JPS622722Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistor for detecting current of a glow plug, and more particularly, to a structure of a resistor for detecting glow plug current used in a starting assist device for a diesel engine.

In order to preheat the glow plug by detecting changes in the heating current that occur as the temperature of the glow plug increases, starting aids for diesel engines, etc. are made of a resistance material with a small temperature coefficient and are used to connect the glow plug and battery. A current detection resistor is provided between the current detection resistor and the current detection resistor. For example, as a conventional current detection resistor of this type,
Examples include those disclosed in Japanese Patent No. 55-67360. As shown in FIG. 1, this current detection resistor consists of a resistance plate 1 formed into a plate shape, and a resistance value setting part 2 for setting the resistance value is formed in the middle part of the resistance plate 1. There is. A notch 3 is formed at one end of the resistance plate 1 for connection with a glow plug, and a nut 4 for fixing the wiring to be connected to the battery with a bolt is formed at the other end by welding or the like. It is fixed by. Nuts 5 and 6 are fixed between the notch 3 and the nut 4 by appropriate means such as welding so that wiring for connecting to the glow plug preheating control circuit can be fixed with bolts. As a result, the voltage generated in the resistive plate portion between the nuts 5 and 6 can be taken out via the nuts 5 and 6. Furthermore, an insulating washer 7 is provided between the nuts 4 and 6, and the other end of the resistance plate 1 is bolted to the engine case via this insulating washer 7, so that it can be directly fixed to the engine. can.

However, according to such a conventional configuration, since the resistor is plate-shaped, a mounting hole corresponding to the insulating washer 7 must be provided on the engine side, but the position of this mounting hole depends on the size of the engine,
Since it is determined appropriately depending on the size, model, etc., it is impossible to manufacture a general-purpose current detection resistor, and it is difficult to reduce costs. Furthermore, since the plate-shaped resistor is placed along the outer surface of the engine, it is easily affected by the heat from the engine, so the wiring connected to the resistor must be a special heat-resistant wire harness. However, a connector for connecting this wire harness to another electric circuit is required, which also has the drawback of increasing the price. In addition, the long and thin plate shape tends to cause mechanical fatigue due to engine vibration, and the exposed resistance plate easily rusts, shortening the service life.

The object of the present invention is therefore to provide a shock-proof design which can be easily and firmly attached to the glow plug without screwing it to the engine case, and which can therefore be easily installed in any type and type of engine.
An object of the present invention is to provide a current detection resistor for a glow plug that has excellent corrosion resistance.

The present invention is a current detection resistor for a glow plug for detecting the magnitude of current flowing through a glow plug for diesel engines. a first terminal member connected to the other end of the resistance element and connected to the wiring on the power supply side, and a pair of signal extraction terminals for taking out the detection signal connected in advance to the resistance element. ,
The base end portions of the first and second terminal members and the resistance element are molded with an electrically insulating material, and the support portion integrally supports the first and second terminal members and the resistance element. . For the resistance element, for example, a wire made of an FeCr-based alloy with a small temperature coefficient can be used, or a ceramic substrate with a resistor printed or vapor-deposited can be used. In addition, the support part is formed by molding the resistance element and the first and second terminal members using a heat-resistant insulating resin.
The terminal members are mechanically supported together. Therefore, simply by screwing the first terminal member onto a predetermined glow plug, the resistor can be reliably attached and at the same time electrical connection with the glow plug can be established. Therefore, there is no need to fix it to the engine case, and it can be attached to any engine. As mentioned above, since the resistor element is molded with the support part, its earthquake resistance is significantly improved, and since the resistor element is isolated from the outside air, the surface of the resistor element is protected from the harsh environment in the engine room. , its lifespan can be extended. The support portion may also be constructed from a material such as ceramic.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 2 shows an embodiment of the current detection resistor according to the present invention, in which the current detection resistor 11 is a resistance element made of FeCr alloy wire, which is a material with a relatively small temperature coefficient of resistance, and is bent in a meandering shape. 12, and connection terminals 13 and 14 respectively connected to both ends of the resistance element 12 by appropriate means such as welding. The connection terminal 13 has a bolt terminal 15 of the glow plug.
A screw hole 17 is formed with a screw groove 16 corresponding to the screw groove of the connecting terminal 1.
4 is integrally formed with a bolt terminal 18 for screwing an end of a wiring (not shown) connected to the battery.

In order to extract the potential drop that occurs in the resistance element 12 when the current flowing through the glow plug is passed through the current detection resistor 11, voltage detection terminals 19,
20 are connected, and these voltage detection terminals are wired to a control circuit to be described later. The free ends of the voltage detection terminals 19 and 20 are configured as claw terminals, and wiring can be connected by simply inserting the ends of the lead wires.

In FIG. 3, only one voltage detection terminal 20 is visible, and the other voltage detection terminal 19 is visible at terminal 2.
0 and does not appear in Figure 3.

In order to mechanically support the resistance element 12 and the connection terminals 13, 14 described above, the bases 13a, 14a of the resistance element 12 and the connection terminals 13, 14 are molded with heat-resistant insulating resin. The target support part 21 is configured. In the illustrated embodiment, as can be seen from FIGS. 2 and 3, the support portion 21
is formed into a cylindrical shape, but its shape can be determined arbitrarily. Furthermore, the support portion 21 may be made of ceramic as well as resin molded.

Next, the operation of the starting assist device 30 using this current detection resistor will be explained with reference to FIG. Here, points A, B, C, and D in FIG. 4 correspond to points a, b, c, and d of the resistance element 12 in FIG. 2. Ignition switch 31
When turned on, the charging time transistor 33 of the capacitor 32 becomes conductive, and the normally open contact 34a of the relay 34
is closed, the preheating indicator lamp 35 is turned on, and at the same time, the normally open contact 36a of the relay 36 is closed, and the glow plug 37 is energized via the current detection resistor 11. While the temperature of the glow plug 37 is low and the resistance of the glow plug is low, the output of the comparator 38 is at a low level and the transistor 33 continues to be conductive.

When the temperature of the glow plug 37 rises and reaches the set temperature, the resistance increases, the resistors 39 and 4
By setting 0, 41, 42, the output of the comparator 38 becomes high level, cutting off the conduction of the transistor 33, and the contacts 34a, 36 of the relays 34, 36.
a to cut off the power to the glow plug 37.

Furthermore, the output of the comparator 38 is at a high level and the relays 34 and 3 are connected to the + input of the comparator 38.
After the contacts 34a and 36a of No. 6 are opened, the current detection resistor 11 is connected so that the output of the comparator 38 remains at a high level even if the input to the comparator 38 via the current detection resistor 11 is cut off. so that a voltage lower than all input voltages is input.
The voltage divided by the resistors 43 and 44 is applied to the diode 4.
Added via 5.

According to such a configuration, the resistance element 12 and the connection terminals 13 and 14 are integrally and firmly supported by the support portion 21, so that the current detection resistor 11 can be connected mechanically by simply screwing the connection terminal 13 to the glow plug. It can be installed firmly and securely, and there is no need to screw it to the engine case, etc., as in the conventional case. Therefore, since it is only necessary to consider compatibility with the glow plug, it is possible to realize a general-purpose current detection resistor that can be used regardless of the model or type of engine. In addition, since the resistor element 12 itself is molded, it has excellent earthquake resistance and can effectively prevent mechanical fatigue of the resistor element due to vibrations from the engine, etc., and has advantages such as a longer service life. have. If there are a plurality of glow plugs as shown in FIG. 4, the glow plugs may be commonly connected by a copper plate or the like, and then a current detection resistor may be screwed onto a predetermined glow plug.

Furthermore, a voltage detection terminal is provided at the tip of which the other party's harness can be extended and inserted, eliminating the need for the heat-resistant special harness and connector used in the past, and reducing costs. . Furthermore, since the voltage detection terminal is connected and fixed to the resistance element in advance, it is possible to solve the conventional problem of managing the tightening torque when connecting the wiring.

Note that the groove 14b formed in the base 14a of the connection terminal 14 in the figure is a groove for locking the blade of a special fastener used when screwing the current detection resistor 11 to the glow plug. This makes it possible to manage the tightening torque.

In the above embodiment, a FeCr-based wire is used as the resistor element 12, but a resistor element formed by printing or vapor depositing a resistor on a ceramic substrate may also be used. , any material can be used. Therefore, as shown in FIG. 5, for example, the resistance element 12 shown in FIG.
The angle between the axes and 14 may be 90°. In the embodiment shown in FIG. 5, the outer shape of the connecting terminal 13 is hexagonal, and the connecting terminal 13 can be tightened to the bolt terminal 15 with a wrench or the like by utilizing this hexagonal shape. Torque management during this tightening is
This can be easily done using a torque wrench. According to such a current detection resistor 11',
This prevents the current detection resistor from becoming taller.
It is possible to effectively utilize the space at the installation location.

According to the present invention, as mentioned above, since the current detection resistor is integrally supported by molding, the installation can be done by simply screwing it onto the glow plug.
Therefore, it is versatile, has excellent earthquake resistance and corrosion resistance, and can have a significantly longer life. Furthermore, since the voltage detection terminals are fixed in advance, there is no need for heat-resistant wire harnesses or connectors, which greatly helps in reducing costs. It also has the advantage of reducing the problem of managing tightening torque.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of a conventional current detection resistor, Fig. 2 is a sectional view of an embodiment of the current detection resistor according to the present invention, and Fig. 3 is a plan view of an example of the current detection resistor shown in Fig. 2. A plan view, FIG. 4 is a circuit diagram showing an example of a control circuit of a diesel engine starting assist device using the current detection resistor shown in FIG. 2, and FIG. 5 is a modification of the embodiment shown in FIG. 2. It is a sectional view showing an example. 11, 11'... Current detection resistor, 12... Resistance element, 13, 14... Connection terminal, 13a, 14
a... Base, 19, 20... Voltage detection terminal, 2
1...Support part.

Claims (1)

[Scope of utility model registration request] A current detection resistor for a glow plug for detecting the magnitude of current flowing through a glow plug for a diesel engine includes a resistor element, and a resistor element connected to one end of the resistor element and screwed to a connection terminal of the glow plug. a second terminal member connected to the other end of the resistance element and connected to wiring on the power supply side; a pair of signal extraction terminals for extracting a detection signal connected in advance to the resistance element; a supporting portion integrally supporting the first and second terminal members and the resistive element, which is formed by molding each base end portion of the first and second terminal members and the resistive element using an electrically insulating material; A current detection resistor for a glow plug, characterized by comprising: