt or diaphragm, having a part fixed relative to the chamber and a part fixed relative to the input or output element respectively.

48. A control means according to any one of claims 32 to 47 wherein the mode defining means comprises a multi-position valve disposed in the flow path of fluid between the input and output means and the means responsive to the fluid pressure in the induction system.

49. A control means according to claim 48 wherein the means responsive to the fluid pressure in the induction system is connected to the induction system via a pressure responsive valve which is operative when the pressure in the induction system rises above a predetermined pressure to disconnect the means from the induction system.

50. A control means according to claim 48 when dependent on claim 34 or any one of claims 35 to 48, when dependent directly or indirectly on claim 34, wherein the valve is positionable in a first position corresponding to said first mode in which flow of fluid is permitted in either direction between the input and output means, and to permit flow of fluid from the output means to the means responsive to fluid pressure in the induction system.

51. A control means according to claim 50 wherein flow of fluid in the reverse direction is prevented.

52. A control means according to claim 50 or claim 51 when dependent on claim 37 or any one of claims 38 to 48, when dependent directly or indirectly on claim 37, wherein the valve is positionable in a second position, corresponding to said second mode, in which flow of fluid between said input and output means is prevented, and flow of fluid in either direction between the output means and the means responsive to fluid pressure in the induction system is permitted.

53. A control means according to any one of claims 50 to 52 when dependent on claim 38 or any one of claims 39 to 48, when dependent directly or indirectly on claim 38, wherein the valve is positionable in a third mode in which flow of fluid between the input and output means is prevented, flow of fluid from the output means to the means responsive to fluid pressure in the induction system is permitted.

54. A control means according to claim 52 wherein flow of fluid in the reverse direction is prevented.

55. A control means according to any one of claims 32 to 54 wherein the control means is provided with means to permit of movement of the throttle valve in a direction towards a closed position as a result of corresponding movement of the manually operable member independently of said mode defining means.

56. A control means according to any one of claims 32 to 55 wherein the control means is provided with overriding means operable when the manually operable member is moved against an override pressure to cause said throttle valve to move in a direction towards an open position independently of said mode defining means.

57. A control means according to claim 56 when dependent directly or indirectly on claim 33 wherein the overriding means comprises a valve to permit passage of fluid from the output means to the input means independently of said mode defining means when the manually operable member is moved against said override pressure.

58. A control means according to claim 57 wherein the overriding valve is a pressure sensitive valve which remains closed when pressure acting thereon is below a predetermined value and opens when pressure acting therein is above a predetermined value, the pressure acting on the valve rising above said predetermined value as a result of movement of the manually operable member against said override pressure.

59. A control means substantially as herein described with reference to the accompanying drawings.

60. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.