Patent Application
20180180017
The present invention relates to control devices and, more particularly, to controls or control devices for controlling glow plugs for diesel engines.
Glow plugs are known and are used to pre-heat diesel combustion engine cylinders before starting the engine, particularly when the diesel engine is cold. Devices for glow plug control devices are widely known in automotive applications. The controllers typically switch and control the current through glow plugs. The switched/controlled currents are comparably high. In cases where the metal-oxide-semiconductor field-effect transistors (MOS-FETs) become defective, there is the hazard that the glow plug current flow may not become turned off, and may continue to heat, which may lead to damage to the glow plug due to overheating or may lead to defects/slewing of power cables or discharged batteries.
To have a redundant instance to the MOS-FETs, fuses in the line of power are often implemented. Typically, one time fuses use bi-metals or the like and might be known but uncommon for that job. Solutions are known where the main power line becomes broke by one single fuse. Other solutions show power line bundles or one single fuse for each power line, which typically equates to the number of the cylinders of the engine.
The present invention provides a control device or control with a thermal fuse that functions as a thermal protection device or system for the control device. The thermal fuse has a first contact soldered at the circuit board at a first solder joint and a second contact soldered at the circuit board at a second solder joint. The thermal fuse is biased by a housing of the control device to exert a force at the circuit board in a direction away from a surface of the circuit board. The circuit element is electrically connected at the circuit board in closer proximity to the first contact of the thermal fuse than to the second contact of the thermal fuse. When a temperature at the circuit element exceeds a threshold temperature, the first solder joint at the first contact melts and the thermal fuse moves the first contact away from the circuit board to break the electrical connection at the first solder joint and between circuitry electrically connected to the first contact and circuitry electrically connected to the second contact. The thermal fuse may use through-hole technology (THT) to electrically connect to circuitry at the printed circuit board (PCB).
These and other objects, advantages, purposes and features of the present invention will become apparent upon review of the following specification in conjunction with the drawings.
In diesel engine applications having a single fuse, if the main power line becomes broken by one single fuse, then after the fuse is gone, all of the glow plugs are out of function. If that should happen, then the engine may not be startable.
In diesel engine applications where each power line has its own fuse, such an arrangement allows the user to start the engine even though one fuse might be blown since the other cylinders are still heatable. However, more fuses cost more and take up more space.
The present invention provides preloaded springs that function to urge or move a device or element at the circuit board (such as a metal-oxide-semiconductor field-effect transistor or MOS-FET or other element or device of the circuit) when the circuit heats to a point where the solder holding the device or element at the circuit board becomes fluid. As soon as the solder becomes fluid, the spring load pushes or moves the device or element relative to the circuit board and out of contact with the conducting portion or contact portion of the circuit board, which breaks the current. Optionally, the present invention may utilize aspects of the control devices described in U.S. Publication Nos. US-2014-0355162 and/or US-2013-0298866, which are hereby incorporated herein by reference in their entireties.
As described in U.S. Publication No. US-2014-0355162 (incorporated above), thermal breaker fuses may be provided for glow plug control devices. In there the contact breaker comprises a functional electronic component which is biased out of position, thereby opening the contacts of the PCB pads by a spring force when the functional element heats up due to a short cut malfunction of the glow plug which leads to the melting of the element's solder. The spring is a separate element which gets tensioned (loaded) when the glow plug control housings lid becomes closed.
As described in U.S. Publication No. US-2013-0298866 (incorporated above), the breaker element is not an electronically functional element. In there the breaker incorporates the spring function, such as one spring possessing two breaker contacts each.
In European patent application No. 12152855.8 (which is hereby incorporated herein by reference in its entirety), the thermal breaker fuse of a vehicle cooling fan incorporates the shunt function as common function with the fuse function. In there the fuse falls off by gravity.
As additional aspects to the systems described in Publication No. US-2014-0355162 incorporated above, the system of the present invention combines the functional base ideas of the systems of U.S. Publication No. US-2013-0298866 and EP12152855.8. The fuse element has elastic properties by itself, and gets tensioned by closing the control device's housing, bracing at a housing's structure, and the fuse incorporates the function as current measuring shunt. Additionally, the fuse does not substantially heat up by the current load carried by itself but by one or more electrical devices (such as a FET or diode) in close proximity to the solder spot of the breaker fuse. The mounting at a PCB may utilize through-hole technology (THT) or surface mount device (SMD) technology. The application may be a control device for a Diesel engine glow plug control or a control of an automotive pump motor or a control of an automotive cooling fan or a control of an automotive alternator or a control of an automotive engine starter motor or a control of an automotive starter generator (combination of starter motor and alternator/generator) or the like.
Examples of the realization as thermal breaker fuse in a Diesel engine glow plug control device in accordance with the present invention are shown in
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Thus, the thermal fuse of the present invention provides a safety function against high power dissipation losses in glow plug control devices (and optionally other control devices), and is capable to be used in various housing types, such as with horizontal PCBs or the like. The thermal fuse may be mounted by the basic structure or connector supplier, such as may be done with the terminals. Thus, no additional assembly steps are needed and no extra part handling is required to implement the spring action or biasing of the thermal fuse of the present invention.
Changes and modifications to the specifically described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law.
The present application is a continuation of U.S. patent application Ser. No. 14/810,797, filed Jul. 28, 2015, now U.S. Pat. No. 9,890,760, which claims the filing benefits of U.S. provisional application Ser. No. 62/030,211, filed Jul. 29, 2014, which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62030211 | Jul 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14810797 | Jul 2015 | US |
| Child | 15890389 | US |
