An electric fluid heater

Abstract

Title: An Electric Fluid Heater. An electric fluid heater 100 comprises 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, on which openings 20a are formed, is mounted at a distance from a base portion 10a of the housing 10. The power transistor assembly 40 comprises a holder 42 and power transistors 44 with connecting lugs 44a for receiving and holding them in the openings 20a of the printed circuit board 20. The power transistor assembly 40 includes a positioning means 46 for positioning the power transistor assembly 40 parallel or orthogonally with respect to the base portion 10a.The power transistor assembly 40 is moved substantially orthogonally to and towards the printed circuit board 20 to allow the connection pins 44a to be received and fixed in the openings 20a. Figure for summary: Fig. 1.

Description

Title of the invention: An electric fluid heater

[0001] The present invention relates to a heat exchanger, in particular, the present invention relates to an electric fluid heater for a vehicle.

[0002] 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 the power supply to the printed circuit board and in particular converts high voltage (HV) direct current into three-phase alternating current (AC) for operation of the electric heating coils. The power transistor received within a power transistor holder includes a plurality of connection legs emanating therefrom and extending outside the power transistor holder.The connection legs are received and held in openings formed on the printed circuit board and are securely connected to the printed circuit board by soldering. The power transistor is inherently heated during operation. The spring element is mounted on a wall of the package, with the power transistor disposed between the package wall and the spring element. In this configuration, the spring element urges the power transistors of the power transistor assembly toward the package wall, with the thermal pad disposed between the power transistor and the package wall. This arrangement improves thermal contact between the power transistor and the package wall, resulting in cooling of the power transistor by fluid circulating within the package on the other side of the wall, which acts as a cooling surface.

[0003] The power transistor connection tabs must be properly positioned within the package and aligned with the openings in the printed circuit board, as misalignment of the connection tabs with the openings can result in poor soldering and solder defects. To achieve proper alignment between the power transistor connection tabs and the openings in the printed circuit board, the power transistor assembly must be properly positioned with respect to the package within a limited space within the package.

[0004] None of the prior art addresses the problem of poor soldering between the printed circuit board and the power transistor connection leads due to poor positioning of the power transistor assembly relative to the package.

[0005] Therefore, there is a need for an electric fluid heater that ensures proper positioning of the power transistor assembly relative to the package to achieve proper soldering between the printed circuit board and the power transistor connection legs.

[0006] An object of the present invention is to provide an electric fluid heater which avoids the disadvantages associated with conventional electric fluid heaters, in particular problems due to poor positioning of the power transistor assembly within a limited space in a housing of the electric fluid heater.

[0007] The main object of the present invention is to provide an electric fluid heater which prevents solder defects between the connection leads emanating from the power transistor and the printed circuit board due to misalignment between the connection leads and the openings formed on the printed circuit board in order to avoid problems due to solder defects.

[0008] An electric fluid heater for a motor vehicle is disclosed in accordance with one 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 defining the interior of the housing. The housing also includes an inlet and an outlet for fluid to enter and exit the housing. The printed circuit board is mounted spaced from the base portion of the housing that is in contact with the fluid to be heated. The at least one heating element is controlled by the printed circuit board and is received within 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 within the at least one power transistor holder. Each power transistor includes a plurality of leads emanating therefrom to extend outside the power transistor holder and received and held in openings formed on the printed circuit board. At least one thermal pad is disposed along at least one of the base and sidewall portions and between the power transistor assembly and the housing. The at least one spring member is mounted on the housing to urge the power transistors against the thermal pad to allow cooling of the at least one power transistor by fluid circulating within the housing.The power transistor assembly includes positioning means for positioning the power transistor assembly parallel or orthogonal to the base portion. The power transistor assembly is moved relative to the package to allow the connection legs. to be received and fixed in the openings.

[0009] Generally, either portion of the base and side walls includes a plurality of screw holes extending toward the respective cover opposite thereto for receiving mounting screws passing through either the printed circuit board and an auxiliary housing for mounting either the printed circuit board and the auxiliary housing to the housing.

[0010] In particular, the first cover covers a first opening of the housing along one side of the printed circuit of the housing.

[0011] Further, a second cover covers a second opening of the housing opposite the first opening.

[0012] Generally, at least one of the portions of the base and the side walls comprises at least one flat platform against which the thermal pads and the corresponding power transistors are pressed and against which the thermal pads bear.

[0013] Generally, the printed circuit board is arranged at a distance from the base portion of the housing and between the base portion and the cover.

[0014] Generally, the positioning means comprises engagement elements formed on the power transistor support that interact with at least one screw hub formed on the housing to position the power transistor assembly relative to the housing.

[0015] In addition, the power transistor support comprises reinforcing ribs.

[0016] In particular, the power transistor holder includes openings formed with cutouts, tabs, and protrusions along the interior sides of the openings to support and securely hold the power transistors within the openings.

[0017] In general, the connection legs are either orthogonal or straight, depending on whether the plane of the power transistor assembly is parallel or orthogonal to the printed circuit board, respectively.

[0018] Furthermore, the power transistor support comprises at least one set of positioning openings corresponding to each power transistor for the passage of the connection legs.

[0019] More specifically, each set of positioning openings includes a central circular opening and lateral oblong openings. The central circular opening securely holds a central lead frame for positioning the power transistor within the corresponding power transistor holder.

[0020] Further, the electric fluid heater comprises at least one guide plate cor corresponding to the at least one power transistor, the at least one guide plate being disposed between the power transistor assembly and the printed circuit board and being mounted on the printed circuit board.

[0021] More specifically, each guide plate includes at least one set of guide holes corresponding to at least one assembly of power transistors for aligning and guiding the connection tabs to the corresponding openings formed on the printed circuit board.

[0022] In particular, the assembly of the power transistor, the thermal pad and the elastic element are arranged parallel to each other and to the printed circuit board.

[0023] More specifically, the power transistor assembly is sandwiched between the thermal pad and the elastic element.

[0024] In one embodiment of the present invention, the connection tabs extend parallel to the plane of the power transistor assembly and are bent to be connected orthogonally to the printed circuit board.

[0025] Generally, the spring is mounted to the housing by means of bolts. Each bolt comprises a threaded portion and a bolt head, the threaded portion engaging the base portion.

[0026] A method of assembling the electric fluid heater includes the steps of receiving, positioning, and securely holding power transistors in a power transistor holder to form a power transistor assembly. Next, the method includes the step of positioning the power transistor assembly parallel or orthogonal to a base portion of the housing of the electric fluid heater by means of engagement features formed on the power transistor holder and at least one screw hub formed on the housing. Next, the method includes the step of moving the power transistor assembly relative to the housing along a direction orthogonal to the base portion and away from the base portion.Simultaneously, the method includes the step of aligning the leads emanating from the power transistor with respect to the openings formed on the printed circuit board using a guide plate. Then, the method includes the step of receiving and securely holding the connection tabs in the openings. Further, the method includes the step of mounting the spring element on a base portion of the package with the power transistor assembly and the thermal pad sandwiched between the spring element and the base portion. Finally, the method includes the step of soldering the connection tabs received in the openings to the printed circuit board.

[0027] Other features, details and advantages of the invention may be deduced from the description of the invention below. A more complete appreciation of the invention and the numerous advantages derived therefrom will be readily obtained as one The invention will be better understood by referring to the following detailed description, taken in conjunction with the accompanying figures, in which:

[0028] [Fig.l] illustrates an isometric view of an electric fluid heater according to one embodiment of the present invention.

[0029] [Fig.2] illustrates an electric fluid heater without a first cover in order to illustrate the internal details of the latter;

[0030] [Fig.3] illustrates an exploded view of the electric fluid heater of [Fig.l];

[0031] [Fig.4] illustrates an isometric view of the electric fluid heater housing of the [Fig.l];

[0032] [Fig.5] illustrates a schematic representation of an assembly of power transistors and a thermal pad disposed between a flat platform and a printed circuit board;

[0033] [Fig.6] illustrates an isometric view of a power transistor holder of the power transistor assembly of [Fig.5];

[0034] [Fig.7] illustrates another view of the power transistor holder of [Fig.6];

[0035] [Fig.8] illustrates an isometric view of a power transistor of the assembly of power transistors of [Fig.5];

[0036] [Fig.9] illustrates an isometric view of a guide plate according to one embodiment of the present invention;

[0037] [Fig. 10] illustrates an isometric view of an electric fluid heater according to another embodiment of the present invention;

[0038] [Fig. 11] illustrates an exploded view of the electric fluid heater of [Fig. 10];

[0039] [Fig. 12] illustrates the exploded view of the elements of a transistor assembly of power and other elements such as spring, bolts and corresponding thermal pads, guide plates and circuit board of the electric fluid heater; and

[0040] [Fig. 13] illustrates a functional diagram describing the different stages of a method of assembling an electric fluid heater.

[0041] It should be noted that the figures describe the invention in sufficient detail to be able to be implemented, said figures helping to better define the invention if necessary. The invention should not, however, be limited to the embodiment described in the description.

[0042] The present disclosure contemplates an electric fluid heater, particularly an electric coolant heater, wherein various elements of the electric fluid heater, such as, for example, 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, are packaged in a limited space within a housing. The housing includes a base portion, side walls, and removable covers that together form an enclosure defining the interior of the housing. Typically, the base portion divides the interior of the housing into a first portion and a second portion, in which the fluid to be heated, particularly the coolant, is heated by an electric heating coil in the first portion of the housing. The power transistor assembly is disposed in the second portion between the base portion and the printed circuit board disposed in the second portion. The power transistor converts high-voltage direct current (HV) to three-phase alternating current (AC) to operate the electric heating coils.The spring urges a power transistor of the power transistor assembly against the flat platform formed on the base portion which acts as a cooling surface for efficient heat dissipation of the power transistor which is heated during operation. The printed circuit board controls the operation of the electric heating coils by controlling the current flow therethrough. The power transistor assembly of the electric fluid heater includes power transistors with connecting tabs emanating therefrom. The connecting tabs are attached to the printed circuit board by soldering. The electric fluid heater of the present invention includes various arrangements such as positioning means for positioning the power transistor in the corresponding power transistor holder and means for positioning the power transistor assembly in the housing.The electric fluid heater further includes a guide plate for guiding the wires emanating from the power transistor to the openings formed on the printed circuit board to ensure proper soldering and avoid soldering defects.Although the present invention is explained with the aid of an example of an electric fluid heater in the following description and accompanying drawings, in which it is necessary to position a power transistor in a limited space within a housing and relative to a printed circuit board to properly align the connection legs emanating from the power transistor with respect to the openings formed on the printed circuit board in order to achieve proper soldering and avoid soldering defects, the present invention may also be applied to other heating systems. However, the present invention is also applicable to any other application in which an electrical component must be positioned in a limited space and must be aligned with respect to a printed circuit board while being pressed against a flat surface of the housing.

[0043] [Fig.l] illustrates an isometric view of an electric fluid heater 100 for a motor vehicle in accordance with one embodiment of the present invention. [Fig.2] illustrates the electric fluid heater 100 without the first cover 10c to illustrate the internal details thereof, as well as an enlarged view depicting a section of the interior of the electric fluid heater 100 showing a spring 60 urging a power transistor 44 against a base portion 10a of the housing 10 for dissipation of heat from the power transistor 44. [Fig.3] illustrates an exploded view of the electric fluid heater 100.

[0044] An electric fluid heater 100 includes a housing 10, a printed circuit board 20, at least one heating element 30, at least one power transistor assembly 40, at least one thermal pad 50, and at least one spring element 60 corresponding to the power transistor assemblies 40.

[0045] The housing 10 comprises the base part 10a, the side walls 10b and the removable covers 10c and 10d forming an enclosure defining the interior of the housing 10. More specifically, the housing 10 comprises the base portion 10a and a side wall 10b, also called a peripheral wall 10b, disposed along the periphery of the base portion 10a. The base portion 10a divides the interior of the housing 10 into a first portion and a second portion. The housing 10 is open on both sides and can be closed by the covers 10c and 10d. The first cover 10c covers a first opening 16a of the housing 10 along the printed circuit side of the housing 10 to define the first portion between the base portion 10a and the first cover 10c. Similarly, a second cover 10d covers a second opening 16b opposite the first opening 16a to define the second portion between the base portion 10a and the second cover 10d.The base portion 10a includes a first side facing the first cover 10c and a second side facing the second cover 10d. The first side of the base portion 10a includes at least one flat platform 10f extending toward the first cover 10c, as shown in [Fig. 5]. The power transistor assembly 40 is disposed in the first portion of the housing 10 between the base portion 10a and the printed circuit board 20. The thermal pads 50 and the corresponding power transistors 44 are pushed against the flat platform 10f and the thermal pads 50 abut against the flat platform 10f when the spring 60 mounted on the first side of the base portion 10a pushes the power transistors toward the base portion 10a.The second side of the base portion 10a facing the second cover 10d is configured with channels that receive the fluid to be heated, in particular the coolant and the heating element 30 in the form of at least one electric heating coil. With such a configuration, the base portion 10a is constantly in contact with the coolant circulating in the channels and acts as a cooling surface. The electric heating coils are kept at a distance from each other inside the channels. The removable covers 10c and 10d provide access to at least one power transistor assembly 40 and the heating coils respectively. The housing 10 further comprises an inlet 12a and an outlet 12b for the inlet and outlet of fluid to be heated. the interior of the housing 10, in particular on the second side of the housing 10. In particular, the inlet 12a and the outlet 12b are in fluid communication with the channels configured on the base portion 10a on its second side facing the second cover, for the inlet and outlet of the fluid to be heated relative to the channels. The housing 10 further comprises an electrical connector 13 for receiving an electrical connector attached to the end of a power cable for supplying electricity to the electric fluid heater 100. According to another embodiment of the present invention, the housing comprises an auxiliary housing 11 extending from one of the side walls 10b of the housing 10 for receiving at least one power transistor assembly 40 therein.The open end of the auxiliary housing 11 is closed by a cover 10e to protect the delicate electronic components of the power transistor assembly 40 from a harsh external environment.

[0046] The printed circuit board 20 is received in the first portion of the housing 10 and is mounted spaced from the base portion 10a of the housing 10. The printed circuit board 20 is disposed parallel to the base portion 10a of the housing 10. The printed circuit board 20 is disposed between the base portion 10a and the first cover 10c. Generally, the first side of the base portion 10a includes a plurality of screw holes 14 that extend toward the first cover 10c and receive mounting screws 14a for mounting the printed circuit board 20 within the housing 10. The printed circuit board 20 further includes openings 20a formed thereon to receive the connection tabs.

[0047] At least one heating element 30 is controlled by the printed circuit board 20 and received within the channels formed on the second side of the base portion 10a facing the second cover 10d. Each channel receives and securely holds at least one electric heating coil. In the case where multiple electric heating coils are received and held in the channel, the multiple electric heating coils are held in a spaced-apart configuration.

[0048] Electric fluid heater 100 includes at least one power transistor assembly 40 received in the second portion of housing 10 between spring member 60 and thermal pad 50. According to one embodiment, power transistor assembly 40 is positioned parallel to base portion 10a, as illustrated in [Fig. 2], by means of engagement members 42a formed on a power transistor carrier 42 which interacts with at least one screw hub 14 extending from base portion 10a toward cover 10c. Each power transistor assembly 40 includes at least one power transistor carrier 42, as illustrated in Figures 6 and 7, and power transistors 44.

[0049] Referring to Figures 6 and 7, the power transistor assembly 40, in par In particular the power transistor holder 42, comprises positioning means 46 in the form of engagement members 42a formed on the outer sides for positioning the power transistor holder 42 relative to the housing 10. In particular, the positioning means comprises engagement members 42a formed on the power transistor holder 42 which interact with at least one screw hub 14 formed on the housing 10 to allow movement of the power transistor assembly 40 in the direction A orthogonal to the base portion 10a and the printed circuit board 20, as illustrated in [Fig. 2]. The power transistor holder 42 also includes openings 42b formed with cutouts 42c, tabs 42d, and protrusions 42e formed along the inner sides of the openings 42b to support and securely hold the power transistors 44 within the openings 42b.In particular, the cutouts 42c formed on the peripheral walls of the power transistor holder 42 support the power transistors 44 within the openings 42b. The tabs 42d extending inwardly from the openings 42b retain the power transistors 44 in the openings 42b and the protrusions formed on the inner walls of the power transistor holder 42 protrude inwardly from the openings 42b to grip the power transistors 42 from the sides. The power transistor holder 42 further includes reinforcing ribs 48. With such a configuration of the power transistor holder 42, the power transistors 44 are received and securely held in the openings 42b of the corresponding power transistor holder 42.The power transistor holder 42 further comprises at least one set of positioning openings 43 corresponding to each power transistor 44 for the passage of the connection tabs 44a emanating from the power transistor 44. If the power transistor assembly 40 is arranged parallel to the base portion 10a, the positioning openings 43 are formed on a portion of the power transistor holder 42 along the plane of the power transistor holder 42. The connection tabs 44a emanating from the power transistors 44 are bent orthogonally and the ends of the connection tabs 44a pass through the positioning openings 43. More specifically, the number of openings in each set of positioning openings corresponds to the number of connection tabs 44a emanating from the corresponding power transistor 44.Each set of locating openings 43 includes a central circular opening 43a and lateral oblong openings 43b disposed on the sides of the central circular opening 43a. The central circular opening 43a securely holds a central connecting tab 44a for locating the power transistor 44 within the corresponding power transistor holder 42.

[0050] Power transistor 44 converts high voltage (HV) direct current into a three-phase alternating current (AC) to operate the electric heating coils. Referring to [Fig. 8], each power transistor 44 includes the connecting legs 44a emanating therefrom and extending outside the power transistor holder 42 and are received and held in the openings 20a formed on the printed circuit board 20. The connecting legs 44a which extend parallel to the plane of the power transistor assembly 40 are bent to be orthogonally connected to the printed circuit board 20. This configuration of the power transistor 44 with orthogonally bent connecting legs 44a is applicable for configuring the connection between the connecting legs and the printed circuit board when the power transistor assembly 40 and the printed circuit board 20 are arranged parallel to the base portion 10a.

[0051] The at least one thermal pad 50 illustrated in [Fig. 3] is disposed along the base portion 10a and between the power transistor assembly 40 and the package 10, in particular between the power transistors 44 and the flat platform 10f formed on the first side of the base portion 10a. The thermal pad 50 improves the surface contact between the power transistors 44 and the flat platform 10f formed on the first side of the base portion 10a which acts as a cooling surface, thereby improving the dissipation of heat from the power transistors 44 which tend to heat up during operation.

[0052] At least one spring element 60 is mounted on the housing 10, in particular on the first side of the base portion 10a, to push the power transistors 44 against the thermal pad 50 to ensure efficient dissipation of heat from the power transistors 44. More specifically, the spring element 60 is mounted on the first side of the base portion 10a by means of bolts 70. Each bolt 70 comprises a threaded rod portion 70a and a bolt head 70b, in which the threaded rod portion 70a engages in the base portion 10a. At least a portion of the spring element 60 passes through the openings 42b formed on the corresponding power transistor holder 42 and pushes the power transistors 44 received in the power transistor holder 43 against the flat platform 10f for cooling of the power transistors 44 by the fluid flowing on the other side of the base portion 10a.

[0053] The electric fluid heater 100 further comprises at least one guide plate 80 corresponding to the power transistor assembly 40. The at least one guide plate 80 is disposed between the power transistor assembly 40 and the printed circuit board 20. The at least one guide plate 80 is mounted on the printed circuit board 20 and aligns and guides the connection tabs 44a emanating from the power transistor 44 to the respective openings 20a formed on the printed circuit board 20 when the power transistor assembly is moved away from the portion of base 10a and brought closer to the printed circuit board 20. Each guide plate 80 includes at least one set of guide holes 82 corresponding to each power transistor assembly 40 for aligning and guiding the connection tabs 44a relative to the openings 20a formed on the printed circuit board 20. The set of guide holes 82 formed on the guide plate 80 are aligned relative to the set of positioning openings 43 formed on the power transistor support 42.

[0054] With such a configuration and arrangement of the printed circuit board 20, the power transistor assembly 40, the thermal pad 50 and the spring element 60 within the housing 10, the power transistor assembly 40, the thermal pad 50 and the spring element 60 are arranged parallel to each other and to the printed circuit board 20. In particular, the power transistor assembly 40 is sandwiched between the thermal pad 50 and the spring element 60.

[0055] According to another embodiment of the present invention illustrated in [Fig.l 1], the power transistor assembly 40 is arranged inside the housing 10 such that the plane of the power transistor assembly 40 is orthogonal to the printed circuit board 20. More specifically, one of the side walls 10b of the housing 10, orthogonal to the base portion 10a, includes an auxiliary housing 11 extending therefrom. The auxiliary housing 11 receives at least one power transistor assembly 40 and the open end of the auxiliary housing 11 is closed by a cover 10e in order to protect the delicate electronic components of the power transistor assembly 40 from a harsh external environment.More specifically, the power transistors 44 of the power transistor assembly are urged against the side wall 10b to cool them by means of the spring 60 mounted on the side wall 10b. The positioning means 46 in the form of engagement elements 42a formed on the power transistor holder 42 interact / engage with the screw hubs 14 extending from the side wall 10b to position the power transistor assembly 40 orthogonal to the base portion 10a. The screw hubs 14 extend from the side wall 10b to the opposite cover 10e to receive the mounting screws passing through the auxiliary housing 11 to mount the auxiliary housing 11 to the housing 10. When the power transistor assembly 40 is arranged orthogonal to the printed circuit board 20, the connection legs 44a emanating from the power transistor 44 are straight.The straight connecting legs 44a are aligned with respect to the openings 20a formed on the printed circuit board 20 by means of the positioning openings formed on an upper wall of the power transistor holder 42 and the guide holes 82 formed on the guide plate 80 and inserted into the openings 20a formed on the printed circuit board 20 when the assembly of . power transistors 40 is moved to the printed circuit board 20. The set of guide holes 82 formed on the guide plate 80 are aligned with the set of positioning openings formed on the upper face of the power transistor holder 42 to allow the passage of the straight connection tabs 44a and guide the straight connection tabs 44a to the openings 20a formed on the printed circuit board 20. The connection tabs 44a are connected to the printed circuit board 20 by soldering, after the connection tabs 44a are securely held in the openings 20a formed on the printed circuit board 20.

[0056] Also disclosed is a method 200 for assembling the electric fluid heater 100 in accordance with one embodiment of the present invention. [Fig. 13] illustrates a block diagram describing the various steps of the method 200 for assembling the electric fluid heater 100.In particular, the method 200 includes the step of receiving, positioning, and securely holding the power transistors 44 in a power transistor holder 42 to configure a power transistor assembly 40 and positioning the power transistor assembly 40 parallel or orthogonal to a base portion of the housing of the electric fluid heater 100 by means of engagement members 42a formed on the power transistor holder and at least one screw hub formed on the housing, at least one screw hub formed on the housing 10, and then moving the power transistor assembly relative to the housing along a direction A orthogonal to the base portion and away from the base portion to insert the leads emanating from the power transistors of the power transistor assembly into the openings formed on the printed circuit board.This method allows the various elements of the electric fluid heater to be packaged in a limited space within the housing and aligns the connection tabs emanating from the power transistor with the openings formed on the printed circuit board to avoid assembly defects when the connection tabs are assembled, particularly by soldering, to the printed circuit board. Although the individual steps of method 200 are represented by blocks in the flowchart, any number of steps described as method blocks may be combined in any order or may be performed in parallel to utilize method 200 or an alternative method. Furthermore, individual blocks may be deleted from the flowchart describing the method without departing from the scope and extent of the present invention. Method 200 should be understood with reference to the following description and [Fig. 10].

[0057] The method 200 of assembling the electric fluid heater 100 includes a step 102 of receiving, positioning and securely holding the power transistors 44 in a power transistor holder 42 by means of cutouts 42c, tabs 42d and protrusions 42e formed along the inner sides of the or 42b formed on the power transistor holder 42 to form a power transistor assembly 40. Next, the method 200 includes a step 104 of positioning the power transistor assembly 40 either parallel or orthogonal to a base portion 10a of the housing of the electric fluid heater 100 by means of an engagement member 42a formed on the power transistor holder 42 and at least one screw hub 14 formed on the housing 10. Next, the method 200 includes the step 106 of moving the power transistor assembly 40 relative to the housing 10 along a direction A substantially orthogonal to the base portion 10a and away from the base portion 10 and toward a printed circuit board 20.Next, the method 200 includes the step 108 of aligning the connection tabs 44a emanating from the power transistor 40 with respect to the openings 20a formed on the printed circuit board 20 using a guide plate 80. Next, the method includes the step 110 of receiving and securely holding the connection tabs 44a in the openings 20a. Next, the method includes the step 112 of mounting the spring member 60 on the base portion 10a with the assembly of the power transistor 40 and the thermal pad 50 sandwiched between the spring member 60 and the base portion 10a of the package 10. Finally, the method 200 includes the step 114 of soldering the connection tabs 44a received in the openings 20a to the printed circuit board 20.

[0058] In any event, the invention cannot and should not be limited to the embodiments specifically described herein, as other embodiments may exist. The invention extends to any equivalent means and any combination of technically operational means.

Claims

Claims

1. An electric fluid heater (100) for a motor 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 the interior of the housing (10), the housing (10) further comprising an inlet (12a) and an outlet (12b) for the entry and exit of fluid relative to the interior of the housing (10); a printed circuit board (20) mounted remotely from the base portion (10a) of the housing (10) which is in contact with a heated fluid; 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 carrier (42); at least one power transistor (44) received and securely held within the power transistor holder (42), each power transistor (44) including connection legs (44a) emanating therefrom to extend outside the power transistor holder (42) and adapted to be received and held in openings (20a) formed on the printed circuit board (20); at least one thermal pad (50) disposed along at least one of the base portions (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) in order to push the at least one power transistor (44) against the thermal pad (50) to allow cooling of the power transistor (44), characterized in that the power transistor assembly (40) comprises positioning means (46) adapted to position the power transistor assembly (40) either parallel or orthogonally to the base portion (10a), the power transistor assembly (40) being adapted to be moved relative to the housing (10) to allow the connection tabs (44a) to be received and secured in the openings (20a).

2. An electric fluid heater (100) according to the preceding claim, wherein the base portion (10a) and the side walls (10b) comprise a plurality of screw hubs (14) extending toward the respective cover (10c, 10e) opposite thereto and adapted to receive mounting screws passing through the printed circuit board (20) and an auxiliary housing (11) for mounting the printed circuit board (20) and the auxiliary housing (11) to the housing (10).

3. An electric fluid heater (100) according to the preceding claim, wherein the first cover (10c) is adapted to cover a first opening (16a) of the housing (10) along one side of the printed circuit board of the housing (10).

4. An electric fluid heater (100) according to claim 3, wherein the second cover (10d) is adapted to cover a second opening (16b) of the housing (10) opposite the first opening (16a).

5. An electric fluid heater (100) according to any preceding claim, wherein at least one of the base portions (10a) and the side walls (10b) comprises at least one flat platform (10f) against which the thermal pads (50) and the corresponding power transistors (44) are pressed and against which the thermal pads (50) bear.

6. An electric fluid heater (100) according to any preceding claim, 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. The electric fluid heater (100) of claim 2, wherein the positioning means (46) comprises engagement members (42a) formed on the power transistor carrier (42) that interact with at least one screw hub (14) formed on the housing (10) to position the power transistor assembly (40) relative to the housing (10).

8. An electric fluid heater (100) according to any preceding claim, wherein the power transistor carrier (42) further comprises reinforcing ribs (48) formed thereon.

9. An electric fluid heater (100) according to one of the preceding claims, wherein the power transistor holder (42) further comprises openings (42b) formed with cutouts (42c), tabs (42d) and protrusions (42e) along the inner sides of the openings (42b) adapted to support and securely hold the power transistors (44) within the openings (42b).

10. An electric fluid heater (100) according to one of the preceding claims, wherein the connection legs are either orthogonal or straight, depending on whether the plane of the power transistor assembly (40) is parallel or orthogonal to the printed circuit board (20), respectively.

11. An electric fluid heater (100) according to any preceding claim, wherein the power transistor holder (42) further comprises at least one set of locating openings (43) corresponding to each power transistor (44) for the connection tabs (44a) to pass therethrough.

12. An electric fluid heater (100) according to the preceding claim, wherein each set of positioning openings (43) comprises a central circular opening (43a) and lateral oblong openings (43b), the central circular opening being adapted to securely hold a central connection tab (44a) for positioning the power transistor (44) within the corresponding power transistor holder (42).

13. An electric fluid heater (100) according to any preceding claim further comprises at least one guide plate (80) corresponding to the at least one power transistor (44), the at least one guide plate (80) being 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. An electric fluid heater (100) according to the preceding claim, each guide plate (80) comprises at least one set of guide holes (82) corresponding to at least one power transistor (44) for aligning and guiding the connection tabs (44a) to the corresponding openings (20a) formed on the printed circuit board (20).

15. An electric fluid heater (100) according to one of the preceding claims, wherein the power transistor assembly (40), the thermal pad (50) and the spring element (60) are arranged parallel to each other and to the printed circuit board (20).

16. An electric fluid heater (100) according to one of the preceding claims, wherein the power transistor assembly (40) is sandwiched between the thermal pad (50) and the spring element (60).

17. An electric fluid heater (100) according to any one of the claims- preceding indications, wherein the connection legs (44a) extending parallel to the plane of the power transistor assembly (40) are bent to be connected orthogonally to the printed circuit board (20).

18. An electric fluid heater (100) according to any preceding claim, wherein the spring (60) is mounted to the housing (10) by means of bolts (70), each bolt (70) comprising a threaded shank portion (70a) and a bolt head (70b), the threaded shank portion (70a) being adapted to engage the base portion (10a).

19. A method of assembling the electric fluid heater (100) according to any preceding claim, 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) parallel or orthogonally to a base portion (10a) of the housing (10) of the electric fluid heater (100) by means of engagement members (42a) formed on the power transistor support (42) and at least one screw hub (14) formed on the housing (10); a step (106) of moving the power transistor assembly (40) relative 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 connection tabs (44a) emanating from the power transistor (40) with respect to the openings (20a) formed on a printed circuit board (20) using a guide plate (80); a step (110) of receiving and securely holding the connecting tabs (44a) in the openings (20a); a step (112) of mounting the spring element (60) on a base part (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 part (10a); and a step (114) of soldering the connection tabs (44a) received in the openings (20a) to the printed circuit board (20).

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