Hybrid vehicle control device

Abstract

To suppress emission of noise even when actual engine rotation speed and output torque do not match their target operation points.SOLUTION: In noise suppression process, a control device controls an internal combustion engine to an operation point where a required engine power is constant and an output torque TQ of the internal combustion engine decreases, as a target operation point. In the noise suppression process, when a density parameter that positively correlates with density of suction air is a first value, the control device controls the internal combustion engine to a corrected operation point C where the required engine power is constant and the output torque TQ decreases as compared to that when the density parameter is a second value that is smaller than the first value, as a target operation point.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle using an internal combustion engine and a motor generator as a drive source. The vehicle in Patent Document 1 is equipped with a first motor generator and a second motor generator as motor generators. The first motor generator and the second motor generator are located on a power transmission path from the internal combustion engine to the drive wheels. The hybrid vehicle also includes a control device. The control device controls the engine speed, output torque, etc. of the internal combustion engine.

[0003] The control device for a hybrid vehicle in Patent Document 1 stores a plurality of operating lines indicating combinations of engine speed and output torque. One of the operating lines is an optimum fuel economy line indicating a combination of engine speed and output torque that optimizes fuel economy. Another of the operating lines is an abnormal noise suppression line indicating a combination of engine speed and output torque that can prevent the occurrence of abnormal noise such as gear rattle. The control device selects the abnormal noise suppression line when an operating state occurs in which abnormal noise is generated in the power transmission path. The control device then controls the internal combustion engine using a combination of engine speed and output torque that is on the abnormal noise suppression line and that satisfies the engine power required of the internal combustion engine as a target operating point. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-67242 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, even if the control device controls the internal combustion engine using an operating point on the abnormal noise suppression line as a target operating point, the actual engine speed and output torque may not coincide with the target operating point. In this way, if the actual engine speed and output torque deviate from the abnormal noise suppression line, it may not be possible to appropriately prevent the occurrence of abnormal noise such as gear rattle. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention is a control device for a hybrid vehicle that can run using an internal combustion engine and a motor generator as a drive source, and is capable of executing: an acquisition process that acquires a density parameter that correlates with the density of intake air flowing into the internal combustion engine; an abnormal noise determination process that determines whether an operating state is present in which abnormal noise will occur on a power transmission path from the internal combustion engine to drive wheels; and an abnormal noise suppression process that, when an operating point is defined as a combination of engine speed and output torque of the internal combustion engine and an output required of the internal combustion engine is defined as requested engine power, controls the internal combustion engine to an operating point at which the requested engine power is the same but the output torque is smaller compared to when the abnormal noise determination process makes a negative determination; and in the abnormal noise suppression process, when the density parameter is a first value, controls the internal combustion engine to an operating point at which the requested engine power is the same but the output torque is smaller compared to when the density parameter is a second value that indicates a density of intake air that is smaller than the density of intake air indicated by the first value.

[0007] In the above configuration, when the density of the intake air is high, the mass of the intake air per unit volume increases. Accordingly, when the density of the intake air is high, the output torque of the internal combustion engine also increases. In this case, even if the output torque of the internal combustion engine is reduced by executing the abnormal noise suppression process, it may not be possible to reduce the output torque of the internal combustion engine as expected.

[0008] According to the above configuration, when the density parameter is a first value, i.e., when the density of the intake air is high, the output torque is small. Therefore, even if the density of the intake air is high and the output torque of the internal combustion engine is higher than expected, the output torque can be sufficiently reduced by the abnormal noise suppression process. Therefore, even when the density of the intake air is high, the abnormal noise suppression process is more likely to be able to suppress the occurrence of abnormal noise. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Figure 2] FIG. 2 is a flowchart of the abnormal noise suppression control executed by the control device. [Figure 3] FIG. 3 is an explanatory diagram for explaining a target operating point when noise suppression control is executed. [Figure 4] FIG. 4 is an explanatory diagram for explaining the noise suppression control of the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Vehicle mechanical configuration> An embodiment of the present invention will now be described with reference to the accompanying drawings. First, the mechanical configuration of a vehicle to which a control device of the present invention is applied will be described.

[0011] 1 , the vehicle 500 includes an internal combustion engine 10, a power split mechanism 40, a reduction mechanism 50, a first motor generator 61, a second motor generator 62, and a plurality of drive wheels 68. The vehicle 500 is a hybrid vehicle that can run using the internal combustion engine 10, the first motor generator 61, and the second motor generator 62 as drive sources. The power split mechanism 40, the reduction mechanism 50, the first motor generator 61, and the second motor generator 62 are located on a power transmission path from the internal combustion engine 10 to the drive wheels 68.

[0012] The internal combustion engine 10 has a crankshaft 11 as an output shaft. The crankshaft 11 is connected to a power split mechanism 40. The power split mechanism 40 is a planetary gear mechanism having a sun gear 41, a carrier 42, a plurality of pinion gears 43, a ring gear 44, and a ring gear shaft 45.

[0013] The sun gear 41, which is an external gear, and the ring gear 44, which is an internal gear, are positioned coaxially. The sun gear 41 is rotatable. The ring gear 44 is rotatable. The sun gear 41 is connected to the ring gear 44 via multiple pinion gears 43. That is, the pinion gears 43 mesh with both the sun gear 41 and the ring gear 44. The carrier 42 supports the pinion gear 43 in a rotatable state. The carrier 42 also supports the pinion gear 43 so that it can revolve. That is, the pinion gear 43 revolves around the sun gear 41. The carrier 42 also rotates coaxially with the sun gear 41 in accordance with the revolution of the pinion gear 43. The carrier 42 is connected to the crankshaft 11. The sun gear 41 is connected to a rotating shaft 61A of the first motor generator 61. The ring gear 44 is connected to a ring gear shaft 45.

[0014] When the torque of the internal combustion engine 10 is input to the carrier 42, the torque of the internal combustion engine 10 is distributed to the sun gear 41 side and the ring gear 44 side. Then, when the torque of the internal combustion engine 10 transmitted via the sun gear 41 is input to the rotating shaft 61A of the first motor generator 61, the first motor generator 61 functions as a generator.

[0015] On the other hand, when the first motor generator 61 is made to function as an electric motor, the torque of the first motor generator 61 is input to the sun gear 41. Then, the torque of the first motor generator 61 input to the sun gear 41 is distributed to the carrier 42 side and the ring gear 44 side. Then, when the torque of the first motor generator 61 transmitted via the carrier 42 is input to the crankshaft 11 of the internal combustion engine 10, the crankshaft 11 of the internal combustion engine 10 rotates. In other words, the first motor generator 61 is able to rotate the crankshaft 11 by transmitting the torque of the first motor generator 61 to the crankshaft 11. In this way, the power split device 40 is a planetary gear mechanism that can distribute the torque of the internal combustion engine 10, the torque of the first motor generator 61, and the torque of the ring gear 44 among each other.

[0016] As shown in Fig. 1, the vehicle 500 includes a transmission mechanism 66 and a differential 67. The transmission mechanism 66 is connected to the ring gear shaft 45. The transmission mechanism 66 includes, for example, a reduction gear mechanism. The transmission mechanism 66 is connected to drive wheels 68 via the differential 67. The differential 67 allows a difference in rotational speed to occur between the left and right drive wheels 68.

[0017] The ring gear shaft 45 is connected to the reduction mechanism 50. The reduction mechanism 50 is a planetary gear mechanism having a sun gear 51, a carrier 52, multiple pinion gears 53, a ring gear 54, and a case 55. The sun gear 51, which is an external gear, and the ring gear 54, which is an internal gear, are positioned coaxially. The sun gear 51 is connected to the ring gear 54 via multiple pinion gears 53. The carrier 52 supports the pinion gear 53 in a rotatable state. The carrier 52 is fixed to a case 55 of the reduction mechanism 50. In other words, the carrier 52 is non-rotatable. Therefore, the pinion gear 53 is prevented from revolving due to the carrier 52. The ring gear 54 is connected to the ring gear shaft 45. The sun gear 51 is connected to a rotating shaft 62A of a second motor-generator 62. In other words, the ring gear 44 of the power split mechanism 40 is connected to the rotary shaft 62A of the second motor generator 62 via the ring gear shaft 45 and the reduction mechanism 50.

[0018] Second motor generator 62 functions as a generator when decelerating vehicle 500, thereby making it possible to generate a regenerative braking force in vehicle 500 according to the amount of power generated by second motor generator 62.

[0019] On the other hand, when the second motor generator 62 is made to function as an electric motor, the torque of the second motor generator 62 is input to the drive wheels 68 via the reduction mechanism 50, the ring gear shaft 45, the transmission mechanism 66, and the differential 67. Then, the torque of the second motor generator 62 causes the drive wheels 68 to rotate.

[0020] <Vehicle electrical configuration> 1, the vehicle 500 includes a first inverter 71, a second inverter 72, and a battery 73. The first inverter 71 adjusts the amount of electric power exchanged between the first motor generator 61 and the battery 73. The second inverter 72 adjusts the amount of electric power exchanged between the second motor generator 62 and the battery 73.

[0021] As shown in FIG. 1, the vehicle 500 includes an accelerator pedal sensor 81, a crank angle sensor 82, an intake air temperature sensor 83, an intake pressure sensor 84, and a vehicle speed sensor 85. The accelerator pedal sensor 81 detects the amount of operation of the accelerator pedal of the vehicle 500 as an accelerator operation amount ACCP. The crank angle sensor 82 detects the angular position CA of the crankshaft 11 of the internal combustion engine 10. The intake air temperature sensor 83 detects the intake air temperature TI of the intake air flowing into the internal combustion engine 10. The intake air temperature sensor 83 detects the air temperature outside the vehicle 500 as the intake air temperature TI. The intake pressure sensor 84 detects the intake pressure PI of the intake air flowing into the internal combustion engine 10. The intake pressure sensor 84 detects the atmospheric pressure outside the vehicle 500 as the intake pressure PI. The vehicle speed sensor 85 detects the vehicle speed SP of the vehicle 500. Each of these sensors outputs a signal according to the value of the detected value.

[0022] <Vehicle control device> The vehicle 500 includes a control device 100. The control device 100 controls an internal combustion engine 10, a first motor generator 61, and a second motor generator 62.

[0023] The control device 100 obtains a signal indicating the accelerator operation amount ACCP from the accelerator pedal sensor 81. The control device 100 obtains a signal indicating the angular position CA from the crank angle sensor 82. The control device 100 obtains a signal indicating the intake air temperature TI from the intake air temperature sensor 83. The control device 100 obtains a signal indicating the intake air pressure PI from the intake air pressure sensor 84. The control device 100 obtains a signal indicating the vehicle speed SP from the vehicle speed sensor 85.

[0024] The control device 100 calculates the engine speed NE, which is the rotation speed of the internal combustion engine 10, based on the angular position CA detected by the crank angle sensor . The control device 100 also calculates a total required power, which is the output required for the entire vehicle 500, based on the accelerator operation amount ACCP, the vehicle speed SP, the remaining charge of the battery 73, and the like. The control device 100 then allocates the total required power to a required engine power PE to be output by the internal combustion engine 10 and a required motor power to be output by the first motor generator 61 and the second motor generator 62, depending on the traveling state of the vehicle 500. For example, when the total required power is small and the remaining charge of the battery 73 is large, the entire total required power is allocated to the required motor power, and as a result, the required engine power PE may become zero. Also, for example, when the remaining charge of the battery 73 is small, the required motor power may become a negative value, causing the first motor generator 61 to generate power. In this case, the required engine power PE is a value obtained by adding the power required for the first motor generator 61 to generate power to the total required power.

[0025] The control device 100 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 100 may also be configured as a circuit including one or more dedicated hardware circuits, such as an application-specific integrated circuit (ASIC), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0026] <About the operating line of an internal combustion engine> As shown in Fig. 3, the control device 100 stores a plurality of types of operating lines that indicate combinations of engine speed NE and output torque TQ that should be achieved depending on the driving conditions. One of the operating lines is an optimum fuel economy line. The optimum fuel economy line is a line that indicates the output torque TQ that provides the best fuel economy at any engine speed NE. The best fuel economy is a state in which the total output torque TQ of the internal combustion engine 10 per unit amount of fuel is maximized. On the optimum fuel economy line, the output torque TQ increases as the engine speed NE increases.

[0027] Another operating line is the abnormal noise suppression line. The abnormal noise suppression line indicates the maximum output torque TQ that can suppress abnormal noise along the power transmission path from the internal combustion engine 10 to the drive wheels 68 at a given engine speed NE, compared to the case of the above-described optimal fuel economy line. In this embodiment, the second motor-generator 62 and the reduction mechanism 50 are assumed to be locations where abnormal noise may occur. On the abnormal noise suppression line, the output torque TQ increases as the engine speed NE increases. Furthermore, for a given engine speed NE, the output torque TQ on the abnormal noise suppression line is smaller than the output torque TQ on the optimal fuel economy line. This abnormal noise suppression line is determined by conducting tests under conditions of a predetermined standard intake temperature TI0 and a predetermined standard intake pressure PI0. The standard intake temperature TI0 is, for example, 300 K. The standard intake pressure PI0 is, for example, 1 atm. Furthermore, the abnormal noise suppression line is determined in anticipation of adjustment of the output torque TQ using a coefficient K, which will be described later.

[0028] Another operating line is the equal engine power line. The equal engine power line is a line that shows the combination of engine speed NE and output torque TQ that can achieve any desired required engine power PE. On the equal engine power line, the engine speed NE and the output torque TQ are generally inversely proportional to each other. Note that while FIG. 3 shows only one equal engine power line, there are an infinite number of equal engine power lines depending on the magnitude of the required engine power PE.

[0029] <About noise suppression control> The control device 100 is capable of executing abnormal noise suppression control. The control device 100 repeatedly executes abnormal noise suppression control while the internal combustion engine 10 is running.

[0030] As shown in FIG. 2, when the control device 100 executes noise suppression control, it first executes the processing of step S10. In step S10, the control device 100 calculates the total required power, which is the output required for the entire vehicle 500, based on the accelerator operation amount ACCP, the vehicle speed SP, the remaining charge amount of the battery 73, and the like. Furthermore, the control device 100 allocates the total required power to a required engine power PE and a required motor power. At this time, the control device 100 allocates the required motor power to a target torque to be output by the first motor generator 61 and a target torque to be output by the second motor generator 62. Thereafter, the processing of the control device 100 proceeds to step S11.

[0031] In step S11, the control device 100 determines whether the engine speed NE is less than a predetermined specified speed NEZ. The specified speed NEZ is determined in advance as follows. As shown in FIG. 3, of the intersections between the optimum fuel economy line and the abnormal noise suppression line, an intersection Z on the side where the engine speed NE is higher is identified. Then, the engine speed NE at this intersection Z is set as the specified speed NEZ. If the engine speed NE is equal to or greater than the specified speed NEZ, the processing of the control device 100 proceeds to step S17. On the other hand, if the engine speed NE is less than the specified speed NEZ, the processing of the control device 100 proceeds to step S12.

[0032] In step S12, the control device 100 determines whether the vehicle is in an operating state in which abnormal noise occurs. Specifically, the control device 100 determines that the vehicle is in an operating state in which abnormal noise occurs when the target torque of the second motor-generator 62 is within a predetermined range. On the other hand, the control device 100 determines that the vehicle is not in an operating state in which abnormal noise occurs when the target torque of the second motor-generator 62 is outside the predetermined range. Note that, when traveling using the internal combustion engine 10 as a driving source, gear rattles may occur between the gears in the path from the rotating shaft 62A of the second motor-generator 62 to the ring gear 54. The predetermined range is determined as a range of torque of the second motor-generator 62 in which such gear rattles may occur. The predetermined range is determined in advance by conducting tests, simulations, or the like. Note that the processing in step S12 is an abnormal noise determination processing. If the determination in step S12 is negative, the processing by the control device 100 proceeds to step S17.

[0033] In step S17, the control device 100 identifies an operating point that satisfies the required engine power PE and provides the best fuel economy. That is, as shown in Fig. 3, the intersection of the equal engine power line corresponding to the required engine power PE and the optimal fuel economy line is identified as the optimal fuel economy operating point A. Then, the control device 100 sets this optimal fuel economy operating point A as the final target operating point.

[0034] On the other hand, as shown in FIG. 2, if the determination in step S12 is affirmative, the processing of the control device 100 proceeds to step S13. In step S13, the control device 100 identifies an operating point that satisfies the required engine power PE and can suppress the occurrence of abnormal noise. That is, as shown in Fig. 3, the intersection of the equal engine power line corresponding to the required engine power PE and the abnormal noise suppression line is identified as the abnormal noise suppression operating point B. Thereafter, as shown in Fig. 2, the processing of the control device 100 proceeds to step S14.

[0035] In step S14, the control device 100 executes an acquisition process to acquire a density parameter DP. Specifically, the control device 100 acquires the intake air temperature TI at the time of the process of step S14 as the actual intake air temperature TI1. The control device 100 also acquires the intake pressure PI at the time of the process of step S14 as the actual intake pressure PI1. Then, the control device 100 calculates and acquires the density parameter DP based on the following arithmetic expression (1).

[0036] Arithmetic formula (1)…DP=(TI0 / TI1)×(PI1 / PI0) Note that, for the same volume of intake air, the smaller the intake temperature TI, the higher the density of the intake air. Also, for the same volume of intake air, the higher the intake pressure PI, the higher the density of the intake air. Therefore, the density parameter DP calculated by the above equation is a parameter that is positively correlated with the density of the intake air. After the density parameter DP is calculated and acquired in this manner, the processing of the control device 100 proceeds to step S15.

[0037] In step S15, the control device 100 calculates the corrected torque TQ1. Specifically, as shown in Fig. 3, the control device 100 specifies the output torque TQ at the abnormal noise suppression operating point B as the standard output torque TQ0. Then, this standard output torque TQ0 and the density parameter DP acquired in step S14 are substituted into the following calculation formula (2) to calculate the corrected torque TQ1.

[0038] Formula (2)...TQ1=K×TQ0×(1 / DP) where K is a predetermined coefficient. The coefficient K indicates the percentage of the density parameter DP that should be reflected in the output torque TQ. The coefficient K is a positive value that is determined in advance by conducting tests or simulations.

[0039] In the process of step S15, the control device 100 identifies the optimal fuel economy operating point A in the same manner as in the process of step S17. Then, it is assumed that the control device 100 calculates the corrected torque TQ1 as a value greater than the output torque TQ at the optimal fuel economy operating point A. In this case, the control device 100 sets the corrected torque TQ1 to the same value as the output torque TQ at the optimal fuel economy operating point A. After the corrected torque TQ1 is calculated in this manner, the process of the control device 100 proceeds to step S16 as shown in FIG. 2.

[0040] In step S16, the control device 100 identifies a post-correction operating point C. Specifically, as shown in FIG. 3, an operating point that coincides with the post-correction torque TQ1 calculated in step S15 on the equal engine power line used when identifying the noise suppression operating point B in step S12 is identified as the post-correction operating point C. The control device 100 then sets this post-correction operating point C as the final target operating point. As shown in FIG. 2, the processing of the control device 100 then proceeds to step S18.

[0041] In step S18, the control device 100 executes abnormal noise suppression processing. Specifically, the control device 100 controls the output torque TQ and engine speed NE of the internal combustion engine 10 so that they coincide with the target operating point identified in step S16 or step S17. Thereafter, the control device 100 ends one cycle of the series of abnormal noise suppression control, and again executes a new cycle of abnormal noise suppression control.

[0042] <Operation of this embodiment> Assume that the abnormal noise suppression control of the above embodiment is executed in an environment where the actual intake air temperature TI1 is lower than the standard intake air temperature TI0 and the actual intake pressure PI1 is higher than the standard intake pressure PI0. In this case, the control device 100 calculates the density parameter DP to a value greater than 1 in step S13. Then, as shown in FIG. 3, when the density parameter DP is greater than 1, the control device 100 calculates the corrected torque TQ1 to a value smaller than the standard output torque TQ0 in step S15. Therefore, when the density parameter DP is greater than 1, a value smaller than the output torque TQ determined by the abnormal noise suppression line becomes the target output torque TQ of the internal combustion engine 10. Then, the larger the density parameter DP, the smaller the output torque TQ at the target operating point of the internal combustion engine 10. In other words, when the density parameter DP is a first value, the control device 100 controls the internal combustion engine 10 to a target operating point at which the output torque TQ is smaller than when the density parameter DP is a second value smaller than the first value.

[0043] The above example shows a case where the density parameter DP is greater than 1. In contrast, when the density parameter DP is less than 1, an operating point where the output torque TQ is greater than the output torque TQ determined by the abnormal noise suppression line is determined as the target operating point of the internal combustion engine 10. Even in this case, the output torque TQ of the target operating point of the internal combustion engine 10 is smaller than the output torque TQ determined by the optimal fuel economy line.

[0044] <Effects of this embodiment> (1) In the above embodiment, the abnormal noise suppression line indicates an operating point at which abnormal noise can be suppressed when the intake air temperature TI is a standard intake air temperature TI0 and the intake pressure PI is a standard intake pressure PI0. Here, when the density of the intake air is high, the mass of the intake air per unit volume increases. Accordingly, when the density of the intake air is high, the output torque TQ of the internal combustion engine 10 also increases. In this case, even if the output torque TQ of the internal combustion engine 10 is reduced by executing abnormal noise suppression processing, there is a possibility that the output torque TQ of the internal combustion engine 10 cannot be reduced as expected. In other words, even if the output torque TQ is reduced to a level at which abnormal noise can be suppressed, there is a possibility that the output torque TQ may not actually be reduced to a level sufficient to suppress abnormal noise.

[0045] According to the above embodiment, the larger the density parameter DP, the smaller the output torque TQ of the internal combustion engine 10 when abnormal noise suppression processing is performed. Therefore, even if the density of the intake air is high and the output torque TQ of the internal combustion engine 10 becomes larger than expected, the output torque TQ can be sufficiently reduced by the abnormal noise suppression processing. Therefore, even when the density of the intake air is high, the abnormal noise suppression processing is more likely to be able to suppress the occurrence of abnormal noise.

[0046] (2) In the above embodiment, the smaller the density parameter DP, the larger the output torque TQ of the internal combustion engine 10 when abnormal noise suppression processing is performed. As described above, an operating point on the abnormal noise suppression line has a smaller output torque TQ than an operating point on the optimal fuel economy line, provided that the engine speed NE is the same. Therefore, by increasing the output torque TQ when the density parameter DP is small, the internal combustion engine 10 can be controlled at an operating point with better fuel economy while suppressing the occurrence of abnormal noise.

[0047] (3) In the above embodiment, the intake air temperature TI is approximately inversely proportional to the density of the intake air. Therefore, using the actual intake air temperature TI1 as the basis for calculating the density parameter DP is advantageous in terms of improving the correlation between the density parameter DP and the density of the intake air.

[0048] (4) In the above embodiment, the intake pressure PI is approximately proportional to the density of the intake air. Therefore, using the actual intake pressure PI1 as the basis for calculating the density parameter DP is advantageous in improving the correlation between the density parameter DP and the density of the intake air.

[0049] <Example of change> The above-described embodiment and the following modified examples can be implemented in combination with each other to the extent that no technical contradiction occurs.

[0050] In the above embodiment, the vehicle 500 is equipped with the first motor generator 61 and the second motor generator 62. However, the vehicle 500 may be equipped with only one motor generator. Even if there is only one motor generator, abnormal noise may occur in the gear mechanism to which the motor generator is connected. In this case, it is preferable to employ the abnormal noise suppression control described above.

[0051] The vehicle 500 does not necessarily have to be configured to be able to continuously change the operating point. For example, the vehicle 500 may have a stepped transmission. In this case, depending on the gear ratio of the transmission, it may not always be possible to make the output torque TQ and engine speed NE of the internal combustion engine 10 coincide with the target operating point. In such a case, the control device 100 may control the operating point of the internal combustion engine 10 so as to approach the target operating point as closely as possible.

[0052] The abnormal sound determination conditions in the abnormal sound determination process can be changed as appropriate. Using a test vehicle 500, various parameters that actually cause abnormal sound along the power transmission path from the internal combustion engine 10 to the drive wheels 68 can be confirmed, and these can be used as conditions for determining in the abnormal sound determination process whether the driving state will cause abnormal sound.

[0053] In the above embodiment, the density parameter DP is calculated using the intake air temperature TI and the intake pressure PI, but this is not limiting. For example, the density parameter DP may be calculated by dividing the actual intake air temperature TI1 from the standard intake air temperature TI0, or may be calculated by dividing the actual intake pressure PI1 from the standard intake pressure PI0. In either case, the density parameter DP is positively correlated with the density of the intake air. Furthermore, the parameters are not limited to those exemplified above, as long as they are positively correlated with the density of the intake air.

[0054] The density parameter DP may be negatively correlated with the density of the intake air. Even in this case, the calculation formula or the like may be changed so that the control device 100 can calculate a target operating point where the output torque TQ decreases as the density of the intake air indicated by the density parameter DP increases.

[0055] In the above embodiment, the corrected torque TQ1, which is the output torque at the target operating point, is calculated by correcting the standard output torque TQ0 at the abnormal noise suppression operating point B. However, the method for determining the target operating point can be changed as appropriate.

[0056] For example, the control device 100 may store a plurality of noise suppression lines. In the example shown in Fig. 4, the control device 100 stores a first line to a fifth line as a plurality of noise suppression lines. When the engine speed NE is constant, the output torque TQ determined by the first line is the smallest. Then, the output torque TQ determined by each line increases in the order of the second to fifth lines.

[0057] When calculating the target operating point of the internal combustion engine 10, the control device 100 selects the first line when the density parameter DP is in a first range indicating a fairly large value. The control device 100 then sets the intersection of the first line and the equal engine power line as the target operating point. The control device 100 also selects the second line when the density parameter DP is in a second range smaller than the first range, and calculates the target operating point based on this. As the density parameter DP decreases in the order of the third range, fourth range, and fifth range, the control device 100 selects the corresponding third line to fifth line, and calculates the target operating point based on these. In this way, the abnormal noise suppression line to be selected depending on the magnitude of the density parameter DP may be stored in advance. Note that in the example of FIG. 4, the control device 100 stores five abnormal noise suppression lines, but the number of suppression lines to be stored need only be two or more.

[0058] In the above embodiment, the control device 100 may store different abnormal noise suppression lines depending on whether the internal combustion engine 10 is warming up or has finished warming up. Even when different abnormal noise suppression lines are used depending on the state of the internal combustion engine 10, the technology of changing the operating point depending on the density parameter DP can be applied. However, the coefficient K in the above embodiment may differ for each abnormal noise suppression line. Note that the technology of using different abnormal noise suppression lines depending on whether the internal combustion engine 10 is warming up or has finished warming up is as disclosed in, for example, Patent Document 1. [Explanation of symbols]

[0059] 10...Internal combustion engine 61...First motor generator 62...Second motor generator 68...Drive wheels 100...Control device DP...density parameter NE: Engine RPM TQ: Output torque

Claims

1. This is applied to a hybrid vehicle that can run using an internal combustion engine and a motor generator as a drive source, an acquisition process for acquiring a density parameter correlated with the density of intake air flowing into the internal combustion engine; an abnormal noise determination process for determining whether an operating state is such that an abnormal noise occurs on a power transmission path from the internal combustion engine to the drive wheels; an abnormal noise suppression process that controls the internal combustion engine, when the abnormal noise determination process determines a positive result, to a target operating point at which the required engine power is the same and the output torque is smaller than when the abnormal noise determination process determines a negative result, where the combination of engine speed and output torque of the internal combustion engine is defined as an operating point and the output required of the internal combustion engine is defined as required engine power; is executable, In the abnormal noise suppression process, when the density parameter is a first value, the internal combustion engine is controlled to have an operating point as a target operating point at which the required engine power is the same and the output torque is smaller than when the density parameter is a second value indicating an intake air density smaller than the intake air density indicated by the first value. A control device for a hybrid vehicle.

2. In the acquisition process, the intake temperature of the intake air is acquired from an intake temperature sensor, and the density parameter is calculated to have a larger value as the intake temperature is smaller. The control device for a hybrid vehicle according to claim 1.

3. In the acquisition process, the intake pressure of the intake air is acquired from an intake pressure sensor, and the density parameter is calculated to have a larger value as the intake pressure increases. The control device for a hybrid vehicle according to claim 1 or 2.

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