Operating procedure for operating an oil pump control valve
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- VOLKSWAGEN AG
- Filing Date
- 2022-09-09
- Publication Date
- 2026-07-30
AI Technical Summary
Existing oil pressure systems in engines face challenges in achieving quick and precise oil supply due to manufacturing tolerances in oil pump control valves, leading to inefficiencies and potential engine wear and diagnostic issues.
A method involving determining a characteristic value of the difference between pilot control and controller PWMG duty cycles, storing this value in memory, and using it for precontrol to adjust the oil pump control valve, thereby bypassing the need for continuous regulation by the controller, ensuring precise and rapid oil pressure adjustment.
This approach enhances oil supply precision and speed, reduces engine wear, and minimizes the likelihood of oil pressure undersupply diagnoses, improving engine operation.
Smart Images
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Abstract
Description
[0001] The presented invention relates to an operating method for operating an oil pump control valve, a computing unit, an oil pump and a computer program product according to the appended claims.
[0002] An oil pressure system is responsible for cooling and lubricating various components of an engine. This can be done using a fixed-displacement pump, a step-adjustable oil pump, or a fully variable oil pump. If a fully variable oil pump is used, it is necessary to measure the oil pressure with an oil pressure sensor and then regulate the oil pressure in the pump with an oil pump control valve so that a specified oil pressure target is reached.
[0003] The oil pump control valve is used to transport oil to a fully variable oil pump or to allow the fully variable oil pump to discharge oil into an oil pan.
[0004] An oil pump can provide higher pressure when there is no oil in the oil pump's control chamber and provide low oil pressure when oil is allowed into the control chamber.
[0005] In a control unit, a voltage is set from 0 to 100% using pulse width modulation (PWM) instead of a continuous current, and the oil pressure is measured instead of a flow rate. A pilot control outputs a pulse width modulation (PWM) duty cycle assigned to a specific operating point according to a predefined assignment scheme.
[0006] Even at the manufacturer's factory, oil pump control valves and proportional valves differ in their flow characteristics due to manufacturing tolerances. To compensate for manufacturing tolerances, oil pressure regulators are used. These are connected downstream of a pilot control and control a respective oil pump control valve with an adapted PWMG. The PWMG is adjusted by the oil pressure regulator until a corresponding oil pump delivers a specified oil pressure.
[0007] An oil pressure regulator needs time to adjust the PWMG and makes the oil supply correspondingly slow.
[0008] Against this background, one object of the invention presented is to enable a fast and accurate supply of oil to an engine.
[0009] Within the scope of the invention presented, an operating method for operating an oil pressure control valve, a computing unit, an oil pump, and a computer program product are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the operating method according to the invention naturally also apply in connection with the computing unit according to the invention, the oil pump according to the invention, or the computer program product according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.
[0010] Thus, according to a first aspect of the invention, an operating method for operating an oil pump control valve is presented. The operating method comprises determining a characteristic value of a difference between a pulse width modulation duty cycle (PWMG) output by a pilot control of the oil pump control valve for a respective operating point and a pulse width modulation duty cycle output by a controller of the oil pump control valve for achieving an oil pressure predetermined for the operating point, storing the characteristic value of the determined difference in a memory, and adjusting the pilot control using the characteristic value stored in the memory at the respective operating point.
[0011] In the context of the invention presented, a pulse width modulation duty cycle (PWMG), also called “duty cycle”, is understood to be a ratio of the duty cycle to the period of a PWM signal.
[0012] The operating method presented is based on determining a characteristic value of a difference between a pulse width modulation duty cycle (PWMG) output by a pilot control of the oil pump control valve for a respective operating point of, for example, an engine to be supplied by an oil pump, and a PWMG output by a controller of the oil pump control valve to achieve an oil pressure specified for the operating point. This means that the characteristic value quantifies a deviation in oil pressure that is to be compensated for by the controller. So that when the operating point is readjusted, the characteristic value assigned to the operating point can be set directly by the pilot control and control by the controller can be dispensed with or the controller only has to correct small deviations. Accordingly, the operating method presented teaches the pilot control and thus the oil pressure control orOil pressure supply has been made more precise and faster, so that the engine is better supplied with oil, its wear is reduced and the likelihood of triggering an engine control unit diagnosis that indicates an oil pressure deficiency or control deviation is reduced.
[0013] The characteristic value provided according to the invention can, for example, be a percentage PWMG, which is added to a PWMG of the pilot control specified for a respective operating point. Together with the PWMG of the controller, this results in a final PWMG, which is used as the manipulated variable of a control loop for controlling the oil pump control valve.
[0014] It can be provided that the characteristic value is only saved if at least one release condition from the following list of release conditions is met: Controller active; control deviation within specified limits; controller value within specified limits; proportional mass of fuel or fuel mass in oil below a specified fuel threshold value; proportional mass of water orWater mass in the oil below a specified water threshold; customer service test to check the oil pressure not active; dynamics of an oil pressure setpoint within specified limits; dynamics of an engine speed of an engine to be supplied by the oil pump control valve within specified limits; dynamics of an oil temperature within specified limits; no oil temperature sensor fault active; no oil pressure sensor fault active; no ambient pressure sensor fault active; no oil pressure undersupply diagnosis active; no oil pressure control valve fault active, no control deviation diagnosis active; no camshaft position fault active; no piston cooling nozzle valve fault active.
[0015] In order not to use a deviation from pulse width modulation duty cycles caused by special cases to adjust the feedforward control, it can be provided, for example, that the characteristic value is only determined in control operation, which is characterized by predetermined criteria.
[0016] It can further be provided that it is first determined whether at least one release condition is fulfilled and, in the event that the at least one release condition is fulfilled, a predetermined waiting time is waited until the characteristic value is stored in the memory and / or the characteristic value is read from the memory.
[0017] A time condition when writing or reading the characteristic value serves the purpose of mapping a dead time in the oil pressure system. For example, if the measured oil pressure changes 150 ms after a change in the duty cycle of the oil pump control valve, applying the characteristic value every 10 ms is too fast and could potentially cause the oil pressure to oscillate. A predefined waiting time prevents this oscillation.
[0018] It can further be provided that the characteristic value is stored in a weighted manner, the weighting being carried out via a characteristic curve to at least one measure from the following list of measures: dynamics of an engine speed of an engine to be supplied by the oil pressure control valve; dynamics of an oil pressure setpoint; amount of the determined difference, ie the control difference of the oil pressure; proportional mass of water in the oil; proportional mass of fuel in the oil.
[0019] In order to avoid having to calibrate the respective release criteria for a characteristic-based setting of an oil pressure control valve within very narrow limits, the characteristic value can be weighted so that not the full characteristic value is used to set the pilot control, but a characteristic value can be saved more often if necessary.
[0020] It can further be provided that respective determined differences are stored in matrices via oil temperature and engine speed of an engine to be supplied by the oil pressure control valve, wherein individual matrices for different oil pressure setpoints are stored in a non-volatile memory and a respective characteristic value is determined from a respective matrix.
[0021] Since in most cases none of the defined support points is ever hit in the direction of the X or Y axis, a value of a determined difference must be divided into four memory cells in a matrix.
[0022] Since the columns and rows of a matrix are only numbered from zero to n-1 and do not show discrete engine speeds or oil temperatures, an assignment is made in advance using characteristic curves.
[0023] To enable the proportional storage of a weighted controller value as a characteristic value, the distance between the neighboring support points (upper and lower) is calculated in the dimensions of engine speed and oil temperature. The lower and upper oil pressure setpoint matrixes are calculated in the same way. The weighted controller value is distributed linearly between the two matrices and is not rounded. The distribution of the engine speed and oil temperature into the memory cells is also performed using a linear distribution.
[0024] Within a matrix, the weighted characteristic value is divided by engine speed and oil temperature, defining a lower and upper speed support point, as well as an upper and lower oil temperature support point. This results in four data points within a matrix.
[0025] An example of the distribution between two speed support points would be an engine speed: 2200 rpm, a lower speed support point: 2000 rpm and an upper speed support point: 2500 rpm, resulting in a share in the lower support point or storage cell of 3 / 5 and a share in the upper support point or storage cell of 2 / 5.
[0026] Since in most cases the oil pressure setpoint is not requested exactly according to a matrix, four values must also be stored in a second matrix.
[0027] The storage is ultimately carried out proportionally via two oil pressure setpoint matrices, each of which contains four data cells.
[0028] The characteristic value can be determined from the respective matrices. The matrices contain both the original pulse width modulation duty cycle data and the interpolation data described below.
[0029] The final applied characteristic value is composed of eight memory cells.
[0030] This involves reversing a calculation used to write the weighted controller value. Four values are read from a matrix located below the current oil pressure setpoint. These values span two interpolation points / memory cells for the engine speed and two interpolation points / memory cells for the oil temperature. These four values are added together.
[0031] The same happens with four values from the matrix that lie above the current oil pressure setpoint. The value of the current oil pressure setpoint determines the proportion of the sum of the four memory cells in the lower matrix and the proportion of the sum of the four memory cells in the upper matrix that are used. The proportions are distributed linearly, as with writing, and are not rounded.
[0032] The feedforward control can be adjusted continuously throughout the life cycle of an engine. In particular, a difference is first determined and then a corresponding characteristic value is written to the memory.
[0033] It can further be provided that within a matrix, respective differences between two determined differences over different engine speeds within a respective oil temperature are interpolated.
[0034] Since some operating points are rarely or never reached, free memory cells containing the value 0.0% are described by interpolation.
[0035] The actual data determined for an operating point, which is divided into eight data cells in two matrices, is referred to as "original data." The cells filled by interpolation are referred to as "interpolation data." For further understanding, the terms "original data" and "reference matrix," as well as "interpolation data" and "adaptation matrix," are introduced.
[0036] To implement the interpolation, the number of matrices is doubled. For example, if 10 "adaptation matrices" for 10 different oil pressure setpoints are to be integrated into the software, from which the adaptation values can be read, there must also be 10 additional "reference matrices" in which only the memory cells are filled with values that were actually calculated from the weighted controller value.
[0037] In each adaptation matrix, interpolation is carried out between two learned values of the engine speed within an oil temperature.
[0038] Interpolation takes place exclusively in the adaptation matrices. The values are interpolated linearly between the interpolation points to which engine speeds are assigned.
[0039] It can further be provided that within a matrix, respective differences over different engine speeds within a respective oil temperature are interpolated to a maximum speed and a minimum speed.
[0040] If the first original value is in the second memory cell in the X direction, the first memory cell remains filled with the value 0.0% and the second memory cell contains the original value.
[0041] If the first original value is located in the third memory cell, interpolation is performed between 0.0% in the first memory cell and the original value in the third memory cell. In this case, the interpolation only affects the second memory cell, which receives half the value of the third memory cell.
[0042] If the first original data is in a memory cell that is not assigned to the lowest engine speed, linear interpolation is carried out to the first memory cell to the value 0.0%.
[0043] The same applies to the last memory location, which corresponds to the highest engine speed. Interpolation is only performed when the last original data is in the third-to-last memory location.
[0044] Interpolation is performed whenever new original data is written. The interpolation algorithm then completely traverses the lower and upper matrix.
[0045] Since interpolation is only performed in the adaptation matrices, new adaptation processes can overwrite the values in the adaptation matrices. These values are transferred from the reference matrices to the adaptation matrices.
[0046] According to a second aspect, the presented invention relates to a computing unit. The computing unit is configured to implement a possible embodiment of the presented operating method.
[0047] In the context of the invention presented, a computing unit is understood to mean a computer, a processor, a control unit or any other programmable circuit.
[0048] It can be provided that the computing unit is configured to determine a difference between a pulse width modulation duty cycle (PWMG) output by a pilot control of the oil pump control valve for a respective operating point and a PWMG output by a controller of the oil pump control valve to achieve an oil pressure predetermined for the operating point, to store a characteristic value of the determined difference in a memory, and to adjust the oil pump control valve at the respective operating point using the characteristic value stored in the memory.
[0049] It can further be provided that the computing unit is a control unit of a vehicle or a control unit of an oil pump comprising the oil pump control valve.
[0050] According to a third aspect, the presented invention relates to an oil pump which comprises a possible embodiment of the presented computing unit.
[0051] According to a fourth aspect, the presented invention relates to a computer program product with program code means which are designed to configure a computer system to carry out a possible embodiment of the presented operating method when the computer program is executed on the computer system.
[0052] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show: Fig. 1 a possible design of the presented operating procedure, Fig. 2 a possible design of the presented oil pump with a possible design of the presented computing unit.
[0053] In Fig. 1 shows an operating method 100 for operating an oil pump control valve. The operating method 100 comprises a determination step 101, in which a characteristic value of a difference between a pulse width modulation duty cycle (PWMG) output by a pilot control of the oil pump control valve for a respective operating point and a PWMG output by a controller of the oil pump control valve to achieve an oil pressure predetermined for the operating point is determined, a storage step 103, in which the characteristic value of the determined difference is stored in a memory, and a setting step 105, in which the pilot control is adjusted at the respective operating point using the characteristic value stored in the memory.
[0054] Optionally, the determination step includes an interpolation step 107, in which a matrix of difference values representing a respective oil pressure setpoint is searched for filled storage cells that are not equal to 0.0%. This begins in row 0, i.e., at the lowest oil temperature on the Y-axis.
[0055] If a memory cell containing the value 0.0% is found above the engine speed on the X-axis, a variable for a counter is incremented by one. The counter starts at zero. If the next memory cell on the X-axis again contains the value 0.0%, the counter is incremented by one again, and so on.
[0056] If the last memory cell on the X-axis is reached, or if a memory cell with a value other than 0.0% is found, a denominator is calculated. The denominator is one greater than the numerator that counted the free memory cells along the engine speed on the X-axis. Thus, for a free memory cell, half the value can be interpolated from the lower memory cell and half from the upper memory cell.
[0057] If there are two free memory cells, thirds are used for interpolation, if there are three free locations, quarters are used, and so on.
[0058] If a denominator is formed, one or more free memory cells with the value 0.0% and then a memory cell with a value other than 0.0% were found.
[0059] The current X coordinate has a value other than 0.0%.
[0060] The current X coordinate is the upper memory cell, with whose value the intermediate cells are interpolated.
[0061] The lower X-coordinate, with which the intermediate memory cells are interpolated, can be determined by the current memory cell minus the denominator.
[0062] The first memory cell to be written to by the interpolation can be calculated by the current X coordinate minus the numerator.
[0063] The values of the memory cells to be interpolated then receive the following values: Value of the memory cell = value of the upper memory cell * (numerator / denominator) + value of the lower memory cell * (1 - numerator / denominator). The counter starts at 1 and increases by one for each additional memory cell.
[0064] For example, the following scheme results: On the X-axis, memory cells 3, 4 and 5 only contain values of 0.0%.
[0065] The lower memory cell, with whose value the interpolation is carried out, is located at X-coordinate 2 and the upper one at X-coordinate 6. The memory cell at X-coordinate 3 is written with a value that is composed of: (1−1 / 4)*value_memory_cell_2+1 / 4*value_memory_cell_6=3 / 4*value_memory_cell_2+1 / 4*value_memory_cell_6
[0066] For memory cell 4: (1−1 / 4)*value_memory_cell_2+2 / 4*value_memory_cell_6=1 / 2*value_memory_cell_2+1 / 2*value_memory_cell_6
[0067] For memory cell 5: (1−3 / 4)*value_memory_cell_2+3 / 4*value_memory_cell_6=1 / 4*value_memory_cell_2+3 / 4*value_memory_cell_6
[0068] This pattern is repeated until all memory cells in the X direction have been scanned for engine speed. This process is then repeated for all subsequent rows in the Y direction for oil temperature. Once all memory cells in the X direction have been scanned for all rows in the Y direction, the entire process is repeated for the upper reference matrix, which represents the oil pressure setpoint that is higher than the current oil pressure setpoint from the current operating point.
[0069] In Fig. 2 shows an oil pump 200. The oil pump 200 comprises a computing unit 201 and an oil pump control valve 203. The computing unit 201 is designed to control the oil pump control valve 203 by means of the operating method 100 according to Fig. 1 configured. List of reference symbols 100 operating procedures 101 Determination step 103 Storage step 105 setting step 107 Interpolation step 200 oil pump 201 computing unit 203 Oil pump control valve
Claims
[1] Operating method (100) for operating an oil pump control valve (203), the operating method (100) comprising: - determining (101) a characteristic value of a difference between a pulse width modulation duty cycle (PWMG) output by a pilot control of the oil pump control valve (203) for a respective operating point and a pulse width modulation duty cycle (PWMG) output by a controller of the oil pump control valve (203) to achieve an oil pressure predetermined for the operating point, - storing (103) the characteristic value of the determined difference in a memory, - Setting (105) the pre-control by means of the characteristic value stored in the memory at the respective operating point. [2] Operating method (100) according to claim 1, characterized by that the characteristic value is only saved if at least one release condition from the following list of release conditions is met: Controller active; control deviation within specified limits; controller value within specified limits; proportion of fuel in oil below a specified fuel threshold; proportion of water in oil below a specified water threshold; customer service test to check oil pressure not active; Dynamics of an oil pressure setpoint within specified limits; dynamics of an engine speed of an engine to be supplied by the oil pump control valve within specified limits; dynamics of an oil temperature within specified limits; No oil temperature sensor error active; no oil pressure sensor error active; no ambient pressure sensor error active; no oil pressure deficiency diagnosis active; no oil pressure control valve error active; no control deviation diagnosis active; no camshaft position error active; no piston cooling nozzle valve error active. [3] Operating method (100) according to claim 2, characterized bythat it is first determined whether at least one release condition is fulfilled and, if the at least one release condition is fulfilled, a predetermined waiting time is waited until the characteristic value is stored in the memory and / or the characteristic value is read from the memory. [4] Operating method (100) according to one of the preceding claims, characterized by that the characteristic value is stored in a weighted manner, the weighting being carried out via a characteristic curve to at least one measure from the following list of measures: dynamics of an engine speed of an engine to be supplied by the oil pressure control valve; dynamics of an oil pressure setpoint; amount of the determined difference, mass of water in the oil; mass of fuel in the oil. [5] Operating method (100) according to one of the preceding claims, characterized bythat respective determined differences are stored in matrices via oil temperature and engine speed of an engine to be supplied by the oil pressure control valve (203), wherein individual matrices for different oil pressure setpoints are stored in a non-volatile memory and a respective characteristic value is determined from a respective matrix. [6] Operating method (100) according to claim 5, characterized by that within a matrix, respective differences between two determined differences over different engine speeds within a respective oil temperature are interpolated (107). [7] Operating method (100) according to claim 5 or 6, characterized by that within a matrix, respective differences over different engine speeds within a respective oil temperature are interpolated to a maximum speed and a minimum speed. [8] Computing unit (201) for controlling an oil pump control valve (203), wherein the computing unit (201) is configured to carry out an operating method (100) according to one of claims 1 to 7. [9] Computing unit (201) according to claim 8, characterized by that the computing unit (201) is configured to - to determine a difference between a pulse width modulation duty cycle (PWMG) output by a pilot control of the oil pump control valve (203) for a respective operating point and a pulse width modulation duty cycle output by a controller of the oil pump control valve (203) to achieve an oil pressure predetermined for the operating point, - to store a characteristic value of the determined difference in a memory, and - to adjust the oil pump control valve (203) at the respective operating point by means of the characteristic value stored in the memory. [10] Computing unit (201) according to claim 8 or 9, characterized bythat the computing unit (201) is a control unit of a vehicle or a control unit of an oil pump (200) comprising the oil pump control valve (203). [11] Oil pump (200) comprising a computing unit (201) according to one of claims 8 to 10. [12] Computer program product comprising program code means adapted to configure a computer system to carry out the operating method (100) according to any one of claims 1 to 7 when the computer program is executed on the computer system.