EP3517747A1

EP3517747A1 - Low temperature heater for exhausted gas purification processing of diesel engine

Info

Publication number: EP3517747A1
Application number: EP19151696.2A
Authority: EP
Inventors: Limin Huang; Lijin HUANG
Original assignee: Guizhou Huangdi Technology Co Ltd
Current assignee: Guizhou Huangdi Technology Co Ltd
Priority date: 2018-01-29
Filing date: 2019-01-14
Publication date: 2019-07-31
Anticipated expiration: 2039-01-14
Also published as: EP3517747B1

Abstract

A low temperature heater for exhausted gas purification processing of a diesel engine is provided. The low temperature heater includes: a tubular combustion chamber including an open end and a closed end; and an intake pipe, where the intake pipe is arranged close to the closed end of the tubular combustion chamber, the intake pipe includes two outlets, a first outlet is inserted into the combustion chamber and an ignition portion, in an eccentric manner, the ignition portion is arranged on a housing of the tubular combustion chamber via a tubular mount seat, the ignition portion is arranged between the first outlet and the closed end, and the mount seat is in communication with a second outlet of the intake pipe.

Description

FIELD

The present disclosure relates to the field of automobile exhausted gas purification processing, and in particular to the field of heating the exhausted gas of a diesel engine to achieve the regeneration of a particulate filter.

BACKGROUND

With the implementation of the Euro 5 emission standard, the diesel particulate filter (DPF) has become an indispensable technology for diesel vehicles. In recent years, with the increase of motor vehicles, the motor vehicles emission has gradually become the main source of air pollution in large cities of China. In the source of atmospheric PM2.5 in Beijing, the exhaust emission of motor vehicles accounts for up to 22%. Moreover, particulate matter emitted by motor vehicles is mainly derived from diesel vehicles. With the establishment of increasingly strict control regulations for diesel vehicle emission of China in recent years, the application of DPF will have a broad market prospect.
In diesel engines, the diesel fuel is burnt based on auto-ignition of different air/fuel mixtures. If the combustion is insufficient, particulates are generated due to oxygen deficiency. Such particulates primarily include carbon (carbon black), sulfates, and insufficiently combusted hydrocarbons. To filter out such particulates, diesel particulate filters have been disclosed in the conventional art.
In a case that a diesel particulate filter is used, the exhaust back pressure generally rises due to an increase in the filter load. Passive or active regeneration of the filter is necessary because an exhaust back pressure exceeding the allowable value is not tolerable for the engine manufacturer, and no maintenance cost due to filter evacuation is expected.
In general, an active diesel particulate filter system includes "electric regeneration system" or "combustor support system". With the system, the regeneration of the DPF may be manually triggered or may be triggered in response to open loop or closed loop control by monitoring the exhaust back pressure.
In the conventional art, the combustor is generally designed to include an ejector having a small opening, so that fuel is atomized in the combustion chamber. In the combustion chamber, the fuel is mixed with air necessary for combustion. A disadvantage of this design is that coking may quickly occur at the tiny atomizing opening of the nozzle due to combustion residues, disturbing the operation of the combustor. For example, combustion residues are formed in a case that the combustor is turned off.
In addition, the currently designed combustor structure is relatively complicated. The conventional combustor has a complicated manufacturing process and a high cost, and problems are prone to occur during the operation of the conventional combustor, for example, as discussed in Chinese Patent Application No. 201310019585.7 . In addition, for some combustors, the DPF can only be regenerated in a case that the vehicle is parked or idling, and cannot be regenerated in a case that the vehicle accelerates or travels at a high speed.
Therefore, it is required in the art a combustor or a low temperature heater that can heat the gas exhausted from a diesel engine to reach the diesel particulate filter regeneration temperature, and can still achieve the regeneration of the particulate filter in a case that the vehicle travels at a high speed or even accelerates. In addition, it is required a combustor or a low temperature heater that can achieve uniform regeneration of the particulate filter in a case that the vehicle travels at a high speed or even accelerates.

SUMMARY

In order to achieve the above object, the inventors of the present application propose a simple structure to realize fuel combustion and exhausted gas heating. In this structure, according to the principle of eccentric air intaking, the introduced fresh air forms a vortex in the combustion chamber, to intensively mix with the hot airflow generated by the combustion, so as to improve the combustion efficiency.
According to an aspect of the present disclosure, a low temperature heater for exhausted gas purification processing of a diesel engine is provided. The low temperature heater includes: a housing that is in fluid communication with an exhaust pipe of the diesel engine; a glow plug that is fixed to the housing via a glow plug seat, and is configured to introduce fuel, preheat the fuel, and ignite the fuel; a combustion chamber including an open end and a closed end, where a side wall of the combustion chamber close to the closed end is connected to the glow plug seat and fixed in the housing via the glow plug seat, an end of the glow plug is aligned with an inner space of the combustion chamber; an intake pipe, where fresh air is inputted through the intake pipe, an outlet end of the intake pipe is fixed to the side wall of the combustion chamber, arranged between the glow plug seat and the open end, and extends into the combustion chamber. In particular, a centerline of the outlet end of the intake pipe is eccentrically arranged with respect to a centerline of the combustion chamber, so that fresh air inputted from the intake pipe flows along the sidewall of the combustion chamber.
For the low temperature heater according to the present disclosure, a rotating piece may be provided at periphery of the sidewall of the combustion chamber. The rotating piece is arranged between the outlet end of the intake pipe and the open end of the combustion chamber, and is configured to rotate gas exhausted from the exhaust pipe.
For the low temperature heater according to the present disclosure, the rotating piece may be composed of an annular metal piece, trapezoidal or triangular cutouts are uniformly distributed on the rotating piece, and the metal piece cut from the cutout is bent or buckled in a direction of the open end of the combustion chamber for guiding flowing of the exhausted gas.
For the low temperature heater according to the present disclosure, a spiral heating wire may be further provided at the open end of the combustion chamber and is configured to block and heat a portion of fuel droplets.
Compared with the conventional art that the ignition is stable and the later installed DPF is regenerated only in a case that the vehicle is parked or idling, with the low temperature heater according to the present disclosure, stable ignition and uniform regeneration of the blocked DPF can be achieved in a case that the vehicle accelerates or event travels at a high speed. Without being limited by certain theory, the flame generated in this way is strongly pushed into the exhausted gas, the flame cannot be blown out even if the exhaust speed is fast or increases, thereby achieving stable ignition and regeneration. In addition, real-time adjustment of the intake air amount and the fuel-air ratio based on the traveling state of the vehicle is beneficial to stable ignition of the low temperature heater according to the present disclosure and uniform regeneration of the DPF under different vehicle conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described with reference to the drawings hereinafter. It should be understood that the drawings are only intended to explain and demonstrate principles of the present disclosure by examples, rather than limiting the present disclosure to the detailed solutions shown in the drawings. In the drawings:

Figure 1 is a schematic cross-sectional view of a low temperature heater according to an embodiment of the present disclosure;
Figure 2 is a schematic top view of a rotating piece according to an embodiment of the present disclosure; and
Figure 3 is a perspective view of a rotating piece according to an embodiment of the present disclosure.

Reference numerals:

1: pagoda head; 2: check valve; 3: straight pipe joint; 4: connecting flange; 5: elbow; 6: glow plug cover; 7: glow plug; 8: glow plug seat; 9; lower base assembly of the glow plug cover; 10: glow plug transfer tube; 11: housing; 12: manifold; 13: straight pipe; 14: heating wire; 15: combustion chamber; 16: rotating piece; 17: sensor base; 18: temperature sensor; 19: blocking plate; 20: combustion chamber bottom plate.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a low temperature heater according to the present disclosure is described in detail with reference to the drawings. It should be understood by those skilled in the art that various embodiments of the present disclosure described below are only intended to enable those skilled in the art to understand the present disclosure without any limitation. The scope of the present disclosure is defined by the claims.
Figure 1 shows a schematic cross-sectional view of a low temperature heater according to an embodiment of the present disclosure. The low temperature heater is configured to raise a temperature of exhausted gas of an engine. The low temperature heater is installed at an end of an exhaust pipe of an automobile (especially a diesel vehicle) engine, and supplies heat by combustion, thereby increasing the temperature of the exhausted gas of the engine and realizing the regeneration of a particulate filter.
In the embodiment shown in Figure 1, the low temperature heater includes: a housing, a glow plug, a combustion chamber and an intake pipe. The housing is in fluid communication with an exhaust pipe of a diesel engine. The glow plug is fixed to the housing via a glow plug seat, and is configured to introduce fuel, preheat the fuel, and ignite the fuel. The combustion chamber includes an open end and a closed end. A side wall of the combustion chamber close to the closed end is connected to the glow plug seat and fixed in the housing via the glow plug seat. An end of the glow plug is aligned with an inner space of the combustion chamber. Fresh air is inputted through the intake pipe. An outlet end of the intake pipe is fixed to the side wall of the combustion chamber, arranged between the glow plug seat and the open end, and extends into the combustion chamber. In particular, a centerline of the outlet end of the intake pipe is eccentrically arranged with respect to a centerline of the combustion chamber, so that fresh air inputted from the intake pipe flows along the sidewall of the combustion chamber.
For example, the housing 11 may be made of a stainless steel material and may have a shape of straight tube cylinder. The housing is configured to be in fluid communication with the exhaust pipe of the diesel engine (not shown) through a connecting flange 4, and is configured to accommodate gas exhausted from the exhaust pipe to heat the gas.
The glow plug 7 is connected to the side wall of the housing 11 via the glow plug seat 8 and a lower base assembly 9 of a glow plug cover. Besides, the glow plug 7 is covered with a square or circular glow plug cover 6 to protect the glow plug 7. The glow plug 7 may be an electric spark plug commonly used in diesel vehicles or a high temperature ignition rod, for igniting fuel from an oil inlet pipe, for example. In a case that the glow plug is a high temperature ignition rod, the glow plug may be a high temperature silicon nitride rod or a boron nitride rod containing a high temperature heating wire, such as a tungsten wire. However, the glow plug is not limited in the present disclosure, as long as the glow plug can generate a high temperature and ignite the fuel. Preferably, a fuel passage (not shown) is provided in the glow plug 7, so that the fuel flows into the passage via a glow plug transfer tube 10, and the fuel is heated to facilitate subsequent combustion.
The combustion chamber 15 has a tubular shape and is connected and fixed to the housing 11 via the glow plug seat 8. The combustion chamber 15 includes a closed end and an open end. The open end faces an exhaust direction of the diesel engine for outputting a hot airflow generated due to combustion of the fuel. The closed end, that is, a combustion chamber bottom plate 20, is configured to guide the generated hot airflow to flow toward the direction of the open end, and block the generated hot airflow from flowing toward an opposite direction of the exhaust direction, so as to improve the thermal efficiency. In an embodiment, the combustion chamber 15 is made of a high temperature resistant metal, such as the stainless steel.
An intake assembly is provided at the closed end of the combustion chamber 15, that is, an intake assembly consisting of a pagoda head 1, a check valve 2, a straight pipe joint 3 and an elbow 5. Due to the check valve, the gas can only be inputted into the combustion chamber 15 from the outside (for example, via a gas pump), and cannot be outputted from the combustion chamber 15, thereby ensuring the stability of an air pressure in the combustion chamber 15.
The intake pipe may be a manifold 12. A first branch of the manifold 12 (that is, a straight pipe 13) extends into the combustion chamber 15 in an eccentric manner. An advantage of such arrangement is that the fresh air inputted through the intake pipe flows along the side wall of the combustion chamber due to the impact of the side wall of the combustion chamber after entering the combustion chamber, thereby forming a swirling flow in the combustion chamber, facilitating intensive mixing with the fuel from the ignition plug, and facilitating driving a flame to swirl, so that the hot airflow generated by the flame is intensively mixed with gas exhausted from the engine. Practically, in an alternative embodiment, a first outlet of the manifold 12 may also be inserted into the combustion chamber in a manner of aligning with a center of the combustion chamber, thereby facilitating combustion and mixing. A second branch of the manifold 12 extends into the glow plug to deliver a portion of fresh air to the ignition plug for mixing with the fuel, so as to provide an initial combustion mixture. Generally, a ratio of the amount of fresh air inputted through the first branch (for example, by volume) to the amount of fresh air inputted through the second branch ranges from 9:1 to 1:1, for example, 8:1. 7:1, 6:1, 5:1, 4:1, 3:1 or 2:1, or any value in a range of 9:1 to 1:1. By changing the amount of fresh air outputted through the first outlet and the second outlet, a fuel-air ratio in the combustion chamber can be flexibly changed, to achieve different combustion conditions. For example, in a case that the diesel engine is stopped or idling, the ratio may be appropriately increased, for example, 8:1. Because the exhausted gas amount at this time is relatively small, and the exhausted gas occupies a low proportion of the gas in the combustion chamber, thus a relatively small amount of fresh air can maintain the sufficient combustion of the fuel. In contrast, in a case that the diesel engine accelerates or operates at a high speed, the exhausted gas amount is relatively large, and the exhausted gas occupies a high proportion of the gas in the combustion chamber. In this case, more fresh air is required to be delivered into the ignition plug to achieve sufficient combustion of the fuel.
In addition, in order to promote the mixing of the hot airflow and the exhausted gas, an annular rotating piece 16 is further sleeved on an outer peripheral wall of the combustion chamber 15 close to the straight pipe 13, as shown in Figure 2 and Figure 3. For example, the rotating piece 16 is made of a stainless steel material. Triangular or trapezoidal notches are equidistantly arranged in an annular portion of the rotating piece 16, and fins generating these notches are obliquely bent or buckled in the direction of the exhaust direction, thereby guiding the airflow to rotate clockwise or counterclockwise to form a swirling airflow, and thus further improving the mixing effect of the hot airflow and the exhausted gas.
In addition, a spiral heating wire 14 is further provided at the open end of the combustion chamber 15. The spiral heating wire is configured to block fuel droplets that have not been fully burned from being directly ejected out from the straight tube 13, and heat to vaporize the fuel droplets.
In order to monitor the gas temperature in the housing 11 conveniently, a temperature sensor 18 is further provided on the side wall of the housing 11, opposite to the glow plug 7. The temperature sensor 18 is fixed to the side wall of the housing 11 via a sensor base 17. In an embodiment, two, three or four temperature sensors 18 are equidistantly arranged.
In order to further enhance the swirling effect, a semicircular or square blocking plate 19 is provided between the glow plug 7 and the straight tube 13 on the side wall of the combustion chamber 15, and is configured to block the air inputted through the manifold 12 from directly contacting with the glow plug 7. The air entering the combustion chamber 15 through the manifold 12 is swirled due to the blocking plate 19, and then is mixed with the flame ejected from the outlet of the glow plug 7, thereby enhancing the combustion effect. In addition, the blocking plate 19 also blocks the flame ejected from the outlet of the glow plug 7 from directly entering the manifold 12.
The low temperature heater according to the present disclosure is described by specific embodiments below. However, it should be understood by those skilled in the art that these embodiments are provided for illustrating the good effect of the low temperature heater according to the present disclosure, and are not intended to limit the present disclosure to these specific embodiments.
First Embodiment: Combustion of a low temperature heater in an idling condition
The configuration of the low temperature heater is shown in Figure 1, which is not described here. The low temperature heater is line-mounted to the engine exhaust pipe. The engine is an engine of a diesel vehicle of Dong Feng Motor Corporation, with a displacement of 2.8 liters. A comparative example is the low temperature heater disclosed in Chinese Patent Application No. 200780021783.1 .
First, the engine is started; the low temperature heater is preheated and ignited according to the program in the conditions of idling, accelerating and operating at a high speed; the ignition reliability of the flame in the idling condition is observed, that is, whether the ignition is stable is observed, and whether the flame is blown out by the exhausted gas is observed, and observation results are recorded.
Next, a used diesel particulate filter, that is, DPF (which accumulates a large amount of soot, but the DPF is intact) is installed at the outlet end of the low temperature heater, and a regeneration experiment is conducted based on the program. During the experiment, it is observed whether the combustion in the DPF is uniform and multiple temperatures are recorded. It is detected whether a crack occurs in the DPF when the experiment ends.
Second Embodiment: Combustion of the low temperature heater in a high speed and acceleration condition
The configuration of the low temperature heater is shown in Figure 1, which is not described here. The low temperature heater is line-mounted to the engine exhaust pipe. The engine is an engine of a diesel vehicle of Dong Feng Motor Corporation, with a displacement of 2.8 liters. A comparative example is the low temperature heater disclosed in Chinese Patent Application No. 200780021783.1 .
First, the engine is started; the low temperature heater is preheated and ignited according to the program in the conditions of idling, accelerating and operating at a high speed; the ignition reliability of the flame in idling is observed, that is, it is observed whether the ignition is stable and whether the flame is blown out by the exhausted gas, and observation results are recorded.
Next, a used diesel particulate filter, that is, DPF (which accumulates a large amount of soot, but the DPF is intact) is installed at the outlet end of the low temperature heater, and a regeneration experiment is conducted based on the program. During the experiment, it is observed whether the combustion in the DPF is uniform, and multiple temperatures are recorded. It is detected whether a crack occurs in the DPF when the experiment ends.
Finally, the regenerated DPF is weighed, and an ash cleaning rate is calculated based on the DPF weight before regeneration. An average of multiple ash cleaning rates is calculated to characterize a regeneration degree.

Results of the first embodiment and second embodiment are shown in Table 1.

Table 1: Results of the first embodiment and second embodiment

	The present disclosure				Comparative example
Index	Ignite Times	Combustion uniformity	crack	Average ash cleaning rate (%)	Ignite times	Combustion uniformity	Crack	Average ash cleaning rate (%)
First Embodiment	5 / 5	uniform	no	92%	5 / 5	uniform	no	85%
Second Embodiment	5 / 5	uniform	no	89%	5 / 5	-	-	-

In the first embodiment and the second embodiment, the low temperature heater according to the present disclosure is stably ignited in both the first embodiment and the second embodiment, the DPF in which the soot is accumulated can be stably regenerated, and the ash cleaning rate reaches about 90%, thereby indicating that the regeneration effect of the DPF is good, and a case where the DPF is broken or cracks does not occur in either the first embodiment or the second embodiment.
In contrast, in the comparative example, the average ash cleaning rate of the DPF is only about 85% in the idling state. Moreover, in the state of acceleration and operating at a high speed, a small flame is observed, and the temperature at the inlet end of the DPF is low, only about 300°C, not meeting the temperature requirement of DPF regeneration, so the ash cleaning rate is almost zero. That is, the low temperature heater disclosed in the comparative example in this state cannot regenerate the DPF at all.
It can be seen from the above experimental data that the low temperature heater according to the present disclosure is superior to the low temperature heater of the comparative example in terms of ignition reliability or stability, DPF ash cleaning rate, etc., in any of the idling state, accelerating state and high speed operating state.

Claims

A low temperature heater for exhausted gas purification processing of a diesel engine, comprising:
a housing, in fluid communication with an exhaust pipe of the diesel engine;

a glow plug, fixed to the housing via a glow plug seat and configured to introduce fuel, preheat the fuel, and ignite the fuel;

a combustion chamber comprising an open end and a closed end, wherein a side wall of the combustion chamber close to the closed end is connected to the glow plug seat and fixed in the housing via the glow plug seat, an end of the glow plug is aligned with an inner space of the combustion chamber; and

an intake pipe, wherein fresh air is inputted through the intake pipe, an outlet end of the intake pipe is fixed to the side wall of the combustion chamber, arranged between the glow plug seat and the open end, and extends into the combustion chamber,
wherein a centerline of the outlet end of the intake pipe is eccentrically arranged with respect to a centerline of the combustion chamber, and wherein the fresh air inputted from the intake pipe flows along the sidewall of the combustion chamber.
The low temperature heater according to claim 1, wherein a rotating piece is further provided at periphery of the sidewall of the combustion chamber, the rotating piece is arranged between the outlet end of the intake pipe and the open end of the combustion chamber, and configured to rotate gas exhausted from the exhaust pipe.
The low temperature heater according to claim 2, wherein the rotating piece is composed of an annular metal piece, trapezoidal or triangular cutouts are uniformly distributed on the rotating piece, and the metal piece cut along the cutout is bent or buckled in a direction of the open end of the combustion chamber for guiding flowing of the exhausted gas.
The low temperature heater according to claim 1, wherein a spiral heating wire is further provided at the open end of the combustion chamber and configured to block and heat a portion of fuel droplets.