Control unit and method for operating a hybrid drive

Abstract

A controller and a method for a hybrid drive, which includes an internal combustion engine and an electrical machine are provided. The internal combustion engine includes adjustment devices that deactivate the intake and exhaust valve opening actuation. The controller is designed in such a way that, in the case of at least one specified condition (such as regeneration during unfired overrun or in the case of electric travel, in particular in the case of operation with high activation frequency of the internal combustion engine, e.g., in charge sustaining or HEV operation), the intake and exhaust valves are kept at least approximately (preferably completely) closed at least approximately simultaneously while the internal combustion engine is unfired. The internal combustion engine must be connected to the electrical machine. If there is a disconnect clutch, the disconnect clutch is brought into the closed state or remains closed.

Claims

1. A controller for a hybrid drive which includes an internal combustion engine and an electric machine, wherein the internal combustion engine includes adjustment devices that deactivate an opening actuation of inlet valves and outlet valves, the controller comprising: a processor programmed to execute instructions; and a memory coupled to the processor and having the instructions stored therein, wherein the instructions are configured to cause the processor to: cause the adjustment devices to deactivate the opening actuation of the inlet valves and the outlet valves based on a determination that the internal combustion engine is non-activated, the internal combustion engine is connected to the electric machine via a closed clutch, and a specified condition of purely electric driving of the hybrid drive is present; wherein the controller provides fully variable valve stroke control on an inlet side and simple deactivation of a valve drive by a first switching actuator system on an outlet side; and wherein the controller is configured such that the inlet valves and the outlet valves are kept closed in a deactivated state only in a case in which a rotational speed of the internal combustion engine has not undershot a minimum rotational speed limit for self-sustained operation.

2. The controller according to claim 1, wherein the specified condition is purely electric driving in a charge sustaining mode of a plug-in hybrid electric vehicle (PHEV).

3. The controller according to claim 1, wherein the specified condition is purely electric driving in a mode from which a defined comparatively high starting frequency is expected.

4. The controller according to claim 1, wherein the adjustment devices include a fully variable valve stroke control means or a valve opening actuator of the valve drive by a second switching actuator system on the inlet side, and a valve opening actuator of the valve drive by the first switching actuator system on the outlet side.

5. A method for operating a hybrid drive including an internal combustion engine and an electric machine, the method comprising: controlling, by a controller, inlet valves and outlet valves to be kept closed by controlling adjustment devices; deactivating, by the controlling adjustment devices, an opening actuation of the inlet valves and the outlet valves based on determinations that the internal combustion engine is non-activated, the internal combustion engine is connected to the electric machine via a closed clutch, and a specified condition of purely electric driving of the hybrid drive is present; providing, by the controller, fully variable valve stroke control on an inlet side and simple deactivation of a valve drive by a switching actuator system on an outlet side; and keeping the inlet valves and the outlet valves closed in a deactivated state only in a case in which a rotational speed of the internal combustion engine has not undershot a minimum rotational speed limit for self-sustained operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a so-called P2 drive train with a drag-torque-reducing measure which can be activated and deactivated according to the invention,

(2) FIG. 2 shows a so-called P1 drive train with a drag-torque-reducing measure which can be activated and deactivated according to the invention, and

(3) FIG. 3 shows a so-called P0 drive train with a drag-torque-reducing measure which can be activated and deactivated according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) As presented at the beginning, the present document is concerned with the operation of a hybrid drive, in particular for activating at least one drag-torque-reducing measure. In this context, FIGS. 1, 2 and 3 show schematic illustrations of a vehicle with exemplary hybrid drive topologies.

(5) In FIG. 1, a P2 drive train comprises an internal combustion engine 3 and an electric machine 5, which can be used individually or together, in order to generate a drive torque for a vehicle 1. The internal combustion engine 3 and the electric machine 5 are arranged in such a way that the torques which are generated by the respective drive motor are added to form a total drive torque which is transmitted, for example, via a transmission 7 and an output shaft of the transmission 7 to one or more wheels of the vehicle 1. The electrical energy for operating the electric machine 5 can be stored in an electrical energy store.

(6) The vehicle 1 also comprises a control unit 10 (e.g., an engine control apparatus) which is configured to determine a requested total drive torque. The requested total drive torque can be specified by a driver of the vehicle, e.g., by means of an accelerator pedal and/or by means of a setting of the transmission 7. For example, a driver can activate the accelerator pedal in order to request an increased total drive torque. The control unit 10 can be configured to divide the requested total drive torque into a first torque (for the internal combustion engine 3) and a second torque (for the electric machine 5). In other words, the control unit 10 can be configured to operate the internal combustion engine 3 and the electric machine 5 as a function of a requested total drive torque.

(7) FIG. 1 shows the part of the drive train of a vehicle with a P2 parallel hybrid drive in which the drive torques of the engine 3 and motor 5 act additively on the common input shaft of the transmission 7. Furthermore, FIG. 1 shows a clutch 8 with which the internal combustion engine 3 and the electric motor 5 can be decoupled. Additionally, it is to be noted that a starter element 6 and optionally a rotary vibration damper 4, which does not necessarily have to be located at the position illustrated in FIG. 1, can be provided. The internal combustion engine 3 has in each case at least one valve control device 2 for the inlet valves and outlet valves which in combination with an SRM (drag torque reduction measure) functional module of the control unit 10 provide the drag torque reduction measure according to the invention.

(8) FIG. 2 shows the part of the drive train of a vehicle 101 with a P1 parallel hybrid drive architecture in which the electric machine 105 acts directly on the crankshaft, without the presence of a clutch which is present between the electric machine 105 and the internal combustion engine 103. Further components are, in a way analogous to FIG. 1, a valve control device 102 for the inlet valves and outlet valves, which provide the drag reduction measure according to the invention in combination with an SRM module of the control unit 10 as well as an optional rotary vibration damper 104, a starter element 106 and a transmission 107.

(9) FIG. 3 shows the part of the drive train of a vehicle 201 with a P0 parallel hybrid drive architecture in which the electric machine 205 is permanently coupled to the internal combustion engine 203 via a connecting element 208 (typically a belt connection) without the presence of a clutch between the electric machine 205 and internal combustion engine 203. Further components are, in a manner analogous to FIG. 1 and FIG. 2, a valve control device 202 for the inlet valves and outlet valves which, in combination with an SRM module of the control unit 10, provide the drag reduction measure according to the invention, as well as an optional rotary vibration damper 204, a starter element 206 and a transmission 207.

(10) The internal combustion engine 1, 101, 201 of a hybrid drive can be at least temporarily deactivated, e.g., in the case of (under certain circumstances purely) electric operation of the hybrid drive and/or in the case of recuperation in so-called overrun mode when the wheels of the vehicle drive the output shaft. The driveshaft of the deactivated internal combustion engine 1, 101, 201 can therefore be driven and/or entrained, in a non-activated, entrained mode, by the electric machine 2 (with the clutch 8 closed), 102, 202 and/or by the one or more wheels of the vehicle 1, 101, 201. A mode of the internal combustion engine which is non-activated and entrained has the advantage that the internal combustion engine can be activated again at short notice and efficiently, in order to contribute drive torque to the total drive of the vehicle.

(11) According to the invention, in order to reduce the relatively high drag losses occurring according to the prior art at least one drag torque-reducing measure is carried out, specifically by closing the inlet valves and outlet valves by means of the valve control devices 2, 102, 202 in combination with an SRM module of the control unit 10.

(12) The functional module SRM of the control unit 10 picks up input signals for checking for the presence of the specified conditions. Output signals of the control unit 10 control the actuators of the valve control devices 2 at least in order to close the inlet valves and outlet valves.

(13) The present invention is not limited to the exemplary embodiments shown. It is in particular to be noted that the description and the figures are intended to illustrate only the principle of the proposed methods, devices and systems.