JPH0538313U - Catalyst early activation device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a catalyst early activation device capable of early activation of the catalyst by reaction heat of a hydrogen storage alloy. [Structure] An outer cylinder 11 for accommodating a hydrogen storage alloy for heating the catalyst 4 is provided around the catalyst 4 provided in the inner cylinder 3 of the exhaust pipe. Further, an electric heater 23 for accommodating the low-temperature activated hydrogen storage alloy 21, the high-temperature activated hydrogen storage alloy 22 and hydrogen gas inside the outer cylinder 11 and further heating the low-temperature activated hydrogen storage alloy 21 is provided. The electric heater 23 is energized to cause hydrogen reactions in the low temperature activated type and high temperature activated type hydrogen storage alloys in order to generate reaction heat and activate the catalyst 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a catalyst early activation device that early activates a catalyst provided in an exhaust path of an automobile engine.

[0002]

[Prior Art]

 Emissions from exhaust gas from automobiles that burn gasoline engines are reduced by performing a redox reaction of HC and CO with a three-way catalyst. However, since the three-way catalyst is activated in a high temperature range and functions as a catalyst, it does not play its role in cold starting.

That is, when the engine is stopped, the three-way catalyst is at room temperature and does not function as a catalyst. However, when the engine is started, the catalyst is heated by the exhaust gas discharged from the engine, and the temperature reaches about 350 ° C. Then, the catalyst carries out redox reaction of HC and CO, but it takes about 3 minutes to rise to the temperature.

Therefore, there is a problem that a large amount of HC and C 2 O are released into the atmosphere after the engine starts and before the temperature of the catalyst rises, and there is a demand for early activation of the catalyst.

Conventionally, it has been known to use a heater or a high frequency as a means for heating the catalyst, but in order to heat the catalyst to a high temperature at an early stage, a large current of about 700 A is required, and it is put to practical use. Is difficult.

Further, recently, a heating device has been known which heats engine cooling water, oil, intake air, etc. by utilizing reaction heat of a hydrogen storage alloy as an alloy highly reactive with hydrogen gas.

This heating device, as disclosed in, for example, Japanese Patent Laid-Open No. 63-198714, connects a heater containing a hydrogen storage alloy, a hydrogen tank storing hydrogen gas, and the heater to the hydrogen tank. And a gas passage having a control valve for controlling.

When the hydrogen tank is heated by the exhaust gas of the engine during cold start or the like, the hydrogen gas is released, and the hydrogen storage alloy inside the heater absorbs the hydrogen gas and heats it. This is a heat pump system that heats the engine cooling water and dissociates the hydrogen gas stored in the hydrogen storage alloy into the hydrogen tank.

[0009]

[Problems to be solved by the device]

 As described above, a heating device for heating engine cooling water, oil, intake air, etc. without using electric power by utilizing the reaction heat of the hydrogen storage alloy is known. At present, no one has solved the problem that a large amount of HC and CO are released into the atmosphere before the temperature rises.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to increase the temperature of the catalyst early after starting the engine to activate the catalyst. It is to provide an early activation device.

[0011]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is directed to activating a catalyst provided in an exhaust path of an engine, in which a case provided to cover the catalyst heats the catalyst and a high temperature activated type. An electric heater for accommodating at least two kinds of hydrogen storage alloy and hydrogen gas is provided in this case for heating the low temperature activated hydrogen storage alloy.

[0012]

[Action]

 When the electric heater is energized by an engine start signal, etc., the low temperature activated hydrogen storage alloy is heated by the electric heater to cause a hydrogen reaction, and the reaction heat is transferred to the high temperature activated hydrogen storage alloy, and the high temperature activated type The hydrogen storage alloy chemically changes and generates heat of reaction at that time. The heat of reaction heats the catalyst and activates it early.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a principle diagram and FIG. 2 is an overall configuration diagram. Reference numeral 1 is an automobile gasoline engine, and 2 is an exhaust pipe as an exhaust path for exhausting the exhaust gas exhausted from the engine 1. An inner cylinder 3 is provided in the middle of the exhaust pipe 2, and a three-way catalyst 4 is provided inside the inner cylinder 3.

As shown in FIG. 3, the inner cylinder 3 is provided with an outer cylinder 11 as a case so as to cover the inner cylinder 3, and an annular space 12 is formed between the inner cylinder 3 and the outer cylinder 11. ing. Backup rings 13 for closing the openings are provided at both ends of the annular space 12.

The backup ring 13 is a metal plate, and the surface of the backup ring 13 is coated with a coating film of a material that is difficult to permeate hydrogen gas. Furthermore, gaskets 14 and 14 made of a copper material having a large thermal expansion are attached to the outer peripheral edge and the inner peripheral edge of the backup ring 13 to seal between the inner cylinder 3 and the outer cylinder 11.

A bellows 15 is provided on the outer side of the backup ring 13 around the entire outer peripheral portion of the inner cylinder 3. One end of the bellows 15 is welded to the outer peripheral surface of the inner cylinder 3, and the other end is welded to the inner peripheral surface of the outer cylinder 11. The bellows 15 is expandable / contractible in the axial direction of the inner cylinder 3 and the outer cylinder 11, absorbs thermal expansion of the inner cylinder 3 and the outer cylinder 11, and absorbs vibration of the three-way catalyst 4 due to fluctuation of exhaust gas pressure. Play a role.

Further, a shim 15 a is interposed between the backup ring 13 and the bellows 15. In this way, the outer cylinder 11 and the annular space 12 sealed by the backup ring 13 are formed on the outer periphery of the inner cylinder 3. Inside the annular space 12, the low temperature activated hydrogen storage alloy 21 and the high temperature activated alloy 21 are formed. Two types of hydrogen storage alloys, hydrogen storage alloy 22, are stored.

The low-temperature activated hydrogen storage alloy 21 is a Zr.Ti.Fe.V.Cr-based alloy that undergoes a hydrogen reaction at about 10 ° C., and the high-temperature activated hydrogen storage alloy 22 is formed of Ti.Fe.Co. It is a Zr-based alloy and is formed so as to cause a hydrogen reaction at about 70 ° C.

The low-temperature activated hydrogen storage alloy 21 is an alloy block which is housed inside a wire mesh 24 having an electric heater 23 in its core and is formed into a substantially columnar shape. These alloy blocks are strip-shaped plate members. Is supported by the annular space 12 by a holder 25 that is curved. Further, the periphery of the low-temperature activated hydrogen storage alloy 21 is covered with the high-temperature activated hydrogen storage alloy 22, and hydrogen gas is accommodated inside the annular space 12.

The electric heater 23 is electrically connected to the engine key 9 to start the engine 1 via the timer switch 26, and the timer switch 26 is set to be turned off 20 seconds after being energized. Has been done.

The engine key 9 is provided in a driver's seat of an automobile and is electrically connected to a battery 10. The engine key 9 has terminals for OFF, ACC, ON, and IGN. When the movable contact 9a contacts the ON terminal 9b, that is, before the IGN switch is turned on, the timer switch 26 is turned on. There is.

As described above, the catalyst early activation device of the present invention, as shown in FIG. 1, has a low temperature activated hydrogen inside the outer cylinder 11 as a case provided so as to cover the ternary catalyst 4. The storage alloy 21, the high-temperature activated storage alloy 22, and hydrogen gas are contained, and these are covered by the electric heater 23.

Next, the operation of the catalyst early activation device configured as described above will be described. Now, when the temperature is 0 ° C., it can be seen that neither the low temperature activated hydrogen storage alloy 21 nor the high temperature activated hydrogen storage alloy 22 causes a hydrogen reaction, as shown in FIG.

Here, when the engine key 9 is input to start the engine 1 and the movable contact 9a comes into contact with the ON terminal 9b, the timer switch 26 is turned ON and the electric heater 23 is energized.

Then, when the electric heater 23 generates heat and the temperature of the low temperature activated hydrogen storage alloy 21 becomes 10 ° C. or higher, the reaction starts, and the reaction heat is generated with the storage of hydrogen gas. The heat of reaction of the low temperature activated hydrogen storage alloy 21 is transferred to the high temperature activated hydrogen storage alloy 22 surrounding it (Ta to Tb).

When the temperature of the high-temperature activated hydrogen storage alloy 22 reaches Tb ′, the reaction starts, and when the hydrogen gas is stored, reaction heat is generated and the reaction proceeds to Tc ′. Since the high temperature activated hydrogen storage alloy 22 also has the same temperature as the low temperature activated hydrogen storage alloy 21, the low temperature activated hydrogen storage alloy 21 becomes Tc at that time, releasing hydrogen gas at a pressure of Pc to release the high temperature activated hydrogen storage alloy 21. Hydrogen gas is supplied to the alloy 22. This reaction continues up to the upper limit of the high temperature activated hydrogen storage alloy 22 at about 25 atm and 190 ° C., and the heat of reaction during that time activates the three-way catalyst 4.

When the three-way catalyst 4 is activated and warming up of the engine 1 and the like is completed and steady operation becomes possible, this time, the catalyst temperature rises due to the heat of the exhaust gas exhausted from the engine 1, and the low temperature activated type The hydrogen gas stored in the hydrogen storage alloy 21 and the high temperature activated hydrogen storage alloy 22 is released into the annular space 12.

Further, the low temperature activated type and the high temperature activated type hydrogen storage alloys 21 and 22 undergo a chemical change, the inner cylinder 3 and the outer cylinder 11 are heated by the reaction heat, and thermal expansion occurs, resulting in a difference in thermal expansion coefficient. As a result, thermal stress is generated, but since the inner cylinder 3 and the outer cylinder 11 are connected by the bellows 15, the bellows 15 expands and contracts to absorb thermal expansion, and the occurrence of thermal strain can be prevented. Although two types of alloys, a low temperature activated hydrogen storage alloy and a high temperature activated hydrogen storage alloy, were used in the above-mentioned examples, three or more types of hydrogen storage alloys may be used.

[0030]

[Effect of the device]

 As described above, according to the present invention, the hydrogen storage alloy for heating the catalyst provided in the exhaust path of the engine is at least two types, that is, the low temperature activated type and the high temperature activated type. By providing the hydrogen storage alloy, it is possible to cause a hydrogen reaction in the hydrogen storage alloy and generate reaction heat to activate the catalyst, and the catalyst can be activated early by the reaction heat of the hydrogen storage alloy. Therefore, it is possible to solve the pollution problem that much HC and CO are released into the atmosphere after the engine is started and before the temperature of the catalyst rises. Furthermore, the catalyst can be activated with a small amount of power consumption, and it is not necessary to provide a hydrogen cylinder, which is structurally simple and can be provided at a low cost.

[Brief description of drawings]

FIG. 1 is a principle view of a catalyst early activation device according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a catalyst early activation device according to the embodiment.

FIG. 3 is an enlarged vertical sectional side view of a case portion of the embodiment.

FIG. 4 is a graph of the example.

[Explanation of symbols]

4 ... 3-way catalyst, 11 ... Outer cylinder, 21 ... Low temperature activated hydrogen storage alloy, 22 ... High temperature activated hydrogen storage alloy, 23 ... Electric heater.

Claims (1)

[Scope of utility model registration request] 1. A catalyst early activation device for activating a catalyst provided in an exhaust path of an engine at an early stage, and a catalyst and a low-temperature activation type which is provided so as to cover the catalyst and heats the catalyst therein. An early catalyst, comprising: a case containing at least two types of high temperature activated hydrogen storage alloys and hydrogen gas; and an electric heater provided in the case for heating the low temperature activated hydrogen storage alloys. Activation device.