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EP-4736577-A1 - AN ELECTRIC FLUID HEATER

EP4736577A1EP 4736577 A1EP4736577 A1EP 4736577A1EP-4736577-A1

Abstract

An electric fluid heater (100) includes a housing (10), a printed circuit board (20), a heating element (30), a power transistor assembly (40), a thermal pad (50) and a spring (60). The printed circuit board (20) with apertures (20a) formed thereon is mounted spaced from a base portion (10a) of the housing (10). The power transistor assembly (40) includes a holder (42) and power transistors (44) with lead frames (44a) to be received and held in the apertures (20a) of the printed circuit board (20). The power transistor assembly (40) includes a positioning means (46) to position the power transistor assembly (40) either parallel or orthogonal with respect to the base portion (10a). The power transistor assembly (40) is moved substantially orthogonal to and towards the printed circuit board (20) to enable the lead frames (44a) to be received and secured in the apertures (20a).

Inventors

  • KOZICKA, Jan

Assignees

  • Valeo Electrification

Dates

Publication Date
20260506
Application Date
20240628

Claims (19)

  1. [Revendication 1] An electric fluid heater (100) for an automotive vehicle, the electric fluid heater (100) comprising : a housing (10) comprising a base portion (10a), side walls (10b) and removable covers (10c, 10d, 10e) forming an enclosure defining an interior of the housing (10), the housing (10) further comprising an inlet (12a) and an outlet (12b) for ingress and egress of fluid with respect to the interior the housing (10); a printed circuit board (20) mounted spaced from the base portion (10a) of the housing (10) that is in contact with a fluid being heated; at least one heating element (30) controlled by the printed circuit board (20) and received inside the housing (10); at least one power transistor assembly (40), each power transistor assembly (40) comprising : at least one power transistor holder (42); at least one power transistor (44) received and securely held inside the power transistor holder (42), each power transistor (44) comprising lead frames (44a) emanating therefrom to extend outside the power transistor holder (42) and adapted to be received and held in apertures (20a) formed on the printed circuit board (20); at least one thermal pad (50) disposed along at least one of the base portion (10a) and the side walls (10b) and between the power transistor assembly (40) and the housing (10); and at least one spring element (60) adapted to be mounted on the housing (10) to urge the at least one power transistor (44) against the thermal pad (50) to enable cooling of the power transistor (44), characterized in that the power transistor assembly (40) comprises a positioning means (46) adapted to position the power transistor assembly (40) either parallel or orthogonal with respect to the base portion (10a), the power transistor assembly (40) adapted to be moved with respect to the housing (10) to enable the lead frames (44a) to be received and secured in the apertures (20a).
  2. [Revendication 2] The electric fluid heater (100) as claimed in the previous claim, wherein either one of the base portion (10a) and the side walls (10b) comprises a plurality of screw-hubs (14) extending there from towards the respective cover (10c, 10e) opposite thereto and adapted to receive mounting screws passing through the either one of the printed circuit board (20) and an auxiliary housing (11) for mounting either one of the printed circuit board (20) and the auxiliary housing (11) to the housing (10).
  3. [Revendication 3] The electric fluid heater (100) as claimed in the previous claim, wherein the first cover (10c) adapted to cover a first opening (16a) of the housing (10) along a printed circuit board side of the housing (10).
  4. [Revendication 4] The electric fluid heater (100) as claimed in the claim 3, wherein the second cover (10d) adapted to cover a second opening (16b) of the housing (10) opposite to the first opening (16a).
  5. [Revendication 5] The electric fluid heater (100) as claimed in any of the preceding claims, wherein at least one of the base portion (10a) and side walls (10b) comprises at least one flat platform (10f) against which the thermal pads (50) and the corresponding power transistors (44) are urged and against which the thermal pads (50) abuts.
  6. [Revendication 6] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the printed circuit board (20) is disposed spaced from the base portion (10a) of the housing (10) and between the base portion (10a) and the cover (10c).
  7. [Revendication 7] The electric fluid heater (100) as claimed in the claim 2, wherein the positioning means (46) comprises engagement elements (42a) formed on the power transistor holder (42) that interacts with at least one screw-hub (14) formed on housing (10) to position the power transistor assembly (40) with respect to the housing (10).
  8. [Revendication 8] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the power transistor holder (42) further comprises reinforcement ribs (48) formed thereon.
  9. [Revendication 9] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the power transistor holder (42) further comprises openings (42b) formed with cut - outs (42c), tabs (42d) and protrusions (42e) along inner sides of the openings (42b) adapted to support and securely hold the power transistors (44) within the openings (42b).
  10. [Revendication 10] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the lead frames are either one of orthogonally bent and straight based on whether plane of the power transistor assembly (40) is parallel to or orthogonal to the printed circuit board (20) respectively.
  11. [Revendication 11 ] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the power transistor holder (42) further comprises at least one set of positioning apertures (43) corresponding to each power transistor (44) for passage of the lead frames (44a) there through.
  12. [Revendication 12] The electric fluid heater (100) as claimed in the previous claim, wherein each set of positioning apertures (43) comprises a central circular aperture (43a) and side oblong apertures (43b), the central circular aperture adapted to securely hold a central lead frame (44a) to position the power transistor (44) inside the corresponding power transistor holder (42).
  13. [Revendication 13] The electric fluid heater (100) as claimed in any of the preceding claims further comprises at least one guiding plate (80) corresponding to the at least one power transistor (44), the at least one guiding plate (80) is disposed between the power transistor assembly (40) and the printed circuit board (20) and adapted to be mounted on the printed circuit board (20),
  14. [Revendication 14] The electric fluid heater (100) as claimed in the previous claim, each guiding plate (80) comprises at least one set of guiding holes (82) corresponding to at least one power transistor (44) for aligning and guiding the lead frames (44a) to the corresponding apertures (20a) formed on the printed circuit board (20).
  15. [Revendication 15] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the power transistor assembly (40), the thermal pad (50) and the spring element (60) are disposed parallel to each other and the printed circuit board (20).
  16. [Revendication 16] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the power transistor assembly (40) is sandwiched between the thermal pad (50) and the spring element (60).
  17. [Revendication 17] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the lead frames (44a) extending parallel to the plane of the power transistor assembly (40) are bent to be orthogonally connected to the printed circuit board (20).
  18. [Revendication 18] The electric fluid heater (100) as claimed in any of the preceding claims, wherein the spring (60) is mounted to the housing (10) by means of bolts (70), each bolt (70) comprises a threaded shaft portion (70a) and a bolt head (70b), the threaded shaft portion (70a) adapted to engage with the base portion (10a).
  19. [Revendication 19] A method of assembling the electric fluid heater (100) comprising: a step (102) of receiving, positioning and securely holding power transistors (44) in a power transistor holder (42) to form a power transistor assembly (40); a step (104) of positioning the power transistor assembly (40) either parallel or orthogonal to a base portion (10a) of housing (10) of the electric fluid heater (100) by means of engagement elements (42a) formed on the power transistor holder (42) and at least one screw-hub (14) formed on housing (10); a step (106) of moving the power transistor assembly (40) with respect to the housing (10) along a direction A orthogonal to the base portion (10a) and away from the base portion (10a); a step (108) of aligning the lead frames (44a) emanating from the power transistor (40) with respect to the apertures (20a) formed on a printed circuit board (20) by using a guiding plate (80); a step (110) of receiving and securely holding the lead frames (44a) in the apertures (20a); a step (112) of mounting the spring element (60) on a base portion (10a) of the housing (10) with the power transistor assembly (40) and the thermal pad (50) sandwiched between the spring element (60) and the base portion (10a); and a step (114) soldering the lead frames (44a) received in the apertures (20a) to the printed circuit board (20).

Description

DESCRIPTION Title : AN ELECTRIC FLUID HEATER [1] The present invention relates to a heat exchanger, particularly, the present invention relates to an electric fluid heater for a vehicle. [2] An electric fluid heater includes a housing, a printed circuit board, at least one heating element, a power transistor assembly, at least one thermal pad, at least one spring element and bolts for mounting the spring element to the housing. The heating element is controlled by the printed circuit board. The power transistor controls current supply to the printed circuit board, particularly converts high voltage (HV) direct current (DC) to a three- phase alternating current (AC) for operation of the electrical heating coils. The power transistor received inside a power transistor holder includes a plurality of lead frames emanating therefrom and extending outside the power transistor holder. The lead frames are received and held in apertures formed on the printed circuit board and are securely connected to the printed circuit board by soldering. The power transistor inherently gets heated during operation thereof. The spring element is mounted on one wall of the housing with the power transistor disposed between the wall of the housing and the spring element. With such configuration, the spring element urges the power transistors of the power transistor assembly towards the wall of the housing with the thermal pad disposed between the power transistor and the wall of the housing. Such arrangement enables improved thermal contact between the power transistor and the wall of the housing, thereby resulting in and cooling of the power transistor by the fluid flowing inside the housing on other side of the wall that acts as a cooling surface. [3] The lead frames of the power transistor are required to be properly positioned inside the housing and aligned to the apertures of the printed circuit board, any misalignment of the lead frames with respect to the apertures may cause improper soldering and soldering defects. For achieving proper alignment between the lead frames of the power transistor and the apertures of the printed circuit board, the power transistor assembly is required to properly positioned with respect to the housing within limited space inside the housing. [4] None of the prior art addresses the problem of improper soldering between the printed circuit board and the lead frames of the power transistor due to improper positioning of the power transistor assembly with respect to the housing. [5] Accordingly, there is a need for an electric fluid heater that ensures proper positioning of the power transistor assembly with respect to the housing to achieve proper soldering between the PCB and the lead frames of the power transistor. [6] An object of the present invention is to provide an electric fluid heater that obviates the drawbacks associated with convention electric coolant heater, particularly, problems due to improper positioning of the power transistor assembly inside limited space in a housing of the electric fluid heater. [7] Primary object of the present invention is to provide an electric fluid heater that prevents defects in soldering between lead frames emanating from power transistor and printed circuit board due to misalignment between the lead frames and apertures formed on printed circuit board to prevent problems arising due to the soldering defects. [8] An electric fluid heater for an automotive vehicle is disclosed in accordance with an embodiment of the present invention. The electric fluid heater includes a housing, a printed circuit board, at least one heating element, at least one power transistor assembly, at least one thermal pad and at least one spring element. The housing includes a base portion, side walls and removable covers assembled to form an enclosure to define an interior of the housing. The housing further includes an inlet and an outlet for ingress and egress of fluid with respect to the interior the housing. The printed circuit board is mounted spaced from the base portion of the housing that is in contact with a fluid being heated. The at least one heating element is controlled by the printed circuit board and is received inside the housing. The at least one power transistor assembly includes at least one power transistor holder and at least one power transistor received and securely held inside the at least one power transistor holder. Each power transistor includes a plurality of lead frames emanating therefrom to extend outside the power transistor holder and received and held in apertures formed on the printed circuit board. The least one thermal pad is disposed along at least one of the base portion and the side walls and between the power transistor assembly and the housing. The at least one spring element is mounted on the housing to urge the power transistors against the thermal pad to enable cooling of the at least one power transistor by the fluid circulating i