JPH04255520A - Hydrocarbon gas component adsorption system in internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the durability of an adsorbing material and to lower pressure loss by providing a space portion for lowering pressure loss on a part of a HC gas component absorbing material rotated according to the operating condition. CONSTITUTION:An internal combustion engine 1 holds a retaining case 4 for an absorbing material 8 for absorbing a hydrocarbon gas component contained in exhaust gas and a mechanism 3 for rotating an absorbing material 8 according to the operating condition. In this arrangement, a space 10 for lowering pressure loss is provided in a part of the adsorbing material 8. Thus, the durability of the adsorbing material 8 can be improved and pressure loss can be lowered.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adsorption system for hydrocarbon (HC) gas components discharged when starting an internal combustion engine of an automobile or the like.

0002

2. Description of the Related Art As a conventional HC gas component adsorption system, one in which an adsorbent is installed in an exhaust pipe is known. If the adsorbent was placed in the exhaust pipe as it was, the function of adsorbing HC gas components could be ensured.

0003

[Problems to be Solved by the Invention] However, such a system has the following problems. (b) Since it is constantly installed in the exhaust pipe, pressure loss occurs, leading to a decrease in efficiency (output, fuel efficiency, etc.) of the internal combustion engine. (b) Since the HC-based gas component adsorbent is exposed to high-temperature exhaust gas, there is a concern that the adsorption capacity will decrease.

0004

[Means for Solving the Problems] This invention has been achieved as a result of various studies focusing on the above-mentioned problems. This relates to an HC gas component adsorption system for an internal combustion engine, in which an adsorbent having a space for reducing pressure loss is installed in an exhaust pipe, and a mechanism is provided to rotate the adsorbent based on the operating condition of the internal combustion engine. be.

In the HC-based gas component adsorbent system of the present invention, HC-based gas components are adsorbed through the adsorbent at the initial stage of starting an internal combustion engine, and when the temperature of the catalyst rises and becomes activated, the adsorbent is rotated. H that was exposed to exhaust gas and adsorbed
The exhaust gas is passed through the space in an operating region in which the C-based gas component is desorbed and the function of the next adsorbent is not performed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings. FIGS. 1 and 2 are diagrams showing an embodiment of the present invention.

In general, in internal combustion engines such as automobiles, the amount of fuel injection is based on the internal combustion engine's rotational speed, intake air amount, cooling water temperature, etc., and the oxygen concentration in the exhaust gas (whether the fuel is richer or leaner than the stoichiometric mixture ratio). ) The electronic control unit 2 calculates and controls the fuel injection amount, taking into account the following conditions. The oxygen concentration in the exhaust gas is detected by the change in electromotive force of an oxygen sensor 7 installed in the exhaust pipe and using a solid electrolyte such as zirconia. In this way, the air-fuel ratio is maintained near the stoichiometric mixture ratio at which the fuel theoretically burns completely.

[0008] Near the stoichiometric air-fuel ratio, the three-way exhaust gas purifying catalyst 5 - which has precious metals such as Pt and Rh supported on a carrier such as alumina - produces nitrogen oxides (NO) and carbon monoxide (CO).
), it has a high conversion rate for hydrocarbons (HC) and can purify them efficiently.

However, at the initial stage of startup, the catalyst is not activated because the temperature of the catalyst is low, and NO, CO,
The exhaust gas purification ability cannot be fully demonstrated against HC, etc. Furthermore, the amount of HC-based gas components discharged at the initial stage of startup is also quite large.

Therefore, as shown in FIG. 1, at the initial stage of startup, the HC gas components in the exhaust gas discharged from the internal combustion engine 1 are removed by rotating the adsorbent in the holding container 4 by the adsorbent rotation mechanism 3. The temperature of the exhaust gas downstream of the catalyst is detected by the exhaust temperature sensor 6, and when the temperature range in which the catalyst functions is reached and the catalyst is activated, it is temporarily adsorbed and retained by the adsorbent in the container 4. It is rotated and exposed to exhaust gas, and the adsorbed HC gas components are desorbed and purified by the downstream catalyst 5.

The adsorbent 8 shown in FIGS. 2(a) and 2(b)
For example, noble metal components such as Pd, Pt, and Rh may be supported on a carrier such as alumina and coated uniformly on a honeycomb carrier, or a material such as zeolite may be coated. The illustrated adsorbent has a through-space part with a circular cross section as a space part 10 for reducing pressure loss in a part thereof, and a through-hole 9 shaped like a rotating shaft in the center part.

The through hole 9 for the rotating shaft provided in the center of the adsorbent is made of stainless steel or the like having excellent heat resistance and corrosion resistance. For example, bearings are installed at both ends of the holding container 4 to ensure smooth rotation. The adsorbent rotation mechanism 3 consists of an electric motor and a transmission part such as a gear that rotates a rotating shaft.

[0013]

[Operation] Next, the operation will be explained. The action will be explained based on the position of the space provided in the adsorbent.

At the end of the operation of the system, the position of the space 10 is as shown by the solid line in FIG. This position is defined as the origin (0°). At this position, the exhaust gas is passing through the voids of the adsorbent.

a) Whether or not the internal combustion engine is ready to be started is determined by the electronic control unit 2 based on a signal from a key insertion detection section installed in the insertion part of the starting key and the cooling water temperature of the internal combustion engine. . Note that FIG. 4 shows a flowchart for controlling the rotation of the adsorbent. If the internal combustion engine is in a cold state (for example, the cooling water temperature is below 50 degrees Celsius, which is T degrees Celsius in the low chart) and it is determined that the restart is not immediately after the engine has stopped (NO), immediately turn the engine on the broken line in Figure 3. Rotate the adsorbent to the position shown. In order to maximize the cross-section of the adsorbent in contact with the exhaust gas, as shown in Figure 3, the radius of the adsorbent: R, the radius of the space: r, the position of the space at startup: δ, then δ=2θ sin θ Rotate by the angle δ determined from =r/(R-r).

b) Rotating the HC-based gas component adsorbent 8 at the same time as detecting the start-up to discharge the maximum amount of HC components;
During the initial startup time, the spatial part (origin) shown by the solid line in Figure 3
Rotate it to the position. H depending on the specifications and characteristics of the internal combustion engine.
Since the time required to discharge more C varies, the time appropriate for each characteristic is measured in advance, and the control pulse for motor operation is set so that the motor rotates to the position of the space shown by the solid line in Figure 3 within that time. Set.

c) The exhaust temperature downstream of the exhaust purification catalyst is preferably detected by an exhaust temperature sensor 6, and the temperature range where the catalyst fully functions (for example, the HC conversion efficiency is 80%) is detected.
% or more (K°C), the adsorbent 8 is rotated 360° again for a certain period of time. The HC components exposed to the exhaust gas undergo a catalytic reaction to some extent on the spot and are partially purified, and then the remainder is desorbed into the exhaust gas and further purified by the downstream catalyst 5.

By controlling the shape and rotation of the HC gas component adsorbent as described above, it is possible to efficiently purify the HC gas component discharged at the initial stage of startup.

In the above embodiment, the space of the adsorbent was a complete space, but in the adsorbent of other embodiments,
For example, if the space of the adsorbent is not a complete space,
) has a rough honeycomb structure in which the space is divided into four equal parts by partition walls. With such a structure, the strength of the entire adsorbent is improved. Furthermore, by thickening the peripheral wall 11 of the space, heat transfer from the exhaust gas to the adsorbent can be reduced.

[0020]

As explained above, according to the present invention, a space is provided in a part of the HC-based gas component adsorbent, and the structure is such that it is rotated depending on the operating condition of the internal combustion engine. The durability of the system gas component adsorbent can be improved, and 2) the effects of reducing pressure loss can be obtained.

Furthermore, as shown in the examples, since the HC gas components are desorbed after reaching the operating temperature range of the catalyst, there is an effect that the purification rate of the adsorbed HC gas components can be increased. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an entire exhaust purification system for an internal combustion engine incorporating an HC-based gas component adsorption system of the present invention.

FIG. 2(a) is a front view of the adsorbent, and FIG. 2(b) is a side view of the adsorbent.

FIG. 3 is an explanatory diagram for determining the initial rotation angle δ of the spatial portion of the adsorbent.

FIG. 4 is a flowchart for controlling the rotation of the adsorbent.

[Explanation of symbols]

1 Internal combustion engine 2 Electronic control device 3 Rotating mechanism for HC gas component adsorbent 4 Holding container for HC gas component adsorbent 5 Exhaust gas purification catalyst 6 Exhaust temperature sensor 7 Exhaust pipe 8 HC gas component adsorbent 9 Rotating shaft Through hole 10 for adsorption material Space 11 Peripheral wall of the space part

Claims (1)

[Claims] [Claim 1] Contained in exhaust gas of an internal combustion engine,
The present invention is characterized in that it includes an adsorbent that adsorbs hydrocarbon-based gas components and a mechanism for rotating the adsorbent depending on the operating condition of an internal combustion engine, and that the adsorbent has a space in a portion thereof that reduces pressure loss. Adsorption system for hydrocarbon gas components in internal combustion engines.