EP3488661B1

EP3488661B1 - Blowby heater

Info

Publication number: EP3488661B1
Application number: EP17737844.5A
Authority: EP
Inventors: Francis Graziotin
Original assignee: Cebi Luxembourg SA
Current assignee: Cebi Luxembourg SA
Priority date: 2016-07-19
Filing date: 2017-07-18
Publication date: 2020-04-15
Anticipated expiration: 2037-07-18
Also published as: EP3488661A1; WO2018015383A1; LU93153B1; ES2795626T3

Description

FIELD OF THE INVENTION

The present invention generally relates to the field of crankcase breathing. In particular the invention relates to a heater system or "blowby heater" of a crankcase fluid.

BACKGROUND OF THE INVENTION

"Blowby heaters" (also spelled "Blow-by") are devices which can be used in recent automobile vehicles with combustion engines in order to prevent leakage. During operation of the combustion engine, "blowby" gazes can leak between the cylinders and the combustion chambers and accumulate as blowby fluid in the crankcase of the combustion engine. This blowby fluid generally contains a mixture of gas, oil, water and other combustion elements and its accumulation can generate leakage through the crankcase. Recent combustion engines are constructed to re-inject said blowby fluid into the combustion engine, for example via the air inlet into the engine. The blowby heater can be used to heat the fluid as it is circulating from the crankcase towards the air inlet in order to improve the fluid flow, in particular in heavy winter conditions in which the blowby heater prevents the water contained in the fluid from freezing.
A blowby heater well known in the art comprises a heater element or Positive Temperature Coefficient (PTC) element as a heating source. The PTC is heating when crossed by an electrical current and it presents a variable resistance with its temperature for a heating power auto regulation. Mispositioning of elements of the blowby heater in case of shock and contamination from the environment can, separately or in combination, lead to short circuit and eventually cause a fire.
US 2015/0139632 A1 discloses a heater system for a fluid that comprises a heater plate, e.g a PTC plate, between two contact plates each equipped with an electrical contact leg in order to transfer electrical current through the heater plate. One of the contact plates rests on a transfer wall formed at the end of a conduit and intended to be in contact with the fluid for heat energy transfer. The heater system further comprises a sealing element that seals the heater plate and the contact plates relative to the fluid in the conduit. In the embodiment presented in figure 9 of US 2015/0139632 , the heater system comprises an elastomer spring that is positioned by the sealing element and that presses the heater plate. Such embodiment is interesting as the sealing element forms a barrier to the contaminants that may come from the fluid and also serves as positioning means. However, the construction is complex and the heater plate is not maintained in position.
DE 10325965 A1 discloses in Figure 1 a heater system with a heater plate which is directly in contact with a conduit destinated to transfer heat to the fluid. The heater system comprises a body overmolding the conduit, said heater plate being positioned by an opening in said body. This embodiment is interesting as the heater plate is maintained in position in the opening, the latter forms however a passage for pollution.
DE 10325965 A1 further discloses in Figure 3 an embodiment of a heater system similar to the heater system presented in Fig. 1, but the body fully overmolds the conduit. The body forms a transfer wall and the heater system comprises a conductive plate being sandwiched between the heater plate and the transfer wall. The body also forms a container receiving the conductive plate and the heater plate. The bottom of said container comprises a cavity receiving the conductive plate and the heater plate, the latter also being presented as being supported by the electrical contact leg of the conductive plate. Such an embodiment is interesting as the heater container forms a barrier to contaminants and a positioning means of the heater plate and the conductive plate. However, the construction of the heater system presents risks for short circuit in particular due the support of the heater plate with the electrical contact leg.
EP 1 674 678 discloses a heating device for blow-by conduits, wherein a PTC element is sandwiched between a lower contact plate, which is adjacent to the outer skirt of the tube, and an upper contact plate (both connected to respective contact blades). An insulating spacer is sandwiched between the lower and upper contact plates, and encloses the PTC element. A projecting part rises from the outer skirt of the tube and engages corresponding passages on the plates.
Other designs of Blowby heater systems are disclosed in EP 2 546 482 , EP 1 557 601 or EP 1 433 994 .

OBJECT OF THE INVENTION

The object of the present invention is to provide a solution which overcomes the disadvantages of the prior art. In particular, the object of the invention is to provide a heater system that is of simple and robust design, namely reducing risks of short circuits.
This object is achieved by a heater system as claimed in claim 1.

SUMMARY OF THE INVENTION

The present invention concerns a heater system for a crankcase fluid, comprising a heater plate, a conductive plate and a transfer wall, said conductive plate being sandwiched between the heater plate and said transfer wall, the latter being intended to transfer heating energy to the fluid; wherein the heater system comprises one or more principal protrusions, preferably cylindrical pins, extending from the transfer wall and arranged to engage one portion of the peripheral edge of the heater plate in order to maintain said heater plate on one contact zone of the conductive plate at distance with one electrical connection zone of said conductive plate situated in front of said one portion of the peripheral edge. As used herein, "contact zone" means the region of the conductive plate that is in contact with the heater plate.
A merit of the present invention it to provide a blowby heater of simple and robust design that reduces risks of short circuits. The principal protrusion(s), provided in the transfer wall and engaging with the peripheral edge of the heater plate, force the electrical current coming from the electrical connection zone of the conductive plate to enter the heater plate only via the contact zone of the conductive plate.
In a preferred embodiment, the conductive plate comprises one or more principal openings traversed by said principal protrusion(s).
In a preferred embodiment, the contact zone extends over up to 99% of the surface of the conductive plate, but is preferably between 20% and 50%. The construction of the conductive plate may thus be adapted to various heating requirements of the heater system.
In a preferred embodiment, the transfer wall is of square or rectangular shape, the contact zone and the electrical connection zone being situated along one length, in the direction in-between said zones, of said transfer wall, the principal protrusion(s) being located generally at mid-distance along said length. This is interesting to facilitate the access to the contact zone and/or the electrical connection zone.
Advantageously, the transfer wall is of polygonal, circular or elliptical shape.
In a preferred embodiment, the heater plate is a PTC plate with a circular peripheral edge. Any appropriate PTC material may be used, as can be devised by those skilled in the art.
Advantageously, the portion of the peripheral edge -that is engaged by the principal protrusion(s)- of the circular PTC plate extends over an angle which is less than 150°.
Advantageously, the heater system comprises two principal protrusions at an angular distance of less than 150° of the circular contact zone of the circular PTC plate.
More advantageously, the principal protrusions comprise two cylindrical pins, preferably of circular cross-section.
Alternatively, the principal protrusion(s) can take the form of a wall extending along the portion of the peripheral edge of the heater plate.
In practice, the heater system may generally comprise a conduit, a body comprising an inner space for accommodating the conduit, said body comprising a heater container open transversally in the direction opposite to that of the innerspace, the transfer wall closing the bottom of said heater container and facing the flank of the conduit. This is interesting to isolate the heater plate and the conductive plate from the fluid line. Preferably, the conductive plate can cover over 80% of the transfer wall. For example, the conductive plate can follow the contour of the transfer wall; therefore the conductive plate location in the heater container is facilitated.
In embodiments, the flank of the conduit comprises a portion with a flattened cross-section, the transfer wall being in contact with said portion.
In embodiments, the heater system further comprises at least one locating pin, preferably two, arranged to engage the heater plate at the opposite of one, respectively preferably each, of two principal protrusions, said locating pin(s) protruding from the heater container. This allows locating the heater plate on the conductive plate. For example, the locating pin(s) may protrude from the side walls of the heater cavity.
Advantageously, the body is made from plastic, the protrusion(s) and/or the locating pins being integral with said body.
In a preferred embodiment, the locating pin(s) protrude(s) from the transfer wall and pass through corresponding opening(s) in the conductive plate. This is interesting to facilitate the fabrication of the body.
Advantageously, the locating pins are cylindrical pins.
In a preferred embodiment, the heater plate is a circular PTC plate positioned on the contact zone of the conductive plate with two locating pins located at the opposite of two principal protruding pins.
In a preferred embodiment, the heater system comprises a connector closing the heater container, said heater system comprising a first spring electrically linked with a first pole of said connector and pressing the heater plate, and a second spring electrically linked with a second pole of said connector and pressing the electrical connection zone of said conductive plate, respectively, against the transfer wall in closed position.
In a preferred embodiment, the heater system further comprises a contact plate, the heater plate being further sandwiched between said conductive plate and said contact plate, the first spring pressing the heater plate via said contact plate. This is interesting to prevent fretting corrosion of the heater plate due to the contact with the first spring.
In a preferred embodiment, the first spring is a helicoidal spring cooperating with a nipple on the contact plate, the principal protrusion(s) being arranged to further engage, beyond the portion of the edge of the heater plate, a corresponding portion of edge of said contact plate. This is particularly interesting to maintain the contact plate in contact with the heater plate and prevent short circuit of said contact plate with the second spring. This is also interesting to maintain the first spring engaged with the contact plate and prevent short circuit with the second spring.
Preferably, the second contact spring is a helicoidal contact spring that cooperates with an auxiliary protrusion provided in the transfer wall and passing through a corresponding auxiliary opening in the conductive plate. This is interesting to maintain the second spring in position on the electrical connection zone of the conductive plate.
Preferably, the auxiliary opening in the conductive plate comprises a raised edge, the corresponding helicoidal spring resting on said raised edge. This is interesting to facilitate the construction of the heater system. The raised edge in the conductive plate can be formed so that the first and the second spring have the same length.
Preferably, the heater container and the connector are made from plastic material and sealingly fixed together by ultra sound welding. This is an efficient way of isolating the heater container from external contaminants. It may also be noticed that the use of the first spring in contact with the contact plate avoids damaging of the heater plate during US welding.
The measures of the invention are in particular interesting for a simple mounting while keeping a tight isolation to pollution. In fact, the power contact elements that are traversing the connector are constructed in advance and tight to pollution. During mounting, the springs are positioned easily in the heater container and the connector is presented easily for welding.
The above and other embodiments and aspects of the invention are also recited in the appended dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of a blowby heater according to an embodiment of the present invention;
Figure 2 is a sectional view II - II of the blowby heater of Figure 1;
Figure 3 presents the body of the blowby heater of figures 1 and 2 in -a- a top view and in -b- a sectional view IIIb - IIIb.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 is an exploded view of a heater system 2 according to an embodiment of the present invention. The heater system 2 is referred to as "blowby heater" in the rest of the description. The blowby heater 2 comprises a heater plate 4, a conductive plate 6 and a transfer wall 8. The blowby heater 2 also comprises a conduit 10, a body 12 and a connector 14. The body 12 has a passage defining an inner space 16 for accommodating the conduit 10 therein. The body 12 also comprises a heater container 18, inside which the heater plate 4 and the conductive plate 6 are mounted. The heater container 18 is open transversally in the direction opposite to that of the innerspace 16. The transfer wall 8 closes the bottom of the heater container 18 in order to face the flank 11 of the conduit when the latter is arranged in the innerspace. The transfer wall 8 is intended and configured to transfer, in use, heating energy to the fluid circulating in the conduit 10. The conductive plate 6 is sandwiched between the heater plate 4 and the transfer wall 8. The connector 14 is attached to the body 12 and is adapted to close the heater container 18.
As it will be understood, the heater container 18 forms a housing for the heater plate 4 and the conductive plate 6. The heater container 18 has a cylindrical shape that can have a circular, elliptical or polygonal cross-section, depending on the application. Consequently, the transfer wall 8 forming the bottom of the heater container may also be circular, elliptical or polygonal. In the present embodiment, the heater cavity 18 has a rectangular cross section, and the transfer wall 8 is also rectangular. The conductive plate 6 may cover over 80% of the transfer wall. In the present embodiment, the conductive plate 6 follows the contour of the transfer wall 8.
The body 12 further comprises two opposite connection portions 20 and 20' for a fluid line. The body extends here longitudinally between the two connection portions 20 and 20', but this does not limit the invention. One of the connection portions could present an angle with the opposite connection portion. As can be seen on this exploded view, the blowby heater 2 also preferably comprises two helicoidal contact springs 22a and 22b and a contact plate 24 in between the first spring 22a and the heater plate 4 as will be described below.
The conductive plate 6 comprises two principal openings 24a and 24b, one auxiliary opening 26 and finally two secondary openings 28a and 28b, opposite the auxiliary opening 26 relative to the principal openings 24a and 24b. It may be noticed in the present embodiment that the auxiliary opening 26 has a larger diameter than the other openings. This is however not limiting the invention.
The blowby heater comprises two principal protrusions 38a and 38b extending from the transfer wall 8 and arranged to engage with a portion 32₁ of the peripheral edge 32 of the heater plate 4 in assembled position (Fig.2), in order to maintain the heater plate 4 on the contact zone 34 of the conductive plate 6 at distance with an electrical connection zone 36 of the conductive plate 6 situated in front of the portion 32₁. The two principal protrusions 38a and 38b pass through the corresponding principal openings 24a and 24b in the conductive plate 6.
In the present embodiment, the contact zone 34 extends over between 20% and 50% of the surface of the contact zone. In other embodiments, it may extend up to 99% of the surface of the conductive plate. The transfer wall 8 forming the bottom of the heater container is of rectangular shape, and the contact zone and the electrical connection zone are situated along one length of the transfer wall 8 in the longitudinal direction of the body. The principal protrusion(s) 38a and 38b may be located at mid-distance along to this length, or at mid-distance longitudinally between the side walls forming the heater container 18.
The transfer wall 8 may also comprise one auxiliary protrusion 40 adapted to cooperate with the auxiliary opening 26 in working position. The transfer wall may further comprise two locating pins 42a and 42b adapted to cooperate with the two secondary openings 28a and 28b.
The connector 14 is adapted to supply power to the heater plate 4. It shall be appreciated that when the connector 14 is closing the heater container 18 the first spring 22a is electrically linked with a first pole (not visible) of the connector 14 and presses the heater plate 4 against the transfer wall 8 and the second spring 22b is electrically linked with a second pole (not visible) of the connector 14 and presses the conductive plate 6 against the transfer wall 8.
Although the functioning principle of the blowby heater 2 is well known to those skilled in the art, we can recall that the heater plate 4 may be a PTC plate as stated in the introduction. The PTC plate 4 is the heating source of the device when traversed by electrical current and the conductive plate is the heat radiating element of the device. In the present embodiment, the PTC plate 4 is of circular shape and the portion 32₁ of the peripheral edge of the PTC circular plate that is intended to engage with the principal protrusions extends over an angle α seen from the center of the PTC plate that is less than 150°.
Figure 2 is a cross sectional view of the blowby heater 2 in a longitudinal direction U. From the bottom to the top, one can identify: the body 12 with the inner space 16 receiving the conduit 10; the transfer wall 8 forming the bottom of the heater container 18 and receiving the conductive plate 6; the heater plate 4; the contact plate 24 above the heater plate; the first and second springs 22a and 22b; and finally the connector 14 shown in a position attached to the heater container 18. One can notice that the heater container 18 is integral with the body 12 that is made from plastic. In the presented embodiment, the principal protrusions 38a and 38b, the auxiliary protrusion 40 and the locating pin(s) 42a and 42b are integral with the transfer wall 8.
The electrical circuit in the blowby heater 2 includes the first spring 22a, in contact with the heater plate 4, itself in contact with the conductive plate 6 via the contact zone 34. The conductive plate 6 is then in contact with the second spring 22b via the electrical connection zone 36. The first and second springs 22a and 22b are connected to corresponding strips in the connector for power supply. The electrical power is supplied to the springs via a pair of wires (not shown) arriving at the connector 14. Heating will occur when a voltage is applied to the heater contact strips via the wires.
One can observe that the conductive plate 6 is sandwiched between the transfer wall 8 and the heater plate 4, and the contact zone 34 on the conductive plate that is in contact with the heater plate 4. One can also observe the peripheral edge portion 32₁ of heater plate, which is situated in front of the electrical connection zone 36 between the helicoidal spring 22b and the conductive plate 6. One can further observe the principal protrusion 38b (only one visible on this sectional view) of the two principal protrusions provided in the transfer wall 8 and which engages with the portion 32₁ of the peripheral edge of the heater plate 4 that is in front of the electrical connection zone 36 in order to maintain the contact zone 34 at distance of the electrical connection zone 36.
One may further notice, in this embodiment, that the principal protrusions 38a and 38b extend beyond the portion 32₁ of the edge of the heater plate 4 in order to engage with a corresponding edge 44 of the contact plate 24. The first helicoidal spring 22a cooperates with a nipple 46 provided on the contact plate 24.
The helicoidal contact spring 22b engages with an auxiliary protrusion 40 provided in the transfer wall 8 and that passes through a corresponding auxiliary opening 26 in the conductive plate 6. In the present embodiment, the auxiliary opening 26 in the conductive plate 6 comprises a raised edge 48 and the corresponding helicoidal spring 22b rests on said raised edge 48. One can observe the electrical connection zone 36 on the raised edge 48 of the auxiliary opening 26.
One can also see one locating pin 42b on the right of the heater container 18, which is arranged to engage the heater plate 4.
The connector 14 and/or the body 12 may be made from any appropriate plastic material, e.g. PBT or PA. The heater container 18 and the connector 14 may thus be conveniently and sealingly fixed together by ultra sound welding.
Figure 3 illustrates the body 12 of the blowby heater with a top view on the top - a - of the drawing sheet and cross sectional view IIIb-IIIb on the bottom - b -. One can see on these two views the heater container 18 with the transfer wall 8 forming the bottom of the heater container 18. One may also notice the principal protrusions 38a and 38b, the locating pins 42a and 42b, the auxiliary protrusion 40 provided in the transfer wall 8.
One may observe on the sectional view -a- that the conduit 10, which presents a rounded section, comprises at the flank 11 a portion 13 with a flat section and the transfer wall 8 is in contact with this flat portion 11 when the conduit is in position in the innerspace 16 of the body 12. This is interesting for an efficient energy transfer; alternatively the rounded section can extend over the entire conduit.
Turning finally to the bottom view -b-, one can observe the transfer wall 8 in rectangular shape and the contact zone 34 delimited with dash points on the right and the electrical connection zone 36 on the left. Those two zones 34 and 36 are situated along the length L of the transfer wall in the longitudinal direction U of the body. In the present embodiment, the principal protrusions 38a and 38b are located at mid-distance according to the length L. One can finally observe that the two locating pins 42a and 42b are situated opposite to the principal protrusions 38a and 38b with regard the center the contact zone 34.

Claims

Heater system (2) for a crankcase fluid, comprising a heater plate (4), a conductive plate (6) and a transfer wall (8), said conductive plate (6) being sandwiched between the heater plate (4) and said transfer wall (8), the latter being intended to transfer heating energy to the fluid;
wherein one or more principal protrusions (38a, 38b), preferably cylindrical pins, extend from the transfer wall (8)
characterized in that said one or more principal protrusions (38a, 38b) is/are arranged to engage a portion (32₁) of the peripheral edge (32) of the heater plate (4) in order to maintain said heater plate (4) on a contact zone (34) of the conductive plate (6) at distance from one electrical connection zone (36) of said conductive plate (6) situated in front of said portion (32₁) of the peripheral edge.
Heater system (2) according to claim 1, characterized in that the conductive plate (6) comprises one or more principal openings (24a, 24b) traversed by said principal protrusion/s (38a, 38b).
Heater system (2) according to claim 1 or 2, characterized in that the contact zone (34) extends over up to 99% of the surface of the conductive plate (6), preferably between 20% and 50%.
Heater system (2) according to anyone of claims 1 to 3, characterized in that the transfer wall (8) is of square or rectangular shape, the contact zone (34) and the electrical connection zone (36) being situated along one length (L) of said transfer wall (8), the protrusion/s (38a, 38b) being located preferably at mid-distance according to said length (L).
Heater system (2) according to anyone of claims 1 to 4, characterized in that the heater plate (4) is a PTC plate with a circular peripheral edge (32).
Heater system (2) according to anyone of claims 1 to 5, characterized by a conduit (10), a body (12) comprising an inner space (16) for accommodating said conduit (10), said body (12) comprising a heater container (18) open transversally in the direction opposite to that of the inner space (16), the transfer wall (8) closing the bottom of said heater container (8) and facing the flank (11) of said conduit (10).
Heater system (2) according to claim 6, characterized in that the flank (11) of the conduit comprises a portion (13) with a flat section, the transfer wall being in contact with said portion (13).
Heater system (2) according to claims 6 or 7, characterized in that it further comprises at least one locating pin (42a, 42b), preferably two, arranged to engage the heater plate (4) at the opposite of one, respectively preferably each of two, principal protrusion/s (38a, 38b), said locating pin/s (42a, 42b) protruding from the heater container (18).
Heater system (2) according to claim 8, characterized in that the locating pin/s (42a, 42b) protrude(s) from the transfer wall (8) and pass through corresponding opening/s (28a, 28b) in the conductive plate (6).
Heater system (2) according to anyone of claims 6 to 9, characterized in that it further comprises a connector (14) closing the heater container (18), said heater system (2) comprising a first spring (22a) electrically linked with a first pole of said connector (14) and pressing the heater plate (4), and a second spring (22b) electrically linked with a second pole of said connector (14) and pressing the electrical connection zone (36) of said conductive plate (6), respectively, against the transfer wall (8) in closed position.
Heater system (2) according to claim 10, characterized in that it further comprises a contact plate (24), the heater plate (4) being further sandwiched between said conductive plate (6) and said contact plate (24), the first spring (22a) pressing the heater plate (4) via said contact plate (24).
Heater system (4) according to claim 11, characterized in that the first spring (22a) is a helicoidal spring cooperating with a nipple (46) on the contact plate (24), the principal protrusion(s) (38a, 38b) being arranged to further engage, beyond the portion (32₁) of the edge (32) of the heater plate (4), a corresponding portion (44) of edge of said contact plate (24).
Heater system (2) according to anyone of claims 10 to 12, characterized in that the second contact spring (22b) is a helicoidal contact spring that cooperates with an auxiliary protrusion (40) provided in the transfer wall (8) and passing through a corresponding auxiliary opening (26) in the conductive plate.
Heater system (2) according to claim 13, characterized in that the auxiliary opening (26) in the conductive plate (6) comprises a raised edge (48), the second helicoidal spring (22b) resting on said raised edge (48).
Heater system (2) according to anyone of claims 10 to 14, characterized in that said heater container (18) and said connector (14) are made in plastic and fixed together by ultra sound welding.