Camshaft adjuster
By designing a control valve with multiple switching positions, independently implementing the OPA and CTA adjustment principles, combining camshaft torque and hydraulic media, the problem of large energy and space consumption of camshaft regulators in the prior art is solved, and flexible adjustment mode switching and Efficient use of hydraulic media.
Patent Information
- Application Number
- CN202080069189.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2019-11-28
- Filing Date
- 2020-09-02
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2040-09-02
AI Technical Summary
When the camshaft regulator in the prior art combines the OPA and CTA adjustment principles, the ratio of the adjustment component is determined by the engine characteristics, resulting in large energy consumption and space occupancy, and limited adjustment speed.
An intelligent phaser camshaft regulator is designed. The OPA and CTA adjustment principles are independently implemented through multiple switching positions of the control valve, and the camshaft torque and hydraulic medium are used for adjustment. The adjustment mode is switched according to the PWM signal to ensure that the adjustment mode is different. Optimize the use of hydraulic media under conditions.
It realizes improving the adjustment speed and efficiency while reducing the use of hydraulic media, saving energy and space, and being able to flexibly switch adjustment modes at different operating points, avoiding the waste of energy and space in the prior art.
Smart Images
Figure CN114787483B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a vane-type hydraulic camshaft adjuster for a motor vehicle transmission system for adjusting the phase position of a camshaft relative to a crankshaft. The camshaft adjuster has a stator and a rotor, the stator being rotatably connected to the crankshaft, and the rotor being rotatably connected to the camshaft and preferably radially arranged in the stator so as to be able to rotate relative to the stator. The camshaft adjuster has a working chamber formed between the stator and the rotor, each of the working chambers being divided into two sub-chambers, also referred to as A chambers and B chambers, by radially protruding vanes of the rotor. The sub-chambers can be pressurized with a hydraulic medium to adjust the rotor relative to the stator. The sub-chambers act in opposite directions. This means that the rotor can be adjusted in a retarding direction relative to the stator by applying pressure to one sub-chamber, and can be adjusted in an advancing direction relative to the stator by applying pressure to another sub-chamber. When one sub-chamber is pressurized, the hydraulic medium is discharged from the other sub-chamber. The camshaft adjuster has a reservoir connected to the subchambers for storing hydraulic medium so that when a negative pressure exists in one of the subchambers, hydraulic medium is supplied from the reservoir to the subchamber. In each case, the reservoir is preferably connected to the subchamber via a non-return valve. Background Art
[0002] Such a vane-type camshaft adjuster is known in the context of the prior art. The alternating torque acting on the camshaft can be used to adjust the rotation angle of the camshaft, which is also referred to as camshaft torque actuation (CTA) adjustment. In this case, with the aid of the alternating torque acting on the camshaft, the hydraulic medium flows from one subchamber to the corresponding other subchamber via a bypass. Alternatively or additionally, an external hydraulic medium supply such as a pump can be used to adjust the rotation angle of the camshaft, which is also referred to as oil pressure actuation (OPA) adjustment. In this case, one subchamber is pressurized by the hydraulic medium supply, while the other subchamber is connected to a pressureless tank / reservoir for discharging the hydraulic medium.
[0003] The advantage of adjusting via the camshaft torque is that only a very small hydraulic medium flow is required, namely to compensate for the leakage between the subchamber and the camshaft adjuster. However, adjusting via the camshaft torque is only possible if the alternating torque acting on the camshaft is sufficiently large, because the adjustment speed that can be achieved is too low in the case of low alternating torques.
[0004] The advantage of adjusting via oil pressure is that the adjustment can be easily controlled even with small adjustment displacements at low adjustment speeds. However, a relatively large hydraulic medium flow is required, which must be supplied via an external hydraulic medium supply, which has a negative impact on the necessary installation space.
[0005] In order to avoid the disadvantages of both types of regulation (OPA and CTA), so-called smart phasers have been developed, the main advantage of which is that they combine the principles of OPA and CTA regulation in order to ensure a higher regulation speed with a reduced amount of hydraulic medium.
[0006] Such a camshaft adjuster is known, for example, from DE 10 2010 005 604 A1. The document discloses a pressure medium-actuated camshaft adjustment device for an internal combustion engine, the camshaft adjustment device having: at least two oppositely acting working chambers, a pressure medium pump, a pressure medium reservoir and a multi-way valve, the multi-way valve comprising: a housing having a number of openings assigned to the working chambers, the pressure medium pump and the pressure medium reservoir, through which the pressure medium is urged to flow in and / or out; a valve body, the valve body being guided in the housing so as to be able to shift between two end positions, and the valve body being able to prevent or allow the pressure medium to flow through the openings in the housing depending on the position of a control edge seated on the housing; and a double check valve, the double check valve arranged in the valve body allowing the pressure medium to flow in two different directions, wherein the control edge is arranged so that in the end position of the valve body, the double check valve urges the pressure medium to flow from the pressure medium pump to the first working chamber, and urges the pressure medium to flow from the second working chamber to the first working chamber, the second working chamber working in the opposite direction to the first working chamber.
[0007] However, the background of the prior art always has the following disadvantages: With previously known camshaft adjusters combining the OPA and CTA adjustment principles, the ratio between the OPA and CTA adjustment components is predetermined by the design of the camshaft adjuster and depends only on the characteristics of the engine in which the camshaft adjuster is installed, such as oil pressure and camshaft torque. This means that the OPA and CTA adjustment principles are partly dependent on the ratio of fuel to camshaft torque energy in one adjustment. In other words, even if the camshaft torque is large enough, even if the energy of the camshaft torque would be sufficient for adjustment, the hydraulic medium from the pump will act on the subchambers.
[0008] The object of the present invention is therefore to avoid or at least reduce the disadvantages of the prior art. In particular, a camshaft adjuster is provided which combines the advantages of two adjustment principles with one another in a particularly effective manner. In addition, the camshaft adjuster should be designed to save energy and space as much as possible. Summary of the invention
[0009] In a general arrangement, this object is achieved according to the invention in that the control valve has a (first) additional switching position in which a first of the two subchambers is connected to the tank and a second of the two subchambers is disconnected from the pump. In other words, this object is achieved according to the invention by means of a camshaft adjuster designed as a so-called smart phaser in which special valves are used in order to be able to implement the OPA and CTA control principles separately from each other / independently.
[0010] This is advantageous because the camshaft adjuster makes it possible to implement the adjustment using only the camshaft torque without the need for hydraulic medium to be supplied by a pump. On the other hand, if the operating point of the engine does not provide a sufficiently large camshaft torque for adjustment, such as in the case of cylinder deactivation, reduced valve lift, valve deactivation or load changes on the high-pressure pump, the OPA principle or a combination of the OPA and CTA principles can be used for adjustment.
[0011] Advantageous embodiments are claimed in the dependent claims and are explained below.
[0012] According to an advantageous further development, the control valve can have a (second) additional switching position in which the first subchamber is disconnected from the pump and the second subchamber is connected to the tank. This means that when the pump is blocked due to the two additional switching positions, both the A chamber and the B chamber can be emptied towards the tank. This enables pure CTA regulation on both sides.
[0013] According to a preferred embodiment, the control valve can be designed as a 4 / 5-way valve, which has an A connection connected to the first subchamber, a B connection connected to the second subchamber, a P connection connected to the pump and a T connection connected to the tank. This means that the control valve according to the invention has two additional switching positions compared to the previously used 4 / 3-way valves. In these two additional switching positions, the P connection / P opening is blocked, i.e. the oil supply from the pump to the valve piston of the control valve is blocked, and only the subchamber of reduced size, i.e. the depressurized subchamber, is connected to the tank.
[0014] According to a preferred embodiment, the control valve can have five switching positions, which can be switched according to a PWM signal from the control device. In other words, only the PWM signal determines whether the regulation is performed using the CTA regulation principle or a combination of the CTA and OPA regulation principles. This means that the control unit decides which regulation principle is used.
[0015] Preferably, in the first additional switching position and / or the second additional switching position, the pressurized hydraulic medium flow is blocked. It is particularly advantageous to achieve the same flow as in a known camshaft adjuster designed as an intelligent phaser in the other switching positions, ie the center position and the end positions.
[0016] According to a preferred embodiment, the control valve can have a valve sleeve and a piston which is arranged axially displaceable in the valve sleeve, wherein the piston comprises four webs, two webs being positioned centrally and two webs being positioned on the outside.
[0017] According to an advantageous refinement, the distance between two axially adjacent webs of the piston webs, in particular the distance between the two central webs, can be substantially as large as the opening of the valve sleeve connected to the pump, i.e. the P connection. Thus, the P connection can be closed as quickly as possible, so that a simple switch between the switching positions is facilitated.
[0018] Furthermore, it is advantageous if the width of the opening of the valve sleeve connected to the pump is substantially as large as the width of the overlap of the control edge of the piston with the opening of the valve sleeve connected to one of the two sub-chambers. This means that the P opening in the valve sleeve is substantially as large as the overlap of the control edge of the piston with the A opening or with the B opening. Thus, when the piston is moved from the adjustment position, the P opening can be quickly closed and the A opening or the B opening can be connected to the tank. In this way, emission control is achieved.
[0019] In a preferred embodiment, the camshaft adjuster can have a locking mechanism for locking the rotor relative to the stator, in particular in the center position, wherein the locking mechanism is unlocked in the end position of the control valve, in particular at a 100% PWM signal. Thus, starting from the center position can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The present invention will be described below with the aid of the accompanying drawings. In the accompanying drawings:
[0021] Figure 1 shows a schematic diagram of a camshaft adjuster according to the present invention in a first switching position,
[0022] Figure 2 shows a schematic diagram of the camshaft adjuster in the second switching position,
[0023] Figure 3 shows a schematic diagram of the camshaft adjuster in the third switching position,
[0024] Figure 4 shows a schematic diagram of a camshaft adjuster in a fourth switching position,
[0025] Figure 5A schematic diagram showing a camshaft adjuster in a fifth switching position, and
[0026] Figure 6 A graph showing the relationship between the hydraulic medium flow rate and the switching position is shown.
[0027] The drawings are merely schematic in nature and are only useful for understanding the present invention. Identical elements are provided with the same reference numerals. DETAILED DESCRIPTION
[0028] Figures 1 to 5 A camshaft adjuster 1 according to the invention is shown in a purely schematic manner. The camshaft adjuster 1 is a vane-type camshaft adjuster for a motor vehicle drive train. The camshaft adjuster 1 serves to adjust the phase position of a camshaft relative to a crankshaft. The camshaft adjuster 1 has a stator 2, which is rotatably coupled to the crankshaft, and a rotor 3, which is rotatably coupled to the camshaft. The rotor 3 is arranged to be rotatable within the stator 2. The stator 2 and the rotor 3 can rotate relative to each other within a limited angular range. The camshaft adjuster 1 has a working chamber 4 formed between the stator 2 and the rotor 3.
[0029] The working chambers 4 are each divided into two sub-chambers, also referred to as A-chambers and B-chambers, by radially protruding blades 5 of the rotor 3. The sub-chambers can be pressurized with a hydraulic medium in order to adjust the rotor 3 relative to the stator 2. The sub-chambers each act in opposite directions. This means that the rotor 3 can be adjusted in a retarding direction relative to the stator 2 by applying pressure to one sub-chamber, for example, the A-chamber, and can be adjusted in an advancing direction relative to the stator by applying pressure to another sub-chamber, for example, the B-chamber. When one sub-chamber is pressurized, the hydraulic medium is discharged from the other sub-chamber.
[0030] The camshaft adjuster 1 has a reservoir 6 connected to the subchambers for storing a hydraulic medium, so that when an underpressure is present in one of the subchambers, hydraulic medium is supplied from the reservoir 6 to the subchamber.
[0031] The camshaft adjuster 1 has a control valve 7 for controlling the flow of hydraulic medium. Depending on the switching position of the control valve 7, the A chamber and the B chamber can be connected to a pump 8 or a tank 9. The reservoir 6 is connected to the tank 9 so that excess hydraulic medium can be discharged. The reservoir 6 is connected to the A chamber and to the B chamber via a check valve 10.
[0032] The reservoir 6 is supplied with hydraulic medium via a control valve 7. According to the invention, the control valve 7 has a switching position in which a first of the two subchambers is connected to the tank 9 and a second of the two subchambers is disconnected from the pump 8. According to a preferred embodiment, the control valve 7 also has a switching position in which the second subchamber is connected to the tank 9 and the first subchamber is disconnected from the pump 8. According to the invention, there are thus two additional switching positions in the control valve 7 in which the pump 8 is blocked and a communication is established between the tank 9 and the subchamber to be depressurized.
[0033] The control valve 7 is designed as a 4 / 5-way valve 11. The control valve 7 has an A connection connected to the A chamber, a B connection connected to the B chamber, a P connection connected to the pump 8, and a T connection connected to the tank 9. The control valve 7 is controlled between five switching positions by a PWM signal.
[0034] Figure 1 The camshaft adjuster 1 is shown in a first switching position of the control valve 7. In the first switching position, the pump 8 is connected to the B chamber and the A chamber is connected to the tank 9. In the first switching position, the camshaft adjuster is in an intelligent operating mode, in which regulation is performed via a combination of camshaft torque (CTA principle) and hydraulic medium pressure (OPA principle). The PWM signal is 0%.
[0035] Figure 2 The camshaft adjuster 1 is shown in the second switching position of the control valve 7. In the second switching position, the P connection and the B connection are blocked and the A chamber is connected to the tank 9. In the second switching position, the camshaft adjuster 1 is in a pure CTA operating mode, wherein regulation is performed only via the camshaft torque. The PWM signal is 25%.
[0036] Figure 3 The camshaft adjuster 1 is shown in the third switching position of the control valve 7. In the third switching position, a center position compensation is performed. This allows the leakage of the camshaft adjuster 1 to be compensated. This means that the connection between the pump 8 and the A chamber and the connection between the pump 8 and the B chamber are slightly opened. Therefore, the connection between the A chamber and the tank 9 and the connection between the B chamber and the tank 9 are blocked. In the third switching position, the camshaft adjuster 1 is in the regulating operating mode. The PWM signal is 50%.
[0037] Figure 4 The camshaft adjuster 1 is shown in the fourth switching position of the control valve 7. In the fourth switching position, the P connection and the A connection are blocked and the B chamber is connected to the tank 9. In the fourth switching position, the camshaft adjuster 1 is in a pure CTA operating mode, in which regulation is carried out only by the camshaft torque. The PWM signal is 75%.
[0038] Figure 5 The camshaft adjuster 1 is shown in the fifth switching position of the control valve 7. In the fifth switching position, the pump 8 is connected to the A chamber and the B chamber is connected to the tank 9. In the fifth switching position, the camshaft adjuster is in the smart operating mode, in which the combination of the camshaft torque (CTA principle) and the hydraulic medium pressure (OPA principle) is used for regulation. The PWM signal is 100%.
[0039] To unlock the camshaft adjuster 1, the PWM signal should be set to 100%. The control valve 7 is then in the end position, which is the fifth switching position. The A chamber is then connected to the P opening and unlocking is performed.
[0040] exist Figures 1 to 5 , a control valve 7 is schematically shown. The control valve 7 has a valve sleeve and a valve piston / piston 12, which is arranged to be displaceable in the valve sleeve. The piston 12 is designed to enable emission control. The valve sleeve has a P opening connected to the pump 8, the P opening forming a P connection. The valve sleeve has a T opening connected to the tank 9, the T opening forming a T connection. The valve sleeve has an A opening connected to the A chamber, the A opening forming an A connection. The valve sleeve has a B opening connected to the B chamber, the B opening forming a B connection.
[0041] The piston 12 has four webs 13. In the first switching position, the B opening is arranged between the first outer web 14 and the first central web 15, the P opening is arranged between the second central web 16 and the second outer web 17, and the A opening is arranged away from the second outer web 17. The distance between the first central web 15 and the second central web 16 corresponds essentially to the width of the P opening. The width of the P opening corresponds essentially to the width of the overlapping part of the control edge of the piston 12 formed by the outer webs 14, 17 and the A opening or with the B opening. Therefore, before the A connection or the B connection (depending on the direction of adjustment) is connected to the tank 9 or the reservoir 6, the P connection is closed. Therefore, when switching from the adjustment state (50%) to 25% or 75%, the P opening can be blocked by the piston 12 and the A opening or the B opening can be opened.
[0042] Figure 6 The flow 18 of the camshaft adjuster 1 according to the invention is shown in comparison with the flow 19 of a known (intelligent phaser) camshaft adjuster. In the first, third and fifth switching positions, the flows 18, 19 are equal. In the second and fourth switching positions, the pump 8 is blocked, so that the flow 18 of the camshaft adjuster 1 is equal to zero.
[0043] Description of Reference Numerals
[0044] 1 Camshaft adjuster 2 Stator 3 Rotor 4 Working chamber 5 Vane 6 Reservoir 7 Control valve 8 Pump 9 Tank 10 Check valve 11 4 / 5-way valve 12 Piston 13 Web 14 First outer web 15 First central web 16 Second central web 17 Second outer web 18 Flow rate 19 Flow rate
Claims
1. A vane-type camshaft adjuster (1) for a motor vehicle drive train, the camshaft adjuster comprising: Stator (2); a rotor (3) arranged so that the rotor can rotate relative to the stator (2); A working chamber (4) is formed between the stator (2) and the rotor (3) and each working chamber is divided into two sub-chambers by radially protruding blades (5) of the rotor (3); and a reservoir (6) for storing a hydraulic medium, the reservoir being connected to the sub-chambers so that, in the event of a negative pressure in one of the sub-chambers, the sub-chamber is supplied with hydraulic medium from the reservoir (6) in order to adjust the rotor (3) relative to the stator (2), wherein the sub-chambers can be adjusted according to the camshaft adjuster (1). The invention relates to a control valve (7) connected to a pump (8) or a tank (9) by changing the switching position of the control valve (7), characterized in that the control valve (7) has a first additional switching position, in which the first sub-chamber of the two sub-chambers is connected to the tank (9) and the hydraulic medium is discharged from the first sub-chamber to the tank (9), and the second sub-chamber of the two sub-chambers is separated from the pump (8), and the control valve (7) has a second additional switching position, in which the first sub-chamber is separated from the pump (8) and the second sub-chamber is connected to the tank (9).
2. The camshaft adjuster (1) according to claim 1, characterized in that The control valve (7) is designed as a five-position four-way valve (11), and has an A connection connected to the first sub-chamber, a B connection connected to the second sub-chamber, a P connection connected to the pump (8), and a T connection connected to the tank (9).
3. The camshaft adjuster (1) according to claim 2, characterized in that The control valve (7) has five switching positions, and the five switching positions can be switched according to a PWM signal.
4. The camshaft adjuster (1) according to claim 1, characterized in that In the first additional shift position and / or in the second additional shift position, a flow of pressurized hydraulic medium is blocked.
5. The camshaft adjuster (1) according to claim 1, characterized in that The control valve (7) comprises a valve sleeve and a piston (12) which is arranged to be axially displaceable in the valve sleeve, wherein the piston (12) comprises four webs (13).
6. The camshaft adjuster (1) according to claim 5, characterized in that The distance between two axially adjacent webs (15, 16) of the webs (13) of the piston (12) is as large as the opening of the valve sleeve connected to the pump (8).
7. The camshaft adjuster (1) according to claim 5 or 6, characterized in that The width of the opening of the valve sleeve connected to the pump (8) is as large as the width of the overlapping portion of the control edge of the piston (12) and the opening of the valve sleeve connected to one of the two sub-chambers.
8. The camshaft adjuster (1) according to claim 1, characterized in that The camshaft adjuster (1) has a locking mechanism for locking the rotor (3) relative to the stator (2), wherein the locking mechanism is unlocked in an end position of the control valve (7).