TORQUE-ACTUATED PHASE CONTROLLER FOR VARIABLE COMPRESSION RATIO

Abstract

A variable compression ratio phaser (200) configured to control a compression ratio of an engine (102) having a crankshaft and a control shaft, the variable compression ratio phaser (200) comprising: a control shaft gear (230) configured to mesh with a gear on the control shaft of the engine (102) and receive torque from the control shaft; a crankshaft gear (220) configured to mesh with a gear on the crankshaft of the engine (102) and deliver torque to the crankshaft; characterized in that the control shaft gear (230) and the crankshaft gear (220) are arranged axially offset from one another; and that the phaser (200) comprises a torque converter mechanism configured to receive torque from the control shaft and convert the torque into a linear force acting in the direction of the axial offset between the control shaft gear (230) and the crankshaft gear (220) and changing the compression ratio of the engine (102).

Description

INTRODUCTION

[0001] The present disclosure relates to a vehicle engine including a transmission for varying the compression ratio of the vehicle engine using a torque-actuated variable compression ratio (VCR) phaser. More particularly, the invention relates to a variable compression ratio phaser according to the preamble of claim 1, as is substantially known from US 2009 / 0 241 910 A1.

[0002] With regard to the further prior art, reference is made to the documents DE 10 2014 201 979 A1, EP 2 022 959 A2 and US 2018 / 0 274 ​​437 A1.

[0003] A variable compression ratio (VCR) engine typically includes an engine block containing a plurality of cylinders, a piston positioned in each cylinder, connecting rods, a crankshaft, a bell crank, timing links, a control shaft, and a transmission. The bell crank is pivoted to the crankshaft. The connecting rod connects the piston to one end of the bell crank. The timing link connects the other end of the bell crank to the timing shaft.

[0004] As each piston moves within a cylinder, the corresponding connecting rod exerts torque on the bellcrank. The control link, in turn, transfers the torque from the bellcrank to the control shaft, causing the control shaft to rotate. The transmission transfers the torque from the control shaft back to the crankshaft, ensuring that the rotation of the two shafts is in time (or in phase). Additionally, the transmission couples an actuator—typically an electric motor or a hydraulic pump—to the control shaft. The actuator varies the speed of the control shaft relative to the speed of the crankshaft, thereby varying the cylinder's compression ratio. SUMMARY

[0005] An object of the disclosure is to provide a variable compression ratio (VCR) phaser configured to control a compression ratio of an engine having a crankshaft and a timing shaft.

[0006] This object is achieved with a phase adjuster which is characterized by the features of claim 1.

[0007] In one embodiment, the linear force of the torque converter phase-shifts the control shaft relative to the crankshaft to thereby increase or decrease the compression ratio of the engine.

[0008] In another embodiment, the linear force from the torque converter mechanism adjusts a phase angle between the crankshaft gear and the timing gear to thereby increase or decrease the compression ratio of the engine.

[0009] In another embodiment, the torque converter mechanism includes a first shaft on which the control shaft gear is mounted, the first shaft being configured to rotate with the control shaft gear.

[0010] In another embodiment, the first shaft on which the control shaft gear is mounted includes a helical lead screw at a distal end of the first shaft.

[0011] In another embodiment, the torque converter mechanism further comprises a spline connector or spline coupling to the helical lead screw such that rotation of the first shaft causes rotation and linear movement of the spline along the first shaft.

[0012] In yet another embodiment, the spline is further configured such that linear movement of the spline along the first shaft adjusts the phase angle between the crankshaft gear and the timing gear to thereby increase or decrease the compression ratio of the engine.

[0013] In another embodiment, the torque converter mechanism further includes a spring stack configured to be compressed by the spline.

[0014] In one embodiment, as the torque absorbed by the control shaft gear increases at higher loads, the spline moves in a first direction with increased linear force and compresses the spring pack, wherein the movement of the spline in the first direction adjusts the phase angle such that the compression ratio decreases.

[0015] In another embodiment, as the torque received by the timing gear decreases at lighter loads, the spring stack expands and moves the spline in a second direction opposite the first direction, wherein movement of the spline in the second direction adjusts the phase angle to increase the compression ratio.

[0016] In another embodiment, the variable compression ratio phaser further includes a control piston that limits the movement of the spline so that it moves only in the first direction when the torque received by the control shaft gear from the control shaft increases at higher loads.

[0017] In another embodiment, the control piston limits the movement of the spline to move only in the second direction when the torque received by the control shaft gear from the control shaft decreases at lower loads.

[0018] In a further embodiment, the control piston is hydraulically active and is controlled by a position of a hydraulic check valve.

[0019] Further applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are provided for purposes of illustration only. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] This disclosure will become more fully apparent from the detailed description and the accompanying drawings, in which: Fig. 1 is a functional block diagram of an exemplary vehicle system including a torque-actuated variable compression ratio (VDR) phaser according to the principles of the present disclosure. Fig. 2 is a perspective view of the exterior of a torque-actuated variable compression ratio (VCR) phaser according to an embodiment of the present disclosure. Fig. 3 is a cross-sectional view of a torque-actuated variable compression ratio (VCR) phaser according to an embodiment of the present disclosure. Fig. 4 is a graph illustrating the dynamic torque profile of a torque-actuated variable compression ratio (VCR) phaser according to an embodiment of the present disclosure.

[0021] In the drawings, reference numerals may be reused to designate similar and / or identical elements. DETAILED DESCRIPTION

[0022] The present disclosure proposes a device with a novel actuation method for retarding or advancing the eccentric shaft on a variable compression ratio (VCR) engine to achieve a desired compression ratio. The disclosed device utilizes the torque oscillations present in the 6-bar linkage mechanism to either increase or decrease the compression ratio. By harnessing torque in the system, a high-power actuator (e.g., an electric motor, a hydraulic pump) can be eliminated, resulting in a more cost-effective solution with advantages in packaging and complexity.

[0023] The disclosed device comprises a torque-actuated VCR phaser that utilizes the energy present in the linkage to actuate the system. In particular, the arrangement of simple machine elements, such as lead screws or ball screws, gears, and springs, offers a competitive advantage over current solutions that utilize electric motors and high-ratio gearboxes. Harnessing torque oscillation eliminates the need for these actuators and allows the high instantaneous power to be used for phasing to quickly achieve the compression ratio (CR) change.

[0024] The present disclosure describes a device that converts torque to linear force via a helical lead screw that can direct power to phase the timing shaft relative to the crankshaft in either direction, depending on the orientation of the oil control valve (OCV) relative to a hydraulic check valve. Known alternatives to this motor include high-ratio transmissions (i.e., harmonic drive, wave strain gear, cycloidal drive) coupled to an electric or hydraulic motor.

[0025] Fig. 1 is a functional block diagram of an exemplary vehicle system 100 including a torque-actuated variable compression ratio (VCR) phaser according to the principles of the present disclosure. While a vehicle system for a hybrid vehicle is shown and described, the present disclosure is also applicable to non-hybrid vehicles that include only an internal combustion engine. Although the example of a vehicle is cited, the present application is also applicable to non-automotive implementations, such as boats and aircraft.

[0026] An engine 102 combusts an air-fuel mixture to produce drive torque. An engine control module (ECM) 106 controls the engine 102 based on one or more driver inputs. For example, the ECM 106 may control the actuation of engine actuators, such as a throttle valve, one or more spark plugs, one or more fuel injectors, valve actuators, camshaft phasers, an exhaust gas recirculation (EGR) valve, one or more boost devices, and other suitable engine actuators.

[0027] The engine 102 may provide torque to a transmission 110. A transmission control module (TCM) 114 controls the operation of the transmission 110. For example, the TCM 114 may control gear selection within the transmission 110 and one or more torque-transmitting devices (e.g., a torque converter, one or more clutches, etc.).

[0028] The vehicle system may include one or more electric motors. For example, an electric motor 118 may be implemented within the transmission 110, as in the example of Fig. 1. An electric motor can operate either as a generator or as a motor at a given time. In its function as a generator, an electric motor converts mechanical energy into electrical energy. The electrical energy can charge a battery 126 via a power control device (PCD) 130. In its function as a motor, an electric motor produces torque that supplements or replaces the torque output of the engine 102. While the example of an electric motor is given, the vehicle may include no or more than one electric motor.

[0029] An inverter control module (PIM) 134 may control the electric motor 118 and the PCD 130. The PCD 130 applies power (e.g., direct current) from the battery 126 to the electric motor (e.g., AC electric motor) 118 based on signals from the PIM 134, and the PCD 130 supplies the power output from the electric motor 118, e.g., to the battery 126. The PIM 134 may be referred to as an inverter module (PIM) in various implementations.

[0030] A steering control module 140 controls the steering / rotation of the vehicle's wheels, e.g., based on the driver's rotation of a steering wheel within the vehicle and / or steering commands from one or more vehicle control modules. A steering wheel angle (SWA) sensor monitors the rotational position of the steering wheel and generates an SWA 142 based on the steering wheel's position. The steering control module 140 may, e.g., control the vehicle's steering via an EPS motor 144 based on the SWA 142. However, the vehicle may also include another type of steering system. An electronic brake control module (EBCM) 150 may selectively control the vehicle's brakes 154.

[0031] Vehicle modules can exchange parameters via a Controller Area Network (CAN) 162. The CAN 162 may also be referred to as a vehicle network (Car Area Network). The CAN 162 may, for example, contain one or more data buses. Various parameters can be made available from a specific control module to other control modules via the CAN 162.

[0032] Driver inputs may include, for example, an accelerator pedal position (APP) 166, which may be provided to the ECM 106. A brake pedal position (BPP) 170 may be provided to the EBCM 150. A park, reverse, neutral, or drive (PRNDL) lever position 174 may be provided to the TCM 114. An ignition status 178 may be communicated to a body control module (BCM) 180. The ignition status 178 may be entered, for example, by a driver via an ignition key, an ignition button, or an ignition switch. At any given time, the ignition status 178 may be one of off, accessory, run, or cranking.

[0033] According to an exemplary embodiment of the present disclosure, engine 102 may include a 6-bar linkage mechanism and a variable compression ratio (VCR) phaser that utilizes the torque oscillations present in the 6-bar linkage mechanism to either increase or decrease the compression ratio. Utilizing system torque in this manner eliminates the need for a high-power drive or actuator (e.g., an electric motor, a hydraulic pump).

[0034] Fig. Figure 2 is a perspective view of the exterior of a torque-actuated variable compression ratio (VCR) phaser 200 according to one embodiment of the present disclosure. The VCR phaser 200 includes a housing 205, a case 210, a crank gear 220, and a timing (or eccentric) gear 230. The crank gear 220 engages the main crankshaft of the engine 102, and the timing gear 230, visible through opening 206, engages the secondary (or timing or eccentric) shaft. The VCR phaser 200 also includes an oil control valve (OCV) 260 and a hydraulic control valve 270.

[0035] The VCR phaser 200 indexes the phase angle between the crankshaft and the timing shaft to vary (or control) the compression ratio. As described further below, the VCR phaser 200 converts torque into linear force via a helical lead screw, which can direct power to phase the timing shaft relative to the crankshaft in either direction, depending on the orientation of the oil control valve (OCV) 260 relative to a hydraulic check valve 270.

[0036] Fig. 3 is a cross-sectional view of a torque-actuated variable compression ratio (VCR) phaser 200 according to an embodiment of the present disclosure. The VCR phaser 200 includes a Belleville spring pack 310, a spline 320, a shaft 330, a shaft 330, and a piston 350. The timing gear 230 is mounted on the shaft 330. At one end, the shaft 330 includes a helical 45° lead screw 331 (generally indicated by a dashed oval) that meshes with threads internal to the spline 320.

[0037] The spline 320 is in Fig. 3 shaded with a vertical line pattern. The spline 320 encloses the shaft 330 near the area of ​​the lead screw 331 of the shaft 330. A wider portion of the spline 320 encloses the spring pack 310. The outer diameter (or surface) of the spline 320 includes a straight spline that meshes with the crank gear 220.

[0038] The interior of the shaft 300 includes a channel 332 that can be used for injecting lubricants. In an exemplary embodiment, the piston 350 is hydraulically controlled and limits the deflection of the spline 320 when it is driven to the left by the spring pack 310. The piston 350 is in Fig. 3 hatched with a crossing line pattern.

[0039] In Fig. 3, the direction of power flow is such that the timing (or eccentric) shaft of engine 102 returns power to the crankshaft via the VCR phaser 200. Thus, timing gear 230 receives torque from the eccentric shaft of engine 102. Timing gear 230 transmits the torque to shaft 330, which then drives spline 320 to the left via lead screw 331. Simultaneously, the straight spline of spline 320 transmits the torque to crank gear 220, which transmits the torque back to the crankshaft of engine 102. Spring pack 310 exerts a large preload in one direction. Spring pack 310 is disposed between spline 320 and crank gear 220.

[0040] For efficiency, engine 102 operates at a high compression ratio at low loads. However, for peak power, engine 102 operates at a low compression ratio at high loads. Fig. 3, the spline 320 is shifted all the way to the left, indicating that the system has the highest compression ratio for efficiency (i.e., light load). In this state, the torque on the timing gear 230 is relatively low due to the light load. Since the torque is relatively low, the linear force generated by the 45° helical lead screw 331 on the spline 320 is also relatively small, and the spring pack 310 pushes the spline 320 all the way to the left against the hard stop.

[0041] However, as the load increases, the torque on the timing gear 230 increases, which in turn increases the linear force generated by the 45° helical lead screw 331. As the linear force increases, the spring pack 310 is compressed, and the shaft 330 drives the spline 320 to the right. This allows the timing gear 230 to advance relative to the crank gear 220. Thus, as the load increases, the compression of the spring pack 310 increases until the lowest compression ratio is reached during full-load operation.

[0042] In an exemplary embodiment, the VCR phaser 200 allows the timing gear to advance by + / - 30 degrees relative to the crankshaft gear. Additionally, in an exemplary embodiment, the spline 320 in the VCR phaser 200 can travel approximately 15 mm between a high compression ratio state and a low compression ratio state.

[0043] Fig. Figure 4 is a graph illustrating the dynamic torque profile of a torque-actuated variable compression ratio (VCR) phaser 200 according to an embodiment of the present disclosure. As previously mentioned, piston 350 is hydraulically controlled and limits the deflection of spline 320 when driven leftward by spring pack 310. According to the principles of the present disclosure, hydraulic check valve 270 may control the operation of piston 350.

[0044] In Fig. In Figure 4, the vertical axis, or Y-axis, represents the spring forces in Newtons (N) for various compression ratios. The torque, or linear force, oscillates around the spring stack force. Line 430 represents an example spring stack force of 3000 N. Thus, there are periods where the linear force is greater than the spring force and periods where the linear force is less than the spring force.

[0045] The curve 420 in Fig. 4 oscillates above and below line 430. The areas below curve 420 and above line 430 are shaded by a horizontal line pattern and indicate areas where hydraulic check valve 270 may be set to decrease the compression ratio and move spline 320 to the right. When curve 420 drops below line 430, check valve 270 controls piston 350 to prevent spline 320 from moving to the left again. Thus, each area shaded by a horizontal line pattern indicates that spline 320 only moves (or detent) to the right, reducing the compression ratio for higher loads.

[0046] Conversely, the areas above curve 410 and below line 430 are shaded by a vertical line pattern and indicate areas where the hydraulic check valve 270 can be set to increase the compression ratio and move the spline 320 to the left. When curve 410 falls below line 430, the check valve 270 controls the piston 350 to prevent the spline 320 from moving back to the right. Thus, any area shaded by a vertical line pattern indicates that the spline 320 only moves (or detent) to the left, increasing the compression ratio for lighter loads. For steady-state operation, the hydraulic check valve 270 can be set to hold the piston 350 stationary so that the compression ratio does not change.

[0047] Those skilled in the art will recognize that the piston 350 need not be controlled hydraulically. In alternative embodiments, for example, an electric motor may be used to control the piston 350.

Claims

[1] A variable compression ratio phaser (200) configured to control a compression ratio of an engine (102) having a crankshaft and a control shaft, the variable compression ratio phaser (200) comprising: a control shaft gear (230) configured to mesh with a gear on the control shaft of the engine (102) and receive torque from the control shaft; a crankshaft gear (220) configured to mesh with a gear on the crankshaft of the engine (102) and deliver torque to the crankshaft; characterized by , that the control shaft gear (230) and the crankshaft gear (220) are arranged axially offset from one another; and that the phaser (200) comprises a torque converter mechanism configured to receive torque from the control shaft and convert the torque into a linear force acting in the direction of the axial offset between the control shaft gear (230) and the crankshaft gear (220) and changing the compression ratio of the engine (102). [2] A variable compression ratio phaser (200) as claimed in claim 1, wherein the linear force from the torque converter mechanism changes the phase of the control shaft relative to the crankshaft to thereby increase or decrease the compression ratio of the engine (102). [3] The variable compression ratio phaser (200) of claim 1, wherein the linear force from the torque converter mechanism adjusts a phase angle between the crankshaft gear (220) and the control shaft gear (230) to thereby increase or decrease the compression ratio of the engine (102). [4] The variable compression ratio phaser (200) of claim 3, wherein the torque converter mechanism includes a first shaft (330) on which the control shaft gear (230) is mounted, the first shaft (330) being configured to rotate with the control shaft gear (230). [5] A variable compression ratio phaser (200) according to claim 4, wherein the first shaft (330) on which the control shaft gear (230) is mounted has a helical lead screw (331) at a distal end of the first shaft (330). [6] The variable compression ratio phaser (200) of claim 5, wherein the torque converter mechanism further comprises a spline (320) engageable with the helical lead screw (331) such that rotation of the first shaft (330) causes rotation and linear movement of the spline (320) along the first shaft (330). [7] The variable compression ratio phaser (200) of claim 6, wherein the spline (320) is further configured such that linear movement of the spline (320) along the first shaft (330) adjusts the phase angle between the crankshaft gear (220) and the timing gear (230) to thereby increase or decrease the compression ratio of the engine (102). [8] The variable compression ratio phaser (200) of claim 7, wherein the torque converter mechanism further comprises a spring stack configured to be compressed by the spline (320). [9] A variable compression ratio phaser (200) according to claim 8, wherein, as the torque received by the control shaft gear (230) increases at higher loads, the spline (320) moves in a first direction with increased linear force and compresses the spring pack, the movement of the spline (320) in the first direction adjusting the phase angle to decrease the compression ratio. [10] A variable compression ratio phaser (200) as claimed in claim 9, wherein the spring stack expands and moves the spline (320) in a second direction opposite the first direction as the torque received by the control shaft gear (230) decreases at lower loads, the movement of the spline (320) in the second direction adjusting the phase angle to increase the compression ratio.

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