Control device for internal combustion engine

Abstract

To provide a control device for an internal combustion engine capable of promptly completing warming-up of the engine.SOLUTION: A control device for an internal combustion engine comprises: the internal combustion engine 1; an electric water pump 2 for circulating cooling water of the internal combustion engine 1; water temperature acquisition means 3 for acquiring a cooling water temperature TW of the internal combustion engine 1; oil temperature acquisition means 4 for acquiring an oil temperature TO of the internal combustion engine 1; and control means 5 for controlling the electric water pump 2 on the basis of a difference between the cooling water temperature TW and the oil temperature TW.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a control device for an internal combustion engine.

Background Art

[0002] As a control device for an internal combustion engine (hereinafter referred to as an engine), a mechanical water pump is provided in parallel with the engine, and the mechanical water pump circulates the cooling water of the engine. At the same time, by exchanging heat between the cooling water heated by the engine and the lubricating oil that lubricates the inside of the engine, a method of raising the oil temperature of this lubricating oil is widely adopted. The mechanical water pump is mechanically connected to the crankshaft of the engine, and the rotational speed of this mechanical water pump has a proportional relationship with the rotational speed of the engine. For this reason, as shown in FIG. 5, if the rotational speed of the engine is constant, the rotational speed of the mechanical water pump will always be constant during the warm-up process regardless of the cooling water temperature or the oil temperature.

[0003] In warming up the engine, it is necessary to rapidly raise the oil temperature together with the cooling water temperature. However, the conventional configuration in which the rotational speed of the mechanical water pump is proportional to the rotational speed of the engine regardless of the cooling water temperature or the oil temperature is not optimal in terms of rapidly raising the oil temperature. Therefore, in the configuration according to Patent Document 1 below, the cooling water temperature of the engine's cooling water and the oil temperature of the lubricating oil are measured respectively. Based on the magnitude relationship between the measured cooling water temperature and the upper limit water temperature, which is the limit temperature allowed for the engine, and between the measured oil temperature and the estimated oil temperature estimated based on the amount of heat supplied to the cylinder block, the rotational speed of the electric water pump is controlled to rapidly perform warm-up, aiming at an effective reduction in friction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As shown as an example in FIG. 5, during the warm-up process, while the cooling water temperature rises relatively rapidly, the oil temperature may lag in temperature rise compared to the cooling water temperature, and the temperature difference between the cooling water temperature and the oil temperature is different at the initial stage, the later stage, and after the warm-up is completed in the warm-up process. In the configuration according to Patent Document 1, it merely controls the rotational speed of the electric water pump based on the magnitude relationship between the measured cooling water temperature and the upper limit water temperature, and between the measured oil temperature and the estimated oil temperature, and it cannot be said that the characteristics of the rise in the cooling water temperature and the oil temperature are fully considered, and there is room for improvement in terms of accelerating the warm-up of the engine.

[0006] Therefore, an object of the present invention is to quickly complete the warm-up of the engine.

Means for Solving the Problems

[0007] In order to solve the above problems, in the present invention, an internal combustion engine, an electric water pump for circulating the cooling water of the internal combustion engine, a water temperature acquisition means for acquiring the cooling water temperature of the internal combustion engine, an oil temperature acquisition means for acquiring the oil temperature of the internal combustion engine, a control means for controlling the electric water pump based on the difference between the cooling water temperature and the oil temperature, constitute a control device for an internal combustion engine having the above.

[0008] In this configuration, the control means when a first condition that the cooling water temperature is less than a predetermined temperature is satisfied, sets the output of the electric water pump as a first output, when a second condition that the cooling water temperature is equal to or higher than the predetermined temperature and the temperature difference obtained by subtracting the oil temperature from the cooling water temperature exceeds a predetermined temperature difference is satisfied, it is preferable to set the output of the electric water pump as a second output larger than the first output.

[0009] In this configuration, the control means when a third condition that the coolant water temperature is equal to or higher than the predetermined temperature and the temperature difference is equal to or lower than the predetermined temperature difference is satisfied, it is preferable that the output of the electric water pump is set to a third output that is larger than the first output and smaller than the second output.

[0010] In this configuration, the control means after the third condition is satisfied, the output of the electric water pump is maintained at the third output until the internal combustion engine automatically stops based on the control of the vehicle, when the internal combustion engine restarts after the automatic stop, when the first condition is satisfied, the output of the electric water pump is set to the first output, and when the first condition is not satisfied, it is preferable that the output of the electric water pump is set to the third output.

[0011] In this configuration, it is preferable that the predetermined temperature difference is set to a smaller value as the rotational speed of the internal combustion engine is higher.

[0012] In this configuration, the internal combustion engine is mounted on a hybrid vehicle having a series running mode and a parallel running mode, it is preferable that the output of the electric water pump when the third condition is satisfied is set to be larger in the parallel running mode than in the series running mode.

Advantages of the Invention

[0013] In this invention, since the control means is configured to control the electric water pump based on the difference between the coolant water temperature and the oil temperature, the output of the electric water pump can be optimized throughout the initial stage, the later stage, and the overall stage after the warm-up process is completed, and the warm-up of the engine can be completed promptly.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0015] An embodiment of a control device for an internal combustion engine according to the present invention (hereinafter abbreviated as the control device) is schematically shown in FIG. 1. This control device mainly includes an internal combustion engine 1 (hereinafter referred to as the engine and given the same reference numeral as the internal combustion engine 1), an electric water pump 2, a coolant temperature acquisition means 3, an oil temperature acquisition means 4, and a control means 5.

[0016] Hereinafter, a hybrid vehicle equipped with a gasoline engine as the engine 1, particularly a plug-in hybrid vehicle (PHEV) capable of external charging or external power supply, will be described as a premise. The hybrid vehicle described here has a series running mode in which the engine 1 is used only for driving a generator and the vehicle is driven only by a motor, and a parallel running mode in which the vehicle is driven by both the engine and the motor. Note that this control device is not limited to hybrid vehicles and can be widely applied to vehicles equipped with an internal combustion engine, such as general gasoline engine vehicles and diesel engine vehicles.

[0017] The engine 1 is provided with a cooling water passage 6 for circulating cooling water for cooling the engine 1. The electric water pump 2 is provided in the cooling water passage 6. The output of the electric water pump 2 is controlled by the control means 5.

[0018] The water temperature acquisition means 3 is a means for acquiring the temperature T of the cooling water for cooling the engine 1, and is provided at a predetermined location of the cooling water passage 6. In this embodiment, a water thermometer is adopted as the water temperature acquisition means 3. W It is provided at a predetermined location of the cooling water passage 6. In this embodiment, a water thermometer is adopted as the water temperature acquisition means 3.

[0019] The oil temperature acquisition means 4 is a means for acquiring the temperature T of the lubricating oil for lubricating the engine 1, and is provided at a predetermined location (for example, the main gallery) of the engine 1. In this embodiment, an oil thermometer is adopted as the oil temperature acquisition means 4. O It is provided at a predetermined location (for example, the main gallery) of the engine 1. In this embodiment, an oil thermometer is adopted as the oil temperature acquisition means 4.

[0020] An oil cooler 7 is provided in parallel with the engine 1. By flowing cooling water and lubricating oil through the oil cooler 7, heat exchange is performed between the two. That is, while the warm-up of the engine 1 is performed by the heat transfer from the cooling water heated by the engine 1 to the lubricating oil, causing the oil temperature T O to rise, the engine 1 can be appropriately cooled by the heat transfer from the lubricating oil to the cooling water.

[0021] The control means 5 is connected to the water temperature acquisition means 3, the oil temperature acquisition means 4, and the electric water pump 2, and is based on the cooling water temperature T acquired by the water temperature acquisition means 3 W , and the cooling water temperature T W and the temperature difference ΔT (= T O -T W -T O ) acquired by the oil temperature acquisition means 4 to control the output of the electric water pump 2.

[0022] Specifically, as shown in FIG. 2, in the warm-up process after the engine is started, the control means 5 controls the cooling water temperature T WWhen a first condition that is less than a predetermined temperature K is satisfied, the output of the electric water pump 2 is set to a first output (low output), and the cooling water temperature T W is equal to or higher than the predetermined temperature K and the cooling water temperature T W from the oil temperature T O except for the temperature difference ΔT is greater than a predetermined temperature difference K 1 When a second condition is satisfied, the output of the electric water pump 2 is set to a second output (high output), and the cooling water temperature T W is equal to or higher than the predetermined temperature K and the temperature difference ΔT is equal to or less than the predetermined temperature difference K 1 When the third condition is satisfied, control is performed such that the output of the electric water pump 2 is set to a third output (medium output) that is greater than the first output and less than the second output.

[0023] In the warm-up process of the engine 1, as shown in FIG. 5, while the cooling water temperature T W rises relatively rapidly, the oil temperature T O may lag in temperature rise compared to the cooling water temperature T W . The predetermined temperature K is a temperature that serves as a measure of when the cooling water temperature T W has reached or is close enough to the warm-up completion temperature, and can be, for example, 80°C. Also, the predetermined temperature difference K 1 is a temperature difference ΔT that serves as a measure of when the lubricating oil has been sufficiently heated (warm-up has been completed), and can be, for example, 0°C. FIG. 2 shows the control when the predetermined temperature difference K 1 is 0°C, and when ΔT becomes 0°C, the transition is made from the second condition to the third condition. Note that the predetermined temperature K and the predetermined temperature difference K 1 can be changed as appropriate.

[0024] The first output of the electric water pump 2 in the first condition is set to a lower output than the output in the steady state where the warm-up of the engine 1 is completed. By reducing the circulation flow rate of the cooling water as such a low output, the cooling of the cooling water by the running wind of the vehicle is suppressed, and the cooling water temperature T W can be rapidly increased.

[0025] On the other hand, the second output of the electric water pump 2 under the second condition is set to a higher output than the output (third output) in the steady state where the warm-up of the engine 1 is completed. By increasing the circulation flow rate of the cooling water as such a high output, heat exchange between the cooling water that has rapidly increased in temperature under the first condition and the lubricating oil is promoted, and the oil temperature T O can be rapidly increased to complete the warm-up of the engine 1.

[0026] The third output of the electric water pump 2 under the third condition is set to an output corresponding to the steady state where the warm-up of the engine 1 is completed. By maintaining the output in this steady state, the cooling water temperature T W and the oil temperature T O can be maintained within an appropriate temperature range. Note that the third output may be changed according to the rotational speed of the engine 1 and the cooling water temperature T W . Also, the second output is set to a higher output than the third output under the same conditions (the state where the rotational speed of the engine 1 and the cooling water temperature T W are the same).

[0027] After the third condition is satisfied, the control means 5, when shifting from engine running in which the vehicle is driven by the driving force of the engine 1 to motor running in which the vehicle is driven by the driving force of the motor, or during an idling stop while waiting for a signal, etc., until the engine 1 automatically stops based on the control of the vehicle, can control to maintain the output of the electric water pump 2 at the third output. Further, when the engine 1 restarts after this automatic stop, when the first condition is satisfied (when the cooling water temperature T W is less than a predetermined temperature K), the output of the electric water pump 2 is set to the first output, and when the first condition is not satisfied (when the cooling water temperature T W is greater than or equal to the predetermined temperature K), as shown in FIG. 3, the output of the electric water pump 2 can be controlled to be the third output (medium output) based on the third condition.

[0028] The oil temperature T O is the cooling water temperature T WSince it is difficult for the temperature to change compared to W if the coolant temperature T O is equal to or higher than the predetermined temperature K, it can be estimated that the oil temperature T O is also maintained at a state where it is about the predetermined temperature K. Therefore, without performing the output control according to the second condition aimed at rapidly increasing the oil temperature T O by promoting the heat exchange between the cooling water and the lubricating oil, it is possible to directly shift to the output control according to the third condition when the warm-up of the engine 1 is completed. Thereby, an increase in power consumption due to increasing the output of the electric water pump 2 can be suppressed.

[0029] On the other hand, when the coolant temperature T W drops below the predetermined temperature K during the automatic stop, as described above, by performing the output control according to the first condition aimed at rapidly increasing the coolant temperature T W the oil temperature T O can be rapidly returned to a high state.

[0030] The predetermined temperature difference K 1 can also be changed corresponding to the rotational speed of the engine 1. Specifically, the larger the rotational speed of the engine 1, the smaller the value can be. When the predetermined temperature difference K 1 is made smaller, the condition for shifting from the first condition to the second condition is relaxed, and heat exchange from the cooling water to the lubricating oil becomes easier, so that the oil temperature T O can be rapidly increased. When the rotational speed of the engine 1 is high, the heat generation of this engine 1 is large and the coolant temperature T W tends to rise. Therefore, even if the output of the electric water pump 2 is increased by the establishment of the second condition to promote heat exchange, there is no hindrance to the rise of the coolant temperature T W .

[0031] Also, as shown in FIG. 4, the third output of the electric water pump 2 under the third condition can be set to be larger in the parallel running mode than in the series running mode. The series running mode is a running mode that emphasizes fuel efficiency and is applied when the vehicle is running at a constant speed, etc., and the engine 1 is driven at an operation point with good fuel efficiency. At this time, the output of the electric water pump 2 is set to the normal output applied when the warm-up operation is completed.

[0032] On the other hand, the parallel running mode is a running mode applied when a high output is required of the engine 1, such as when the vehicle is accelerating or under high load, etc., and the output of the electric water pump 2 is set higher than the normal output applied when the warm-up operation is completed. Thus, by increasing the output of the electric water pump 2 in the parallel running mode, an excessive rise in the cooling water temperature T W is suppressed, and heat exchange from the lubricating oil to the cooling water is promoted, and an excessive rise in the oil temperature T O can be suppressed.

[0033] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. Therefore, the scope of the present invention is shown not by the above description but by the scope of claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims are included.

Explanation of Reference Numerals

[0034] 1 Internal combustion engine (engine) 2 Electric water pump 3 Cooling water temperature acquisition means 4 Oil temperature acquisition means 5 Control means 6 Cooling water passage 7 Oil cooler T W Cooling water temperature T O Oil temperature K Predetermined temperature ΔT Temperature difference K 1 Predetermined temperature difference

Claims

1. An internal combustion engine, an electric water pump for circulating the cooling water of the internal combustion engine, a water temperature acquisition means for acquiring the cooling water temperature of the internal combustion engine, an oil temperature acquisition means for acquiring the oil temperature of the internal combustion engine, control means for controlling the electric water pump based on the temperature difference obtained by subtracting the oil temperature from the cooling water temperature, and having, the control means, when a first condition that the cooling water temperature is less than a predetermined temperature is satisfied, sets the output of the electric water pump to a first output, when a second condition that the cooling water temperature is equal to or higher than the predetermined temperature and the temperature difference obtained by subtracting the oil temperature from the cooling water temperature exceeds a predetermined temperature difference is satisfied, sets the output of the electric water pump to a second output greater than the first output, the control means, when a third condition that the cooling water temperature is equal to or higher than the predetermined temperature and the temperature difference is equal to or less than the predetermined temperature difference is satisfied, sets the output of the electric water pump to a third output greater than the first output and less than the second output A control device for an internal combustion engine.

2. The control means, after the third condition is satisfied, maintains the output of the electric water pump at the third output until the internal combustion engine automatically stops based on the control of the vehicle, when the internal combustion engine restarts after the automatic stop, when the first condition is satisfied, sets the output of the electric water pump to the first output, and when the first condition is not satisfied, sets the output of the electric water pump to the third output The control device for an internal combustion engine according to Claim 1.

3. Sets the predetermined temperature difference to a smaller value as the rotational speed of the internal combustion engine is higher The control device for an internal combustion engine according to Claim 1 or 2.

4. The internal combustion engine is mounted on a hybrid vehicle having a series running mode and a parallel running mode, The output of the electric water pump when the third condition is satisfied is set to be larger in the parallel running mode than in the series running mode The control device for an internal combustion engine according to any one of Claims 1 to 3.

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