Control device of electric heating type catalyst

Abstract

To provide a control device of an electric heating type catalyst capable of performing energization to the electric heating type catalyst while suppressing electric leakage due to deterioration of insulation resistance, even after engine starts.SOLUTION: A control device for an electric heating type catalyst comprises a processor. The processor performs preheat control to electrically heat a catalyst before an engine is started, and postheat control to electrically heat the catalyst even after the engine is started, and does not perform postheat control when an insulation resistance value of the catalyst is a predetermined threshold value or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a control device for an electrically heated catalyst. [Background technology]

[0002] Patent document 1 discloses a technology that determines whether the insulation resistance of the carrier holding portion has fallen below a predetermined value, and prohibits the passage of electricity through the electrically heated catalyst if it is determined that the insulation resistance has fallen below the predetermined value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 114451 Summary of the Invention [Problem to be solved by the invention]

[0004] After the engine starts, the insulation resistance may decrease due to water vapor in the exhaust gas, but the technology disclosed in Patent Document 1 does not take this into consideration.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a control device for an electrically heated catalyst that can supply current to the electrically heated catalyst while suppressing leakage current caused by a decrease in insulation resistance, even after the engine is started. [Means for solving the problem]

[0006] The control device for an electrically heated catalyst according to the present disclosure includes a processor that performs preheat control to electrically heat the catalyst before starting the engine, and postheat control to electrically heat the catalyst even after starting the engine, and does not perform the postheat control if the insulation resistance value of the catalyst is below a predetermined threshold value. Effect of the Invention

[0007] According to the present disclosure, even after the engine has been started, it is possible to supply current to the electrically heated catalyst while suppressing leakage current caused by a decrease in insulation resistance. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a vehicle to which a control device for an electrically heated catalyst according to an embodiment is applied. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of the electrically heated catalyst according to the embodiment. [Diagram 3] FIG. 3 is a flowchart showing the flow of current control (first embodiment) of the electrically heated catalyst executed by the control device for the electrically heated catalyst according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing the flow of the electrically heated catalyst current supply request process executed by the control device for the electrically heated catalyst according to the embodiment. [Diagram 5] FIG. 5 is a flowchart showing the flow of current supply control (second embodiment) of the electrically heated catalyst executed by the control device for the electrically heated catalyst according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing the flow of current control (third embodiment) of the electrically heated catalyst executed by the control device for the electrically heated catalyst according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A control device for an electrically heated catalyst according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily replaceable by a person skilled in the art, or those that are substantially the same.

[0010] (Control device for electrically heated catalyst) The configuration of the control device for an electrically heated catalyst according to the embodiment will be described with reference to Figures 1 and 2. Examples of vehicles to which the control device for an electrically heated catalyst according to the embodiment is applied include hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs).

[0011] 1, the vehicle 1 includes a control unit 11, an engine 12, a motor 13, a first catalyst 14, and a second catalyst 15. Note that the figure illustrates only the components of the vehicle 1 that are necessary to realize the control device for the electrically heated catalyst according to the embodiment. Therefore, the actual vehicle 1 naturally includes components (e.g., a battery, an inverter, etc.) other than those illustrated in the figure.

[0012] The control unit 11 is an electronic control unit (ECU) whose main components are a microcomputer including, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), etc. The control unit 11 realizes functions that meet a predetermined purpose by controlling each component of the vehicle 1 through the execution of various programs.

[0013] The control unit 11 performs control (preheat control) to electrically heat the first catalyst 14 before starting the engine 12, for example. In the preheat control, a predetermined amount of electric power is supplied to the first catalyst 14 before starting the engine 12, to warm up the first catalyst 14. Then, the control unit 11 starts the engine 12 after warming up the first catalyst 14.

[0014] Furthermore, the control unit 11 performs control (post-heat control) to electrically heat the first catalyst 14 even after the engine 12 is started. In the post-heat control, a predetermined amount of electric power continues to be supplied to the first catalyst 14 even after the engine 12 is started.

[0015] Here, the control unit 11 determines whether or not to execute the above preheat control and postheat control, depending on the insulation resistance value Rt of the first catalyst 14. The insulation resistance value Rt of the first catalyst 14 is measured by an insulation resistance value measuring means (not shown) attached to the first catalyst 14. For example, when the insulation resistance value of the first catalyst 14 exceeds a predetermined second threshold value A2 (e.g., 1.0 MΩ), the control unit 11 executes both the preheat control and the postheat control.

[0016] Furthermore, when the insulation resistance value of the first catalyst 14 is equal to or less than a predetermined second threshold value A2 (e.g., 1.0 MΩ) and exceeds a predetermined first threshold value A1 (e.g., 0.1 MΩ), the control unit 11 performs only preheat control and does not perform postheat control. Furthermore, when the insulation resistance value of the first catalyst 14 is equal to or less than a predetermined second threshold value A2 (e.g., 1.0 MΩ) and exceeds a predetermined first threshold value A1 (e.g., 0.1 MΩ), the control unit 11 does not perform both preheat control and postheat control.

[0017] That is, the control unit 11 does not perform (prohibits) the post-heat control when the insulation resistance value of the first catalyst 14 is equal to or lower than the second threshold value A2 (for example, 1.0 MΩ). Note that, during the pre-heat control, the control unit 11 may increase the amount of ignition retard for the first catalyst 14 immediately after the start of the engine 12.

[0018] The engine 12 is a power source of the vehicle 1. When performing preheat control, the engine 12 is started after warming up the first catalyst 14. The motor 13 is a power source of the vehicle 1, similar to the engine 12. The motor 13 is, for example, an AC synchronous motor, and functions as an electric motor and a generator.

[0019] The first catalyst 14 is an electrically heated catalyst (EHC) and is disposed in an exhaust passage of the engine 12, for example, as shown in Fig. 2. The first catalyst 14 is also connected to a high-voltage battery via a transformer by a high-voltage cable (not shown).

[0020] The first catalyst 14 is composed of, for example, a catalyst carrier, a case that houses the catalyst carrier, and an insulating member interposed between the catalyst carrier and the case. The first catalyst 14 is also equipped with an insulation resistance measuring means (not shown) that can measure the insulation resistance between the catalyst carrier and the case.

[0021] The second catalyst 15 is an under-floor catalyst, and is arranged in the exhaust passage of the engine 12 together with the first catalyst 14, for example, as shown in FIG.

[0022] (Electrically heated catalyst current control (first embodiment)) A first aspect of the power supply control of the electrically heated catalyst executed by the control device for the electrically heated catalyst according to the embodiment will be described with reference to Fig. 3. This control refers to control (pre-heat control, post-heat control) for electrically heating the first catalyst 14 (hereinafter referred to as "EHC") in the vehicle 1.

[0023] First, the control unit 11 determines whether the vehicle 1 is "Ready ON", i.e., whether preparations for traveling are complete (step S1). If it is determined in step S1 that the vehicle 1 is "Ready ON" (Yes in step S1), the control unit 11 determines whether the EHC current request is ON (step S2). The method of determining whether the EHC current request is ON in step S2 will be described in detail later (see FIG. 4).

[0024] In step S2, when it is determined that the EHC power supply request is ON (Yes in step S2), the control unit 11 calculates the target power amount Q0 (step S3). In step S3, the control unit 11 calculates the target power amount Q0 by referring to a map ("Map(Q0, Tcat1)") that shows the relationship between the target power amount Q0 and the EHC temperature Tcat1, for example, that is prepared in advance.

[0025] Next, the control unit 11 measures the insulation resistance value Rt of the EHC using an insulation resistance value measuring means attached to the EHC (step S4). Next, the control unit 11 determines whether the insulation resistance value Rt exceeds a predetermined second threshold value A2 (e.g., 1.0 MΩ) (step S5).

[0026] In step S5, if it is determined that the insulation resistance value Rt exceeds the second threshold value A2 (Yes in step S5), the control unit 11 instructs the EHC to supply power W0 (step S6) and prohibits starting of the engine 12 (step S7). Next, the control unit 11 energizes the EHC (step S8). In step S8, the control unit 11 energizes the EHC so that, for example, "the amount of power Q(t) = ∫W0dt [kJ]" is satisfied.

[0027] Next, the control unit 11 determines whether the electric energy Q(t) is equal to or greater than the target electric energy Q0 (step S9). If it is determined in step S9 that the electric energy Q(t) is equal to or greater than the target electric energy Q0 (Yes in step S9), the control unit 11 starts the engine 12 (step S10), and then stops energizing the EHC (step S11), completing this process.

[0028] Here, if it is determined in step S1 that the vehicle 1 is not "Ready ON" (No in step S1), the control unit 11 ends this process. Also, if it is determined in step S2 that the EHC power supply request is not ON (No in step S2), the control unit 11 ends this process.

[0029] Furthermore, in step S5, if it is determined that the insulation resistance value Rt does not exceed the second threshold value A2 (is less than or equal to the second threshold value A2) (No in step S5), the control unit 11 determines whether the insulation resistance value Rt exceeds a predetermined first threshold value A1 (e.g., 0.1 MΩ) (step S12).

[0030] If it is determined in step S12 that the insulation resistance value Rt exceeds the first threshold value A1 (Yes in step S12), the control unit 11 sets the insulation resistance decrease flag F2 to ON (step S13) and proceeds to step S6. On the other hand, if it is determined in step S12 that the insulation resistance value Rt does not exceed the first threshold value A1 (is equal to or less than the first threshold value A1) (No in step S12), the control unit 11 sets the current supply prohibition flag F1 to ON (step S14) and proceeds to step S10.

[0031] Here, if it is determined in step S9 that the power amount Q(t) is not equal to or greater than the target power amount Q0 (is less than the target power amount Q0) (No in step S9), the control unit 11 determines whether or not the required output Pusr of the vehicle 1 is greater than a predetermined value A (step S15). If it is determined in step S15 that the required output Pusr is greater than the value A (Yes in step S15), the control unit 11 starts the engine 12 (step S16).

[0032] Next, the control unit 11 determines whether the insulation resistance decrease flag F2 is OFF (step S17). If it is determined in step S17 that the insulation resistance decrease flag F2 is OFF (Yes in step S17), the control unit 11 energizes the EHC (step S18). In step S18, the control unit 11 energizes the EHC so that, for example, "power amount Q(t) = ∫Wpdt [kJ]" is satisfied.

[0033] Next, the control unit 11 determines whether the amount of power Q(t) is equal to or greater than the target amount of power Q0 (step S19). If it is determined in step S19 that the amount of power Q(t) is equal to or greater than the target amount of power Q0 (Yes in step S19), the control unit 11 proceeds to step S10.

[0034] Here, if it is determined in step S15 that the required output Pusr is not greater than the value A (is equal to or less than A) (No in step S15), the control unit 11 proceeds to step S8. If it is determined in step S17 that the insulation resistance decrease flag F2 is not OFF (is ON) (No in step S17), the control unit 11 proceeds to step S11. If it is determined in step S19 that the amount of power Q(t) is not greater than or equal to the target amount of power Q0 (is less than the target amount of power Q0) (No in step S19), the control unit 11 proceeds to step S18.

[0035] Thus, in this embodiment, if the insulation resistance value Rt of the EHC exceeds the first threshold value A1 (e.g., 0.1 MΩ) or the second threshold value A2 (e.g., 1.0 MΩ), pre-heat control of the EHC is performed before starting the engine 12 after "Ready ON". Also, in this embodiment, if the insulation resistance value Rt of the EHC is equal to or less than the second threshold value A2 (e.g., 1.0 MΩ) after starting the engine 12, post-heat control is not performed.

[0036] As a result, it is possible to energize the EHC while suppressing leakage current caused by a decrease in insulation resistance even after starting the engine 12. In addition, since preheat control can be executed, it is possible to suppress deterioration of emissions.

[0037] (Electrically heated catalyst power supply request processing) An example of an electrically heated catalyst power supply request process executed by the control device for the electrically heated catalyst according to the embodiment will be described with reference to Fig. 4. This control shows an example of a method for determining whether the EHC power supply request is ON in step S2 in Fig. 3.

[0038] First, the control unit 11 determines whether the battery's SOC (State Of Charge) is smaller than a predetermined current start threshold F [%] (step S21). If the control unit 11 determines in step S21 that the SOC is smaller than the current start threshold F (Yes in step S21), the control unit 11 determines whether the EHC temperature Tcat1 is smaller than a predetermined value T0 (e.g., 300° C.) (step S22).

[0039] In step S22, when it is determined that the EHC temperature Tcat1 is smaller than the value T0 (Yes in step S22), the control unit 11 determines that the power supply request for the EHC has been turned ON (step S23), and ends this process.

[0040] Here, if it is determined in step S21 that the SOC is not smaller than the power supply start threshold F (is equal to or greater than the power supply start threshold F) (No in step S21), the control unit 11 completes this process. Also, if it is determined in step S22 that the EHC temperature Tcat1 is not smaller than the value T0 (is equal to or greater than the value T0) (No in step S22), the control unit 11 completes this process.

[0041] (Electrically heated catalyst current control (second embodiment)) A second aspect of the power supply control for the electrically heated catalyst executed by the control device for the electrically heated catalyst according to the embodiment will be described with reference to FIG.

[0042] First, the control unit 11 determines whether the vehicle 1 is "Ready ON", i.e., whether preparations for traveling are complete (step S31). If it is determined in step S31 that the vehicle 1 is "Ready ON" (Yes in step S31), the control unit 11 determines whether the EHC current request is ON (step S32). The method of determining whether the EHC current request is ON in step S32 is as shown in FIG. 4 above.

[0043] In step S32, when it is determined that the EHC power supply request is ON (Yes in step S32), the control unit 11 calculates the target power amount Q0 (step S33). In step S33, the control unit 11 calculates the target power amount Q0 by referring to a map ("Map(Q0, Tcat1)") that shows the relationship between the target power amount Q0 and the EHC temperature Tcat1, for example, that is prepared in advance.

[0044] Next, the control unit 11 measures the insulation resistance value Rt of the EHC using an insulation resistance value measuring means attached to the EHC (step S34). Next, the control unit 11 determines whether the insulation resistance value Rt exceeds a predetermined second threshold value A2 (e.g., 1.0 MΩ) (step S35).

[0045] In step S35, if it is determined that the insulation resistance value Rt exceeds the second threshold value A2 (Yes in step S35), the control unit 11 instructs the EHC to supply power W0 (step S36) and prohibits starting of the engine 12 (step S37). Next, the control unit 11 energizes the EHC (step S38). In step S38, the control unit 11 energizes the EHC so that, for example, "the amount of power Q(t) = ∫W0dt [kJ]" is satisfied.

[0046] Next, the control unit 11 determines whether the electric energy Q(t) is equal to or greater than the target electric energy Q0 (step S39). If it is determined in step S39 that the electric energy Q(t) is equal to or greater than the target electric energy Q0 (Yes in step S39), the control unit 11 starts the engine 12 (step S40), and then stops energizing the EHC (step S41), completing this process.

[0047] Here, if it is determined in step S31 that the vehicle 1 is not "Ready ON" (No in step S31), the control unit 11 ends this process. Also, if it is determined in step S32 that the EHC power supply request is not ON (No in step S32), the control unit 11 ends this process.

[0048] Furthermore, in step S35, if it is determined that the insulation resistance value Rt does not exceed the second threshold value A2 (is equal to or less than the second threshold value A2) (No in step S35), the control unit 11 determines whether the insulation resistance value Rt exceeds a predetermined first threshold value A1 (e.g., 0.1 MΩ) (step S42).

[0049] If it is determined in step S42 that the insulation resistance value Rt exceeds the first threshold value A1 (Yes in step S42), the control unit 11 sets the insulation resistance decrease flag F2 to ON (step S43) and proceeds to step S36. On the other hand, if it is determined in step S42 that the insulation resistance value Rt does not exceed the first threshold value A1 (is equal to or less than the first threshold value A1) (No in step S42), the control unit 11 sets the current supply prohibition flag F1 to ON (step S44) and proceeds to step S40.

[0050] Here, if it is determined in step S39 that the power amount Q(t) is not equal to or greater than the target power amount Q0 (is less than the target power amount Q0) (No in step S39), the control unit 11 determines whether or not the required output Pusr of the vehicle 1 is greater than a predetermined value A (step S45). If it is determined in step S45 that the required output Pusr is greater than the value A (Yes in step S45), the control unit 11 starts the engine 12 (step S46).

[0051] Next, the control unit 11 determines whether the insulation resistance decrease flag F2 is OFF (step S47). If it is determined in step S47 that the insulation resistance decrease flag F2 is OFF (Yes in step S47), the control unit 11 energizes the EHC (step S48). In step S48, the control unit 11 energizes the EHC so that, for example, "power amount Q(t) = ∫Wpdt [kJ]" is satisfied.

[0052] Next, the control unit 11 determines whether the execution time t of the post-heat control (step S48) is equal to or greater than a predetermined time limit tL (step S49). If it is determined in step S49 that the execution time t of the post-heat control (step S48) is not equal to or greater than the time limit tL (is less than the time limit tL) (No in step S49), the control unit 11 determines whether the power amount Q(t) is equal to or greater than the target power amount Q0 (step S50). If it is determined in step S50 that the power amount Q(t) is equal to or greater than the target power amount Q0 (Yes in step S50), the control unit 11 proceeds to step S41.

[0053] Here, in step S45, if it is determined that the required output Pusr is not greater than the value A (is equal to or less than A) (No in step S45), the control unit 11 proceeds to step S38. Also, in step S47, if it is determined that the insulation resistance decrease flag F2 is not OFF (is ON) (No in step S47), the control unit 11 proceeds to step S41. Also, in step S49, if it is determined that the execution time t of the post-heat control (step S48) is equal to or greater than the time limit tL (Yes in step S49), the control unit 11 proceeds to step S41. Also, in step S50, if it is determined that the power amount Q(t) is not equal to or greater than the target power amount Q0 (is less than the target power amount Q0) (No in step S50), the control unit 11 proceeds to step S48.

[0054] Here, the time limit tL in step S49 can be calculated, for example, as follows. First, the control unit 11 determines whether or not the insulation resistance value Rt of the EHC exceeds the second threshold value A2. Then, when the control unit 11 determines that the insulation resistance value Rt of the EHC exceeds the second threshold value A2, it calculates the time limit tL by referring to, for example, a map ("Map(tL, Rt, Pe)") showing the relationship between the time limit tL [s], the insulation resistance value Rt [MΩ], and the engine load (engine output) Pe. Thus, in this embodiment, a time limit is set for the execution time t of the post-heat control according to the insulation resistance value Rt of the EHC. At that time, the magnitude of the time limit tL may be changed according to the engine load Pe after starting.

[0055] In step S49, a limit may be set on the accumulated air amount ΣGa of the post-heat control instead of the execution time t of the post-heat control. In this case, in step S49, the control unit 11 determines whether the accumulated air amount ΣGa of the post-heat control (step S48) is equal to or greater than a predetermined limit amount gasum L.

[0056] The restriction amount gasum L at this time can be calculated, for example, as follows. First, the control unit 11 determines whether the insulation resistance value Rt of the EHC exceeds the second threshold value A2. Then, when the control unit 11 determines that the insulation resistance value Rt of the EHC exceeds the second threshold value A2, it calculates the restriction amount gasum L, for example, by referring to a map ("Map(gasum L, Rt, Pe)") showing the relationship between the restriction amount gasum L [g / s], the insulation resistance value Rt [MΩ], and the engine load Pe. In this way, a restriction may be set on the integrated air amount ΣGa of the post-heat control according to the insulation resistance value Rt of the EHC. Also, at this time, the magnitude of the restriction amount gasum L may be changed according to the engine load Pe after starting.

[0057] In this manner, in this embodiment, a limit is set on the execution time t of the post-heat control according to the insulation resistance value Rt of the EHC, and the magnitude of the limit time tL is changed according to the engine load Pe after startup. Also, in this embodiment, a limit gasum L is set on the integrated air amount ΣGa of the post-heat control according to the insulation resistance value Rt of the EHC, and the magnitude of the limit gasum L is changed according to the engine load Pe after startup.

[0058] This allows current to be supplied to the EHC while suppressing leakage current caused by a drop in insulation resistance even after the engine has started. In addition, by executing post-heat control as much as possible, it is possible to suppress deterioration of emissions.

[0059] (Electrically heated catalyst current control (third embodiment)) A third aspect of the power supply control for the electrically heated catalyst executed by the control device for the electrically heated catalyst according to the embodiment will be described with reference to FIG.

[0060] First, the control unit 11 determines whether the vehicle 1 is "Ready ON", i.e., whether preparations for traveling are complete (step S61). If it is determined in step S61 that the vehicle 1 is "Ready ON" (Yes in step S61), the control unit 11 determines whether the EHC current request is ON (step S62). The method of determining whether the EHC current request is ON in step S62 is as shown in FIG. 4 above.

[0061] In step S62, when it is determined that the EHC power supply request is ON (Yes in step S62), the control unit 11 calculates the target power amount Q0 (step S63). In step S63, the control unit 11 calculates the target power amount Q0 by referring to a map ("Map(Q0, Tcat1)") that shows the relationship between the target power amount Q0 and the EHC temperature Tcat1, for example, that is prepared in advance.

[0062] Next, the control unit 11 measures the insulation resistance value Rt of the EHC using an insulation resistance value measuring means attached to the EHC (step S64). Next, the control unit 11 determines whether the insulation resistance value Rt exceeds a predetermined first threshold value A1 (for example, 0.1 MΩ) (step S65).

[0063] In step S65, when it is determined that the insulation resistance value Rt exceeds the first threshold value A1 (Yes in step S65), the control unit 11 instructs the EHC to supply power W0 (step S66) and prohibits starting of the engine 12 (step S67). Next, the control unit 11 energizes the EHC (step S68). In step S68, the control unit 11 energizes the EHC so that, for example, "the amount of power Q(t) = ∫W0dt [kJ]" is satisfied.

[0064] Next, the control unit 11 determines whether the electric energy Q(t) is equal to or greater than the target electric energy Q0 (step S69). If it is determined in step S69 that the electric energy Q(t) is equal to or greater than the target electric energy Q0 (Yes in step S69), the control unit 11 starts the engine 12 (step S70), and then stops energizing the EHC (step S71), completing this process.

[0065] Here, if it is determined in step S61 that the vehicle 1 is not "Ready ON" (No in step S61), the control unit 11 ends this process. Also, if it is determined in step S62 that the EHC power supply request is not ON (No in step S62), the control unit 11 ends this process.

[0066] Furthermore, in step S65, if it is determined that the insulation resistance value Rt does not exceed the first threshold value A1 (is less than or equal to the first threshold value A1) (No in step S65), the control unit 11 turns on the power supply prohibition flag F1 (step S72) and proceeds to step S70.

[0067] Here, if it is determined in step S69 that the power amount Q(t) is not equal to or greater than the target power amount Q0 (is less than the target power amount Q0) (No in step S69), the control unit 11 determines whether or not the required output Pusr of the vehicle 1 is greater than a predetermined value A (step S73). If it is determined in step S73 that the required output Pusr is greater than the value A (Yes in step S73), the control unit 11 starts the engine 12 (step S76).

[0068] Next, the control unit 11 determines whether the lower limit value f(Rt) of the insulation resistance value Rt exceeds a predetermined first threshold value A1 (e.g., 0.1 MΩ) (step S75). If it is determined in step S75 that the lower limit value f(Rt) of the insulation resistance value Rt exceeds the first threshold value A1 (Yes in step S75), the control unit 11 energizes the EHC (step S76). In step S76, the control unit 11 energizes the EHC so that, for example, "the amount of power Q(t) = ∫Wpdt [kJ]" is satisfied.

[0069] Next, the control unit 11 determines whether the amount of power Q(t) is equal to or greater than the target amount of power Q0 (step S77). If it is determined in step S77 that the amount of power Q(t) is equal to or greater than the target amount of power Q0 (Yes in step S77), the control unit 11 proceeds to step S71.

[0070] Here, if it is determined in step S73 that the required output Pusr is not greater than the value A (is equal to or less than A) (No in step S73), the control unit 11 proceeds to step S68. If it is determined in step S75 that the lower limit f(Rt) of the insulation resistance value Rt does not exceed the first threshold value A1 (is equal to or less than the first threshold value A1) (No in step S75), the control unit 11 proceeds to step S71. If it is determined in step S77 that the amount of power Q(t) is not equal to or greater than the target amount of power Q0 (is less than the target amount of power Q0) (No in step S77), the control unit 11 proceeds to step S76.

[0071] Here, the lower limit value f(Rt) of the insulation resistance value Rt in step S75 can be calculated, for example, as follows: First, the control unit 11 reads various values ​​(insulation resistance value Rt, outside air temperature To, engine load Pe, and accumulated air volume (wall temperature) ΣGa). Next, the control unit 11 calculates the lower limit value f(Rt) of the insulation resistance value Rt based on these values.

[0072] In this manner, in this embodiment, the lower limit f(Rt) of the insulation resistance value Rt is estimated based on the insulation resistance value Rt, the outside air temperature To, the engine load Pe, the accumulated air volume ΣGa, etc., and post-heat control is executed while the lower limit f(Rt) exceeds the first threshold value A1.

[0073] This allows current to be supplied to the EHC while suppressing leakage current caused by a drop in insulation resistance even after the engine has started. In addition, by executing post-heat control as much as possible, it is possible to suppress deterioration of emissions.

[0074] Further advantages and modifications may readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof. [Explanation of symbols]

[0075] 1 vehicle 11 Control section 12 Engine 13 Motor 14 First Catalyst 15 Second catalyst

Claims

[Claim 1] A processor is provided. The processor, Preheat control to electrically heat the catalyst before starting the engine; a post-heat control for electrically heating the catalyst even after the engine is started; Do the following: When the insulation resistance value of the catalyst is equal to or lower than a predetermined threshold value, the post-heat control is not performed. Control device for electrically heated catalyst.

Images