Abnormality determination device for variable geometry turbocharger

The present application relates to an abnormality determination device for a variable geometry turbocharger having a nozzle mechanism capable of changing a flow path area of exhaust gas with an actuator. The abnormality determination device includes: a first detection part configured to be capable of detecting at least one of a load of the actuator or supply energy to the actuator; and a determination part configured to determine that an abnormality is present, if a detection result by the first detection part is out of an allowable range corresponding to an operational state of the variable geometry turbocharger.

TECHNICAL FIELD

The present disclosure relates to an abnormality determination device for a variable geometry turbocharger including an actuator-driven nozzle mechanism.

BACKGROUND ART

In a variable geometry turbocharger (VGT), the supercharging efficiency is improved by changing the area of an exhaust flow passage in an exhaust turbine in accordance with the rotation speed of the engine to control the exhaust flow rate to the exhaust turbine blade. Such a control on the area of an exhaust flow passage is performed by driving a nozzle mechanism with an actuator. For instance, if the engine rotation speed is relatively low, the area of the exhaust flow passage is narrowed (reduced) with the nozzle mechanism to increase the flow rate of exhaust gas and increase the output torque. If the engine rotation speed is relatively high, the area of the exhaust flow passage is expanded (increased) by opening (increasing) the nozzle mechanism to improve the fuel consumption.

Meanwhile, if a trouble like sticking occurs in a nozzle mechanism, which is an important constituent element of a variable geometry turbocharger, it is no longer possible to adjust (narrow or expand) the area of an exhaust flow passage as described above. To prevent such troubles, it is important to detect at an early stage an abnormality such as a trouble in a nozzle mechanism and a behavior that seems to develop a trouble.

As a technique related to abnormality detection of such a type of variable geometry turbocharger, Patent Document 1 discloses, for instance, performing a wiping motion that drives a nozzle mechanism from a full-open position to a full-closed position when the engine is stopped, and detecting an abnormality on the basis of the time required for the wiping motion.

CITATION LIST

Patent Literature

SUMMARY

Problems to be Solved

However, the abnormality detection in Patent Document 1 requires intentional driving of the nozzle mechanism, and can be performed only when the engine is stopped. In other words, the abnormality detection cannot be performed while the engine is in operation, thus failing to sufficiently meet the demand to detect an abnormality of a nozzle mechanism at an early stage with high accuracy.

At least one embodiment of the present invention was made in view of the above described problem, and an object is to provide an abnormality determination device for a variable geometry turbocharger whereby it is possible to detect an abnormality of a nozzle mechanism at an early stage with high accuracy.

Solution to the Problems

(1) An abnormality determination device according to at least one embodiment of the present invention is for a variable geometry turbocharger having a nozzle mechanism capable of changing a flow path area of exhaust gas with an actuator, and comprises: a first detection part configured to be capable of detecting at least one of a load of the actuator or supply energy to the actuator; and a determination part configured to determine that an abnormality is present, if a detection result by the first detection part is out of an allowable range corresponding to an operational state of the variable geometry turbocharger.

With the above configuration (1), presence or absence in the variable geometry turbocharger is determined on the basis of whether at least one of the load of the actuator or the supply energy to the actuator is out of an allowable range. The allowable range used as a determination criteria is set corresponding to the operational state of the variable geometry turbocharger, and thus it is possible to determine an abnormality accurately at an early stage for various operational states of a vehicle to which the variable geometry turbocharger is mounted.

(2) In some embodiments, in the above configuration (1), the abnormality determination device further comprises: a second detection part configured to detect the operational state of the variable geometry turbocharger; and a storage part configured to store a map which defines a relationship between the operational state of the variable geometry turbocharger and the allowable range. The determination part is configured to set the allowable range corresponding to the operational state detected by the second detection part on the basis of the map.

With the above configuration (2), a map is stored in advance, defining a relationship between the operational state of the variable geometry turbocharger and the allowable range, and thereby the determination part can set a suitable allowable range corresponding to the operational state of the variable geometry turbocharger by referring to the map.

(3) In some embodiments, in the above configuration (2), the map comprises a plurality of maps prepared corresponding to an opening degree of the nozzle mechanism.

With the above configuration (3), the map comprises a plurality of maps prepared corresponding to an opening degree of the nozzle mechanism, for setting the allowable range, and thereby it is possible to build maps that can define an allowable range that correspond to various operational states thoroughly.

(4) In some embodiments, in any one of the above configurations (1) to (3), the first detection part is configured to detect both of the load of the actuator and the supply energy to the actuator. The determination part is configured to determine that an abnormality is present in an energy supply path to the actuator, if the load of the actuator is small with respect to the supply energy to the actuator as compared to a target value corresponding to the supply energy.

With the above configuration (4), abnormality determination is performed on the basis of both of the load of the actuator and the supply energy to the actuator, and thus it is possible to perform even more accurate determination. In particular, if the load (output energy) of the actuator is small compared with a target value corresponding to the supply energy (input energy) (that is, the target value being an output expected from an input), it can be determined that there is a risk of an abnormality such as leakage of supply energy, and thus there is an abnormality in the energy supply path to the actuator.

(5) In some embodiments, in any one of the above configurations (1) to (4), the abnormality determination device further comprises: a housing to which a reaction force of the actuator is applicable; and a piezoelectric element interposed between the actuator and the housing. The first detection part is configured to detect the load of the actuator on the basis of an output voltage of the piezoelectric element.

With the above configuration (5), a reaction force applied to a housing when the actuator is driven is detected as an output voltage of a piezoelectric element interposed between the actuator and the housing. Accordingly, it is possible to obtain a load of the actuator efficiently as an electric signal.

(6) In some embodiments, in the above configuration (5), the actuator is connected to the nozzle mechanism via a rod member configured to be drivable along an axial direction. The piezoelectric element is disposed on an opposite side from a side of the actuator to which the rod member is connected.

With the above configuration (6), a reaction force is most likely to be applied to the housing from the actuator at the opposite side to the side of the actuator with the driving rod connected thereto, and thereby disposing the piezoelectric element in the above position makes it possible to detect a load of the actuator accurately.

(7) In some embodiments, in any one of the above configurations (1) to (6), the abnormality determination device further comprises an energy sensor disposed in an energy supply path connecting an energy supply source and the actuator. The first detection part is configured to detect the supply energy on the basis of a detection value of the energy sensor.

With the above configuration (7), the energy sensor is disposed in the energy supply path connecting the energy supply source and the actuator, and thus it is possible to detect supply energy to the actuator.

(8) In some embodiments, in any one of the above configurations (1) to (7), the operational state is determined including at least one of a boost pressure of the variable capacity turbocharger or the load of the actuator.

(9) In some embodiments, in any one of the above configurations (1) to (8), the supply energy is one of electric energy or pressure energy.

(10) In some embodiments, in any one of the above configurations (1) to (9), the abnormality determination device further comprises a transmission part for sending a determination result by the determination part to a control unit for controlling an engine supercharged by the variable geometry turbocharger.

With the above configuration (10), a determination result by the determination part is transmitted to a control unit for controlling the engine, and thus it is possible to provide components related to the above abnormality determination as separate members from the control unit of the engine. Accordingly, it is possible to reduce the computation load of the control unit, and thus it is possible to increase the processing speed and to reduce the costs.

Advantageous Effects

According to at least one embodiment of the present invention, it is possible to provide an abnormality determination device for a variable geometry turbocharger whereby it is possible to detect an abnormality of the nozzle mechanism accurately at an early stage.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.

With reference toFIG. 1, the overall configuration of a diesel engine (hereinafter, referred to as “engine”)1including a variable geometry turbocharger (hereinafter, “turbocharger”)2according to an embodiment of the present invention will be described.FIG. 1is a schematic overall configuration diagram of the engine1including the turbocharger2according to an embodiment of the present invention.

The turbocharger2includes an exhaust turbine8disposed in an exhaust pipe6connected to an exhaust manifold4, and a compressor14disposed in an intake pipe12connected to an intake manifold10. The exhaust turbine8and the compressor14are coupled to each other, and when the exhaust turbine8is driven by exhaust gas of the engine1, the compressor14coupled to the exhaust turbine8is driven to compress and supply intake air (supercharging).

Further, an air cleaner16for purifying supply air is disposed in the vicinity of the inlet of the intake pipe12. An inter cooler18for cooling the supply air compressed and heated by the compressor14is disposed in the intake pipe12, at the downstream side of the compressor14. A muffler20for canceling noise is disposed in the vicinity of the outlet of the exhaust pipe6.

The turbocharger2is a variable geometry turbocharger equipped with a nozzle mechanism22including nozzle vanes provided for the exhaust turbine8, the nozzle vanes having an opening degree which is variable in response to the engine rotation speed. The nozzle mechanism22is configured such that the opening degree is adjustable by an actuator56that can be driven by utilizing electric energy or pressure energy, for instance.

The nozzle mechanism22is provided with an opening degree sensor24for detecting an opening degree θ.

Next, with reference toFIG. 2, a control system30of the engine1having the above configuration will be described.FIG. 2is a schematic configuration diagram of the control system30of the engine1.FIG. 3is a functional block diagram of the interior configuration of a dedicated ECU34in the control system30ofFIG. 2.

The control system30includes: a main ECU32which integrally processes various controls for the entire vehicle, including the engine1; a dedicated ECU34which processes local controls related to the turbocharger2; a power supply line36for supplying driving power to the control system30; an abnormality diagnosis line38for transmitting and receiving signals related to abnormality diagnosis in the turbocharger2; and a network line40for transmitting and receiving control signals between the control system30and an external device.

For the network line40, the CAN communication system is employed to improve the reliability.

The main ECU32includes: a power circuit42which distributes driving power supplied from the power supply line36to each part of the main ECU32; transceivers44A and44B for transmitting and receiving various signals to and from the abnormality diagnosis line38and the network line40; a CPU46which serves as a computational processing unit that performs various computational processes; and a memory47capable of storing data or the like used for various processes performed by the CPU46.

The dedicated ECU34includes: a power circuit48which distributes driving power supplied from the power supply line36to each part of the dedicated ECU34; transceivers50A and50B for transmitting and receiving various signals to and from the abnormality diagnosis line38and the network line40, respectively; a CPU52which serves as a computational processing unit that performs various computational processes for the dedicated ECU34; and a memory54capable of storing information or the like used for various processes performed by the CPU52.

As described above, the control system30is of a central control type, in which the main ECU32performs processing computation related to the entire vehicle, while the dedicated ECU34performs local controls related to the turbocharger2. Accordingly, processing loads of the main ECU32are reduced.

Next, the interior configuration of the CPU52of the dedicated ECU34will be described in terms of function. As shown inFIG. 3, the CPU52includes: a first detection part58configured to be capable of detecting at least one of a load of the actuator56or supply energy to the actuator56; a second detection part60configured to detect the operational state of the turbocharger2; a determination part62configured to determine presence or absence of an abnormality; and a drive control part64which performs a drive control of the actuator56. In the present embodiment, the following abnormality determination control is performed through the above configuration. Hereinafter, an embodiment will be described in more detail.

First Example

With reference toFIGS. 4 to 7, an abnormality determination control according to the first embodiment will be described.FIG. 4is a schematic diagram of a configuration of the dedicated ECU34according to the first embodiment.FIG. 5is a schematic diagram showing an exemplary structure for detecting a load of the actuator56.FIG. 6is a flowchart showing the abnormality determination control according to the first embodiment by steps.FIG. 7is an example of a map66stored in advance in the memory54inFIG. 4.

In the following description, the same features in the above description are associated with the same reference numerals, and not described again unless necessary.

In the first embodiment, a load of the actuator56is detected, and abnormality determination is performed on the basis of the detection result. The actuator56is, for instance, a motor (electric motor) which can be driven by driving power (electric energy) supplied from the power circuit48. In the example ofFIG. 5, rotational motion of the motor is converted into reciprocating motion by a non-depicted power transmission mechanism, and then transmitted to a driving rod68. The nozzle mechanism22is configured such that the opening degree of the nozzle mechanism22is variable through the reciprocating motion of the driving rod68described above.

As depicted inFIG. 5, the actuator56is housed inside a housing70formed so as to surround the vicinity of the actuator56. The actuator56is surrounded by the housing70at three sides, and the driving rod68is connected to an open side of the actuator56. A piezoelectric element72for detecting loads is disposed between the actuator56and the housing70. The piezoelectric element72detects a reaction force generated between the actuator56and the housing70when the actuator56is driven, and outputs a voltage signal corresponding to the reaction force. The CPU34(the first detection part58) obtains the voltage signal outputted from the piezoelectric element72as described above, and thereby is capable of detecting loads of the actuator56.

Particularly in the present embodiment, the piezoelectric element72is disposed opposite from a side of the actuator56to which the driving rod68is connected. A reaction force is most likely to be applied to the housing70from the actuator56at the opposite side to the side of the actuator56with the driving rod68connected thereto. Thus, with the piezoelectric element72disposed in the above described position, it is possible to detect loads of the actuator56accurately.

Next, with reference toFIG. 6, an abnormality determination method performed on the basis of the above configuration will be described.

The second detection part60obtains a detection signal from the opening degree sensor24, and thereby detects an operational state of the turbocharger2(step S11).

Next, the dedicated ECU34accesses the memory54and thereby obtains the map66stored in the memory44in advance (step S12).FIG. 7is a diagram showing an example of the map66. An allowable range Llimit(allowable upper limit Lmaxand allowable lower limit Lmin) is defined for each opening degree θ of the nozzle mechanism22which represents the operational state of the turbocharger2, with regard to the relationship between the boost pressure of the turbocharger2and the load. The determination part62sets an allowable range Llimit(allowable upper limit Lmaxand allowable lower limit Lmin) corresponding to the operational state detected in step S11, on the basis of the map66obtained in step S12(step S13).

The first detection part58obtains the voltage signal of the piezoelectric element72, and detects a load of the actuator56(step S14). It is determined whether the load of the actuator detected in step14is within the allowable range Llimitset in step S13(step S15). As a result of the determination, if the load of the actuator56is within the allowable range Llimit(step S15: YES), the determination part62performs normal determination (step S16). If the load of the actuator56is not within the allowable range Llimit(step S15: NO), the determination part62performs abnormality determination (step S17), and issues an alert for notifying the abnormality (S18).

As described above, according to the first embodiment, the piezoelectric element72detects a load of the actuator56, and abnormality is determined on the basis of whether the detection result is within the allowable range Llimitset in accordance with the operational state. The above abnormality determination can be performed whether or not the engine1is in operation, and thus it is possible to detect abnormality of the nozzle mechanism22accurately at an early stage.

Second Example

With reference toFIGS. 8 and 9, an abnormality determination control according to the second embodiment will now be described.FIG. 8is a block configuration diagram of the dedicated ECU34according to the second embodiment.FIG. 9is a flowchart showing the abnormality determination control performed by the dedicated ECU34inFIG. 8by steps.FIG. 10is an example of a map78stored in advance in the memory54inFIG. 8.

As depicted inFIG. 8, in the second embodiment, the dedicated ECU34is provided with a current sensor76disposed in the power supply line74for supplying driving power to the actuator56from the power circuit48, to detect a current value of electric current that flows through the power supply line74. Accordingly, the CPU52can monitor a consumption power value (i.e., supply energy) in the actuator56on the basis of the detection value of the current sensor76.

Next, with reference toFIG. 9, an abnormality determination method performed on the basis of the above configuration will now be described.

The second detection part60obtains a detection signal from the opening degree sensor24, and thereby detects an operational state of the turbocharger2(step S21). Next, the dedicated ECU34accesses the memory54and thereby obtains the map66stored in advance in the memory54(step S22).

The first detection part58obtains the signal of the current sensor76, and detects supply energy (electric energy) to the actuator56(step S24). It is determined whether the supply energy to the actuator detected in step24is within the allowable range Llimitset in step S23(step S25). As a result of the determination, if the supply energy of the actuator56is within the allowable range Llimit(step S25: YES), the determination part62performs normal determination (step S26). If the supply energy to the actuator56is not within the allowable range Llimit(step S25: NO), the determination part62performs abnormality determination (step S27), and issues an alert for notifying the abnormality (S28).

As described above, according to the second embodiment, the current sensor76detects supply energy (electric energy) to the actuator56, and abnormality is determined on the basis of whether the detection result is within the allowable range Llimitset in accordance with the operational state. The above abnormality determination can be performed whether or not the engine1is in operation, and thus it is possible to detect abnormality of the nozzle mechanism22accurately at early stage.

Third Example

Subsequently, with reference toFIGS. 11 and 12, the third embodiment will be described.FIG. 11is a block configuration diagram of the dedicated ECU34according to the third embodiment.FIG. 12is a flowchart showing the abnormality determination control performed by the dedicated ECU34inFIG. 11by steps.

As depicted inFIG. 11, in the third embodiment, a load of the actuator56can be detected by the piezoelectric element72similarly to the first embodiment, and supply energy to the actuator56can be detected by the current sensor76similarly to the second embodiment. Accordingly, the CPU52can perform abnormality determination on the basis of the detection values of both of the piezoelectric element72and the current sensor76.

Next, with reference toFIG. 12, an abnormality determination method performed on the basis of the above configuration will be described.

The second detection part60obtains a detection signal from the opening degree sensor24, and thereby detects an operational state of the turbocharger2(step S31). Next, the dedicated ECU34accesses the memory54and thereby obtains the maps66,78stored in the memory54in advance (step S32). The maps66,78are similar to those shown inFIGS. 7 and 10, and each defines an allowable range Llimit(allowable upper limit Lmaxand allowable lower limit Lmin) for each opening degree θ of the nozzle mechanism22which represents the operational state of the turbocharger2, with regard to the relationship between the boost pressure of the turbocharger2and the load or the current value. The determination part62sets an allowable range Llimit(allowable upper limit Lmaxand allowable lower limit Lmin) corresponding to the operational state detected in step S31, on the basis of the maps66,78obtained in step S32(step S33).

The first detection part58obtains the signal from the piezoelectric element72to detect a load of the actuator56(step S34), and also obtains the signal from the current sensor76to detect supply energy to the actuator56(step S35). It is determined whether the load of the actuator56detected in step S34and the supply energy to the actuator detected in step35are both within the allowable range Llimitset in step S33(step S36). If the determination result is true (step S36: YES), the determination part62performs normal determination (step S37).

If the determination result is false (step S36: NO), the determination part62further determines whether the load is small with respect to the supply energy (step S38). Specifically, the determination part62determines whether the load of the actuator56detected in step S34is smaller than a load that is expected from the supply energy to the actuator56detected in step S35. If the determination result is true (step S38: YES), the determination part62determines that supply energy is not normally supplied to drive the actuator56and there is an abnormality (e.g. short circuit or leakage) in the energy supply path (step S39). If the determination result is false (step S38: NO), the determination part62determines that there is an abnormality of another type (step S40).

As described above, according to the third embodiment, abnormality determination is performed on the basis of both of the load of the actuator56and the supply energy to the actuator56, and thus it is possible to perform determination even more accurately. In particular, if the load (output energy) of the actuator56is small compared with a target value corresponding to the supply energy (input energy) (that is, the target value being an output expected from an input), it can be determined that there is a risk of an abnormality such as leakage of supply energy and thus there is an abnormality in the energy supply path to the actuator56.

Fourth Example

Next, with reference toFIG. 13, the fourth example will be described.FIG. 13is a block diagram of the configuration of the dedicated ECU34according to the fourth example.

In the above embodiments, the turbocharger is provided with the actuator56that can be driven by driving power (electric energy) supplied from the power supply line74. Instead, in the fourth embodiment, the turbocharger2including the actuator56that can be driven by pressure energy will be described.

The fourth embodiment includes a pressure source80that can compress and accumulate a fluid that comprises gas or liquid, a flow path82for supplying the compressed fluid supplied from the pressure source80to the actuator56, and a pressure sensor84disposed in the flow path82. The actuator56is driven by pressure energy of the compressed fluid supplied via the flow path82, and thereby is capable of operating the nozzle mechanism22.

While the supply energy (electric energy) to the actuator56is detected on the basis of the electric value obtained by the current sensor76in the above second and third embodiments, the supply energy (pressure energy) to the actuator56can be detected on the basis of the pressure value obtained by the pressure sensor84. Further, the actuator56is provided with the piezoelectric element72similarly to the above described first to third embodiments, and can detect the load of the actuator56by obtaining the signal of the piezoelectric element72.

Accordingly, in the fourth embodiment, the actuator56is driven by supply energy other than electric energy, such as pressure energy. In this case, an abnormality can be determined on the basis of a control similar to that in the above second and third embodiments, by replacing the detection by the current sensor76with the detection by the pressure sensor.

The above control may be performed on the basis of the flow rate of the compressed fluid by using a flow rate sensor, instead of the pressure sensor84.

As described above, according to the above described embodiment, it is possible to provide an abnormality determination device for a variable geometry turbocharger whereby it is possible to detect an abnormality of the nozzle mechanism22accurately at an early stage.

INDUSTRIAL APPLICABILITY

The present disclosure can be applied to an abnormality determination device for a variable geometry turbocharger including an actuator-driven variable nozzle mechanism.

DESCRIPTION OF REFERENCE NUMERALS