JPS645048Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust gas purification device for a diesel engine, and more specifically, it removes carbon particles and similar particulate matter (exhaust particulates or particulates) contained in exhaust gas by a physical method. The present invention relates to a structure of a particulate trap suitable for collecting on a suitable collection material such as a filter element, periodically incinerating the collected exhaust particulates, and regenerating the collection material.

Most of these types of exhaust particulates are flammable, such as carbon particles, and diesel particulates collect these flammable particulates and incinerate them to regenerate the collection material. Various traps are known. An electric heater is generally used as a means for burning the collected particulate and regenerating the trap. That is, an electric heater is attached to the front end surface of the collection material, and the heater burns the exhaust particulates adhering to the surface of the collection material, which is used as a heat source to cause the downstream particulates to self-combust. However, none of the conventional particulate traps controls the temperature of the heater. in general,
In order to reliably ignite and burn the particulate, it is necessary to heat the heater to a high temperature of several hundred degrees, but this temperature condition naturally changes depending on the flow rate of exhaust gas passing through the trap or fluctuations in the battery voltage of the power supply. It is something that should be done. Otherwise, if the heater temperature is not controlled, if the exhaust gas flow rate decreases or the battery voltage increases, the heater temperature will become higher than the originally planned temperature (design temperature), resulting in overheating. However, in the past, the heater temperature was designed according to the most general usage conditions, and once it was set to the designed value, it was not controlled according to the operating conditions.

In view of this, the present invention constantly detects the temperature of the electric heater or a physical quantity representing it, and stops power supply to the heater when the heater reaches a predetermined temperature based on the detection signal. The purpose is to prevent the temperature of the heater from exceeding a set value regardless of changes in external or internal factors, thereby preventing overheating of the heater and thereby preventing melting and deterioration of the heater.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall structure of a particulate trap according to the present invention, and a trap container 1 has a collection material (trap material) 3 therein. As the collection material 3, known foamed ceramic or similar materials can be used. That is, the collection material 3
has a three-dimensional mesh structure, through which exhaust gas can flow, and exhaust particulates contained in the exhaust gas can be collected between the meshes.

A trap container 1 is placed in an exhaust pipe 2 of a diesel engine. It is assumed that the exhaust gas flows in the direction of the arrow in FIG.

An electric heater 10 is provided at the inlet side (upstream side) end of the trap container 1, if necessary, for igniting and burning the exhaust particulates collected by the collection material 3 to regenerate the trap.

The heater 10 may be, for example, as shown in FIG. 2, in which two heater wires bent in a zigzag pattern are arranged so as to extend over the entire trap entrance; however, the shape and type of the heater is not limited thereto; It may also be a porous disk-shaped ceramic heater having through-holes, a PTC (positive characteristic thermistor) heater, or the like.

As is well known, the timing of energizing the heater, that is, the timing of trap regeneration, is appropriately controlled by the control unit ECU (Fig. 2) based on various control parameter signals S such as engine speed, load, engine water temperature, back pressure, etc. be done.

The heater 10 is generally brought into contact with the front end surface of the collecting material 3, but may be slightly separated from the front end surface of the collecting material 3 as shown in FIG.

According to the present invention, the heater 10 is provided with a detector 13 for measuring the temperature of the heater 10. Detector 1
3 may be a thermocouple attached directly to the heater 10, for example. The thermocouple is preferably mounted on a heater close to the trap vessel 1 so as not to be directly exposed to the exhaust gas stream. This is because the further away from the center of the exhaust gas flow the heater is less likely to be cooled down by the exhaust gas flow, making it easier to reach the maximum temperature of the heater.
Apart from this, for example, when a PTC heater is used, the temperature change of the heater is represented by a resistance (voltage) change, so the heater itself can be considered to have a built-in detector. The signal from the detector 13 is
The signal is sent to the ECU, and the switch means 17 is controlled to turn on and off based on the signal. The switch means 17 is provided in the wiring connecting the heater 10 and the power source (battery) 15. The switching means may be, for example, a conventional relay switch. This relay switch is turned on when the temperature of the heater becomes below T° C. again, and starts supplying current to the heater.

With the above configuration, according to the present invention, when the heater 10 reaches the predetermined temperature T° C. (FIG. 3), the control parameter signal S
Even if all of the conditions for energizing the heaters are satisfied, the energization to the heaters is forcibly stopped by the switch means 17. In this way, overheating of the heater is effectively prevented and the original purpose can be achieved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing the overall configuration of the exhaust particulate purification device according to the present invention, and FIG. 2 is a diagram showing a circuit for controlling the energization timing to the heater according to the present invention.
FIG. 3 is a flowchart of the main parts of the control circuit shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Trap container, 2... Exhaust pipe, 3... Collection material, 10... Heater, 13... Detector, 17...
…Switch means.

Claims (1)

[Scope of utility model registration request] An electric heater is attached to the inlet side end of the exhaust particulate collection material installed in the exhaust pipe of the diesel engine, and the electric heater is connected to a power source to ignite and burn the exhaust particulates collected by the collection material at a predetermined time. In an exhaust particulate purification device designed to
a detector for detecting the temperature of the electric heater is provided near the outer periphery of the heater away from the center of the exhaust gas flow, and the heater and the power source are turned on based on a signal from the detector; An exhaust particulate purification device for a diesel engine, characterized in that it is connected by a switch means for off-controlling.