KR20120015386A - Operation controling system of waste gate unit for turbocharger - Google Patents

Abstract

PURPOSE: A control system for the operation of a waist gate of a turbocharger is provided to minimize heat loss by allowing exhaust gas to bypass a turbine wheel. CONSTITUTION: A control system for the operation of a waist gate of a turbocharger comprises a waist gate valve(88) and an actuator(90). The waist gate valve controls the opening area of a bypass path(87). The actuator actuates the waist gate valve and has a diaphragm(91). The diaphragm divides the actuator into a pressure chamber(92) and a negative pressure chamber(100). The pressure chamber is connected to a pipe by inserting a solenoid valve(97) into a supercharged air path of an intake compressor(81). The negative pressure chamber is connected to a pipe toward a surge tank(102). The bypass path is opened using the pressure difference between the pressure and negative pressure chambers.

Description

Operation control system of waste gate unit for turbocharger

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger for increasing the output of an engine. More specifically, a wastegate unit of a turbocharger that supercharges an air or a mixer in an engine using exhaust gas discharged to the outside is provided. Relates to an operation control system.

The turbocharger for an internal combustion engine drives the turbine using the exhaust energy of the engine, compresses the air with a compressor on the same shaft as the turbine, and supplies it to the engine to recover the pressure and thermal energy of the exhaust gas and use the air flowing into the engine. Compressor, which is used in most diesel engines to improve output with an intercooler that cools the temperature of intake air.

Typical turbochargers include turbine wheels and compressor wheels. Exhaust gas discharged through the exhaust port of the engine rotates the turbine wheel of the turbocharger, as a result of which a compressor wheel connected to the turbine wheel via a connecting shaft is rotated.

The compressor wheel is installed in the intake port of the engine to compress the air flowing into the engine by the rotation.

Therefore, it is possible to supply higher density air to the combustion chamber of the engine without directly using the power of the engine.

Since the air of higher density is supplied to the combustion chamber by the turbocharger, the amount of air supplied to the combustion chamber is increased and the fuel injection amount is correspondingly increased. Therefore, the output can be improved by the amount corresponding to the increased fuel injection amount.

In the case of a vehicle equipped with such a turbocharger, it is possible to obtain fuel savings, soot and noise reduction, an increase in power per weight, an increase in engine cooling performance, and an increase in power in an alpine area.

However, since the amount of exhaust gas discharged from the engine varies according to the rotational speed and the displacement of the engine, there is a problem that the compression ratio of the turbocharger varies according to the rotational speed and the displacement of the engine.

That is, when the rotation speed of the engine is low or the engine exhaust amount is small, the amount of exhaust gas flowing into the turbine wheel of the turbocharger is reduced, so that the energy that can be recovered from the exhaust gas is reduced. As a result, there is a limit to the compression ratio of the compressor connected to the blown wheel. In addition, when the rotational speed of the engine is high or the engine displacement is large, the air compressed too much by the compressor is supplied to the combustion chamber. As a result, the ratio of air to fuel in the combustion chamber becomes too high, and the adverse effect of reducing the engine output due to the operation of the turbocharger appears.

In order to solve this problem, when the engine rotation speed is low or the engine displacement is small, the turbine wheel is used as efficiently as possible to recover as much energy as possible from the exhaust gas. On the contrary, when the rotation speed of the engine is high or the engine displacement is large, the waste gate is opened at the inlet side of the turbine housing (in which the turbine wheel is disposed) of the turbocharger. If a vent valve (also called a "bypass valve") is installed and over-compressed air enters the combustion chamber, the vent valve is driven so that part of the exhaust gas is discharged directly without passing through the turbine wheel. The rotation speed of the wheel is reduced.

If the boost pressure applied in the intake manifold is too large, it may cause detonation and damage to the engine, and the turbocharger is equipped with a waste gate unit to suppress excessive boost pressure.

By this waste gate unit, when the boost pressure reaches a predetermined value, a part of the exhaust gas bypasses the turbine and flows to the waste gate, and is exhausted to the outside without rotating the turbine.

The method of opening and closing the waste gate includes a positive pressure type, a negative pressure type, and an electronic type. Among them, the most economical method is the most commonly used as the positive pressure type, and thus, the engine and the constant pressure turbocharger will be described below with reference to FIGS. And the operation of the waste gate unit.

1 is a view schematically showing an engine in order to explain a general waste gate unit, and FIG. 2 is a view showing a turbocharger equipped with a conventional waste gate unit.

In the cylinder 1 of the engine, the compressed mixer is ignited and expanded to open the exhaust valve 2b, and the piston 3 rises up again to discharge the burned gas. The exhaust gas discharged in this way rotates the turbine 11 while passing through the exhaust gas inlet pipe 15 of the turbocharger 10.

As the fan 13a of the compressor 13 rotates in synchronism with the turbine 11 rotated by the exhaust gas, external air is forcibly charged into the cylinder 1 to increase the engine output. However, when all the exhaust gas exhausted rotates the turbine 11, excessive boost pressure may be generated in the intake manifold 5, resulting in abnormal combustion or engine abnormality.

In order to solve this problem, a waste gate unit 20 is provided, a waste gate 15a is formed in the exhaust gas inlet pipe 15 upstream of the turbine 11, and the waste gate 15a is a waste gate valve 29. Is selectively shielded by).

Therefore, when excessive boost pressure is generated in the intake manifold 5, the waste gate valve 29 is opened so that a part of the exhaust gas discharged from the cylinder 1 bypasses the turbine 11 immediately without rotating. (bypass) to prevent excessive boost pressure.

The conventional waste gate unit 20 includes an actuator 21, an actuator rod 23, a hinge bar 25, a connection bar 27, and a waste gate valve 29. do.

The actuator 21 is driven to selectively shield the waste gate 15a. When the actuator 21 is above a certain boost pressure, the actuator 21 opens the waste gate 15a so that a part of the exhaust gas is bypassed. Shut off 15a to allow the exhaust gas to rotate the turbine 11.

The actuator rod 23 is operated by the actuator 21, one end of which is connected to the actuator 21 side, and the other end of the actuator rod 23 to a hinge bar 25 to be described later.

The hinge bar 25 has one end pin connected to the actuator rod 23 and the other end fixed to the connection bar 27 to be described later. As the actuator 21 linearly moves, the pin connection part 26 is rotated as a center of rotation. Rotate.

The connecting bar 27 is rotated in synchronism with the hinge bar 25 rotated by the actuator rod 23, and the other end thereof is fixed to the waste gate valve 29 by welding or the like so that the waste gate valve 29 is connected to the connecting bar 27. It is synchronized with (27).

The waste gate valve 29 is fixed to the connecting bar 27 as described above and rotated in synchronization with the connecting bar 27. Such a waste gate valve 29 selectively shields the waste gate 15a by rotating the connecting bar 27 as the rotation axis. Therefore, the waste gate valve 29 is rotated so that the waste gate 15a is shielded so that the waste gate valve 29 is tilted with respect to the connecting bar 27.

As described above, in the conventional waste gate unit 20, when the boost pressure is greater than or equal to the predetermined pressure, the actuator 21 is operated so that the actuator rod 23 linearly moves in the direction of arrow B of FIG. The hinge bar 25 is rotated counterclockwise in the drawing. The connecting bar 27 rotates in the rotational direction of the hinge bar 25 and the waste gate valve 29 installed on the connecting bar 27 opens the waste gate 15a so that a part of the exhaust gas is the waste gate 15a. Bypass through to adjust the boost pressure.

On the other hand, when the boost pressure drops below a predetermined pressure, the actuator rod 23 is linearly moved in the direction of arrow A of FIG. 2 by the actuator 21, and the hinge bar 25 is rotated clockwise in the drawing in conjunction with this. . The connecting bar 27 rotates in the rotational direction of the hinge bar 25 and the waste gate valve 29 fixed to the connecting bar 27 closes the waste gate 15a so that the exhaust gas is not bypassed and the turbocharger ( It is comprised so that the turbine 11 of 10 may be rotated.

Meanwhile, in the case of a conventional gasoline turbocharged engine, in order to activate a catalyst for purifying exhaust gas, it is necessary to open a waste gate to reduce heat loss at the initial stage of engine start-up to promote heating of the catalyst, which is a heat loss to the turbocharger. It is necessary to minimize the amount of harmful exhaust gas emitted at the beginning of the start-up by heating the catalytically purified catalyst to reach the activation temperature in a short time.

However, the turbocharger of the positive pressure type, which is widely used in consideration of economical efficiency recently, controls the ratio of the constant pressure and atmospheric pressure of the compressor outlet through the solenoid valve to adjust the air pressure acting on the actuator, and the waste according to the driving of the actuator. According to the opening and closing degree of the gate valve to control the air compression amount due to acceleration and deceleration, such a constant pressure turbocharger, the compressed air discharged through the outlet of the compressor is supplied to the solenoid valve through the constant pressure line, and discharged from the engine In the case of the above-mentioned constant pressure type, it is difficult to secure the opening force of the waste gate because it is difficult to secure the opening force of the waste gate. Not suitable There is neundaneun disadvantage, despite the excellence of cost-effectiveness and there is a problem you can not avoid the initial start-up of the engine exhaust gas purification ability decreases, and pointed to shortcomings.

In contrast, Japanese Laid-Open Patent Publication JP 2006-274831 proposes the use of an electronic waste gate actuator (EWGA) operated by electronic control instead of the static pressure method using the boost pressure formed on the compressor side. In addition, the method of opening and closing the waste gate using the electronic waste gate actuator has been found to have a high accuracy and convenience of operation, but it has been found to have a problem in securing durability in an environment of expensive and high-temperature exhaust gases.

Another method of opening and closing the waste gate is a technique of applying a negative pressure waste gate, in which case there is a problem in that an expensive vacuum pump facility is required to make a negative pressure, which is disadvantageous in terms of cost.

Therefore, the present invention has been proposed in view of the above problems, and its purpose is to open the initial waste gate of the engine by using both the positive pressure and the negative pressure generated in the constant pressure turbocharged engine without the use of expensive devices or complicated structures. The present invention provides a turbocharged waste gate operation control system capable of reducing exhaust gas emissions by controlling catalyst activation time of a turbocharged engine.

In order to achieve the above object, the waste gate operation control system of the turbocharger of the present invention is provided in a turbocharger including an exhaust turbine, an intake compressor disposed in the intake passage, and a bypass passage bypassing the exhaust turbine. A waste gate valve (WGV) configured to control the opening area of the bypass passage, and an actuator configured to operate the waste gate valve, the actuator having a diaphragm that divides the pressure chamber and the negative pressure chamber; The pressure chamber is connected to a pipe via a positive pressure solenoid valve on a side of a boost air passage of the intake compressor, and the negative pressure chamber is connected as a pipe to a surge tank side under which a negative pressure condition is formed. The solenoid on the positive pressure side The valve is controlled to open so that the bypass passage is opened by operating the actuator by using a pressure difference between positive pressure and negative pressure.

In addition, according to the present invention, one side of the surge tank is provided with a separate vacuum chamber for storing the negative pressure formed in the surge tank during idle driving or low load operation of the engine, the negative pressure chamber is connected to the vacuum chamber as a pipe line do.

In addition, the negative pressure chamber is characterized in that it is provided with a return spring that is responsive to the pressure acting on the pressure chamber side in the direction to push the diaphragm at all times.

According to the present invention, the negative pressure chamber is connected to the vacuum chamber via a negative pressure side solenoid valve via a pipe line, and the electronic controller controls to open the positive pressure side and the negative pressure side solenoid valves at the initial stage of engine start. do.

According to the present invention as described above, the diaphragm operation of the actuator by connecting the room containing the return spring of the actuator for opening and closing the waste gate valve of the conventional hydrostatic turbocharger to the side of the surge tank in which the negative pressure is formed to form a negative pressure chamber It is difficult to secure the opening force of the waste gate valve due to the low pressure in the chamber (operating chamber, constant pressure chamber). By opening the waste gate valve, exhaust gas can be bypassed without passing through the turbine wheel, thereby minimizing heat loss, and the catalyst device can be activated early to improve the exhaust gas purification efficiency. .

1 is a view schematically showing an engine structure to explain a waste gate unit of a conventional hydrostatic turbocharger,
2 is a view showing a turbocharger showing a mounting state of an actuator for opening and closing a conventional waste gate.
3 is a view showing a waste gate operation control system of a turbocharger according to the present invention.

In order to fully understand the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment of the present invention may be modified in various forms, the scope of the invention should not be construed as limited to the embodiments described in detail below. This embodiment is provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the elements in the drawings and the like may be exaggerated to emphasize a more clear description. It should be noted that the same members in each drawing are sometimes shown with the same reference numerals. In addition, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention are omitted.

Hereinafter, by describing the preferred embodiment of the present invention with reference to the accompanying drawings, the waste gate operation control system of the turbocharger of the present invention will be described in detail.

Superchargers, such as turbochargers, are applied to internal combustion engines to improve intake efficiency, thereby improving engine power.

The turbocharger 80 of the present invention includes an intake compressor 81 and an exhaust turbine 82. The intake compressor 81 is provided to the intake pipe 85. The exhaust turbine 82 is provided to the exhaust pipe 86. The exhaust pipe 86 is connected with a bypass passage 87 that bypasses the exhaust turbine 82. A waste gate valve (WGV) 88, which operates to exhaust the exhaust gas bypassing the turbine 82, is provided in the bypass passage 87, and the waste gate valve WGV, 88 is provided in the bypass passage 87. When it comes in close contact with the valve seat 95, the bypass passage 87 is blocked. When the valve seat 95 is spaced apart from the valve seat 95, the bypass passage 87 opens to exhaust gas from the exhaust turbine 82. As such, the bypass passage 87 is provided to bypass the exhaust turbine 82 provided in the exhaust pipe. A waste gate valve 88 is provided in the bypass passage 87 to control the amount of exhaust gas flowing to the exhaust turbine 82, thereby controlling the charging pressure, The waste gate valve 88 is configured to be controlled using a positive pressure actuator 90.

To this end, the WGV 88 is connected with an actuator 90 having a pressure chamber 92 partitioned by a diaphragm 91. WGV 88 operates according to the pressure in pressure chamber 92. The intake air pressure (supercharge pressure) downstream of the intake compressor 81 is applied to the pressure chamber 92 through the pipe 93. The WGV actuator 90 operates to cause the WGV 88 to change the opening area of the bypass passage 87, thereby controlling the amount of exhaust gas flowing through the bypass passage 87, and the WGV 88. ) Serves as a charging condition variable unit for controlling the charging pressure.

When the solenoid valve 97 to be described later is opened, the boost pressure is applied directly to the pressure chamber 92 so that the WGV 88 is operated in accordance with the boost pressure. In particular, as the boost pressure increases, the pressure in the pressure chamber 92 also increases. In this condition, the WGV 88 is operated at its opening side, so that the power of the exhaust turbine 82 is reduced. Therefore, the power of the intake compressor 81 is also reduced, so that the boost pressure is reduced.

In the above configuration, in general, when the boost pressure rises, the WGV 88 is opened to suppress the excessive increase in the boost pressure. In particular, the WGV 88 is maintained in the closed position under normal conditions, and the WGV 88 is slightly open in one of the high load conditions and the high rotation range. In this condition, the position of the WGV 88 is limited by the boost pressure.

The positive pressure side solenoid valve 97 in which the operation is controlled by the electronic control device 96 is provided in the middle of the pipe 93, and the diaphragm 91 is driven by the boost pressure acting in the pressure chamber 92. The return spring 99 which lowers and pushes the working rod 98 to open the WGV 88 (waist gate valve) to bypass the exhaust gas and returns the diaphragm 91 when the boost pressure is lowered is lowered. The lower chamber 100 (negative pressure chamber) is installed in the chamber 100, and is installed on the side of the surge tank 102, more preferably on one side of the surge tank 102 via the pipe 101, to drive the engine idle. The negative pressure chamber 100 is connected to the vacuum chamber 103 that stores the intake negative pressure formed in the surge tank 102 during the low speed operation.

In the middle of the pipe 101 connecting the negative pressure chamber 100 and the vacuum chamber 103, a negative pressure side solenoid valve 104 for opening and closing a pipe is provided. The negative pressure side solenoid valve 104 is electronically controlled. Operation is controlled by the device 96.

Referring to the operation of the system according to the present invention as follows.

The electronic control unit 96 which determines that the engine is cold started based on information from the low-speed driving section or the idle state of the sensor 105, for example, the cooling water temperature sensor after the engine is started, is the positive pressure side and the negative pressure side. The solenoid valves 97 and 104 are operated to open.

When both valves 97 and 104 are simultaneously opened, the outlet pressure of the intake compressor 81 acts on the pressure chamber 92 of the actuator 90, and the negative pressure of the surge tank 102 in the negative pressure chamber 100. The vacuum negative pressure of the stored vacuum chamber 103 is applied. Accordingly, even if the pressure applied to the pressure chamber 92 is low due to the initial low speed, the relative pressure difference with the vacuum pressure acting on the negative pressure chamber 100 increases, and the diaphragm 91 is returned by such a large pressure difference. The compression of the spring 99 lowers and pushes the working rod 98, and the exhaust gas is exhausted through the bypass passage 87 in which the conduit is opened by the WGV 88 being spaced apart from the valve seat 95. ), Bypassing), which reduces heat loss, which leads to an early rise of the activation temperature and normalization of the exhaust gas purification function.

Embodiments of the waste gate operation control system of the turbocharger according to the present invention described above are merely illustrative, and those skilled in the art to which the present invention pertains have various modifications and equivalent embodiments. You can see that it is possible. Therefore, it will be understood that the present invention is not limited to the forms mentioned in the above detailed description. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims. It is also to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

80: turbocharger 81: intake compressor
82: exhaust turbine 85: intake pipe
86: exhaust pipe 87: bypass passage 88: waste gate valve (WGV) 90: actuator
91: diaphragm 92: pressure chamber
93: pipeline 95: valve seat 96: electronic control device 97: positive pressure side solenoid valve 98: operating rod 99: return spring 100: negative pressure chamber (lower chamber) 101: piping 102: surge tank 103: vacuum chamber 104: negative pressure side solenoid valve
105: sensor

Claims (4)

A turbocharger including an exhaust turbine, an intake compressor disposed in the intake passage, a waste gate valve (WGV) provided in the bypass passage bypassing the exhaust turbine, and configured to control the opening area of the bypass passage; And an actuator configured to operate the waste gate valve, wherein the actuator has a diaphragm for dividing the pressure chamber and the negative pressure chamber, and the pressure chamber has a positive pressure side solenoid valve on a side of a boost air passage of the intake compressor. The negative pressure chamber is connected as a pipe to the surge tank side under which the negative pressure condition is formed, and the electronic control unit controls the positive pressure side solenoid valve to open the positive pressure side during the initial idle operation or the low speed operation of the engine. The actuator is operated by using a pressure difference between Turbocharger wastegate operation control system characterized in that the thereby opening the bypass passage. According to claim 1, One side of the surge tank is provided with a separate vacuum chamber for storing the negative pressure formed in the surge tank during the idle drive or low load operation of the engine, the negative pressure chamber is connected to the vacuum chamber by piping. Waste gate operation control system of turbocharger. 3. The waste gate operation control of a turbocharger according to claim 1 or 2, wherein the negative pressure chamber is provided with a return spring which repels the diaphragm at all times in response to pressure acting on the pressure chamber side. system. The negative pressure chamber is connected to the vacuum chamber by a pipe via a negative pressure side solenoid valve, and the electronic control unit controls to open the positive pressure side and the negative pressure solenoid valves at the initial stage of engine start. Waste gate operation control system of turbocharger.

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