JPH0538314U - Catalyst early activation device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a catalyst early activation device that can activate the catalyst early by the reaction heat of a hydrogen storage alloy without using a heater or high frequency and can prevent the occurrence of thermal strain. [Structure] An outer cylinder 11 for accommodating a hydrogen storage alloy 5 for heating the catalyst 4 is provided around the catalyst 4 provided in the inner cylinder 3 of the exhaust pipe. Further, both ends of the inner cylinder 3 and the outer cylinder 11 are connected to each other by a bellows 15 which is axially expandable and contractible. On the other hand, hydrogen is supplied from the hydrogen cylinder to the hydrogen storage alloy 5 through the hydrogen pipe, and a hydrogen reaction is caused in the hydrogen storage alloy 5 to generate heat of reaction to activate the catalyst 4. When the hydrogen storage alloy 5 undergoes a hydrogen reaction to generate reaction heat, the inner cylinder 3 and the outer cylinder 11 are heated to cause thermal expansion, and thermal stress is generated due to a difference in thermal expansion coefficient, but the bellows 15 expands and contracts. And absorbs thermal expansion.

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-mentioned object, the present invention provides an inner cylinder, which is provided in an exhaust path of an engine and accommodates a catalyst therein, and an inner cylinder, which is provided so as to cover the inner cylinder and heats the catalyst therein. It has a double structure with an outer cylinder containing a hydrogen storage alloy.One end of the outer cylinder is fixed to the inner cylinder and the other end is fixed to the outer cylinder on both axial sides of the outer cylinder. An expandable bellows is provided in the hydrogen storage alloy, hydrogen is supplied to the hydrogen storage alloy, and hydrogen gas is supplied to the hydrogen storage alloy to activate the catalyst by causing a hydrogen reaction to generate a reaction heat. ..

According to a second aspect of the present invention, an inner cylinder provided in the exhaust path of the engine and containing the catalyst therein, and a low temperature activated type and a high temperature activated type which are provided to cover the inner cylinder and heat the catalyst inside At least two types of hydrogen storage alloys and an outer cylinder containing hydrogen gas have a double structure, and an electric heater for heating the low-temperature activated hydrogen storage alloy is provided in the outer cylinder. Further, on both axial ends of the outer cylinder, one end is fixed to the inner cylinder and the other end is fixed to the outer cylinder, and bellows that are expandable and contractible in the axial direction of the inner cylinder and the outer cylinder are provided.

[0013]

[Action]

 According to the first aspect, when hydrogen is supplied to the hydrogen storage alloy by a start signal of the engine or the like, the hydrogen storage alloy chemically changes and reaction heat is generated at that time. The heat of reaction heats the catalyst and activates it early. When the hydrogen storage alloy generates heat, the inner cylinder and the outer cylinder thermally expand, but the expansion is absorbed by the bellows to prevent thermal strain.

According to a second aspect of the present invention, when the electric heater is energized by a start signal of the engine or the like, the electric heater heats the low temperature activated hydrogen storage alloy to cause a hydrogen reaction, and the reaction heat thereof is converted to the high temperature activated type. When transmitted to the hydrogen storage alloy, the high temperature activated hydrogen storage alloy undergoes a chemical change and generates heat of reaction at that time. The heat of reaction heats the catalyst and activates it early. Further, when the high temperature activated hydrogen storage alloy generates heat, the inner cylinder and the outer cylinder thermally expand, but the expansion is absorbed by the bellows to prevent thermal strain.

[0015]

【Example】

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

1 to 4 show a first embodiment, 1 is a gasoline engine of an automobile, and 2 is an exhaust pipe as an exhaust path for discharging 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. Further, a Zr.Ti.Fe.V.Cr-based hydrogen storage alloy 5 is provided outside the inner cylinder 3.

Further, 6 is a hydrogen cylinder as a hydrogen supply means, and this hydrogen cylinder 6 communicates with the hydrogen storage alloy 5 through a hydrogen pipe 7. An electromagnetic opening / closing valve 8 is provided in the middle of the hydrogen pipe 7, and the electromagnetic opening / closing valve 8 is electrically connected to the battery 10 via an engine key 9 provided in the driver's seat of the automobile.

The engine key 9 has terminals for OFF, ACC, ON, and IGN. When the movable contact 9a comes into contact with the ON terminal 9b, that is, before the IGN switch is turned on, A valve opening signal is input.

An outer cylinder 11 is provided on the inner cylinder 3 so as to cover it, and an annular space 12 is formed between the inner cylinder 3 and the outer cylinder 11. 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 thereof is coated with a coating film of a material that is difficult to permeate hydrogen gas. Further, gaskets 14 and 14 made of a copper material having a high coefficient of 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 over the entire circumference of the 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.

Furthermore, a shim 15 a is interposed between the backup ring 13 and the bellows 15. Thus, the outer space 11 and the annular space 12 sealed by the backup ring 13 are formed on the outer periphery of the inner cylinder 3, and the hydrogen storage alloy 5 is accommodated in the inner space 12.

Further, a plurality of pipes 16 are provided penetrating the inside of the annular space 12, and the pipes 16 are formed with through holes 16 a. The base end of the pipe 16 is connected to the hydrogen pipe 7.

Next, the operation of the catalyst early activation device configured as described above will be described. First, when the temperature of the three-way catalyst 4 is Ta as shown in FIG. 4 while the engine is stopped, the minimum pressure required for the hydrogen storage alloy 5 to store hydrogen is Pa. 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 electromagnetic opening / closing valve 8 opens.

When the electromagnetic on-off valve 8 is opened, hydrogen gas pressurized from the hydrogen cylinder 6 to Pa or more is supplied to the hydrogen storage alloy 5 inside the annular space 12 via the hydrogen pipe 7. ..

When hydrogen gas is supplied to the hydrogen storage alloy 5, as shown in FIG. 1, the hydrogen storage alloy 5 takes in the hydrogen gas and undergoes a chemical change to generate reaction heat. This reaction heat heats the three-way catalyst 4 via the inner cylinder 3 and activates the catalyst early.

Here, when the hydrogen storage alloy 5 is a Zr.Ti.Fe.V.Cr system, it is 7.6 kcal / molH ₂ , and the temperature increases up to 350 ° C. at which the three-way catalyst 4 is activated. The required amount of heat of 30 kcal can be covered by an alloy reaction of about 20 g.

When the three-way catalyst 4 is activated and the warm-up of the engine 1 and the like is finished and steady operation becomes possible, this time, as shown in FIG. 2, the heat of the exhaust gas exhausted from the engine 1 causes the catalyst temperature to rise. Becomes Tb, the hydrogen gas stored in the hydrogen storage alloy 5 is released until the pressure reaches Pb, and returns to the hydrogen cylinder 6 through the hydrogen pipe 7.

Here, when the electromagnetic opening / closing valve 8 is closed, hydrogen gas having a pressure sufficient to cause the hydrogen storage alloy 5 to react next is stored in the hydrogen cylinder 6. Therefore, the ternary catalyst 4 can be activated early by the reaction heat of the hydrogen storage alloy 5 without using a heater or a high frequency.

Further, the hydrogen storage alloy 5 undergoes a chemical change, and the reaction heat thereof heats the inner cylinder 3 and the outer cylinder 11 to cause thermal expansion, which causes thermal stress due to the difference in thermal expansion coefficient. Since the inner cylinder 3 and the outer cylinder 11 are connected by the bellows 15, the bellows 15 expands and contracts to absorb the thermal expansion, and the occurrence of thermal strain can be prevented. 5 to 7 show the second embodiment, and the portions common to the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Two types of hydrogen storage alloys, a low temperature activated hydrogen storage alloy 21 and a high temperature activated hydrogen storage alloy 22, are accommodated in the annular space 12 provided on the outer periphery of the inner cylinder 3 that accommodates the three-way catalyst 4. Has been done. 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. The high-temperature activated hydrogen storage alloy 22 is a Ti / Fe / Co / Zr-based alloy. It 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.

Further, the electric heater 23 is electrically connected to the engine key 9 for starting 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.

Next, the operation of the catalyst early activation device configured as described above will be described. Now, when the temperature is 0 ° C., it is understood 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 reaction heat is generated with the storage of hydrogen gas 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 finished 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 high temperature activated type hydrogen storage alloys 21 and 22 undergo a chemical change, and the heat of reaction heats the inner cylinder 3 and the outer cylinder 11 to cause thermal expansion, resulting in a difference in coefficient of thermal expansion. 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.

[0040]

[Effect of the device]

 As described above, according to claim 1 of the present invention, a hydrogen storage alloy for heating a catalyst provided in an exhaust path of an engine is provided, hydrogen is supplied to the hydrogen storage alloy, and a hydrogen reaction is performed on the hydrogen storage alloy. By activating the catalyst to generate heat of reaction to activate the catalyst, the catalyst can be activated early by the heat of reaction of the hydrogen storage alloy without using a heater or a high frequency. Therefore, it is possible to solve the pollution problem that a large amount of HC and CO are released into the atmosphere after the engine is started and before the temperature of the catalyst rises. In addition, the hydrogen storage alloy undergoes a chemical change, and the heat of reaction heats the inner and outer cylinders, causing thermal expansion, which causes thermal reaction due to the difference in the coefficient of thermal expansion. Since it is connected to the outer cylinder by a bellows, the bellows expands and contracts to absorb thermal expansion and prevent thermal strain.

According to the second aspect, by using the hydrogen storage alloy having different characteristics of the low temperature activated type and the high temperature activated type hydrogen storage alloy, the catalyst can be activated with a small power consumption and it is not necessary to provide a hydrogen cylinder. It is structurally simple and can be provided at a low price.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a catalyst early activation device according to a first embodiment of the present invention when hydrogen gas is supplied.

FIG. 2 is an overall configuration diagram when hydrogen gas is released in the catalyst early activation device of the same 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.

FIG. 5 is an overall configuration diagram of a catalyst early activation device according to a second embodiment of the present invention.

FIG. 6 is an enlarged vertical sectional side view of a case portion of the embodiment.

FIG. 7 is a graph of the example.

[Explanation of symbols]

3 ... Inner cylinder, 4 ... 3-way catalyst, 5 ... Hydrogen storage alloy, 6 ... Hydrogen cylinder, 11 ... Outer cylinder, 15 ... Bellows, 21 ... Low temperature activated hydrogen storage alloy, 22 ... High temperature activated hydrogen storage alloy, 23
… Electric heater.

Claims (2)

[Scope of utility model registration request] 1. An inner cylinder provided in an exhaust path of an engine and containing a catalyst therein, an outer cylinder provided so as to cover the inner cylinder and containing a hydrogen storage alloy for heating the catalyst, and an outer cylinder thereof. It is provided on both axial ends of the cylinder, one end is fixed to the inner cylinder and the other end is fixed to the outer cylinder, and the bellows which can be expanded and contracted in the axial direction of the inner cylinder and the outer cylinder and hydrogen are supplied to the hydrogen storage alloy. And a hydrogen gas supplying means for activating the catalyst by causing a hydrogen reaction in the hydrogen storage alloy to generate reaction heat, and an early activation device of the catalyst. 2. An inner cylinder provided in an exhaust path of an engine and containing a catalyst therein, and at least two types of a low temperature activated type and a high temperature activated type which are provided so as to cover the inner cylinder and heat the catalyst therein. An outer cylinder containing a hydrogen storage alloy and hydrogen gas, an electric heater provided in the outer cylinder for heating the low-temperature activated hydrogen storage alloy, and provided on both axial ends of the outer cylinder, one end of which is the inner portion. An early activation device for a catalyst, comprising: a bellows, which is fixed to a cylinder and the other end of which is fixed to an outer cylinder, and which is capable of expanding and contracting in the axial direction of the inner cylinder and the outer cylinder.