WO2012028914A1

WO2012028914A1 - A thermostat valve

Info

Publication number: WO2012028914A1
Application number: PCT/IB2011/001846
Authority: WO
Inventors: Giorgio Girondi
Original assignee: Ufi Filters S.P.A.
Priority date: 2010-09-01
Filing date: 2011-08-09
Publication date: 2012-03-08
Also published as: ITRE20100067A1

Abstract

A valve (1 ) comprising: a first body (2) provided with an inlet (22) for a fluid, a first outlet (23) and a second outlet (24) for the fluid; a heat-sensitive unit (3) arranged in the first body (2) and comprising a casing (31 ) destined to be struck by the fluid entering from the first inlet (22) and a mobile stem (32) destined to be activated by heat dilation of a material contained in the casing (31 ); and an obturator (4) associated to the stem (32) for selective opening/closing of the first outlet (23) and the second outlet (24); further comprising a second body (6) provided with an inlet hole (62) for the fluid, communicating with the inlet (22) of the first body (2), a first outlet hole (63) and a second outlet hole (64) of the fluid; the first body (2) being associated to the second body (6) such as to be mobile between a first position, in which the first outlet (23) is in communication with the first outlet hole (63) and the second outlet (24) is in communication with the second outlet hole (64), and a second position, in which the first outlet (23) and the second outlet (24) are both in communication with the second outlet hole (64); the first body (2) being arranged such as to be pushed by the fluid pressure entering by the inlet hole (62) towards the second position, in contrast with thrust means (7) destined to push the first body (2) into the first position.

Description

A THERMOSTAT VALVE

Technical Field

The present invention relates to a thermostat valve, in particular a thermostat valve for lubricating circuits of internal combustion engines.

Prior Art

An advantageous application of this thermostat valve is in internal combustion engines equipped with a heat exchanger between the lubricant oil of the lubricating circuit and the engine's coolant fluid, such as for example internal combustion engines of many motor vehicles, heavy duty vehicles and the like.

For these applications, the prior art comprises thermostat valves which are integrated into the body of the filter of the lubricating oil, which also comprises the heat exchanger and the relative connecting channels.

These valves are used to pass the flow of lubricating oil through the heat exchanger when the oil is below a determined minimum temperature, in order to direct the oil towards the engine when the oil is at an intermediate temperature between the minimum temperature and a determined maximum temperature, and to pass the oil once more through the heat exchanger when the temperature of the oil exceeds a maximum temperature.

Between these functioning stages there can also be transitory stages, in which the lubricating oil is sent partly towards the heat exchanger and towards the engine.

A first type of thermostat valve of known type comprises a body provided with an inlet for the oil which is connected to the engine lubricating circuit, and a first and a second outlet which are respectively connected to the exchanger and to a by-pass line of the exchanger. The valve is further provided with a heat-sensitive unit which comprises a casing arranged internally of the body, such that it can be struck by the oil in inlet, and a mobile stem projecting from the casing.

The casing contains a thermally dilatable material, for example wax, which is destined to expand and move the stem from a retracted position towards and extracted position as a consequence of the increase in the oil temperature in inlet.

The thermostat valve finally comprises an obturator associated to the stem for controlling closing and opening of the first and second outlets, and elastic means which press on the obturator to return the stem to the retracted position.

In this first type of thermostat valve of known type, the opening or closing of the first and second outlets therefore depends exclusively on the temperature of the oil which operates on the heat-sensitive unit.

This characteristic can however be a drawback, as it has been found that overpressures in the lubricating circuit can damage the thermostat valve and thus compromise its functioning.

To obviate this drawback, a second type of thermostat valve has been proposed, the obturator of which is associated to a further elastic element which, should an overpressure occur in the lubrication circuit, enables the obturator to perform an extra-run, thanks to which the oil reaching the thermostat valve is sent directly to the engine, without passing through the heat exchanger.

This extra-run can however take place only when the oil in the lubrication circuit is at high temperatures, i.e. when the stem of the heat-sensitive unit is in the completely extracted position.

Disclosure of the Invention An aim of the present invention is to realise a thermostat valve which enables deviation of the oil flow in lubricating circuits of internal combustion engines both according to the temperature and the pressure of the oil, in any use conditions.

A further aim is to attain the above-mentioned objective with a solution that is simple, rational and relatively inexpensive.

These aims are attained by the characteristics of the invention reported in the independent claims. The dependent claims delineate preferred and/or particularly advantageous aspects of the invention.

In particular, an embodiment of the invention makes available a valve which comprises: a first body provided with an inlet for a fluid, a first outlet and a second outlet for the fluid; a heat-sensitive unit arranged in the first body and comprising a covering destined to be struck by the fluid entering from the inlet and a mobile stem destined to be activated by the heat dilation of a material contained in the covering; and an obturator associated to the stem for selectively opening/closing the first outlet and second outlet.

According to the invention, the valve comprises a second body provided with an inlet hole for the fluid, communicating with the inlet of the first body, a first outlet hole and a second outlet hole for the fluid.

The first body is associated to the second body such as to be mobile between a first position, in which the first outlet is in communication with the first outlet hole and the second outlet is in communication with the second outlet hole, and a second position, in which the first outlet and the second outlet are both in communication with the second outlet hole.

The first body is further arranged such as to be pushed by the fluid pressure entering from the inlet hole towards the second position, in contrast with thrust means destined to push the first body into the first position. Thanks to a valve of this type, the constituent elements of the valve are not damaged by an eventual overpressure of the fluid internally of the lubricating circuit, whether the overpressure occurs at low temperatures or at high temperatures, thus safeguarding the functioning of the valve at the same time.

In a particularly simple and economical embodiment of the invention, the thrust means comprise elastic means, for example a spring.

In a preferred aspect, the first body exhibits an elongate shape with a development prevalently along a longitudinal axis thereof, the inlet being situated at an end of the first body, the first outlet and the second outlet being situated on a lateral wall of the first body.

The second body comprises a cavity destined to house the first body, such as to enable the first body to move between the first and the second position sliding in the direction of the longitudinal axis thereof, the first outlet hole and the second outlet hole being situated at a wall of the second body which laterally delimits the cavity.

These specifications enable realising a thermostat valve exhibiting contained dimensions, which is particularly compact and functional for the aims thereof, and for the use thereof in lubricating circuits in motor vehicle applications, heavy duty applications and the like.

In a further preferred aspect, the cavity is at least partially delimited by an annular portion of the second body, which is coaxially inserted, substantially snugly, on the first body, and is destined to separate the first outlet hole from the second outlet hole.

This specification enables isolating the two outlet holes with a consequent possibility of varying the flow of the fluid selectively towards one or the other of the outlet holes. In a particularly simple and economical embodiment of the invention, the stem of the heat-sensitive unit is mobile between at least a retracted position and progressively extracted positions, by effect of the increase in the temperature of the fluid entering from the inlet, while the valve comprises elastic means destined to push the stem towards the retracted position.

This specification enables a regulation of the opening of the first and second outlet as a function of the temperature of the fluid entering the inlet of the first body and consequently the distribution of the fluid itself.

A further aspect of the invention is that the obturator is slidably associated internally of the first body and is provided with first, a second and a third annular tract, axially superposed and distanced from one another by interspaces, which are destined to cooperate with the first outlet and the second outlet for the opening, the closing and the partial opening thereof. Further, the obturator comprises a through-cavity developing longitudinally with respect to the longitudinal axis of the first body, which through-cavity is such as to cross at least the first annular tract and the second annular tract for the passage of fluid from the inlet of the first body to the interspaces.

These specifications enable realisation of a thermostat valve having various functioning stages and enabling flowpaths of fluid in various configurations, both transitory and operating, such as to optimise the functioning cycle of the lubrication circuit.

A further embodiment of the invention provides a lubrication circuit for circulation of lubricant fluid in an internal combustion engine, which comprises a thermostat valve, as described above, the inlet hole of which is in communication with an injection branch of the lubricating oil, the first outlet hole is in communication with the engine via a heat exchanger, and the second outlet hole is in communication with the engine via a by-pass branch of the heat exchanger. A further embodiment of the invention provides a control method of the lubricant fluid flow in lubricating circuits of internal combustion engines provided with a heat exchanger, comprising the stage of guiding the lubricant fluid to by-pass the heat exchanger when the pressure of the lubricant fluid in the circuit exceeds at least a threshold value, independently of the temperature of the lubricant fluid.

This solution improves the flow control of lubricant fluid in the circuit.

Further characteristics and advantages of the invention will emerge from a reading of the following description provided by way of non-limiting example, with the aid of the figures illustrated in the accompanying tables of drawings. Brief Description of the Drawings

Figure 1 is a view in lateral elevation of a thermostat valve of the invention; figure 2 is section ll-ll of figure 1 with the thermostat valve in a first functioning configuration;

figures from 3 to 6 are figure 2 shown with the thermostat valve in four different functioning configurations.

Figure 7 is a schematic view of a lubricant circuit of an internal combustion engine, according to the invention.

Best Mode for Carrying out the Invention

With particular reference to the accompanying figures of the drawings, 1 denotes in its entirety a thermostat valve, in particular a thermostat valve for lubricating circuits of internal combustion engines, for example of motor vehicles, heavy duty vehicles and the like.

The thermostat valve 1 comprises a first hollow body 2, which exhibits an elongate shape with a prevalent development along a longitudinal axis L and a substantially constant transversal section along the longitudinal axis L. In the illustrated embodiment, the first body 2 is substantially cylindrical, an end 21 thereof is closed while the opposite end is open such as to define a substantially axial inlet 22 for the fluid.

The first body 2 comprises a first outlet 23 and a second outlet 24 for the fluid.

The first outlet 23 and the second outlet 24 are realised on the lateral wall of the first body 2, at a substantially median zone.

The first outlet 23 is situated in an axially proximal position with respect to the inlet 22 and the second outlet 24 is situated in an axially distal position with respect to the inlet 22; thus they are separated from one another in the direction defined by the longitudinal axis L.

A heat-sensitive unit 3 (see figure 2) is housed coaxially internally of the first body 2, which comprises a casing 31 destined to be struck by the fluid entering from the inlet 22, and a stem 32 projecting from and axially slidable with respect to the casing 31.

A heat-dilatable material is contained internally of the casing 31 , i.e. having a high coefficient of heat dilation, for example wax.

For this reason, the heat-sensitive unit 3 is conventionally known as a thermowax valve.

In this way, the stem 32 can slide between a retracted position in the casing 31 and progressively extracted positions, activated by the heat dilation of the thermally-dilatable material by effect of an increase in the temperature of the fluid entering the inlet 22.

The thermostat valve 1 further comprises a slide valve 4 slidably associated internally of the first body 2, which is fixed to the free end of the stem 32 in order to enable selective opening/closing of the first outlet 23 and the second outlet 24. The thermostat valve 1 comprises first elastic means, in the example a first compression helix spring 5, destined to press the stem 32 towards the retracted position thereof.

In particular, the first spring 5 is interposed between the closed end 21 of the first body 2 and the obturator 4.

The obturator 4 comprises a first, a second and a third annular tract, respectively 41 , 42 and 43, axially superposed and distanced from one another by two interspaces.

The first, the second and the third annular tracts 41 , 42 and 43, are three occluding elements, substantially in dragging contact with the internal wall of the first body 2, and are such as to cooperate with the first outlet and the second outlet, respectively 23 and 24, for closing the selective opening thereof.

The obturator 4 comprises a through-cavity 44 developing longitudinally with respect to the longitudinal axis L and being such as to cross the first two annular tracts 41 and 42 in order to enable passage of the fluid from the inlet 22 towards the two interspaces which are defined between the annular tracts. The third annular tract 43 is substantially dish-conformed such as to rest on the first spring 5, and exhibits holes which are prolongations of the cavity 44 for passage of the fluid.

In particular for the objectives of the present invention, the thermostat valve 1 comprises a second body 6, having a generally cylindrical external shape, which comprises an internal cavity 65 that is elongate and substantially cylindrical and substantially coaxial.

The cavity 65 exhibits a closed end 61 and an opposite substantially open end destined to define an inlet hole 62 which enables fluid flow in a substantially axial direction with respect to the cavity 65. The second body 6 further comprises a first outlet hole 63 and a second outlet hole 64 for the fluid, which are realised on the lateral wall delimiting the cavity 65, in a substantially median zone comprised between the closed end 61 and the inlet hole 62.

In particular, the first outlet hole 63 is situated in a proximal position to the inlet hole 62, while the second outlet hole 64 is situated in a distal position to the inlet hole 62, such that the outlet holes 63 and 64 are distanced from one another in the direction of the longitudinal axis of the cavity 65.

The first body 2 is coaxially housed internally of the cavity 65, in such a way that the closed end 21 faces the closed end 61 of the cavity 65, while the inlet 22 is constantly in communication with the inlet hole 62.

Thanks to this coupling, the first body 2 is destined to slide internally of the cavity 65, in the direction of the longitudinal axis L thereof, from a first position (illustrated in figures from 2 to 4), in which the first outlet 23 is in communication with the first outlet hole 63 and the second outlet 24 is in communication with the second outlet hole 64, to a second position (illustrated in figures 5 and 6), in which the first outlet 23 and the second outlet 24 are both in communication with the second outlet hole 64, while the first outlet hole 63 is completely closed.

In particular, the displacement of the first body 2 from the first to the second position occurs thanks to the push exerted by the fluid entering from the inlet hole 62, which acts in contrast to thrust means which press in the direction of returning the first body 2 into the first position.

In order to obtain this effect, the first body 2 comprises a holed cover 25, which is fixed at the inlet 22 and is destined to define a surface 26, perpendicular with respect to the longitudinal axis L, on which the pressure of the fluid entering the inlet hole 62 acts. The thrust means comprise elastic means, in the example a second helix compression spring 7, which is interposed between the closed end 21 of the first body 2 and the closed end 61 of the second body 6, such as to exert a contrasting force to the pressure of the fluid.

Finally an abutting element 66 is fixed to the second body 6 at the inlet hole 62, such as to function as an endrun for the first body 2.

In more detail, the second body 6 comprises an annular portion 81 interposed between the first outlet hole 63 and the second outlet hole 64, which is substantially snugly inserted on the first body 2 in order to realise a seal.

The annular portion 81 is such as to engage an intermediate zone between the first outlet 23 and the second outlet 24 of the first body 2 when the first body 2 is in the first position (see figures from 2 to 4), while it is such as to be arranged upstream of the first outlet 23 and the second outlet 24 with respect to the inlet 22, when the first body 2 is in the second position (see figures 5 and 6).

The annular portion 81 is lip-shaped, such as to be in dragging contact with the first body 2, leaving a narrow space 82 destined to set the second outlet hole 64 in communication with the first outlet 23, when the first body 2 is in the second position (see figures 5 and 6).

The second body 6 is destined to be housed internally of a special housing seating (not illustrated), which is generally realised in a component of the fluid circulation circuit in which the thermostat valve 1 is inserted, and comprises seal organs 9, which guarantee separation between the inlet hole 62, the first outlet hole 63 and the second outlet hole 64, when the second body 6 is housed in the seating. In this way the valve 1 can be mounted and demounted to and from the fluid circulation circuit independently of the device to which it is coupled. As illustrated in figure 7, the thermostat valve 1 is preferably inserted in a lubricating circuit, denoted in its entirety by 100, of an internal combustion engine 101.

An appropriate lubricant oil circulates in the lubricating circuit 100.

The inlet hole 62 of the second body 6, and therefore also the inlet 22 of the first body 2, is in communication with an injection branch 102 of the lubricant oil.

The first outlet hole 63 is in communication with the engine 101 via a heat- exchanger 103, while the second outlet hole 64 is in communication with the engine 101 through a by-pass branch 104 destined to by-pass the heat exchanger 103.

The circuit 100 further comprises a pump 105 for circulation of the lubricant oil, which is arranged upstream of the thermostat valve 1 , and a filter unit 106 for filtering the oil, arranged on the injection branch 102 downstream of the pump 105 and upstream of the thermostat valve 1.

In an embodiment, the above-mentioned housing seating of the thermostat valve 1 can be afforded in the body of the filter unit 106, which can also be provided with connecting channelling for connecting to the injection branch 102, the by-pass branch 104 and the heat exchanger 103.

In an advantageous aspect, the heat exchanger 103 can also be defined as being integral with the filter unit 106, obtaining a lubricating circuit 100 that is particularly compact and functional.

The functioning of the thermostat valve 1 in the lubricating circuit 100 is the following.

From the injection branch 102 of the lubrication circuit 100, the oil enters the thermostat valve 1 through the inlet hole 62 and the inlet 22.

According to the pressure and the temperature of the lubricant oil at the inlet, the thermostat valve 1 can assume different operating configurations. In particular, as long as the thrust exerted by the second spring 7 on the first body 2 is greater than the force that the oil pressure exerts on the holed cover 25, the first body 2 remains in the first position with respect to the second body 6 (see figures from 2 to 4), in which the first outlet 23 is in communication with the first outlet hole 63 and the second hole 24 is in communication with the second outlet hole 64.

In the first configuration, the thermostat valve 1 is controlled only by the temperature of the lubricant oil, in the way described herein below.

If the temperature of the lubricant oil is lower than a predetermined minimum temperature, the stem 32 of the heat-sensitive unit 3 remains in the completely retracted position, illustrated in figure 2.

In this way, the first outlet 23 is completely open, while the second outlet 24 is completely closed by the third annular tract 43 of the obturator 4, such that the flow of oil is entirely conveyed to the heat exchanger 103.

When the oil entering the thermostat valve 1 exceeds the minimum temperature, the stem 32 begins to exit the casing 31 , causing the obturator 4 to slide in the first body 2, such that the first annular tract 41 partially closes the first outlet 23 while the second annular tract 42 partially opens the second outlet 24, sending the oil flow both towards the heat exchanger 103 and the by-pass branch 104.

When the oil temperature exceeds a predetermined intermediate temperature, which is greater than the minimum temperature, the stem 32 moves into the partially extracted position illustrated in figure 3, in which the first outlet 23 is completely closed by the first annular tract 41 while the second outlet 24 is completely open, such that the oil flow is conveyed entirely into the by-pass branch 104 of the heat exchanger 103.

When the temperature of the oil exceeds the intermediate temperature, the stem 32 exits further from the casing 31 , such that the second annular tract 42 partially closes the second outlet 24 while the first annular tract 41 partially opens the first outlet 23, newly sending the oil flow both towards the heat exchanger 103 and towards the by-pass branch 104.

When, finally, the oil temperature exceeds a predetermined maximum temperature, greater than the intermediate temperature, the stem 32 reaches the completely extracted position illustrated in figure 4, in which the first outlet 23 is completely open and the second outlet 24 is completely closed by the second annular tract 42.

In this way, the oil flow is newly conveyed entirely into the heat exchanger 103.

Obviously as the oil temperature decreases, the stem 32 tends to flow backwards in the various above-described configurations, thrust by the first spring 5.

At any instant during this functioning, if the pressure of the oil in inlet rises above a threshold value such as to overcome the thrust exerted by the second spring 7, the first body 2 is brought into the second position with respect to the second body 6 (see figures 5 and 6), in which the first outlet 23 and the second outlet 24 are both in communication with the second outlet hole 64.

In this second position, the first body 2 completely closes the first outlet hole 63 of the second body 6.

In this way, the thermostat valve 1 enables the oil to flow out only in the bypass branch 104, enabling the heat exchanger 103 to be by-passed, independently of the temperature of the oil itself, as can be understood from a comparison between figures 5 and 6.

When the pressure condition has returned to lower than the threshold value, the first body 2 returns into the first position and the functioning of the thermostat valve 1 returns to the control of the temperature, as described herein above.

The invention as conceived herein is susceptible to numerous modifications and variants, all falling within the ambit of the inventive concept.

Further, all the details can be substituted by other technically-equivalent elements.

The materials used, as well as the forms and contingent dimensions, can be any according to needs, without its forsaking the ambit of protection of the following claims.

Claims

1 ) . A valve (1 ) comprising: a first body (2) provided with an inlet (22) for a fluid, a first outlet (23) and a second outlet (24) for the fluid; a heat-sensitive unit (3) arranged in the first body (2) and comprising a casing (31 ) destined to be struck by the fluid entering from the first inlet (22) and a mobile stem (32) destined to be activated by heat dilation of a material contained in the casing (31 ); and an obturator (4) associated to the stem (32) for selective opening/closing of the first outlet (23) and the second outlet (24);

characterised in that it comprises a second body (6) provided with an inlet hole (62) for the fluid, communicating with the inlet (22) of the first body (2), a first outlet hole (63) and a second outlet hole (64) of the fluid;

the first body (2) being associated to the second body (6) such as to be mobile between a first position, in which the first outlet (23) is in communication with the first outlet hole (63) and the second outlet (24) is in communication with the second outlet hole (64), and a second position, in which the first outlet (23) and the second outlet (24) are both in communication with the second outlet hole (64)and the first outlet hole (63) is completely closed;

the first body (2) being arranged such as to be pushed by the fluid pressure entering by the inlet hole (62) towards the second position, in contrast with thrust means (7) destined to push the first body (2) into the first position.

2) . The valve (1) of claim 1 , characterised in that the thrust means comprise elastic means (7).

3) . The valve (1 ) of claim 1 , characterised in that the first body (2) exhibits an elongate shape with a prevalent development along a longitudinal axis (L), the inlet (22) being situated at an end of the first body (2), the first outlet (23) and the second outlet (24) being situated on a lateral wall of the first body (2), and in that the second body (6) comprises a cavity (65) destined to house the first body (2), in such a way as to enable the first body (2) to move between the first position and the second position by sliding in a direction of the longitudinal axis (L) thereof, the first outlet hole (63) and the second outlet hole (64) being situated at a wall of the second body (6) which laterally delimits the cavity.

4). The valve (1) of claim 3, characterised in that the cavity is at least partially delimited by an annular portion (81 ) of the second body (6), which annular portion (81 ) is coaxially snugly inserted on the first body (2) and is destined to separate the first outlet hole (63) from the second outlet hole (64).

5). The valve (1 ) of claim 1 , characterised in that the stem (32) is mobile between at least a retracted position and progressively extracted positions, by effect of an increase in the fluid temperatures entering from the inlet (22), and in that it comprises elastic means (5) destined to push the stem (32) towards the retracted position.

6). The valve (1 ) of claim 1 , characterised in that the obturator (4) is slidably associated internally of the first body (2) and is provided with a first (41 ), a second (42) and a third (43) annular tract, axially superposed and distanced from one another by interspaces, destined to cooperate with the first outlet

(23) and the second outlet (24) for opening, closing and partial opening of the first outlet (23) and the second outlet (24).

7) . The valve (1 ) of claims 5 and 6, characterised in that the obturator (4) comprises a through-cavity (44) developing longitudinally with respect to the longitudinal axis (L) and being such as to cross at least the first annular tract (41 ) and the second annular tract (42) for passage of the fluid from the inlet (22) of the first body (12) to the interspaces.

8) . The valve of claim 5 or 6, characterised in that the first (41 ), second (42) and third (43) annular tract of the obturator (4), and the first (23) and second

(24) outlets of the first body (2), are configured such that with the obturator (4) in the retracted position, the first outlet (23) is open and the second outlet (24) is closed by the third annular tract (43) and in that, by effect of the increase in the temperature of the fluid entering from the inlet (22), the obturator (4) can reach a partially extracted position, in which the first outlet (23) is closed by the first annular tract (41 ) and the second outlet (24) is open, and a further extracted position, in which the first outlet (23) is open and the second outlet (24) is closed by the second annular tract (42).

9) . A lubricating circuit (100) for circulation of lubricant fluid in an internal combustion engine (101 ), characterised in that it comprises a valve (1 ) as in any one of claims from 1 to 8, an inlet hole (62) of which valve (1 ) is in communication with an injection branch (102) of the lubricant oil, the first outlet hole (63) of which is in communication with the engine (101 ) via a heat exchanger (103), and the second outlet hole (64) of which valve (1 ) is in communication with the engine (101 ) via a by-pass branch (104) of the heat exchanger (103).

10) . The lubricating circuit (100) of claim 9, characterised in that the second body (6) of the valve (1 ) is accommodated in a seating afforded in a further component (106) of the lubricating circuit (100).

11 ) . A control method for the lubricant fluid flow in lubricating circuits ( 00) of internal combustion engines provided with a heat exchanger (103), characterised in that it uses a valve (1 ) according to any one of claims from 1 to 8 for guiding the lubricant fluid to by-pass the heat exchanger (103) when the pressure of the lubricant fluid in the circuit (100) exceeds at least a threshold value, independently of the temperature of the lubricant fluid itself.