JPH02173312A - Catalyst converter - Google Patents

Abstract

PURPOSE:To attempt to improve emission purification efficiency by ventilating the sub-current of exhaust gas from a by-pass passage to unburnt gas absorbent when a catalyst comes up to an activating temperature and by discharging it to a catalyst support having activated hydrocarbon once trapped. CONSTITUTION:The inlet of a by-pass passage 11 is shut as well as the inlet of a catalyst case 3 is opened by turning a changeover valve 17 upward when the temperature of catalyst supported on a plural number of catalyst supports 8 and 9 respectively reaches an activating temperature. Then, the main current of exhaust gas is ventilated from the inlet port of the catalyst case 3 to each of the catalyst supports 8 and 9. Additionally, after the sub-current of exhaust gas is ventilated to the by-pass passage 11 on the upstream of unburnt gas absorbent 16, that is, an upstream by-pass passage 12 through the leak hole 21 of the changeover valve 17, it is ventilated between respective catalyst supports 8 and 9 through unbrunt gas absorbent 16 and a downstream by-pass passage 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a catalytic converter provided with a hydrocarbon adsorbent that adsorbs gas that is generated when an engine is started, for example, when the catalyst does not reach its activation temperature.

(Prior art) Conventionally, the catalytic converter of the above example is
There is an apparatus described in Japanese Patent No. 0-190923.

In other words, a catalyst is installed in the exhaust system of the engine to purify harmful components in the exhaust gas, and a catalyst is installed upstream of the catalyst in the exhaust system to remove unburned gas from the exhaust gas when the exhaust gas is at a low temperature. This catalytic converter includes an adsorbent for unburned gas that adsorbs the gas, and a moisture adsorbent that adsorbs moisture in the exhaust gas and is disposed upstream of the adsorbent for unburned gas that also enters the exhaust system.

This conventional catalytic converter has the following problems because the above-mentioned unresolved gas adsorbent is arranged in series on the upstream side of the catalyst carrier.

In other words, the activation temperature of the above catalyst is approximately 200-300°C.
Since the hydro-bon release temperature of the pre-gas adsorbent is about 100 to 200°C, when the above-mentioned catalyst does not reach its activation temperature at engine start (cold), the pre-gas adsorbent absorbs water in the exhaust gas. Although it is possible to wrap the unresolved gas (hydrocarphone) in -・U1~,
When this unburned gas adsorbent reaches the hydrocarbon release temperature, for example 100°C, the catalyst will reach the activation temperature (approximately 200-300°C).
00°C), and the hydrocarbons partially trapped by the unburned gas adsorbent mentioned above are released via the unactivated catalyst carrier, resulting in a low emission purification efficiency. was.

(Objective of the Invention) An object of the present invention is to provide a catalytic converter that can significantly improve emission purification efficiency.

(Structure of the Invention) In this invention, a catalyst carrier is disposed in the case 1 to the case, branched from the upstream side of the catalyst carrier, and then the catalyst carrier is
A bypass passage connected to the upstream side is provided, a gas adsorbent is disposed in the bypass passage, and a switching means is provided at the upstream branch part for controlling switching of the exhaust gas to the catalyst case inlet and the bypass passage inlet 1]. In addition, the catalytic converter is characterized in that a leakage portion is formed to prevent part of the exhaust gas from leaking into the bypass passage of the first flow of the gas adsorbent when the bypass passage inlet is closed by the switching means.

(Effects of the Invention) According to the present invention, when the engine starts when the catalyst does not reach the activation temperature, the above-mentioned switching means opens the bypass passage inlet and closes the case inlet to the catalytic converter 1, so that the exhaust gas is released. The exhaust gas flows from the bypass passage entrance to the unburned gas adsorbent, and the unburned gas (hydrocarbon) in the exhaust gas is trapped by the unburned gas adsorbent.

Furthermore, when the above-mentioned catalyst reaches the activation temperature, when the above-mentioned switching means opens the CALRIS 1-Case 1 and closes the bypass passage inlet, the main flow of exhaust gas flows from the CALRIS 1-Case inlet to the catalyst carrier. On the other hand, a part of the exhaust gas flows through the first flow bypass passage to the unburned gas adsorbent through two leakage parts, and is lapped once. Hydrocarbons are released onto an activated catalyst support.

As a result, the double emitted hydrocarbons are reliably purified by the activated catalyst carrier, which has the effect of significantly improving the emission purification efficiency.

(Example) An embodiment of the present invention will be described in detail below based on the drawings.

The drawing shows a catalytic converter, and in Fig. 1, a front exhaust pipe 2 is connected to the rear of the exhaust manifold 1, and a pipe 4 is connected to the middle exhaust 1 after the front exhaust pipe 2 through the gearris 1 and the case 3. In addition, a main silencer 5 is connected to the rear stage of the middle exhaust pipe 4 to form an exhaust system.

As shown in FIG. 2, the above-mentioned catalyst case 3 has a first-stage catalyst carrier 8 and a second-stage catalyst carrier 9 arranged in series through ring-shaped steel pins 1 to 67 and inkram pines 1 to 6a, 7a. They are housed separately.

A rectangular cylindrical switching valve housing 10 is integrally formed on the upstream side of the above-mentioned front catalyst carrier 8 and in the middle part of the above-mentioned front exhaust pipe 2, and this switching valve housing 10 and the carris 1-case are integrally formed. A bypass passage FRt11 is formed that communicates between the catalyst carriers 8 and 9 at the front and rear stages in the catalyst carrier 3.

This bypass passage 11 includes an inverted I-shaped upstream bypass passage 12, an inverted I-shaped downstream bypass passage 13, and an I (C adsorption device 14) interposed between these two passages 1.2.13. , this HC adsorption device 14 houses an unburned gas adsorbent 16 in a case 15.

The unburned gas adsorbent 16 includes a carrier such as metal or Gorgely 1, and an adsorbent such as zeolite.

By the way, in the switching valve housing 10 mentioned above, exhaust gas is passed through the passages 1 to 3 and the bypass passage 11.
There are four switching valves 17 as switching means for switching control between the population and the population.

A valve shaft 18 (see FIG. 3) of this switching valve 17 is led out to the outside of the switching valve housing 10, and an actuator 20 is connected to this leading end via one link as shown in FIG. .

'' The two actuators 20 are driven and controlled by a boost signal, an engine rotation speed signal, an exhaust gas temperature signal, a time signal, etc., and the catalysts on the catalyst carriers 8 and 9 reach the activation temperature (approximately 200℃).
-300 DEG C.), the switching valve 17 is switched to the solid line position shown in FIG. 2, and when the catalyst activation temperature is not reached, the switching valve 17 is switched to the phantom line position shown in FIG.

'' The two switching valves 17 are controlled to switch as shown by the imaginary lines in FIG. A leak hole 21 serving as a leakage portion for leaking into the upstream side bypass passage 11, that is, the above-mentioned upstream bypass passage 12, is formed in the above-mentioned switching valve 17 as shown in FIGS. 2 and 3.

The illustrated embodiment is constructed as described above, and its operation will be explained below.

The catalyst of the catalyst carriers 8 and 9 described above has an activation temperature (approximately 200 to 3
When starting the engine, the temperature does not reach 00°C, the switching valve 17 in the solid line position opens the bypass passage 11 and closes the catalyst case 3.
Exhaust gas flows through the switching valve housing 10 as an upstream branch part.
The exhaust gas then reaches the unburned gas adsorbent 16 of the HC adsorption device 14 via the upstream bypass passage 12, where the unburned gas (hydrocarbon) in the exhaust gas is wrapped.

Further, the catalyst of the catalyst carriers 8 and 9 described above has an activation temperature (approximately 20
0 to 300°C), the actuator 20 is operated to switch the switching valve 17 from the solid line position in FIG. 2 to the imaginary line position in the same figure. , occlude the bypass passage 11 population.

Therefore, the main stream of exhaust gas flows from the catalyst case 3 to the catalyst carriers 8 and 9, while a part of the exhaust gas passes through the leak hole 21 formed in the above-mentioned switching valve 17 to the unburned gas adsorbent 16. After flowing through the upstream bypass passage 11, that is, the upstream bypass passage 12, the gas flows between the front and rear catalyst carriers 8 and 9 in the catalyst case 3 via the unburned gas adsorbent 16 and the downstream bypass passage 13, and the above-mentioned Some of the hydrocarbons trapped by the unburned gas adsorbent are released onto the activated downstream catalyst carrier 9.

As a result, the above-mentioned emitted hydrocarbon is reliably purified by the activated downstream catalyst carrier, which has the effect of significantly improving the emission purification efficiency.

In addition, if the leak hole 21 is formed as a leakage part in the above-mentioned switching valve 17 as shown in the embodiment, a part of the exhaust gas at the time of starting the engine can be guided from the leak hole 21 to the front stage catalyst carrier 8. Therefore, the first-stage catalyst carrier 8 can reach the activation temperature quickly, and the reaction heat of the catalyst carrier 8 can also shorten the time it takes for the second-stage catalyst carrier 9 to reach the activation temperature.

FIG. 4 shows another embodiment of the catalytic converter. In this embodiment, the exhaust pipe connection part 23 on the front side of the taper cone part 22 of the catalyst case 3 is used as an upstream branch part, and this exhaust pipe connection part 23 and each catalyst carrier A bypass passage 24 is provided to communicate between the catalyst case 3 and the bypass passage 24, and the bypass passage 24 is provided along the outer surface of the catalyst case 3, so that the catalyst case 3 and the bypass passage 24 are closely integrated.

Further, an unburned gas adsorbent 16 is disposed inside the bypass passage 24 corresponding to the pre-catalyst carrier 8, and when the bypass passage 24 is blocked by the switching valve 17, a part of the exhaust gas is transferred to the unburned gas adsorbent 16. A leak hole 25 is formed in the above-mentioned taper cone portion 22 so as not to leak into the upstream bypass passage 24 .

With this configuration, it is possible to warm up the unburned gas adsorbent 16 with the reaction heat of the pre-catalyst carrier 8, thereby facilitating the release of hydrocarbons trapped in the adsorbent 16, and at the same time, it is possible to easily release the hydrocarbons trapped in the adsorbent 16. This has the effect of making it smaller and lighter.

In other respects, the operation and effects are substantially the same as in the previous embodiment, so the same parts in FIG. 4 as in FIG. 2 are given the same numbers, and detailed explanation thereof will be omitted.

In the correspondence between the configuration of the present invention and the embodiments described above, the upstream branch section of the present invention corresponds to the switching valve housing 10 of the first embodiment and the exhaust pipe connection section 23 of the second embodiment, and the same applies hereafter. Although the switching means corresponds to the switching valve 17 and the leakage portion corresponds to the leak hole 21.25, the present invention is not limited to the configuration of the above-described embodiment.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is a side view of an engine exhaust system equipped with a catalytic converter, FIG. 2 is a sectional view of the catalytic converter, FIG. 3 is a perspective view of a switching valve, and FIG. 4 is a side view of an engine exhaust system equipped with a catalytic converter. FIG. 3 is a sectional view showing another embodiment of the catalytic converter. 3... Catalyst case 8... Front stage M! Medium carrier 10...Switching valve housing 11, . 24...Bypass passage 16...Unburnt gas adsorbent 17 21.25...Leak hole 23...Exhaust pipe connection part 9...Late stage catalyst carrier...Switching valve 3...Catawast case 8 ...Da ■ 9 Milk J side 9... Ih stage - O 16... Gas intake port O 17... Cut off m 23... Exhaust @ J# Marobe 24... Hypanu Wakuro 25...l Norku FL Figure 3 Figure 4

Claims (1)

[Claims] (1) A catalyst carrier is disposed in the catalyst case, a bypass passage is provided that branches from the upstream side of the catalyst carrier and connects again to the upstream side of the catalyst carrier, and a gas adsorbent is disposed in the bypass passage. , A switching means is provided in the upstream branch part to switch the exhaust gas between the catalyst case inlet and the bypass passage inlet, and when the bypass passage inlet is closed by the switching means, a part of the exhaust gas is transferred to the gas adsorbent beforehand. A catalytic converter with a leakage part that leaks into the upstream bypass passage.