A control method for a piston cooling jet

Abstract

This invention discloses a control method for a piston cooling spray hook, relating to engine control technology. The method involves acquiring the engine's oil pressure and temperature, and combining these to obtain a first oil flow requirement for the oil pump. A second oil flow rate for the piston cooling spray hook is calibrated based on the engine's real-time throttle opening, and the change in oil flow rate of the piston cooling spray hook is obtained based on the change in the second oil flow rate. This change in oil flow rate is then superimposed on the first oil flow requirement to obtain a target flow requirement. Finally, the oil pump is controlled to output an oil flow rate consistent with the target flow requirement. This invention achieves coordinated control of the oil pump flow rate and the piston cooling spray hook flow rate, ensuring lubrication and cooling functions are met under high loads, while reducing oil flow rate and decreasing the driving power of the oil pump under low loads.

Description

Technical Field

[0001] This invention relates to engine control technology, and more specifically, to a control method for a piston cooling spray hook. Background Technology

[0002] Lubricating oil is an essential medium for engine operation. The oil pump draws and pressurizes the oil from the oil pan, continuously delivering it to the surfaces of various parts to lubricate them and maintain normal engine operation. Simultaneously, the oil also cools critical components, such as the piston. After being pressurized by the oil pump, the oil is precisely delivered to the piston's internal cooling oil passages via piston cooling spray hooks. Under the vibrations of piston movement, it effectively cools the piston, ensuring that it can still operate normally under the influence of high-temperature gases.

[0003] The flow rate of lubricating oil must meet both the lubrication and piston cooling requirements. However, different engine operating conditions necessitate different oil flow rates. Existing technologies generally meet the requirements at the maximum heat load point, but because the flow rates of the oil pump and cooling spray nozzles are uncontrollable, additional power is required to drive the oil pump, which consumes fuel and increases fuel consumption.

[0004] In some applications, a pressure regulating valve is installed in the oil pump to prevent excessive oil pressure, but this device cannot adjust the oil pump flow rate. Another patent, CN114738074A, discloses a control method, device, vehicle, and storage medium for a variable flow oil pump. This control method acquires the engine speed and torque; determines a target oil pressure based on the speed and torque; acquires the oil temperature; determines a target opening degree for the variable flow oil pump based on the target oil pressure and oil temperature; considers the influence of temperature on the variable flow oil pump opening degree, ensuring high accuracy of the target opening degree; then the variable flow oil pump operates at the target opening degree; acquires the actual oil pressure; and corrects the target opening degree based on the actual oil pressure and the target oil pressure to make the actual oil pressure equal to the target oil pressure. Because the target opening degree has high accuracy, only a small amount needs to be corrected during correction, which can avoid large fluctuations in oil pressure and thus protect the engine. In addition, patent CN114622978A discloses a piston cooling spray hook and its control method. The spray hook includes a spray hook body, and the output end of the spray hook body is equipped with a solenoid valve, which is electrically connected to an ECU controller. The input end of the spray hook body is equipped with a pressure accumulator, which is connected to an oil pump through a first oil pipe. This invention also discloses a control method for a piston cooling spray hook. It controls the solenoid valve to open at the start of injection and closes it after a sustained injection duration. This reduces oil injection while ensuring lubrication, thus reducing the pressure drop in the oil lubrication system and maintaining the pressure of the oil lubrication system even at low engine speeds (such as idling).

[0005] However, the above-disclosed technologies only consider adjusting the oil flow and pressure from a local perspective, without taking a holistic approach to controlling the oil flow. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a control method for piston cooling spray hook that addresses the shortcomings of the prior art, thereby achieving coordinated control of the flow rate of the oil pump and the flow rate of the piston cooling spray hook.

[0007] The present invention discloses a control method for a piston cooling spray hook, which involves acquiring the engine oil pressure and oil temperature, and combining the oil pressure and oil temperature to obtain a first oil flow requirement for the oil pump; calibrating a second oil flow requirement for the piston cooling spray hook based on the real-time throttle opening of the engine, and obtaining the change in oil flow of the piston cooling spray hook based on the change in the second oil flow requirement; superimposing the change in oil flow onto the first oil flow requirement to obtain a target flow requirement, and controlling the oil pump to output an oil flow consistent with the target flow requirement.

[0008] As a further improvement, the flow rate requirement of the piston cooling spray hook is calibrated in the following way:

[0009] When the engine speed is accelerating, if the real-time throttle opening is greater than the first throttle opening threshold, then the second oil flow demand is the first demand threshold; if the real-time throttle opening is greater than the second throttle opening threshold, then the second oil flow demand is the second demand threshold; if the real-time throttle opening is greater than the third throttle opening threshold, then the second oil flow demand is the third demand threshold.

[0010] When the engine speed is decelerating, if the real-time throttle opening is less than the third throttle opening threshold, the second oil flow requirement is the second requirement threshold; if the real-time throttle opening is less than the second throttle opening threshold, the second oil flow requirement is the first requirement threshold; if the real-time throttle opening is less than the first throttle opening threshold, the second oil flow requirement is set to the minimum flow rate.

[0011] Furthermore, during the acceleration of the engine speed, the opening of the piston cooling spray hook increases by a proportion of the first spray hook opening threshold until the second oil flow demand equals the calibrated value.

[0012] Furthermore, during the deceleration of the engine speed, the opening of the piston cooling spray hook is reduced by a proportion of the second spray hook opening threshold, and the second spray hook opening threshold is less than the first spray hook opening threshold.

[0013] Furthermore, the first throttle opening threshold is 25%-35%; the second throttle opening threshold is 45%-55%; the third throttle opening threshold is 65%-75%; the first demand threshold is 35%-45%; the second demand threshold is 65%-75%; the third demand threshold is 100%; the first spray hook opening threshold is 0.5% / ms-1% / ms; and the second spray hook opening threshold is 0.2% / ms-0.5% / ms.

[0014] Furthermore, the values ​​of the first demand threshold, the second demand threshold, or the third demand threshold must ensure that the actual maximum temperature of the piston is less than 95% of the maximum temperature limit of the piston.

[0015] Furthermore, when the engine throttle opening is 0, the second oil flow requirement is set to the minimum flow rate.

[0016] Further improvements are made by obtaining the atmospheric pressure value of the engine's current operating environment and correcting the target flow rate requirement based on the atmospheric pressure value.

[0017] Furthermore, the target flow demand is corrected as follows: if the atmospheric pressure value decreases, the target flow demand is positively corrected using a set correction coefficient; otherwise, the target flow demand is negatively corrected using the correction coefficient.

[0018] Beneficial effects

[0019] The advantages of this invention are as follows: by calibrating the oil flow requirement of the piston cooling spray hook through the throttle opening, and simultaneously determining the oil flow requirement of the oil pump based on the change in oil flow of the piston cooling spray hook, the coordinated control of the oil pump flow and the piston cooling spray hook flow is achieved. This enables the lubrication and cooling functions to be met under high load, while reducing the oil flow under low load, reducing the driving power of the oil pump, and simultaneously reducing the flow of the piston cooling spray hook, thereby reducing the heat transfer loss of in-cylinder energy, improving combustion efficiency, and reducing heat transfer loss, thus improving the engine's fuel consumption and emission performance. Attached Figure Description

[0020] Figure 1 This is a control logic diagram of the piston cooling spray hook control method of the present invention;

[0021] Figure 2 This is a schematic diagram of the engine oil control system framework of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0023] See Figures 1-2 The present invention provides a method for controlling a piston cooling spray hook, comprising the following steps.

[0024] Step 1: Obtain the engine oil pressure and oil temperature, and combine these to determine the initial oil flow requirement for the oil pump. Specifically, obtain the engine's operating speed and throttle characteristics. From these characteristics, the corresponding oil pressure can be obtained from existing characteristic curves. Then, based on the oil pressure and the current oil temperature in the oil pan, the oil pump's flow requirement can be determined. This is existing technology, therefore, it will not be discussed further in this article.

[0025] Step 2: Calibrate the required opening of the piston cooling spray hook based on the engine's real-time throttle opening. The oil flow rate can then be determined from the characteristic curve of the piston cooling spray hook based on this required opening. This oil flow rate is then used as the required flow rate for the piston cooling spray hook. The change in oil flow rate of the piston cooling spray hook is obtained based on the change in the second required oil flow rate.

[0026] In this step, the flow rate requirement of the piston cooling spray hook is calibrated in the following way:

[0027] (1) When the engine throttle opening is 0, the second oil flow requirement is set to the minimum flow rate. This minimum flow rate only needs to ensure that the actual maximum piston temperature is within 95% of the maximum allowable temperature limit when the engine is idling.

[0028] (2) When the engine speed is accelerating, if the real-time throttle opening is greater than the first throttle opening threshold, the second oil flow demand is the first demand threshold; if the real-time throttle opening is greater than the second throttle opening threshold, the second oil flow demand is the second demand threshold; if the real-time throttle opening is greater than the third throttle opening threshold, the second oil flow demand is the third demand threshold. The values ​​of the throttle opening and the second oil flow demand can be set as follows: the first throttle opening threshold is 30%; the second throttle opening threshold is 50%; the third throttle opening threshold is 70%; the first demand threshold is 40%; the second demand threshold is 70%; and the third demand threshold is 100%.

[0029] For the first, second, or third demand threshold values, it is necessary to ensure that the actual maximum temperature of the piston is below 95% of the maximum piston temperature limit. Currently, when designing piston cooling spray hooks, the initial critical dimensions of the piston cooling spray hook are designed by combining the engine's combustion model, power output, and piston heat dissipation area to estimate the piston's heat dissipation (generally, engineering experience shows that the relationship between the output power of aluminum pistons and the cooling spray hook flow rate is 4-6 kg / kWh, and the relationship between the output power of steel pistons and the cooling spray hook flow rate is 5-7 kg / kWh). Then, experiments are conducted to check whether the current piston cooling spray hook flow rate meets the current power output requirements. If not, the spray hook flow rate is adjusted until the actual maximum piston temperature is within 95% of the allowable maximum temperature limit. In this way, the cooling performance of the piston cooling spray hook can be ensured. After the piston's maximum temperature meets the design target, the relationship between the final power output and the piston cooling spray flow rate is determined as the basis for subsequent control strategies. Based on different ranges of the first, second, and third throttle opening thresholds, the actual piston temperature at the highest heat load point of different throttle characteristics is verified. The relationship between the output power and the piston cooling spray flow rate of different throttle characteristics is corrected based on the experimental results, and the characteristic curve of the final output power and piston cooling spray flow rate is determined. The first, second, and third demand thresholds all lie on this characteristic curve.

[0030] Furthermore, when the real-time throttle opening increases, the opening of the piston cooling spray hook also increases. In order to avoid the problem of excessive power consumption caused by the sudden increase in oil pump power, the valve opening of the piston cooling spray hook in this embodiment is increased by a proportion of the first spray hook opening threshold until the second oil flow demand is equal to the calibrated value, so as to ensure a stable increase in oil volume, which is beneficial to low power consumption and protection of the oil pump.

[0031] (3) When the engine speed is decelerating, if the real-time throttle opening is less than the third throttle opening threshold, the second oil flow requirement is the second requirement threshold; if the real-time throttle opening is less than the second throttle opening threshold, the second oil flow requirement is the first requirement threshold; if the real-time throttle opening is less than the first throttle opening threshold, the second oil flow requirement is set to the minimum flow rate, which effectively ensures the cooling performance index of the piston cooling spray hook and also meets the design requirements of low energy consumption of the oil pump.

[0032] During engine deceleration, the opening of the piston cooling spray hook decreases proportionally to the second spray hook opening threshold. In this embodiment, the second spray hook opening threshold is lower than the first spray hook opening threshold to ensure that the cooling oil flow increases rapidly during acceleration and decreases slowly during deceleration, ensuring that the piston's heat is fully dissipated while also taking into account the low power consumption requirements of the oil pump. Furthermore, a delay time is set for adjusting the piston cooling spray hook when the throttle is reduced, effectively preventing thermal load overload caused by frequent acceleration and deceleration, thus ensuring piston reliability. Specifically, the first spray hook opening threshold is 0.5% / ms, and the second spray hook opening threshold is 0.2% / ms.

[0033] Step 3: Superimpose the change in oil flow rate onto the initial oil flow rate demand to obtain the target flow rate demand. Then, determine the duty cycle of the oil pump PWM valve based on the target flow rate demand, thereby ensuring the oil pump outputs an oil flow rate consistent with the target flow rate demand. This achieves coordinated control of the oil pump flow rate and the piston cooling spray flow rate, meeting lubrication and cooling requirements under high loads while reducing oil flow rate under low loads. This reduces the driving power of the oil pump and the piston cooling spray flow rate, lowering in-cylinder heat transfer losses, improving combustion efficiency, and ultimately improving engine fuel consumption and emissions performance.

[0034] Step 4: Obtain the atmospheric pressure value of the engine's current operating environment and adjust the target flow requirement based on the atmospheric pressure value.

[0035] Generally, as altitude increases, the inlet pressure of the oil pump decreases, and its output pressure also decreases. Therefore, it is necessary to increase the duty cycle to improve the oil pump's oil supply capacity and achieve the target oil pressure. Thus, in this embodiment, the correction method for the target flow rate requirement is as follows: if the atmospheric pressure decreases, the target flow rate requirement is positively corrected using a set correction factor; otherwise, the target flow rate requirement is negatively corrected using the same correction factor.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for controlling a piston cooling spray hook, characterized in that, The engine oil pressure and oil temperature are obtained, and the first oil flow requirement of the oil pump is obtained by combining the oil pressure and oil temperature; the second oil flow requirement of the piston cooling spray hook is calibrated according to the real-time throttle opening of the engine, and the change in oil flow of the piston cooling spray hook is obtained according to the change in the second oil flow requirement; the change in oil flow is superimposed on the first oil flow requirement to obtain the target flow requirement, and the oil pump is controlled to output an oil flow that is consistent with the target flow requirement according to the target flow requirement; The flow rate requirement of the piston cooling spray hook is calibrated in the following way. When the engine speed is accelerating, if the real-time throttle opening is greater than the first throttle opening threshold, the second oil flow requirement is the first requirement threshold; if the real-time throttle opening is greater than the second throttle opening threshold, the second oil flow requirement is the second requirement threshold; if the real-time throttle opening is greater than the third throttle opening threshold, the second oil flow requirement is the third requirement threshold; the opening of the piston cooling spray hook increases proportionally to the first spray hook opening threshold until the second oil flow requirement equals the calibrated value. When the engine speed is decelerating, if the real-time throttle opening is less than the third throttle opening threshold, the second oil flow requirement is the second requirement threshold; if the real-time throttle opening is less than the second throttle opening threshold, the second oil flow requirement is the first requirement threshold; if the real-time throttle opening is less than the first throttle opening threshold, the second oil flow requirement is set to the minimum flow rate; the opening of the piston cooling spray hook is reduced by a proportion of the second spray hook opening threshold, and the second spray hook opening threshold is less than the first spray hook opening threshold.

2. The control method for a piston cooling spray hook according to claim 1, characterized in that, The first throttle opening threshold is 25%-35%; the second throttle opening threshold is 45%-55%; the third throttle opening threshold is 65%-75%; the first demand threshold is 35%-45%; the second demand threshold is 65%-75%; the third demand threshold is 100%; the first spray hook opening threshold is 0.5% / ms-1% / ms; the second spray hook opening threshold is 0.2% / ms-0.5% / ms.

3. The control method for a piston cooling spray hook according to claim 2, characterized in that, The values ​​of the first demand threshold, the second demand threshold, or the third demand threshold must ensure that the actual maximum temperature of the piston is less than 95% of the maximum temperature limit of the piston.

4. The control method for a piston cooling spray hook according to claim 1, characterized in that, When the engine throttle opening is 0, the second oil flow requirement is set to the minimum flow rate.

5. The control method for a piston cooling spray hook according to claim 1, characterized in that, Obtain the atmospheric pressure value of the engine's current operating environment, and correct the target flow rate requirement based on the atmospheric pressure value.

6. The control method for a piston cooling spray hook according to claim 5, characterized in that, The target flow demand is corrected as follows: if the atmospheric pressure value decreases, the target flow demand is positively corrected using a set correction coefficient; otherwise, the target flow demand is negatively corrected using the correction coefficient.

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