JP2014020344A - Control device of variable flow-type pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally control a cooling water discharge amount without affected by delay in response and failure of a cooling water temperature sensor, with respect to a control device of a variable flow-type pump.SOLUTION: A control device of a variable flow-type pump 14 in which the cooling water discharge amount can be adjusted, includes the cooling water temperature sensor 22 for detecting a cooling water temperature, an oxygen concentration sensor 35 detecting an oxygen concentration in intake air, a cooling water discharge amount control section 51 for increasing and decreasing the cooling water discharge amount of the variable flow-type pump 14 on the basis of a detection value of the cooling water temperature sensor 22, a cooling water temperature sensor failure determining section 53 for determining the failure when the detection value of the cooling water temperature sensor 22 does not rise in decreasing the cooling water discharge amount, and a feedback control section 54 for increasing the cooling water discharge amount of the variable flow-type pump 14 in a case where a detection value of the oxygen concentration sensor 35 is higher than a target oxygen concentration when the cooling water discharge amount is decreased, and the failure of the cooling water temperature sensor 22 is determined.

Description

  The present invention relates to a control device for a variable flow rate pump, and in particular, a variable flow rate provided in a cooling water circuit of an engine including an exhaust gas recirculation device (hereinafter referred to as an EGR device) that recirculates a part of exhaust gas to an intake system. The present invention relates to a control device for a mold pump.

  2. Description of the Related Art Conventionally, there is known a variable flow type pump that can adjust a discharge amount of cooling water flowing through a cooling water circuit of an engine according to an engine operating state. For example, Patent Literature 1 discloses a control device for a variable flow rate pump that increases a cooling water discharge amount when a detected value of a cooling water temperature sensor becomes a predetermined value or more.

JP-A-8-86284

  By the way, in the control device for the variable flow rate pump of the conventional example, the cooling water discharge amount of the variable flow rate pump is increased or decreased based on the detection value of the cooling water temperature sensor. In such a case, there is a possibility that the discharge amount cannot be optimally controlled.

  In particular, since an EGR cooler that performs heat exchange between recirculated exhaust (hereinafter referred to as EGR gas) and cooling water is exposed to high-temperature exhaust, the engine coolant has a large increase in cooling water per unit time. For this reason, if the variable flow rate pump is not properly controlled due to a failure of the cooling water temperature sensor or the like, and the state in which the cooling water discharge amount is reduced continues for a long time, the cooling efficiency of the EGR cooler decreases and the cooling water temperature in the EGR cooler Significantly increase. As a result, the cooling water flow path is damaged due to a cavitation phenomenon or the like, and the cooling water leaks into the exhaust gas passage, which may cause engine damage.

  The present invention has been made in view of the above points, and its object is to respond to the operating state of the engine with the cooling water discharge amount of the variable flow pump without being affected by the response delay or failure of the cooling water temperature sensor. Is to control it optimally.

  In order to achieve the above object, a control device for a variable flow rate pump according to the present invention is provided in an engine coolant circuit including an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake system. A control device for a variable flow rate pump capable of adjusting a discharge amount of flowing cooling water, a cooling water temperature sensor for detecting a temperature of the cooling water, and an oxygen concentration for detecting an oxygen concentration in intake air supplied to the engine A first discharge amount control unit for increasing or decreasing a cooling water discharge amount of the variable flow pump, and a cooling water discharge amount based on an operating state of the engine including a detection value of the sensor and the cooling water temperature sensor; When the detected value of the cooling water temperature sensor does not increase, a failure determination unit that determines that the cooling water temperature sensor is failed, a cooling water discharge amount is decreased, and the cooling water temperature sensor is determined to be failed. When A second discharge amount control unit configured to increase a cooling water discharge amount of the variable flow rate pump when the detected value of the oxygen concentration sensor is higher than a target oxygen concentration determined in advance according to the operating state of the engine; It is characterized by providing.

  In addition, the second discharge amount control unit may increase the cooling water discharge amount of the variable flow pump so that the detection value of the oxygen concentration sensor becomes the target oxygen concentration. The cooling water discharge amount may be feedback controlled.

  The exhaust gas recirculation device may include a heat exchanger that exchanges heat between the circulating cooling water and the intake air, and the cooling water temperature sensor may detect the temperature of the cooling water flowing into the heat exchanger. Good.

  According to the control apparatus for a variable flow rate pump of the present invention, the coolant discharge amount of the variable flow rate pump is optimally controlled according to the operating state of the engine without being affected by a response delay or failure of the coolant temperature sensor. be able to.

It is a typical whole lineblock diagram showing the cooling water circuit concerning one embodiment of the present invention. 1 is a schematic overall configuration diagram showing an intake / exhaust system of an engine according to an embodiment of the present invention. It is a functional lineblock diagram showing an electronic control unit (ECU) concerning one embodiment of the present invention. It is a flowchart which shows the control content by the control apparatus of the variable flow type pump which concerns on one Embodiment of this invention.

  Hereinafter, a variable flow pump control apparatus according to an embodiment of the present invention will be described with reference to the drawings. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  First, a cooling water circuit of a diesel engine (hereinafter simply referred to as an engine) 10 to which the control device for a variable flow pump according to this embodiment is applied will be described with reference to FIG.

  The cooling water circuit of this embodiment is provided on the cooling water inlet side of the oil cooler 12, the oil cooler 12 formed in the lower part in the cylinder block 11, the water jacket 13 formed in the upper part in the cylinder block 11, and the oil blocker 11. The variable flow pump 14, the radiator 15 that exchanges heat between the cooling water and the outside air, the radiator upstream flow path 16 that connects the water jacket 13 and the radiator 15, the radiator 15, and the variable flow pump 14. A radiator downstream flow path 17 to be connected, an EGR upstream flow path 18 that connects an oil cooler 12 and an EGR cooler 43, which will be described in detail later, and an EGR downstream flow that connects the EGR cooler 43 and the variable flow pump 14. A path 19 and a cooling water tank 23 for storing cooling water are provided.

  A known thermostat 21 is provided at a branching portion 20 between the radiator upstream channel 16 and the EGR downstream channel 19. The thermostat 21 opens when the cooling water temperature becomes higher than a predetermined temperature (for example, 70 ° C.) such as when the warm-up is completed, and causes the cooling water to flow through the radiator upstream flow path 16.

  The variable flow pump 14 has a known structure and is mechanically connected to a crankshaft (not shown) of the engine 10. The cooling water discharge amount by the variable flow pump 14 is configured to be adjustable according to an instruction signal input from an electronic control unit (hereinafter referred to as ECU) 50 which will be described in detail later.

The cooling water temperature sensor 22 is a known thermocouple, for example, and detects the temperature of the cooling water flowing into the EGR cooler 43. For this reason, the cooling water temperature sensor 22 is provided at the downstream end of the EGR upstream channel 18 located in the vicinity of the cooling water inlet side of the EGR cooler 43. The detection value of the cooling water temperature sensor 22 (hereinafter, cooling water temperature T _C ) is input to the electrically connected ECU 50.

  Next, based on FIG. 2, the structure of the intake / exhaust system of the engine 10 according to this embodiment will be described.

An intake passage 30 is connected to the intake manifold 10a of the engine 10, and an exhaust passage 31 is connected to the exhaust manifold 10b. A compressor 32 a of the supercharger 32 and an intercooler 33 are provided in the intake passage 30 sequentially from the upstream side, and a turbine 32 b of the supercharger 32 is provided in the exhaust passage 31. An intake flow rate sensor 34 is provided in the intake passage 30 upstream of the compressor 32a, and an oxygen concentration sensor 35 is provided in the intake passage 30 downstream of the compressor 32a. The detected value of the intake flow sensor 34 (hereinafter referred to as intake flow I _F ) and the detected value of the oxygen concentration sensor 35 (hereinafter referred to as oxygen concentration O ₂ ) are input to the electrically connected ECU 50.

  The EGR device 40 includes an EGR passage 41 that connects the exhaust passage 31 upstream of the turbine 32b and the intake passage 30 downstream of the compressor 32a, an EGR valve 42 that adjusts the flow rate of EGR gas, and EGR. And an EGR cooler (heat exchanger) 43 for cooling the gas. The flow rate of EGR gas by the EGR device 40 is adjusted by controlling the opening degree of the EGR valve 42 in accordance with an instruction signal input from the ECU 50.

  The engine rotation sensor 36 detects the rotation speed of a crankshaft (not shown) of the engine 10, and a detection value (hereinafter referred to as engine rotation speed N) is input to the electrically connected ECU 50. The accelerator position sensor 37 detects an operation amount of an accelerator pedal (not shown) by a driver, and the detected operation amount is input to an electrically connected ECU 50.

  Next, the ECU 50 of the present embodiment will be described based on FIG.

  The ECU 50 performs various controls such as fuel injection of the engine 10, and includes a known CPU, ROM, RAM, input port, output port, and the like. In order to perform these various controls, output signals from various sensors such as the engine rotation sensor 36, the accelerator position sensor 37, the cooling water temperature sensor 22, the intake flow rate sensor 34, and the oxygen concentration sensor 35 are input to the ECU 50.

  The ECU 50 also includes a cooling water discharge amount control unit (first discharge amount control unit) 51, an EGR control unit 52, a cooling water temperature sensor failure determination unit 53, and a feedback control unit (second discharge amount control unit). 54 as a part of functional elements. In the present embodiment, these functional elements are described as being included in the ECU 50, which is an integral piece of hardware. However, any one of these functional elements may be provided in separate hardware.

Cooling water discharge amount control unit 51, variable flow-type on the basis of the engine rotational speed N, fuel consumption amount converted from the amount of operation of an accelerator pedal Q, the cooling water temperature T _C, the input value from the various sensors such as the intake air flow rate I _F The cooling water discharge amount of the pump 14 is controlled. For example, when the cooling water temperature T _C rises to the upper limit temperature T _L (for example, 70 ° C.) due to high load operation, the cooling water discharge amount control unit 51 is variable until the cooling water temperature T _C becomes lower than the upper limit temperature T _L. An instruction signal for increasing the coolant discharge amount is output to the flow rate pump 14. In addition, when the cooling water temperature T _C is lower than the upper limit temperature T _L due to low load operation, the cooling water discharge amount control unit 51 sets the cooling water discharge amount to the variable flow rate pump 14 in order to reduce the friction of the engine 10. An instruction signal to be decreased is output.

The EGR control unit 52 controls the opening degree of the EGR valve 42 according to the operating state of the engine 10. More specifically, the ECU 50 stores an intake air flow rate map (not shown) that defines a target intake air flow rate I _FT to the engine 10 using the engine speed N and the fuel injection amount Q as parameters. The EGR control unit 52 reads the target intake flow rate I _FT corresponding to the engine speed N and the fuel injection amount Q at that time from the intake flow rate map, and also receives the intake flow rate I _F (fresh air + EGR) input from the intake flow rate sensor 34. The opening degree of the EGR valve 42 is controlled so that the gas) becomes the target intake flow rate _IFT .

The coolant temperature sensor failure determination unit 53 determines failure of the coolant temperature sensor 22 based on the detection value of the coolant temperature sensor 22. The failure mentioned here includes not only the case where the coolant temperature sensor 22 cannot accurately detect the temperature but also the case where the sensor value is not input to the ECU 50 due to disconnection or the like. When the cooling water discharge amount of the variable flow rate pump 14 decreases, the cooling water temperature rises. Therefore, when the cooling water temperature sensor 22 is normal, the detected value also follows up. The cooling water temperature sensor failure determination unit 53 determines that a failure has occurred when the cooling water temperature T _C input from the cooling water temperature sensor 22 does not increase when the cooling water discharge amount of the variable flow pump 14 decreases.

The oxygen concentration feedback control unit 54 feedback-controls the cooling water discharge amount of the variable flow rate pump 14 based on the oxygen concentration O ₂ input from the oxygen concentration sensor 35 when it is determined that the cooling water temperature sensor 22 has failed. . More specifically, the ECU 50 stores an oxygen concentration map (not shown) that defines the target intake oxygen concentration O _2T to the engine 10 using the engine speed N and the fuel injection amount Q as parameters. When the cooling water temperature sensor 22 fails, the oxygen concentration feedback control unit 54 reads the target intake oxygen concentration O _2T corresponding to the engine speed N and the fuel injection amount Q at that time from the oxygen concentration map. When the oxygen concentration O ₂ input from the oxygen concentration sensor 34 is lower than the target intake oxygen concentration O _2T (O ₂ <O _2T ), the oxygen concentration feedback control unit 54 determines that the detected value of the oxygen concentration sensor 35 is the target. The cooling water discharge amount of the variable flow pump 14 is feedback controlled so that the intake oxygen concentration is O _2T .

  In this embodiment, the purpose of using the oxygen concentration sensor 35 when the cooling water temperature sensor 22 fails is as follows. When the discharge amount of the variable flow pump 14 is reduced, the cooling water temperature rises significantly in the EGR cooler 43 that is exposed to particularly high-temperature exhaust. And the cooling efficiency of EGR cooler 43 falls and the density of EGR gas becomes small because fresh air and EGR gas in a high temperature state merge. Therefore, in order to secure a necessary intake amount, the opening degree of the EGR valve 42 is controlled to be small, and as a result, the oxygen concentration in the intake air increases due to the decrease in the EGR gas flow rate. That is, when the cooling water discharge amount is decreased, there is a correlation between the increase of the cooling water temperature and the increase of the intake oxygen concentration, and it is considered that the oxygen concentration sensor 35 can be substituted when the cooling water temperature sensor 22 fails. Because it is.

  Next, based on FIG. 4, the control flow by the control apparatus of the variable flow type pump of this embodiment is demonstrated. This control starts simultaneously with the start of the engine 10 (key switch ON of the ignition switch).

  In step (hereinafter, simply referred to as “S”) 100, the cooling water discharge amount control unit 51 confirms whether or not the cooling water discharge amount of the variable flow rate pump 14 has been reduced. When the cooling water discharge amount of the variable flow pump 14 is decreased, the process proceeds to S110. On the other hand, when the cooling water discharge amount of the variable flow pump 14 is not decreased (increase or constant), the process returns.

In S110, the cooling water temperature sensor failure determination unit 53 determines whether or not the cooling water temperature sensor 22 has failed. If the cooling water temperature T _C input from the cooling water temperature sensor 22 does not increase, it is determined as a failure and the process proceeds to S120. On the other hand, if the cooling water temperature T _C input from the cooling water temperature sensor 22 increases, it is determined to be normal. The process proceeds to S140.

In S120, the target intake oxygen concentration O _2T corresponding to the engine speed N and the fuel injection amount Q at that time can be read from the oxygen concentration map, and the oxygen concentration O ₂ and the target intake oxygen concentration O input from the oxygen concentration sensor 35 are read. _2T is compared. When the oxygen concentration O ₂ is lower than the target intake oxygen concentration O _2T (O ₂ <O _2T ), the process proceeds to S130, while when the oxygen concentration O ₂ is equal to or higher than the target intake oxygen concentration O _2T (O ₂ ≧ O _2T ). Will be returned.

In S130, the oxygen concentration feedback control unit 54 performs feedback control to increase the cooling water discharge amount of the variable flow rate pump 14 so that the oxygen concentration O ₂ input from the oxygen concentration sensor 35 becomes the target intake oxygen concentration O _2T. Once this control is performed, the control is returned.

On the other hand, when the process proceeds from S110 to S140, it is confirmed whether or not the cooling water temperature T _C input from the cooling water temperature sensor 22 exceeds the upper limit temperature T _L. When the cooling water temperature T _C does not exceed the upper limit temperature T _L (T _C ≦ T _L ), the process is returned. On the other hand, when the cooling water temperature T _C exceeds the upper limit temperature T _L (T _C > T _L ), the cooling water of the variable flow rate pump 14 is cooled until the cooling water temperature T _C becomes lower than the upper limit temperature T _L in S150. The discharge amount is increased and returned. Thereafter, the control flow described above is repeatedly executed until the engine 10 is stopped (ignition switch key switch OFF).

  Next, functions and effects of the variable flow rate pump control device according to this embodiment will be described.

  In a conventional variable flow rate pump control device, the discharge amount of the variable flow rate pump is increased when the sensor value exceeds a predetermined value based on the detection value of the cooling water temperature sensor. Therefore, when the cooling water temperature sensor fails, there is a possibility that the discharge amount of the variable flow pump cannot be optimally controlled.

  In particular, since the EGR cooler is exposed to high-temperature exhaust gas, if the cooling water discharge amount is reduced due to a failure of the cooling water temperature sensor or the like for a long time, the cooling efficiency of the EGR cooler decreases, and the cooling inside the EGR cooler decreases. Increase water temperature. As a result, the cooling water flow path is damaged due to a cavitation phenomenon or the like, and the cooling water leaks into the exhaust gas passage, which may cause engine damage.

  In addition, when the temperature of the EGR gas rises due to a decrease in the cooling efficiency of the EGR cooler, the fresh air comes into contact with the hot EGR gas and the density decreases. Is done. As a result, the EGR gas flow rate decreases in combination with the decrease in the EGR gas density, and the exhaust gas performance may be deteriorated due to an increase in oxygen concentration in the intake air (fresh air + EGR gas).

  On the other hand, in the control device for the variable flow rate pump of the present embodiment, when the cooling water temperature sensor 22 fails, the coolant discharge amount of the variable flow rate pump 14 is determined based on the detected value of the oxygen concentration sensor 35. Control is performed according to 10 operating states.

  Therefore, according to the control device for the variable flow rate pump of the present embodiment, it becomes possible to safely control the cooling water discharge amount of the variable flow rate pump 14 even when the cooling water temperature sensor 22 breaks down. Damage to the cooler 43 and the engine 10 can be prevented, and exhaust gas deterioration can be effectively suppressed.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, although the cooling water temperature sensor 22 has been described as detecting the temperature of the cooling water flowing into the EGR cooler 43, the cooling water temperature sensor 22 detects cooling water temperature flowing into the radiator 15, etc. It is also possible to apply to a water temperature sensor (not shown). Also in this case, the same effect as the above-described embodiment can be obtained. Further, the EGR passage 41 of the EGR device 40 may communicate the exhaust passage 31 on the exhaust downstream side of the turbine 32b and the intake passage 30 on the intake upstream side of the compressor 32a.

DESCRIPTION OF SYMBOLS 10 Engine 14 Variable flow type pump 22 Cooling water temperature sensor 35 Oxygen concentration sensor 40 EGR apparatus (exhaust gas recirculation apparatus)
43 EGR cooler (heat exchanger)
50 ECU
51 Cooling water discharge amount control unit (first discharge amount control unit)
53 Cooling water temperature sensor failure determination unit (failure determination unit)
54 Feedback control unit (second discharge amount control unit)

Claims (3)

A control device for a variable flow rate pump that is provided in an engine cooling water circuit including an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake system, and that can adjust the discharge amount of the cooling water flowing through the cooling water circuit. And
A cooling water temperature sensor for detecting the temperature of the cooling water;
An oxygen concentration sensor for detecting the oxygen concentration in the intake air supplied to the engine;
A first discharge amount control unit for increasing or decreasing a coolant discharge amount of the variable flow rate pump based on an operating state of the engine including a detection value of the coolant temperature sensor;
When the cooling water discharge amount is reduced, if the detection value of the cooling water temperature sensor does not increase, a failure determination unit that determines that the cooling water temperature sensor is a failure,
When the cooling water discharge amount is decreased and the detected value of the oxygen concentration sensor is higher than the target oxygen concentration determined in advance according to the operating state of the engine when the cooling water temperature sensor is determined to be malfunctioning, A control device for a variable flow rate pump, comprising: a second discharge rate control unit that increases a coolant discharge rate of the variable flow rate pump.   The second discharge amount control unit is configured to increase the cooling water discharge amount of the variable flow pump so that the detected value of the oxygen concentration sensor becomes the target oxygen concentration. The control apparatus for a variable flow rate pump according to claim 1, wherein the discharge amount is feedback-controlled.   The said exhaust gas recirculation apparatus contains the heat exchanger which performs heat exchange with the cooling water and the intake air which are distribute | circulated, The said cooling water temperature sensor detects the temperature of the cooling water which flows in into this heat exchanger. The control device of the variable flow type pump.

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