WO2006025803A1

WO2006025803A1 - A glow plug with an integrated controller

Info

Publication number: WO2006025803A1
Application number: PCT/SI2005/000021
Authority: WO
Inventors: Damjan Golob; Robert Kovacic; Mark Plesko; Urban Simoncic
Original assignee: Cosylab, D.O.O.
Priority date: 2004-07-19
Filing date: 2005-07-19
Publication date: 2006-03-09
Also published as: EP1802918A1; SI21857A

Abstract

The subject of the invention is a glow plug for diesel engines with internal combustion, which has a mechanically connected or integrated electronic controller with an analog and/or digital decision circuit, which in some cases 5 improves the conditions for self-ignition of the diesel fuel and its combustion. The integrated controller enables the glow plug to regulate preheating operation based on measurements and communicated data, it optionally acquires and analyzes measurements of the plug parameters and controls execution of functions necessary at start-up, which includes control of the plug's glow part heating power and communication with other devices. The integration of the controller and glow plug into one unit brings numerous advantages : the number of wire connections and connector junctions is reduced ; the system is more reliable, since every plug has its own independent controller. In the process of plug manufacture, data about electrical characteristics of the glow part of each individual plug can be downloaded separately to its integrated controller.

Description

A GLOW PLUG WITH AN INTEGRATED CONTROLLER

Field of the Invention

This invention relates to the field of diesel engine cold start equipment, in particular to the field of heating control of glow plugs for diesel engine preheating.

Description of the Problem

The problem to be solved is to improve the construction of the glow plug for diesel engines, which enables to reduce the number of parts in the whole cold start system for diesel engines, improves reliability of operation and simplifies assembly. The goal of the invention is a glow plug with an electronic controller which is mechanically connected or integrated into the plug. The electronic controller has an analog and/or digital decision circuit, which regulates the operation of preheating based on measurements and communication data. Optionally, it acquires and analyzes measurements of plug parameters and controls the execution of plug functions needed for engine start-up and in addition enables other functions that become possible because of the integration.

Description of Related Art

Glow plugs in diesel engines enable self-ignition of fuel while the engine is not warm enough. At the start up of cold diesel engines without glow plugs the conditions for self-ignition are not suitable and self-ignition would not be possible or would be delayed. Plugs are embedded in a way that their glow tips extend into the engine combustion chamber. Preheating is active only until the engine is not warm enough, then the glow plugs are turned off. The plugs are sometimes turned on also when the engine is warm. Glow plugs are usually self-regulating, so that the plug comprises the so-called control coil, which is connected in series to the heating coil and whose resistance increases with increasing temperature. Heating of the glow plugs is usually controlled by a controller, which comprises switches for the supply of electric power, a control logic that can be realized partially outside of the controller, and a communication interface. In a diesel engine there are usually as many plugs as there are cylinders, whereas the glow plug controller is common for all the plugs. Some controllers are able to regulate the voltage on the plugs according to different regimes of engine operation. The common controller requires many wire connections, because it is connected with every plug separately over one thick wire connection. The controller has at least one supply wire. Usually, the supply for the heating of glow plugs is separated from the supply for the electronics of the controller. Due to the high current intensity, it is necessary to use a thick wire conductor for the glow plugs power supply, while for the supply of the electronics a thin wire conductor is sufficient. The ground potential for the controller is provided with a grounding conductor or by mounting the controller on a well conductive surface that is on ground potential. Often there is an additional one-wire or multi-wire communication connection used for data transmission.

An electronic circuit that is embedded in the plug is described in patents US6150634, DE19935025 and US6549013, but in all those patents the plugs differ in the basis from the glow plug with an integrated programmable guided controller, which is the subject of this invention. The integrated electronic circuit in the mentioned patents is intended only to measure ion currents and not for a dynamic regulation of the plug parameters, neither for the acquisition and processing of measurements from optional sensors in the plug, nor for executing programmed functions and sending and receiving regulation and sensor parameters over the communication interface, as is the purpose of the present invention.

Detailed Description of the Invention

The main idea of the glow plug with an integrated controller in accordance with the invention is that the electronic controller is mechanically connected or integrated into the plug. The electronic controller has an analog and/or digital decision circuit, which is preferably implemented with a circuit or chip of the ASIC type, programmable logic type or of microcontroller type. It regulates preheating operation based on measurements and communication data, optionally acquires and analyses measurements of the plug parameters and controls the execution of programmable plug functions. The regulation in the glow plug with an integrated controller in accordance with the invention includes attaining and maintaining the reference value of one or more physical parameters associated with the operation of the plug, the engine or the complete vehicle. The reference value, known in advance, is set over the communication block or calculated in the decision circuit from other parameters. The regulation in the glow plug with an integrated controller in accordance with the invention comprises furthermore tracking of given or calculated time dependencies of parameters. Acquisition and analysis of measurements in the glow plug with an integrated controller in accordance with the invention comprise processing of any type of measurement and direct acquisition of data from any built-in sensors, or processing of parameter values that were delivered to the integrated controller over the communication block. The communication block allows for subsequent reprogramming or changes of the glow plug functionality, also at engine maintenance, if the decision circuit is equipped with a reprogrammable memory. The invention is independent of the mechanical construction of the glow plug and can be used with any mechanical architecture and design of the glow plug, be it a plug with a heating coil, with or without regulating coil, a ceramic plug, a plug adapted for ion current measurements, a plug, where the glow tube is connected to or disconnected from the plug body, or anything else.

By replacing ordinary plugs and their separate controllers in the preheating system with glow plugs that have an integrated controller in accordance with the invention, the number of assembly parts is reduced and the assembly in the engine region is simplified, while assuring additional functionality. The reliability of operation is increased, because every plug has its own independent controller and a possible failure of one controller discontinues operation of only one plug, thus still allowing the engine to start, whereas in case of the common controller, failure of the controller ceases the operation of all plugs. The costs of mounting the preheating system are reduced, since the mounting of a common controller and its intermediary cable connections are not necessary. Identical glow plugs with the integrated controller can be used for different engines that require the same built- in dimensions of the plugs, even if the number of cylinders is different. In present solutions with one dislocated electronic controller, it is necessary to use different controllers for engines with a different number of cylinders. According to the invention, the controller is an inseparable part of the plug, therefore it is possible during the process of production to load or build in data about electrical characteristics of the glow part. This is not practically feasible on a solution with a separate controller, since there is no unique relation between the controller and the plug. With such a construction of the glow plug in accordance with the invention, it is possible to achieve higher accuracy of heating control, or allowing less tight tolerances for the manufacturing of glow parts, thereby reducing scrap. All functions that are or should be implemented by separate controllers are possible.

The glow plug with an integrated controller in accordance with the invention is further illustrated in detail on the example of a plug with one heating coil with the following figures:

Figure 1 - the longitudinal section of the plug,

Figure 2 - the block schematics of the programmable controller built into the plug,

Figure 3 - the configuration of four plugs together with the corresponding leads.

Example 1

The integrated controller used in the most common type of plugs:

The glow plug shown in figure 1 has an integrated controller, which provides appropriate control and regulation of the glow plug heating. The glow plug in accordance with the invention has a body 5, which is screwed on the engine. The controller 6 can be built in anywhere inside the body of the glow plug, preferably in the upper part 2, which is formed to have an appropriate place for embedding the controller 6. On the upper part 2 of the glow plug is a connector 7 with terminals 8 and 8', of which at least one is a terminal to supply power to the glow part 1 of the plug. There can be additional terminals of type 8\ which can serve for communication. An implementation without terminals of type 8' is also possible. The glow tube 3 is electrically connected with the body 5 of the plug, therefore it is on zero potential. At the end of the glow tube 3 is the glow part 1 with the heating element 9, which can be composed of one or more heating coils with one or more regulating coils built into the glow tube 3, or without any regulating coils. The glow part 1 is electrically connected with the glow tube. The heating coil is connected to the controller 6 by electrode 4.

The controller is made as one or more units, which are inserted anywhere in the glow plug body. It consists of the switching block 15, the control block 14 and the communication block 13. The switching block 15 is connected with the electrode 4 and with at least one of the terminals 8 and 8' on connector 7. It is made of a semiconducting or different switching element and allows to turn the power supply of the glow part on and off, or it varies the analog electric voltage, current, or resistance. The switching block 15, which is preferably implemented as a field effect transistor, can comprise also sensor 16 for measuring the electric current through the heating element 9. The measured value of the current is transmitted to the control block 14. The control block 14 performs regulation and supervises data acquisition, preferably by executing programmed instructions. It comprises the analog and/or digital decision circuit 19, which regulates the switching block 15 based on measurements and/or data obtained from communications, and is connected with the communication block 13 and the switching block 15. The decision circuit 19 is capable of measuring various input values, receiving or transmitting data over the communication block 13 and controlling the switching block 15. The communication block 13 comprises the communication interface, for adjusting the signal for wire or wireless communication with external devices, or for communication over optical fibres.

The housing 11 of the integrated controller is such that components have sufficient heat drain towards the outside and do not overheat during operation. Electric grounding is achieved by mounting the glow plug into the engine, which is on ground potential. A separate zero conductor is also possible.

Example 2 Simplified connectors:

Terminals 8 and 8' can be implemented in such a way that the outer terminal encircles the inner one. The inner terminal forms a cylinder or a tube and the outer forms a tube, which has a larger diameter so that the inner terminal can be in its center. If the connector has more than two terminals, additional connections can be implemented as tubes with different diameters. Terminals can have different lengths. The benefit of this cylindrically symmetric configuration of terminals is that it does not matter how the corresponding female connector is rotated, thus simplifying assembly.

Example 3 Integration of the controller into the plug over the connector: Conceptually and from the point of view of functionality, applicability and advantages of the presented invention it is completely the same, if the controller is integrated in the housing that is fixed to the remaining glow plug for its life time, or if the controller is integrated in such a way that it is possible to remove it from the remaining part of the glow plug during an intervention, but is mechanically connected with the otherwise independent part of the glow plug. In example 3 there is a connector junction between the electrode 4 and the controller 6, so that the electrode 4 has a male connector and the controller 6 has a corresponding female one. With a suitable level of miniaturisation, the controller 6 becomes a part of the connector, to which only the power conductor or also the communication conductors are directly and steadily fixed.

Example 4

Miniaturisation of the integrated controller in accordance with the invention:

In order to miniaturise the circuit and to simplify the production and the assembly of the glow plug with the integrated controller in accordance with the invention, it is possible to design and to produce dedicated chips, with the use of integration technologies such as »System on Chip«, »System in Package« and others, which combine parts of the communication block 13, the switching block 15 and the control block 14 individually, in pairs or all in one chip.

Example 5

Algorithms for the regulation of some parameters which are affected by the glow plug:

In the glow plug in accordance with the invention the integrated electronic controller with the analog and/or digital decision circuit performs an arbitrary number and type of functions. It performs such tasks as already known and described in other solutions that use an external controller or self-regulation in the plug, whereby the logic in the integrated controller 6 replaces the functionality of self-regulation. The electronic controller regulates the temperature or other measurable parameters, such as the composition and quantity of exhaust gases and soot at engine start-up by setting the electric power delivered to the heating coil with respect to reference values that it keeps and measurements that it makes, or with respect to values acquired over the communication block.

The input power is controlled preferably by the method of pulse width modulation PWM, which is used to turn on and off the switching block 15. The same method is used for adapting the plug to a different power supply voltage, e.g. for the new standard of 42 V, or when the voltage is unstable, as is a consequence of other loads or instability of the power supply.

Example 6

Operation of glow plugs with the integrated controller in accordance with the invention as a whole in the preheating system:

In figure 3, a possible configuration of glow plugs in a diesel engine with four plugs is shown. The example can be reasonably extended to an arbitrary number of plugs. In this configuration, four plugs 21 , 22, 23, 24 are used, which are connected with two conductors in a serial connection from one plug to another. The thinner conductor 25 is intended for the mutual communication amongst the glow plugs in accordance with the invention and for communication with other devices, e.g. the central engine computer. The thicker cable 26 is intended for supplying power to the plugs. In order to have a smaller number of wire connections, the wires to the glow plugs can be laid serially, from plug to plug, as shown in figure 3. Since the connections are serial from one plug to another, only one cable is needed for all connections between the plugs and the power supply. When the communication line 25 is needed, it can be also laid serially, i.e. from plug to plug. In case of wireless radio communication or communication over the power conductor, the communication conductors are not necessary. In the same way as when using the external plug controller, synchronization of operation of all the plugs with the integrated controller in accordance with the invention is possible. This means that during pulse width modulation, the time when the switch of a given glow plug is open is optimized in such a way that the maximal value of the current form the source is minimized or is as close as possible to its average value. The only difference between the two solutions is that in the case of the plugs with the integrated controller, the synchronisation happens over the communication line. It is reasonable and possible to provide synchronisation support also to other devices in the vehicle, whose power consumption is not negligible and are regulated by pulse width modulation of the supply voltage, which means that their supply periodically turns on and off.

Example 7

Simplified assembly of electric power supply to the preheating system, when it is composed of glow plugs with the integrated controller in accordance with the invention:

In the configuration that is described in example 6 and shown in figure 3, the supply conductor 26 is replaced with a rigid conductive rod of suitable shape and dimensions, which has built-in connectors for connections 8 such that the rod is attached to all plugs in the engine simultaneously. This implementation is easier to manufacture and also the integration in vehicles or robot assembly is simplified. The rod or the built-in connectors can have a hole for every plug through which the communication cable 25 or its connector are lead to the plug.

Claims

1. A glow plug with an integrated controller wherein an electronic controller (6) is integrated into or mechanically connected to the glow plug anywhere, preferably in the upper part (2) of the glow plug, irrespective of the type and the implementation of the glow plug.

2. A glow plug with an integrated controller, according to claim 1 , wherein the electronic controller (6) includes an analog and/or digital decision circuit (19).

3. A glow plug with an integrated controller, according to claim 1 , wherein the electronic controller (6) is programmable.

4. A glow plug with an integrated controller according to claims 1 , 2 or 3, wherein the electronic controller (6) is made from logical elements, a circuit or chips of type ASIC, programmable logic or a microcontroller.

5. A glow plug with an integrated controller according to one of the claims 1 to 4, wherein the integrated controller (6) includes the control block (14) and the communication block (13), which can receive communication signals from or transmit them to the environment.

6. A glow plug with an integrated controller according to claim 5, wherein one terminal (8') or more terminals (8') on the plug are connected with, the communication block (13) and are used to transmit communication signals over conductive wires or over optical fibres.

7. A glow plug with an integrated controller according to claim 5, wherein the communication signals received or transmitted by the communication block (13) are electromagnetic waves.

8. A glow plug with an integrated controller according to claims 3 and 5, wherein it allows for loading of data, programming or changing the functionality of the glow plug at any time before, during or after manufacture, for example at engine maintenance.

9. A glow plug with an integrated controller according to one of the claims 1 to 4, wherein it further includes a switching block (15), which either switches digitally, preferably as a field effect transistor (FET), or through setting the analog voltage, current or resistance.

10. A glow plug with an integrated controller according to claims 5 and 9, wherein parts of the communication block (13), the switching block (15) and the control block (14) are individually, in pairs, or all together part of one chip.

11. A glow plug with an integrated controller according to one of the claims 1 to 10, wherein the controller (6) controls execution of the programmed functions of the plug.

12. A glow plug with an integrated controller according to one of the claims 1 to 10, wherein the controller (6) acquires and analyzes measurements of physical and chemical quantities through processes in the plug and through sensors that are built into the plug.

13. A glow plug with an integrated controller according to one of the claims 1 to 10, wherein the controller (6) regulates the operation of the plug in such a way as to attain and maintain constant or time dependent reference values of one or more physical parameters that affect operation of the plug, the engine or the whole vehicle, where the reference values are known in advance and are set through the communication block (13), or are calculated from other parameters.

14. A glow plug with an integrated controller according to one of the claims 1 to 13, wherein the controller (6) is integrated in such a way that it is possible, by utilizing a suitable force, to nondestructively plug it out from the remaining part of the plug and then to plug it back in.

15. A glow plug with an integrated controller according to claim 14, wherein between the electrode (4) of the plug and the controller (6) there is a connector junction, so that the electrode (4) has a male connector and the controller (6) has a corresponding female one.

16. A glow plug with an integrated controller according to claim 14, wherein the controller (6) is a part of the connector, to which either only the power conductor or also possible communication conductors can be directly and steadily fixed.

17. A glow plug with an integrated controller according to one of the claims 1 to 13, wherein the glow plug has a heating element (9), preferably a heating coil, included in the glow tube (3), has a body (5) with a built-in controller (6), which controls the plug operation, preferably by adjusting electric heating power, and has also a connector with one or more connections.

18. A glow plug with an integrated controller according to claim 17, wherein the glow tube (3) is electrically connected to the body (5) of the plug and the heating element (9) is electrically connected to the glow tube (3).

19. A glow plug with an integrated controller according to claims 17 or 18, wherein at least one terminal (8) or (8¹) on connector (7), which is on the body (5), is a power connection and is connected with to heating element (9) in the glow tube (3) via the switching block (15).

20. A glow plug with an integrated controller according to claims 17 or 18, wherein the integrated controller (6) includes a sensor for measuring the electric current through the heating element.

21. A glow plug with an integrated controller according to claims 17 and 18, wherein the plug when placed in the engine is connected with other plugs in the engine with a rigid conductive rod of suitable shape and dimensions, which has built-in connectors for power connections to the plugs, made in a way that the rod is attached to all plugs in the engine simultaneously, whereby the rod or connectors can have a hole for each plug, through which the communication cable or its connector is lead to the plug.