Oil life determination system

Abstract

To provide a deterioration parameter calculation system which calculates a deterioration parameter of a lubrication oil while inhibiting increase of the number of components.SOLUTION: A deterioration parameter calculation system calculates a deterioration parameter indicating a degree of deterioration of a lubrication oil used to lubricate a gear mechanism, having at least one gear and connected to a rotary shaft, and stirred by the gear as the gear rotates. The deterioration parameter calculation system calculates the deterioration parameter based on torque of the rotary shaft and a rotation number of the rotary shaft. The process allows the deterioration parameter calculation system to calculate the deterioration parameter of the lubrication oil while inhibiting increase of the number of components.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a deterioration parameter calculation system.

Background Art

[0002] Conventionally, as this type of deterioration parameter calculation system, there has been proposed one that calculates the degree of deterioration of lubricating oil for lubricating an engine, a transmission, etc. based on engine torque, lubricating oil temperature, vehicle speed, and driving distance (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described deterioration parameter calculation system, in order to calculate the deterioration parameter of the lubricating oil, four types of information, namely engine torque, lubricating oil temperature, vehicle speed, and driving distance, are required. Therefore, in a vehicle that does not use all of these four types of information for engine or transmission control, it is necessary to newly provide sensors to acquire the missing information, resulting in an increase in the number of parts.

[0005] The main object of the deterioration parameter calculation system of the present invention is to calculate the deterioration parameter of the lubricating oil while suppressing an increase in the number of parts.

Means for Solving the Problems

[0006] The deterioration parameter calculation system of the present invention employs the following means to achieve the above-mentioned main objective. The deterioration parameter calculation system of the present invention is a system for calculating deterioration parameters that indicate the degree of deterioration of lubricating oil that lubricates a gear mechanism having at least one gear and connected to a rotating shaft, and that is stirred by the gear as the gear rotates, and the gist of the system is to calculate the deterioration parameters based on the torque of the rotating shaft and the rotational speed of the rotating shaft. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing the general configuration of the oil life determination system 10. [Figure 2] This is a flowchart showing an example of a replacement decision routine. [Figure 3] This is an example of the relationship between the degradation parameter Pdg and the kinematic viscosity estimate Kvest. [Modes for carrying out the invention]

[0008] Next, embodiments for carrying out the present invention will be described using examples. [Examples]

[0009] Figure 1 is a schematic diagram showing the configuration of an oil life determination system 10 equipped with a degradation parameter calculation system as one embodiment of the present invention. As shown in the figure, the oil life determination system 10 comprises a hybrid vehicle 20, a data storage server 80, a replacement determination server 82, and a dealer server 84.

[0010] The hybrid vehicle 20 comprises an engine 22, planetary gears 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and an electronic control unit (hereinafter referred to as "ECU") 70 that controls the entire vehicle.

[0011] The rotor of motor MG1 is connected to the sun gear of planetary gear 30, the drive shaft (rotating shaft) 36, which is connected to drive wheels 39a and 39b via differential gear 38, and motor MG2 are connected to the ring gear, and the crankshaft 23 of engine 22 is connected to the carrier. Planetary gear 30, differential gear 38, and motors MG1 and MG2 are housed in the same case. Lubricating oil is stored at the bottom of this case. The differential gear 38 is partially immersed in the lubricating oil and agitates the oil as it rotates. The differential gear 38 also agitates the lubricating oil and distributes it over planetary gear 30 and motors MG1 and MG2, cooling them. Inverters 41 and 42 are connected to battery 50 via power line 54. Motors MG1 and MG2 are driven to rotation by the ECU 70, which controls the switching of multiple switching elements (not shown) of inverters 41 and 42. The ECU 70 is a microcomputer equipped with a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The ECU 70 receives signals from various sensors necessary for controlling the operation of the engine 22, such as the vehicle speed V from the vehicle speed sensor 72 and the accelerator opening Acc from the accelerator position sensor 74, as well as signals from various sensors necessary for driving and controlling motors MG1 and MG2, such as the rotational positions θm1 and θm2 of motors MG1 and MG2 from the rotational position sensor, and signals from various sensors necessary for managing the battery 50. The ECU 70 outputs various control signals for controlling the operation of the engine 22 and control signals to inverters 41 and 42.

[0012] In the hybrid vehicle 20 configured in this way, the ECU 70 basically controls the vehicle to operate in either a hybrid driving mode (HV driving) mode, in which the vehicle is driven with the engine 22 running, or an electric driving mode (EV driving) mode, in which the vehicle is driven with the engine 22 stopped. For example, in HV driving mode, the required torque Td* corresponding to the accelerator opening Acc and vehicle speed V is set from a map showing the relationship between the accelerator opening Acc, vehicle speed V, and the required torque Td* required for the drive shaft 36. The target rotational speed Ne* and target torque Te* of the engine 22, and the torque commands Tm1* and Tm2* of the motors MG1 and MG2 are set so that the required torque Td* is output to the drive shaft 36. The inverters 41 and 42 are controlled so that the engine 22 is driven based on the target rotational speed Ne* and target torque Te*, and the motors MG1 and MG2 are driven by the torque commands Tm1* and Tm2*.

[0013] The data storage server 80, although not shown in the diagram, includes a microcomputer with a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The data storage server 80 receives various data from the hybrid vehicle 20 via communication and stores the received data in flash memory.

[0014] The replacement decision server 82, although not shown in the diagram, is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The replacement decision server 82 receives various data from the data storage server 80 via communication and determines whether or not the lubricating oil should be replaced based on the received data. The determination of whether or not to replace the lubricating oil will be described later.

[0015] The dealership server 84 is installed in the dealership that sold the hybrid vehicle 20 and, although not shown in the diagram, is equipped with a microcomputer that includes a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The dealership server 84 receives various information from the exchange decision server 82 via communication.

[0016] Next, the operation of the oil life determination system 10 of the embodiment configured in this way will be described. The data storage server 80 receives the vehicle speed V detected by the vehicle speed sensor 72 and the accelerator opening degree Acc detected by the accelerator position sensor 74 from the hybrid vehicle 20 via communication at predetermined time intervals of tref1 (for example, every 60 seconds), and stores the received vehicle speed V and accelerator opening degree Acc at predetermined time intervals of tref1 in the flash memory as time-series vehicle speed data V(1)~V(n) and accelerator opening degree data Acc(1)~Acc(n) (where n is an integer of value 2 or greater). The time-series vehicle speed data V(1)~V(n) and accelerator opening degree data Acc(1)~Acc(n) stored by the data storage server 80 are stored in the flash memory of the data storage server 80 without being erased until a data reset is requested.

[0017] Figure 2 is a flowchart showing an example of a replacement decision routine executed by the replacement decision server 82. This routine is executed repeatedly at predetermined intervals of tref2 (for example, every two days).

[0018] When this routine is executed, the CPU of the exchange determination server 82 performs the process of receiving the vehicle speed data V(1)~V(n) and accelerator opening data Acc(1)~Acc(n) stored in the data storage server 80 (step S100). Next, the received data is preprocessed (step S110). In the preprocessing, first, all the received data is arranged in chronological order. Next, any received data that falls outside a predetermined range is replaced with the data immediately preceding it. Also, if there is any missing data when the received data is arranged in chronological order, the missing data is linearly interpolated using the data before and after the missing data. In the following explanation of steps S120~S180, the vehicle speed data V(1)~V(n) and accelerator opening data Acc(1)~Acc(n) after preprocessing will be referred to as "vehicle speed data V(1)~V(n)" and "accelerator opening data Acc(1)~Acc(n)".

[0019] Next, based on each of the vehicle speed data V(1) to V(n), the radius rw of the drive wheels 39a and 39b, and the gear ratio Gdiff of the differential gear 38, rotational speed data Nd(1) to Nd(n) as time-series data of the rotational speed Nd of the drive shaft 36 is calculated (step S120).

[0020] Subsequently, in the same manner as the setting of the required torque Td* in the control in the HV running mode, based on each of the vehicle speed data V(1) to V(n) and the accelerator opening data Acc(1) to Acc(n) corresponding to each of the vehicle speed data V(1) to V(n), required torque data Td(1) to Td(n) as time-series data of the required torque Td* is set (step S130).

[0021] Next, using the required torque data Td(1) to Td(n) and the rotational speed data Nd(1) to Nd(n), the degradation parameter Pdg, which indicates the degree of degradation of the lubricating oil, is calculated using the following equation (1) (step S140). In equation (1), "F(Td(n))" is a weighting function greater than 0 and less than or equal to 1, and is set to be larger when the required torque data Td(n) is large compared to when it is small, and is set to be larger when the required torque data Td(n) is above a predetermined value compared to when it is below a predetermined value. The indices "m1" and "m2" are set to be 1 or greater for each type of lubricating oil based on the properties of the lubricating oil. In general, when the gears of the gear mechanism slip under a large load due to the torque of the rotating shaft, the degree of degradation of the lubricating oil increases. It is thought that this degree of degradation of the lubricating oil is greater when the torque and rotational speed of the rotating shaft are large compared to when they are small. The first term of equation (1) is larger when the required torque data Td(n) and rotational speed data Nd(n) are large compared to when they are small, indicating the degree of deterioration of the lubricating oil due to the differential gear 38 slipping under a large load due to the torque of the drive shaft 36. Furthermore, the degree of deterioration increases when the rotational speed of the gears immersed in the lubricating oil of the gear mechanism is high and the lubricating oil is vigorously agitated. This degree of lubricating oil deterioration is thought to be larger when the rotational speed of the rotating shaft is high compared to when it is low. The second term of equation (1) is larger when the rotational speed data Nd(n) is large compared to when it is small, indicating the degree of lubricating oil deterioration due to the vigorous agitation of the lubricating oil at the high rotational speed of the differential gear 38. Therefore, the deterioration parameter Pdg is a parameter that indicates the degree of lubricating oil deterioration. The calculation of the deterioration parameter Pdg only requires two types of information: the required torque data Td(n) and the rotational speed data Nd(n). Since the required torque data Td(n) and rotational speed data Nd(n) are necessary information for driving the hybrid vehicle 20, they can be obtained without adding sensors to calculate the degradation parameter Pdg. Therefore, the degradation parameter Pdg of the lubricating oil can be calculated while suppressing an increase in the number of parts.

[0022]

Number

[0023] When the deterioration parameter Pdg is calculated in this way, the estimated value of the kinematic viscosity (kinematic viscosity estimated value) Kvest of the lubricating oil is calculated using the following formula (2) or formula (3) (step S150). FIG. 3 is an explanatory diagram showing an example of the relationship between the deterioration parameter Pdg and the kinematic viscosity estimated value Kvest. Formulas (2) and (3) are formulas representing the relationship illustrated in FIG. 3. In Formulas (2) and (3), "e", "f", "g", "h", "i", and "Pdref" can be obtained from the relationship in FIG. 3.

[0024]

Number

[0025] Subsequently, the product of each of the vehicle speed data V(1) to V(n) and a predetermined time tref1, which is the time interval at which the data storage server 80 inputs the vehicle speed V from the hybrid vehicle 20 via communication, is integrated and calculated as the current travel distance Lnow (step S160).

[0026] Then, it is determined whether at least one of the condition that the kinematic viscosity estimated value Kvest is smaller than the threshold value Kvth and the condition that the travel distance Lnow is larger than the threshold value Lth is satisfied (step S170). The threshold value Kvth is a value determined in advance through experiments, analysis, etc. as the minimum value of the kinematic viscosity guaranteed when using the lubricating oil. The threshold value Lth is the distance guaranteed in the use environment against the oxidative deterioration of the lubricating oil and is a value determined in advance through experiments, analysis, etc. Therefore, step S170 is a process for determining whether the deterioration of the lubricating oil has progressed and it is better to replace the lubricating oil.

[0027] In step S170, if the estimated kinematic viscosity Kvest is greater than or equal to the threshold Kvth, and the mileage Lnow is less than or equal to the threshold Lth, it is determined that it is not necessary to change the lubricating oil, and this routine is terminated.

[0028] In step S170, if at least one of the following is true, the kinematic viscosity estimate Kvest is less than the threshold Kvth, or the mileage Lnow is greater than the threshold Lth, the system determines that it is better to change the lubricating oil and notifies the dealer server 84 that the oil should be changed (step S180), and then terminates this routine. Upon receiving the notification that the oil should be changed, the dealer server 84 prompts the dealer staff to change the oil by displaying on a display (not shown) that the oil needs to be changed when the hybrid vehicle 20 is brought in, or by notifying the dealer staff.

[0029] According to the oil life determination system 10 equipped with the degradation parameter calculation system of the embodiment described above, the degradation parameter Pdg of the lubricating oil can be calculated while suppressing an increase in the number of parts by calculating the degradation parameter Pdg based on the required torque data Td(n) and rotational speed data Nd(n).

[0030] In the oil life determination system 10 equipped with the degradation parameter calculation system of the embodiment, steps S170 and S180 determine whether at least one of the following is true: the estimated kinematic viscosity Kvest is less than the threshold Kvth, or the mileage Lnow is greater than the threshold Lth, and notify the dealer server 84 of the oil change. However, instead of S170 and S180, the remaining distance Lr1, which is the distance from the current position until the estimated kinematic viscosity Kvest falls below the threshold Kvth, and the remaining distance Lr2, which is the distance from the current position until the mileage Lnow exceeds the threshold Lth, may be calculated, and the shorter of the remaining distances Lr1 and Lr2 may be notified to the dealer server 84 as the remaining distance until the oil change. Here, the remaining distance Lr1 is the distance obtained by subtracting the mileage Lnow from the mileage Lkv at which the estimated kinematic viscosity Kvest becomes the threshold Kvth. The mileage Lkv can be derived by substituting the threshold Kvth into the kinematic viscosity estimate Kvest in equation (3) above, and substituting the degradation parameter Pdgkv into the degradation parameter Pdg, transforming the equation into equation (4) to obtain the degradation parameter Pdgkv, and then multiplying the ratio of the degradation parameter Pdgkv to the current degradation parameter Pdg by the current mileage Lnow using equation (5). The remaining mileage Lr2 is the value obtained by subtracting the mileage Lnow from the threshold Lth. In this way, the sales staff can be informed of how far the hybrid vehicle 20 can travel before an oil change is required.

[0031]

number

[0032] In the oil life determination system 10 equipped with the degradation parameter calculation system of the embodiment, the data storage server 80 stores data on vehicle speed V and accelerator opening Acc. However, the storage of data on vehicle speed V and accelerator opening Acc is not limited to the data storage server 80, but may also be done by the hybrid vehicle 20, the replacement determination server 82, or the dealership server 48.

[0033] In the oil life determination system 10 equipped with the degradation parameter calculation system of the embodiment, at least a portion of the replacement determination routine illustrated in Figure 2 may be performed by the hybrid vehicle 20, the data storage server 80, or the dealership server 84.

[0034] In the embodiment, the degradation parameter calculation system of the present invention is applied to a hybrid vehicle 20. However, the present invention may be applied to any device that has a gear mechanism having at least one gear connected to a rotating shaft, lubricated with lubricating oil, and in which the lubricating oil is agitated by the gear as the gear rotates. For example, it may be applied to a vehicle that has an engine and a transmission as a gear mechanism but no motor for driving, or it may be applied to a machine tool or endurance bench equipped with such a gear mechanism.

[0035] Although embodiments for carrying out the present invention have been described above using examples, the present invention is not limited in any way to these embodiments, and can of course be carried out in various forms without departing from the spirit of the present invention. [Explanation of symbols]

[0036] 10 oil life determination systems, 20 hybrid vehicles, 82 oil change determination servers.

Claims

[Claim 1] An oil life determination system for use in a vehicle equipped with a gear mechanism having at least one gear connected to a rotating shaft and lubricated by lubricating oil, wherein the lubricating oil is agitated by the gear as the gear rotates, and the system includes a degradation parameter calculation system that calculates a degradation parameter indicating the degree of degradation of the lubricating oil, The degradation parameter is calculated based on the torque of the rotating shaft and the rotational speed of the rotating shaft. Using the calculated degradation parameters, an estimated kinematic viscosity value is calculated as an estimated value of the kinematic viscosity of the lubricating oil. If at least one of the following conditions is met, the calculated kinematic viscosity estimate is smaller than a first threshold value, which is the minimum kinematic viscosity guaranteed when using the lubricating oil, or the vehicle's mileage is greater than a second threshold value, which is the distance guaranteed in the operating environment against oxidative degradation of the lubricating oil, then a notification will be issued indicating that the oil should be changed. Oil life determination system.

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