GB2133079A - Regulating the temperature intake air drawn in by I.C. engines - Google Patents

Abstract

The unfiltered air pipe 17 of an air filter is divided into two conduits 21,22. A first control valve 32 has vanes 34,35 which are influenced by a thermostatically-controlled, vacuum- operated setting-motor (31), Fig. 1 (not shown). Vane 34 in first conduit 21 controls the through-aperture 23 in a heated air pipe 19, and vane 35 in second conduit 22 controls an unheated air pipe 18. A second control valve 50 disposed downstream of the vane 35 of the first control valve 32 is operated by a wax thermostat 54 exposed to the mixed air temperature. In each of its end positions, the valve 50 closes the unheated air pipe 18 or the through- aperture 24 in the heated air pipe 19, respectively. During idling and partial- loading operations, the thermostatically controlled vacuum regulation permits intake air to be supplied at a relatively high temperature. During full-load operation, the valve 50 regulates the supply of intake air at a lower temperature. The apparatus prevents full-load icing and facilitates rapid warm-up. <IMAGE>

Description

SPECIFICATION Apparatus for regulating the temperature of the intake air drawn-in by mixture-compressing internal combustion engines The present invention relates to apparatus for regulating the temperature of the intake air drawn-in by mixture-compressing internal combustion engine, including a first control valve which is pivotally mounted in an unfiltered air inlet passage of the intake pipe of an air filter and cooperates with a pneumatic actuator or settingmotor in order to close a heated air duct if a desired vacuum is not reached and simultaneously open an unheated air duct in an end position, and the control valve moves with the setting motor via a return spring extending through a control pressure chamber, whereby the control pressure chamber of the setting-motor is connected, via a control pressure pipe, to the portion of the induction port disposed downstream of a main throttle valve which is actuable as desired, and the control pressure pipe has a valve which is actuated in dependence on the temperature and contains a valve closure body actuated by a bimetallic device and, when the desired temperature is reached, the valve closure body moves into its open position and opens a connection with the filtered air chamber of the air filter, said apparatus also including a wax thermostat disposed in the intake pipe to control the supply of heated air when the intake air has temperatures below a pre-determined value.

Apparatus of such type serves to keep the temperature of the intake air within a predetermined range. The internal combustion engine needs to draw-in colder air only when the throttle valve is open, i.e. during full-load operating conditions, so that a higher degree admission and a higher performance output are achieved. In addition, some heated air is mixed with the intake air at low intake air temperatures to prevent fullload icing.

A regulating device or apparatus of the abovedescribed type is known from German Offenleggungsschrift No. 2 624210. It is provided with a single control valve which is acted upon by the pneumatic setting motor and the wax theremostat which is in the form of a movable stop member and is onlytxposed to cold air. The valve is actuated in dependence on temperature and is generally combined with a thermostaticallycontrolled relief valve which, during the warmingup period of the internal combustion engine, ensures that heated air is supplied during full-load operation and when the intake air temperature is low. This causes the internal combustion engine to be heated-up in an accelerated manner.

However, provision of the relief valve necessitates additional construction costs. The individual component parts of the relief valve are also relatively fragile, and particular care has to be taken during the manufacturing process. In addition, due to the narrow tolerances required, the processing of the valve component parts is complicated. There is also a risk that the operation of the valve will be impaired by dirt contamination.

The angular position of the control valve is determined, during full-load operation and at a low intake air temperature, by the wax thermostat which is only exposed to the unheated air, and such angular position depends on various criteria.

Thus, for example, the length and cross-section of the heated air duct, as well as the provision of the air filter in the motor chamber, all affect the extent to which the control valve needs to be kept open to achieve the desired mixed air temperature.

Some work is involved in determining the angular position. However, due to the unavoidable tolerances of the individual component parts, deviations from the required angular position may occur, and hence deviations from the desired mixed air temperature may also occur.

Compensation could only be achieved by special measures, for example, by adjusting the wax thermostat, but such means would increase construction costs. The heated air supply is limited by the pre-determined, maximum open position of the control valve, which position is invariable during operation of the internal combustion engine, so that the desired mixed air temperature is not reached in certain circumstances.

It is also known from German PS No.

1 526 662 to actuate a control valve exclusively by a wax thermostat exposed to the mixed air.

When the control valve is operated in such manner, the temperature of the intake air is kept within a pre-determined range. However, no provision is made for a regulating process adapted to the actual operating conditions of the internal combustion engine, and such process is not even possible.

The invention seeks to improve the regulating apparatus of the above-described type by simple means to ensure that intake air is supplied at the desired temperature for every operating condition of the internal combustion engine and also to prevent full-load icing.

According to the present invention there is provided an apparatus for regulating the temperature of the intake air drawn-in mixturecompressing internal combustion engines, including a first control valve which is pivotally mounted in an unfiltered air inlet passage of the intake pipe of an air filter and co-operates with a pneumatic actuator or setting-motor in order to close a heated air duct if a desired vacuum is not reached and simultaneously open an unheated air duct in an end position, and the control valve moves with the setting motor via a return spring extending through a control pressure chamber, whereby the control pressure chamber of the setting-motor is connected, via a control pressure pipe, to the portion of the induction port disposed downstream of a main throttle valve which is actuable as desired, and the control pressure pipe has a valve which is actuated in dependence on the temperature and contains a valve closure body actuated by a bimetallic device and, when the desired temperature is reached, the valve closure body moves into its open position and opens a connection with the filtered air chamber of the air filter, said apparatus also including a wax thermostat disposed in the intake pipe to control the supply of heated air when the intake air has temperatures below a pre-determined value, characterised in that the ulfiltered air inlet passage is longitudinally divided into a first conduit, which is provided with a first through-aperture extending to the heated air duct, and a second conduit which is connectable to the unheated air duct and is provided with a second through-aperture extending to the heated air duct; the first control valve has two vanes rigidly mounted beside each other on their common axle, the first vane controlling the first through-aperture in the heated air duct and the second vane controlling the unheated air duct; and a second control valve is disposed downstream of the second vane in the second conduit of the unfiltered air connection, said second control valve being pivotable from its one end position, which closes the unheated air duct, into its other end position, which closes the second through-aperture in the heat air duct, in opposition to the force of a return spring as the mixed air increases in temperature by means of a stationary wax thermostat disposed in the second conduit.

By dividing the unfiltered air duct into two conduits which have different types of air streams flowing therethrough, it is possible for two inexpensive regulating systems, known per se to be advantageously combined with each other. The thermostatically-controlled vacuum regulation system ensures that the internal combustion engine receives intake air at a relatively high temperature during idling and partial-load operations. During full-load operation, the second control valve, which is disposed in the second conduit and is actuable by means of a wax thermostat exposed to the mixed air temperature, governs the supply of intake air having a constant, but lower temperature. When the external temperature is low, therefore, the carburettor always receives heated air, and the risk of carburettor icing is thereby positively eliminated.

In addition, the operating temperature is rapidly reached in the warming-up period without an additional valve being required. The pre-requisite for maintaining the pre-determined intake air temperature is no longer a previously-set angular position of the control valve. Instead, the second control valve always assumes a position which is dependent on the mixed air temperature and may also, therefore, be fully open, for example.

The arrangement of the invention permits the first control valve to be manufactured in a simple manner, in that the vanes of the first control valve are mounted on their common axle at the same angular position relative to each other.

A more compact construction which therefore requires less space is produced when, in the case of a regulating apparatus having the axle of the first control valve disposed in the central plate of the unfiltered air connection, the first vane is mounted eccentrically, and the second valve is mounted in its longitudinal direction centrally on their common axle, and the vanes are also mounted thereon so that they are rotated through an angle relative to each other.

In order to ensure that sufficient mixed air flows around the wax thermostat, an air guidance means is provided in a further embodiment of the invention disposed in the second conduit, said air guidance means directing the mixed air stream onto the wax thermostat and at least partially covering the wax thermostat.

The invention will be described further, by way of example, with reference to the accompanying drawings which illustrate schematically two embodiments of the invention and in which: Fig. 1 illustrates an air filter which is connected to the induction manifold or port of an internal combustion engine and is provided with the regulating apparatus according to the invention; Fig. 2 is an enlarged, sectional view through part of the regulating apparatus, taken along the line 2-2 of Fig. 1; and Fig. 3 is an enlarged view of a different embodiment of the regulating apparatus.

An internal combustion engine (not shown) has an induction port or manifold 10 which carries a carburettor 11 having a main butterfly or throttle valve 12 which is actuable as desired. An air filter 1 3 is mounted on the carburettor 11, and has an annular filter insert 1 5 and an inlet 16; said filter insert 1 5 enclosing a filtered air chamber 14 and, in use, having air flowing radially therethrough from the outside to the inside. The inlet 1 6 includes a connection pipe 1 7 for unfiltered air and into which pipe there leads a duct 1 8 for unheated air and a duct 1 9 for heated air. The heated air is supplied from the vicinity of the exhaust pipe of the internal combustion engine through a flexible pipe (not shown).

The unfiltered air connection pipe 1 7 is divided longitudinally by means of a dividing wall 20, into a first conduit 21 and a second conduit 22. The first conduit 21 has a first through-aperture 23 extending to the heated air duct 1 9. The second conduit 22 is connected to the unheated air duct 18 and has a second through-aperture 24 extending to the hot air duct 1 9.

The drive rod 30 of a pneumatic setting device or motor 31 engages with a first control valve 32 which is pivotally disposed in the unfiltered air connection pipe 17 and is provided with a pivotal axle 33. In the embodiment illustrated in Figs. 1 and 2, the control valve 32 is provided with two vanes, 34, 35 rigidly mounted beside each other on their common axle 33 and at the same angular position relative to each other. The setting-motor 31 is provided with a rubber diaphragm 36 and a restoring or return spring 39 which extends through a control pressure chamber 37, and the setting-motor 31 is connected to the induction manifold 10 of the internal combustion engine via a control pressure pipe 40 downstream of the main throttle valve 1 2 of the carburettor 11.The pneumatic setting-motor 31 causes the first control valve 32 to be pivotable, in opposition to the force of the return spring 39, from its end position (shown by solid lines), in which the first vane 34 closes the first through-aperture 23 in the heated air duct 19 and the second vane 35 simultaneously opens the unheated air duct 18, into its other end position (shown by dotted lines) in which the second vane 35 closes the unheated air duct 18 and the first vane 34 opens the first through-aperture 23 in the heated air duct 1 9.

The control pressure pipe 40 contains an air inlet valve in the form of a valve 45 which is operated in dependence on temperature. One end of a bimetallic strip 47 is secured to the valve housing 46, and the free end of said bimetallic strip 47 carries a valve body 48. When the desired temperature is reached, the valve body 48 opens a connection 49 with the filter air chamber 14 of the air filter 13. The temperature within the air filter 13 is transmitted from the filtered air chamber 14 to the bimetallic strip 47 through an aperture (not shown) which is small compared with the connection 49 and permits, in known manner, an air stream to pass from the filtered air chamber 14 to the interior of the valve housing 46, such air stream only affecting the pressure ratios to an insignificant extent.

A second control valve 50 is disposed in the second conduit 22 of the unfiltered air connection pipe 1 7 downstream of the second vane 35 of the first control valve 32 and is eccentrically mounted with its axle 51 in the outer wall of the unfiltered air connection pipe 17 and in the dividing wall 20.

A drive rod 53 is pivotally connected to a pivotal lever 52, and a wax thermostat 54 acts upon said drive rod 53. The wax thermostat 54 is secured, in known manner, in the second conduit 22 of the unfiltered air connection pipe 1 7 at a location where the drawn-in air flows around the wax thermostat 54. In order to ensure that sufficient air flows around the wax thermostat 54, an air guidance means 55 is disposed in the second conduit 22, said air guidance means 55 deflecting the mixed air stream onto the wax thermostat 54 and partially covering the wax thermostat 54. A platelike member 56 is securedly connected to the drive rod 53 and supports a return spring 57 which is in the form of a compression spring and surrounds the drive rod 53.The other end of the return spring 57 abuts against a wall portion of the unfiitered air connection pipe 17, said wall portion having the drive rod 53 slidably extending therethrough. The return spring 57 keeps the drive rod 53 in frictional connection with the thermostat 54. In addition, an overload spring (not shown) surrounds the end of the drive rod 53 facing the pivotal lever 52.

During operation of the internal combustion engine, a vacuum subsists in the entire induction system, and such vacuum is at its highest in the induction manifold 10 and decreases in the direction of the unheated air duct 1 8. The high vacuum of the induction manifold 10 is transmitted, through the control pressure pipe 40, to the control pressure chamber 37 of the pneumatic setting-motor 31 above the rubber diaphragm 36. It exerts there a force for adjusting the first control valve 32, depending on the vacuum pressure subsisting on either side of the rubber diaphragm and depending on the diaphragm surface.In addition, air within the air filter 13 may have a substantial influence on the pressure ratios in the control pipe 40, since such air can enter the valves 45, operated in dependence upon temperature, through the connection 49 and can therefore enter the control pressure pipe 40 when the bimetallic strip 47 has been upwardly bent above a pre-determined temperature and the valve body 48 has opened the connection 49.

When the main throttle valve 12 is closed, during idling operation, for example, the vacuum in the inlet manifold 10 is particularly high. When the drawn-in air has a correspondingly low temperature and the connection 49 is closed, the high vacuum existing in the pneumatic settingmotor 31 above the rubber diaphragm 36 can pivot the first control valve 32, in opposition to the force of the return spring 39, into the position shown by dotted lines in Fig. 1, wherein the first vane 34 has opened the first through-aperture 23 in the heated air pipe 19 and the second vane 35 closes the unheated air pipe 18.

The air enters the unfiltered air connection pipe 17 from the heated air pipe 19 through the first conduit 21 and, after traversing the filter insert 15, enters the filtered chamber 14 and hence influences the valve 45, actuated in dependence on temperature; if the air has a temperature which exceeds a pre-determined value, the bimetallic strip 47 begins to bend upwardly. The valve closure body 48 releases the connection 49 to the filter air chamber 14 and, in addition, filtered air can enter the control pressure pipe 40 and reduce the vacuum there.As a consequence thereof, the first control valve 32 pivots so far away from its end position, which closes the unheated air pipe 18, until the mixed air has the temperature, for example 400 Celsius, at which an equilibrium state is set between the force of the return spring 39, on the one hand, and the forces which occur on the rubber diaphragm 36 of the pneumatic setting-motor 31 and on the first control valve 32, on the other hand.

As the main throttle valve 12 of the carburettor 11 increasingly opens, the vacuum in the intake conduit 10 decreases. When the main throttle valve 12 is completely open, the vacuum in the induction manifold 10, and hence in the control pressure chamber 37 of the pneumatic settingmotor 31, is then so low that it is no longer adequate to overcome the force of the return spring 39. The first through-aperture 23 in the heated air pipe 1 9 is then closed in each case and the unheated air pipe 18 is open.If the second control valve 50 has also closed the second throughaperture 24 in the heated air pipe 19, the internal combustion engine only receives air through the unheated air pipe 1 8. The lower temperature of the intake air, produced by closure of the heated air pipe 1 9, causes the engine to have a higher degree of admission, so that better performance is achieved even during full-load operation.

If, however, the air drawn-in through the unheated air pipe 1 8 during full-load operation is below the pre-determined temperature of 200 Celsius, for example, the wax thermostat 54 displaces the drive rod 53 by means of the return spring 57 in such a manner that the control valve 50 pivots so far out of its one end position, which is shown by solid lines in Fig. 1 and closes the second through-aperture 24 in the heated air pipe 19, towards the other end position shown by dash-dotted lines in Fig. 1 and thereby permits the supply of heated air, until the pre-determined temperature of the drawn-in air is reached again.

During full-load operation, therefore, the second control valve 50 disposed in the second conduit 22 of the unfiltered air connection pipe 17 govems the supply of intake air with a constant, but lower temperature. Accordingly, even with a very low external temperature, the carburettor always received heated air, thereby completely eliminating the risk of carburettor icing. In addition, in the warming up period of the internal combustion engine during full-load operation, when the pneumatic setting-motor 31 pivots the first control valve 32 into the position shown by solid lines in Fig. 1, an intake air temperature is governed by the wax thermostat 54 and set so that the internal combustion engine rapidly reaches its operating temperature.

In the regulating apparatus shown in Fig. 3, the suction pipe 60 has an unfiltered air connection 62 into which an unheated air pipe 63 and a heated air pipe 64 discharge. The unfiltered air inlet 61 is longitudinally divided, by means of a dividing wall 62, into a first conduit and a second conduit. The first conduit has a first throughaperture 65 extending to the heated air pipe 64.

The second conduit is connected to the unheated air pipe 63 and has a second through-aperture 66 extending to the heated air pipe 64.

A first control valve 70, having a pivotal axle 71, is disposed in the unfiltered air connection 61.

The drive rod 72 of a pneumatic setting-motor 73 engages with the first control valve 70. The pivotal axle 71 of the first control valve 70 is disposed in the central plane of the unfiltered air connection 61 and extends through the walls of the unfiltered air connection 61 and through the dividing wall 62. The first control valve 70 has a first vane 74 which is eccentrically secured on the pivotal axle 71. Asecond vane 75 is mounted in its longitudinal direction centrally on the common axle 71 so that it is rotated through an angle relative to the vane 74.

Like the second control valve 50 illustrated in Figs. 1 and 2, a second control valve 77 is driven by a wax thermostat and is disposed in the second conduit of the unfiltered air connection 61. In terms of construction, arrangement and operation, this part of the regulating apparatus is largely identical to the part of the device described with reference to Figs. 1 and 2. A more compact structural form can be achieved for the regulating apparatus by providing the first control valve 70 in the central plane of the unfiltered air connection 61 with the structure and mounting illustrated in Fig. 3.

Claims (5)

1. Apparatus for regulating the temperature of the intake air drawn-in by mixture-compressing internal combustion engines, including a first control valve (32, 70) which is pivotally mounted in an unfiltered air inlet passage (1 7 or 61) of the intake pipe of an air filter and co-operates with a pneumatic actuator or setting-motor (31) in order to close a heated air duct (19, 64) if a desired vacuum is not reached and simultaneously open an unheated air duct (18, 63) in an end position, and the control valve (32, 70) moves with the setting-motor (31) via a return spring (39) extending through a control pressure chamber (37), whereby the control pressure chamber (37) of the setting-motor (31) is connected, via a control pressure pipe (40), to the portion of the induction port (10) disposed downstream of a main throttle valve (12) which is actuable as desired, and the control pressure pipe (40) has a valve (45) which is actuated in dependence on the temperature and contains a valve closure body (48) actuated by a bimetallic device (47) and, when the desired temperature is reached, the valve closure body (48) mlves into its open position and opens a connection (49) with the filtered air chamber (14) of the air filter (13), said apparatus also including a wax thermostat (54) disposed in the intake pipe (17) to control the supply of heated air when the intake air has temperatures below a pre-determined value, characterised in that the unfiltered air inlet passage (17 or 61, respectively) is longitudinally divided into a first conduit (21), which is provided with a first through-aperture (23 or 65, respectively) extending to the heated air duct (19 or 64, respectively) and a second conduit (22), which is connectable to the unheated air duct (1 8 or 63, respectively) and is provided with a second through-aperture (24 or 66, respectively) extending to the heated air duct (1 9 or 64, respectively); the first control valve (32 or 70, respectively) has two vanes (34, 35 or 74, 75, respectively) rigidly mounted beside each other on their common axle (33 or 71, respectively), the first vane (34 or 74, respectively) controlling the first through-aperture (23 or 65, respectively) in the heated air duct (19 or 64, respectively) and the second vane (35 or 75, respectively) controlling the unheated air duct (18 of 63, respectively); and a second control valve (50 or 77, respectively) is disposed downstream of the second vane (35 or 75, respectively) in the second conduit (22) of the unfiltered air connection (17 or 61 respectively), said second control valve (50 or 77, respectively) being pivotable from its one end position, which closes the unheated air duct (1 8 or 63, respectively), into its other end position, which closes the second through-aperture (24 or 66, respectively) in the heated air duct (1 9 or 64, respectively), in opposition to the force of a return spring (57) as the mixed air increases in temperature by means of a stationary wax thermostat (54) disposed in the scond conduit (22).

2. Apparatus as claimed in claim 1, in which the vanes (34, 35) of the first control valve (32) are mounted on their common axle (33) at the same angular position relative to each other.

3. Apparatus as claimed in claim 1, in which the vanes (74, 75) of the first control valve (70) are secured to pivot on the common axle (71) so that they are rotated through an angle relative to each other.

4. Apparatus as claimed in claims 1 to 3 having the axle of the first control valve disposed in the central plane of the unfiltered air connection, characterised in that the first vane (34 or 74, respectively) is mounted eccentrically, and the second vane (35 or 75, respectively) is mounted in its longitudinal direction centrally on their common axle (33 or 71, respectively).

5. Apparatus claimed in claims 1 to 4, in which an air guidance means (55) is disposed in the second conduit (22), said air guidance means (55) steering the mixed air stream onto the wax thermostat (54) and at least partially covering the wax thermostat (54).