Variable cam timing phaser

Abstract

A variable cam timing phaser includes a housing disposed about an axis and having an inner housing surface defining an interior of the housing. The variable cam timing phaser includes a rotor movable between an advance position and a retard position. The rotor includes a hub portion and a vane, wherein the rotor and the housing define a chamber. The vane further defines the chamber into an advance chamber and a retard chamber. The variable cam timing phaser further includes a control valve assembly including a valve housing and a control piston. The variable cam timing phaser further includes a chamber biasing assembly disposed in one of the advance chamber and the retard chamber and configured to bias the rotor into a predetermined position between the advance position and the retard position. The chamber biasing assembly includes a chamber piston, a chamber biasing member, and a chamber check valve.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims priority and all benefits to U.S. Provisional Patent Application No. 63 / 309,315, filed on February 11, 2022, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates generally to a variable cam timing phaser, and more specifically, to a variable cam timing phaser for a variable cam timing system. Background Technology

[0004] A conventional variable cam timing system includes a camshaft and a variable cam timing phaser. The variable cam timing phaser includes a housing, a rotor, and a control valve assembly. The conventional control valve assembly includes a valve housing and a piston. The valve housing can engage with the camshaft to secure it to the camshaft or to secure the variable cam timing phaser to the camshaft. The piston is disposed within the valve housing to control the flow of hydraulic fluid, causing the rotor to rotate about the housing to adjust the camshaft timing.

[0005] In recent years, there has been an increasing demand for vehicles with internal combustion engines that reduce emissions, particularly during engine start-up. Therefore, there remains a need for variable camshaft timing phasers and variable camshaft timing systems that incorporate them, which reduce emissions during engine start-up. Summary of the Invention

[0006] A variable cam timing phaser for a variable cam timing system including a camshaft includes a housing disposed about an axis and having an inner housing surface defining the interior of the housing. The variable cam timing phaser includes a rotor at least partially disposed within the housing and movable about the housing between an advance position and a retard position different from the advance position. The rotor includes a hub and blades extending from the hub away from the axis toward the inner housing surface, wherein the rotor and housing define a chamber capable of being filled with hydraulic fluid to rotate the rotor about the axis about the housing between the advance and retard positions. The blades are disposed in the chamber and further define the chamber as an advance chamber and a retard chamber. The variable cam timing phaser also includes a control valve assembly including a valve housing defining the interior of a valve housing and a control piston disposed within the valve housing and movable about the valve housing between at least a first position and a second position to control the flow of hydraulic fluid through the interior of the valve housing. The variable cam timing phaser also includes a chamber biasing assembly disposed in one of the advance and retard chambers and configured to bias the rotor to a predetermined position between the advance and retard positions. The chamber biasing assembly includes a chamber piston, a chamber biasing member, and a chamber check valve.

[0007] Therefore, the variable cam timing phaser, including the chamber bias assembly, helps reduce emissions during the start-up of an internal combustion engine. Attached Figure Description

[0008] Other advantages of the invention will become readily apparent when considered in conjunction with the accompanying drawings and with reference to the following detailed description. This patent or application contains at least one figure executed in color. Copies of this patent or patent application disclosure having one or more color figures will be provided by the office upon request and payment of the necessary fees.

[0009] Figure 1 It is a cross-sectional view of a variable cam timing phaser including the housing, rotor, and chamber biasing assembly;

[0010] Figure 2 It is a cross-sectional view of a variable cam timing system including a camshaft and a variable cam timing phaser including a control valve assembly;

[0011] Figure 3 This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0012] Figure 4 This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0013] Figure 5 yes Figure 3 A cross-sectional view of another embodiment of the variable cam timing phaser, including another embodiment of the chamber bias assembly and the second chamber bias assembly, and illustrating the rotor holding position;

[0014] Figure 6 yes Figure 3 A cross-sectional view of a variable cam timing phaser, in which the rotor moves toward an advanced position;

[0015] Figure 7 yes Figure 3 A cross-sectional view of a variable cam timing phaser, in which the rotor moves toward the retarded position;

[0016] Figure 8A This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0017] Figure 8B yes Figure 8A A cross-sectional view of the variable cam timing phaser, with the rotor in the advanced position at the middle position;

[0018] Figure 8C yes Figure 8A A cross-sectional view of the variable cam timing phaser, with the rotor in a delayed position at the middle position;

[0019] Figure 9 This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0020] Figure 10 This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0021] Figure 11 This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0022] Figure 12 This is a cross-sectional view of another embodiment of the variable cam timing phaser;

[0023] Figure 13 This is a cross-sectional view of another embodiment of the variable cam timing phaser. Detailed Implementation

[0024] Referring to the accompanying drawings, in which the same reference numerals indicate the same parts throughout several views, the variable cam timing phaser 30 of the variable cam timing system 32 is... Figure 1 and Figure 2 The overall view is shown in the middle. The variable cam timing system 32 includes a camshaft 34. The variable cam timing phaser 30 includes a housing 36 disposed about axis A and has an inner housing surface 40 defining the interior 42 of the housing.

[0025] The variable cam timing phaser 30 also includes a rotor 44, which is at least partially disposed within a housing 42 and is movable about the housing 36 between an advance position and a retard position. The rotor 44 includes a hub 46 and blades 48 extending from the hub 46 away from axis A toward the inner housing surface 40. The rotor 44 and housing 36 define a chamber 50 that can be filled with hydraulic fluid to rotate the rotor 44 about axis A about the housing 36 between the advance and retard positions. The blades 48 are disposed in the chamber 50 and further define the chamber 50 as an advance chamber 52 and a retard chamber 54. It should be understood that the blades 48 can separate the advance chamber 52 and the retard chamber 54 from each other to prevent hydraulic fluid from flowing directly between the advance chamber 52 and the retard chamber 54. It should also be understood that the blades 48 can allow some hydraulic fluid to flow directly between the advance chamber 52 and the retard chamber 54.

[0026] Special Reference Figure 2The variable cam timing phaser 30 also includes a control valve assembly 56. The control valve assembly 56 includes a valve housing 58 extending along axis A and defining a valve housing interior 60. The control valve assembly 56 further includes a control piston 62 disposed within the valve housing interior 60 and movable along axis A about the valve housing 58 between at least a first position and a second position to control the flow of hydraulic fluid through the valve housing interior 60. The first position of the control piston 62 may be referred to as an advance position, corresponding to an advance position of the rotor 44, and the second position of the control piston 62 may be referred to as a retarded position, corresponding to a retarded position of the rotor 44. The control piston 62 may have other positions, such as a zero position between the advance and retarded positions, and a full-out position. The full-out position typically corresponds to a predetermined position of the rotor 44. It should be understood that the control piston 62 may also have any number of defined positions. Typically, the first position of the control piston 62 corresponds to the advance position of the rotor 44, and the second position of the control piston 62 corresponds to the retarded position of the rotor 44. The control valve assembly 56 may also include a control sleeve 64 disposed within the valve housing 60 and surrounding the control piston 62.

[0027] The valve housing 58 of the control valve assembly 56 may extend along axis A and through rotor 44, such that the valve housing 58 is configured to couple to camshaft 34. The valve housing 58 may be configured to couple the variable cam timing phaser 30 to a center bolt on the camshaft 34. The valve housing 58 may be pressed onto or coupled to rotor 44. The valve housing 58 may be disposed outside rotor 44, for example, remotely mounted to the engine.

[0028] refer to Figure 1 and Figure 3-13The variable camshaft timing phaser 30 further includes a chamber biasing assembly 66 disposed in one of the advance chamber 52 and the retard chamber 54. The chamber biasing assembly 66 is configured to bias the rotor 44 to a predetermined position between the advance and retard positions. Specifically, when hydraulic pressure is not applied to the hydraulic fluid in the variable camshaft timing phaser 30 (e.g., when the vehicle's internal combustion engine is shut down), the chamber biasing assembly 66 biases the rotor 44 to a predetermined position relative to the housing 36 between the advance and retard positions. The predetermined position in which the rotor 44 is positioned is a function of the biasing torque applied by the chamber biasing assembly 66. The predetermined position of the rotor 44 can be determined based on any number of factors, such as positioning the rotor 44 relative to the housing 36 to reduce emissions during camshaft 34 rocking and internal combustion engine starting, as may be required by an engine calibrator. Because the chamber biasing assembly 66 allows camshaft phase adjustment during engine rocking, emissions can be reduced. Furthermore, the chamber bias assembly 66 improves the actuation speed at cold temperatures and can also provide an intermediate position stop function. Typically, the chamber bias assembly 66 is configured to bias the blade 48 about axis A, which in turn biases the rotor 44 about axis A. It should be understood that the blade 48 can be integrated with the rotor 44 (i.e., a single piece), or the blade 48 can be a separate component from the rotor 44 (i.e., two pieces).

[0029] The chamber biasing assembly 66 includes a chamber piston 68, a chamber biasing member 70 (such as a spring), and a chamber check valve 86. The chamber check valve can be a ball, disc, flapper, strap, etc. In some embodiments, the chamber piston 68 can define a chamber piston interior 72, such as... Figure 1 , Figure 4 , Figures 8A-8C , Figure 10 as well as Figure 11-13 As shown in Figure 8, the chamber biasing member 70 is disposed within the chamber piston 72. The chamber piston 68 can be cylindrical, circular, rectangular, or have any other suitable configuration. As shown in Figure 8, the chamber piston 68 can define a chamber annular portion 106, such as... Figure 8B As shown, it is configured to selectively fluid couple to stop line D1.

[0030] The chamber piston 68 may be able to engage with the inner housing surface 40. The inner housing surface 40 may have a curved configuration with respect to the blade 48. In other embodiments, the chamber piston 68 may be able to engage with the blade 48. It should be understood that the inner housing surface 40 may have any suitable profile. For example, the inner housing surface 40 may have a constant radius, or the inner housing surface 40 may have a variable profile, such as... Figure 12 and Figure 13As shown in the diagram, the outer piston surface 110 of the chamber piston 68 can cooperate with the inner contour of the inner housing surface 40, thereby optimizing the contact surface area between the chamber piston 68 and the inner housing surface.

[0031] refer to Figure 1 and Figure 3-13 The variable cam timing phaser 30 may include a second chamber biasing assembly 74 disposed in the chamber 50, wherein the second chamber biasing assembly 74 includes a second chamber piston 68, a second chamber biasing member 96, and a second chamber check valve 88. Figure 8A As shown in -C, the second chamber piston 68 can define the second chamber annular portion 108, such as Figure 8C As shown, it is configured to selectively fluid couple to stop line D2. When in Figure 8A When the rotor 44 is in the position shown, the rotor 44 is in the middle position, wherein the annular portion 106 of the chamber and the annular portion 108 of the second chamber are blocked from the stop lines D1 and D2, respectively.

[0032] A chamber biasing assembly 66 may be disposed in the advance chamber 52 and a second chamber biasing assembly 74 may be disposed in the retardation chamber 54. In this embodiment, the chamber biasing assembly 66 and the second chamber biasing assembly 74 are configured to bias the rotor 44 into a predetermined position between the advance chamber 52 and the retardation chamber 54. Typically, the chamber biasing assembly 66 and the second chamber biasing assembly 74 bias the rotor 44 in opposite directions (i.e., opposite to each other) about axis A. The predetermined position in which the rotor 44 is positioned is a function of the balance of biasing torques between the chamber biasing assembly 66 and the second chamber biasing assembly 74. In other words, the chamber biasing assembly 66 is configured to provide a first force to the rotor 44 to bias the rotor 44 to rotate about axis A, and the second chamber biasing assembly 74 provides a second force to the rotor 44 opposite to the first force to bias the rotor 44 to rotate about axis A. The first force and the second force may be equal to each other, such that the rotor 44 is biased into an intermediate position. It should be understood that if only the chamber biasing component 66 is present, the rotor 44 will be positioned at a predetermined location at the earlier or later stop. The first force and the second force can be different from each other, such that the rotor 44 is biased to a more earlier or later predetermined position. The first force and the second force can be adjusted based on the desired predetermined position of the rotor 44. For example, the sweep volume and radius of the chamber piston 68 and the second chamber piston 94 can be adjusted, the biasing strength of the chamber biasing component 70 and the second chamber biasing component 96 can be adjusted, and / or the strength of the chamber check valve 86 and the second chamber check valve 88 can be adjusted.

[0033] The rotor 44 may have a second blade 76 extending from the hub 46 away from axis A toward the inner housing surface 40. In this embodiment, the rotor 44 and housing 36 define a second chamber 78, which can be filled with hydraulic fluid to rotate the rotor 44 about axis A about the housing 36 between an advanced position and a retarded position. The second blade 76 is disposed in the second chamber 78 and further defines the second chamber 78 as a second advanced chamber 80 and a second retarded chamber 82. Figure 1 , Figure 4 , Figure 10 as well as Figure 11 As shown, a second chamber biasing assembly 74 may be disposed in a second chamber 78, wherein the second chamber biasing assembly 74 is configured to bias the rotor 44 to a predetermined position between the advance chamber 52 and the retard chamber 54. The chamber biasing assembly 66 and the second chamber biasing assembly 74 are typically adjusted such that the chamber biasing assembly 66 and the second chamber biasing assembly 74 bias the rotor 44 to the predetermined position.

[0034] Due to the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74, the variable cam timing phaser 30 can eliminate the need for a locking pin to lock the rotor 44 relative to the housing 36. Specifically, because the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74 bias the rotor 44 into a predetermined position, the biasing force provided by the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74 can be adjusted so that the rotor 44 is fixed in the predetermined position without the use of a locking pin, especially when the internal combustion engine is shut down. When the variable cam timing phaser 30 eliminates the locking pin, it does not have the problems faced by variable cam timing phasers that include a locking pin. Specifically, when a variable cam timing phaser includes a locking pin, sometimes the locking pin cannot be unlocked when the engine oil pressure is low or unavailable. Eliminating the possibility that the locking pin cannot be unlocked allows the rotor 44 to move relative to the housing 36 as soon as it is commanded during engine cranking, without delay. The hydraulic preventer of the variable camshaft timing phaser 32, coupled to the camshaft spring of the camshaft 34, loads the first and second chambers 50, 78 and prevents oil leakage from the first and second chambers 50, 78 after the engine is stopped. Oil leakage from the chambers of the variable camshaft timing phaser, including the locking pin, is a problem faced by conventional VCT designs (which have attempted to overcome the aforementioned unlocking problem by simply eliminating the locking pin). Removing the load on the hydraulic chambers after the engine is stopped reduces oil leakage from the variable camshaft timing phaser 30, allowing the variable camshaft timing phaser 30 to remain full of oil. By doing so, the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74 automatically correct the cam position offset after the engine is stopped to hold the rotor 44 in a predetermined position relative to the housing 36, which eliminates the need for alternative correction measures (such as the ECU) for positioning the rotor 44.

[0035] Similarly, due to the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74, the variable cam timing phaser 30 can eliminate the need for a torsion spring to bias the rotor 44 relative to the housing 36. Specifically, since the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74 bias the rotor 44 into a predetermined position, the biasing force provided from the chamber biasing assembly 66 and (when present) the second chamber biasing assembly 74 can be adjusted so that the rotor 44 is fixed in the predetermined position without the use of a torsion spring, especially when the internal combustion engine is turned off.

[0036] Typically (when present), chamber biasing assembly 66 and second chamber biasing assembly 74 are opposite to each other. Specifically, chamber biasing assembly 66 can bias rotor 44 clockwise about axis A toward an advanced position, and second chamber biasing assembly 74 can bias rotor 44 counterclockwise about axis A toward a delayed position, or vice versa.

[0037] As mentioned above, such as Figure 3 and Figure 5-9 As shown, chamber biasing members 66 and 74 can both be installed in the same chamber (i.e., chamber 50), or as... Figure 1 , Figure 4 , Figure 10-13 As shown, they can each be placed in separate chambers (i.e., chamber 50 and the second chamber 78) for better packability of chamber biasing members 66, 74.

[0038] In one embodiment, such as Figure 1 , Figure 3-8C ,as well as Figure 11-13 As shown, blade 48 defines a blade orifice 90, in which a chamber piston 68, a chamber biasing member 70, and a chamber check valve 86 are disposed. In such an embodiment, the chamber piston 68 and the chamber check valve 86 serve as a pressure chamber 112 in the blade orifice 90. Furthermore, in such an embodiment (when present), a second blade 76 may define a second blade orifice 98, in which a second chamber piston 94, a second chamber biasing member 96, and a second chamber check valve 88 are disposed. The second chamber piston 94 and the second chamber check valve 88 form a second pressure chamber 114 in the second blade orifice 98. In such an embodiment, the chamber piston 68 and the second chamber piston 94 are respectively biased outward against the inner housing surface 40 by the chamber biasing members 70 and 96, such that the chamber piston 68 and the second chamber piston 94 can move within the blade orifice 90 and the second blade orifice 98, respectively. The chamber piston 68 forms a pressure chamber defined by the chamber piston 68, the vane orifice 90, and the chamber check valve 86 located at the bottom of the vane orifice 90. Similarly, the second chamber piston 94 forms a pressure chamber defined by the second chamber piston 94, the second vane orifice 98, and the second chamber check valve 88.

[0039] like Figure 9 and Figure 10 As shown, housing 36 defines housing bore 92, in which chamber piston 68, chamber biasing member 70, and chamber check valve 86 are disposed. In such an embodiment, chamber piston 68 and chamber check valve 86 form a pressure chamber 112 in housing bore 92. Figure 10 As shown, the chamber biasing member 70 can be disposed inside the chamber piston 72. The chamber piston 68 can move within the housing bore 68.

[0040] refer to Figure 9 and Figure 10The housing 36 may define a second housing bore 100, wherein a second chamber piston 94, a second chamber biasing member 96, and a second chamber check valve 88 are disposed in the second housing bore 100, wherein the second chamber piston 94 and the second chamber check valve 88 form a second pressure chamber 114 in the second housing bore 100. In such an embodiment, the housing bore 92 and the second housing bore 100 may be adjacent to the chamber 50, and subsequently, as Figure 9 As shown, the advance chamber 52 and the retardation chamber 54 may be adjacent to chamber 50, respectively, or housing aperture 92 may be adjacent to chamber 80, and the second housing aperture 100 may be adjacent to the second chamber 80, as shown. Figure 10 As shown in the image.

[0041] Chamber 50 can create a fluid reservoir from which chamber piston 68 and second chamber piston 94 can draw hydraulic fluid. Furthermore, chambers 50 and 78 can be configured to fluidly couple to form a fluid reservoir when control piston 62 is in a predetermined position (such as the full-out position), such that chamber piston 68 and second chamber piston 94 are configured to draw hydraulic fluid from the fluid reservoir. Pressure chambers 112 and 114 can draw hydraulic fluid from the reservoir as needed during pumping at cam torque pulses. Once the chamber pistons are fully pumped up (i.e., the pressure chambers are full of hydraulic fluid), hydraulic adjustment of chamber biasing assemblies 66 and 74 relative to each other biases rotor 44 into a predetermined position. As a function of the axial position of control piston 62, the pressure chambers of chamber biasing assemblies 66 and 74 can hydraulically contract by ventilating chamber biasing assemblies 66 and 74 via control valve assembly 56. Rotor 44 may define a face passage and be used to fluidly connect the pressure chamber port to control valve assembly 56. On either side of a predetermined position of rotor 44, one of the chamber piston 68 and the second chamber piston 94 retracts, returning rotor 44 to the predetermined position. The retraction of either chamber piston 68 or the second chamber piston 94 determines whether rotor 44 moves in an advance direction, a retard direction, or remains in another position (such as the predetermined position). Furthermore, the variable cam timing phaser 30 may include a stop line that adds robustness to the predetermined position of rotor 44 during engine rocking. When present, the face passage and bore in rotor 44 fluidly connect the stop port to control valve assembly 56. For controlling the flow of hydraulic fluid, chamber piston 68 may have a first engagement portion 102 and a second engagement portion 104. The first and second engagement portions 102, 104 may be of the same size (i.e., of the same length), such as... Figure 1 As shown in Figure 8, the first engagement portion 102 may be larger (i.e., longer) than the second engagement portion 104, or vice versa.

[0042] By actuating the rotor 44 of the variable cam timing phaser 30 through the pumping operation of chamber piston 68 and second chamber piston 94, the total swept oil volume of the variable cam timing phaser 30 can be reduced, which is beneficial for cold performance. Furthermore, the pumping operation of chamber piston 68 and second chamber piston 94 (which inherently increases at cold temperatures) provides a reduced response time during cold-temperature actuation of the rotor 44. Specifically, when the engine oil supply pressure is low due to one or more chamber biasing members, the variable cam timing phaser 30 can change the phase of the rotor 44 during engine idling (before engine start), which improves the speed of phase adjustment, especially at colder temperatures.

[0043] For particular engine applications where the cam torque energy may be insufficient to power the chamber piston, the variable cam timing phaser 30 may include additional hydraulic chambers, such as a torsion assist chamber or a hydraulic actuation chamber, which eliminate the need for chamber biasing components to supplement the chamber(s) including the chamber biasing component. The hydraulic chambers eliminating the chamber biasing component (when present) function independently, but act synchronously with the chamber(s) including the chamber biasing component when the rotor 44 is phase-adjusted or held. For example, when the control piston 62 is in the zero position, all chambers of the variable cam timing phaser 30 hold the camshaft in position, and on either side of the zero position (i.e., when the control piston 62 moves axially from the zero position), all chambers of the variable cam timing phaser 30 operate to move the camshaft toward an advance or retarded position. When the control piston 62 is fully extended, for example, when the engine is stopped, the advance and retarded sides connect to each other and to the piston reservoir for the pressure chambers of the chamber biasing component. This allows the hydraulic chambers without chamber biasing components to not bear any cam load and not leak their respective chamber oil during free-rotation shutdown. This allows the camshaft position to shift after shutdown. This also maintains the oil in the variable cam timing phaser 30. Furthermore, by connecting the hydraulic chambers without chamber biasing components to the chamber (i.e., chamber 50), the hydraulic chambers without chamber biasing components can replenish reservoir capacity at startup for piston pump-start operation until the oil supply pressure can be restored to the variable cam timing phaser 30. Additionally, when the control piston 62 is in the full-out position, (if present) the stop circuit is also activated, and the intermediate-position stop circuit can, once rocking begins, robustly self-correct any possible shift in the cam position after shutdown by utilizing the pumping operation of the chamber piston to move the rotor 44 to the predetermined position.

Claims

1. A variable cam timing phaser for a variable cam timing system including a camshaft, the variable cam timing phaser comprising: A housing, which is arranged about an axis and has an inner housing surface that defines the interior of the housing; A rotor, at least partially disposed within the housing and movable about the housing between an advanced position and a delayed position different from the advanced position, wherein the rotor includes a hub and blades extending from the hub away from the axis toward a surface of the inner housing, wherein the rotor and the housing define a chamber capable of being filled with hydraulic fluid to cause the rotor to rotate about the axis about the housing between the advanced position and the delayed position, and wherein the blades are disposed in the chamber and further define the chamber as an advanced chamber and a delayed chamber; Control valve assembly, including, Valve housing, which defines the interior of the valve housing, and A control piston is disposed inside the valve housing and is movable about the valve housing between at least a first position and a second position to control the flow of hydraulic fluid through the valve housing. as well as A chamber biasing assembly is disposed in one of the advance chamber and the retard chamber, and configured to bias the rotor to a predetermined position between the advance position and the retard position; The chamber biasing assembly includes a chamber piston, a chamber biasing member, and a chamber check valve; and The rotor has a second blade extending from the hub away from the axis toward the surface of the inner housing, wherein the rotor and the housing define a second chamber capable of being filled with hydraulic fluid to rotate the rotor about the axis between the advanced and retarded positions about the housing, and wherein the second blade is disposed in the second chamber and further defines the second chamber as a second advanced chamber and a second retarded chamber. It further includes a second chamber biasing assembly, the second chamber biasing assembly including a second chamber piston, a second chamber biasing member, and a second chamber check valve disposed in the second chamber, wherein the chamber biasing assembly and the second chamber biasing assembly are opposite to each other.

2. The variable cam timing phaser of claim 1, wherein the blade defines a blade orifice, wherein the chamber piston, the chamber biasing member, and the chamber check valve are disposed in the blade orifice, and wherein the chamber piston and the chamber check valve form a pressure chamber in the blade orifice.

3. The variable cam timing phaser according to claim 1, wherein the housing defines a housing bore, wherein the chamber piston, the chamber biasing member, and the chamber check valve are disposed in the housing bore.

4. The variable cam timing phaser of claim 2, wherein the second blade defines a second blade orifice, wherein the chamber piston, the chamber biasing member, and the chamber check valve are disposed in the blade orifice, wherein the second chamber piston, the second chamber biasing member, and the second chamber check valve are disposed in the second blade orifice, wherein the chamber piston and the chamber check valve form a pressure chamber in the blade orifice, and wherein the second chamber piston and the second chamber check valve form a second pressure chamber in the second blade orifice.

5. The variable cam timing phaser of claim 3, wherein the housing defines a second housing bore, wherein the chamber piston, the chamber biasing member, and the chamber check valve are disposed in the housing bore, wherein the second chamber piston, the second chamber biasing member, and the second chamber check valve are disposed in the second housing bore, wherein the chamber piston and the chamber check valve form a pressure chamber in the housing bore, and wherein the second chamber piston and the second chamber check valve form a second pressure chamber in the second housing bore.

6. The variable cam timing phaser of claim 1, wherein the chamber and the second chamber are configured to be fluidly coupled to each other to form a fluid reservoir when the control piston is in a predetermined position, such that the chamber piston and the second chamber piston are configured to draw hydraulic fluid from the fluid reservoir.

7. The variable cam timing phaser according to any one of claims 1-3, wherein the chamber piston defines a first engagement portion and a second engagement portion, wherein the length of the first engagement portion is greater than the length of the second engagement portion.

8. The variable cam timing phaser according to any one of claims 1-3, wherein the valve housing of the control valve assembly extends along the axis and through the rotor such that the valve housing is configured to be coupled to the camshaft.

9. The variable cam timing phaser according to any one of claims 1-3, wherein the valve housing is disposed outside the rotor.

10. A variable cam timing phaser for a variable cam timing system including a camshaft, the variable cam timing phaser comprising: A housing, which is arranged about an axis and has an inner housing surface that defines the interior of the housing; A rotor, at least partially disposed within the housing and movable about the housing between an advanced position and a delayed position different from the advanced position, wherein the rotor includes a hub and blades extending from the hub away from the axis toward a surface of the inner housing, wherein the rotor and the housing define a chamber capable of being filled with hydraulic fluid to cause the rotor to rotate about the axis about the housing between the advanced position and the delayed position, and wherein the blades are disposed in the chamber and further define the chamber as an advanced chamber and a delayed chamber; Control valve assembly, including, Valve housing, which defines the interior of the valve housing, and A control piston is disposed inside the valve housing and is movable about the valve housing between at least a first position and a second position to control the flow of hydraulic fluid through the valve housing. as well as A chamber biasing assembly is disposed in one of the advance chamber and the retard chamber, and configured to bias the rotor to a predetermined position between the advance position and the retard position; The chamber biasing assembly includes a chamber piston, a chamber biasing member, and a chamber check valve; and The chamber biasing assembly is disposed in the advance chamber, and further includes a second chamber biasing assembly disposed in the retardation chamber, wherein the second chamber biasing assembly includes a second chamber piston, a second chamber biasing member, and a second chamber check valve, and wherein the chamber biasing assembly and the second chamber biasing assembly are opposite to each other.

11. The variable cam timing phaser of claim 10, wherein the blade defines a blade orifice, wherein the chamber piston, the chamber biasing member, and the chamber check valve are disposed in the blade orifice, wherein the rotor has a second blade extending from the hub away from the axis toward the inner housing surface, wherein the second blade defines a second blade orifice, wherein the second chamber piston, the second chamber biasing member, and the second chamber check valve are disposed in the second blade orifice, wherein the chamber piston and the chamber check valve form a pressure chamber in the blade orifice, and wherein the second chamber piston and the second chamber check valve form a second pressure chamber in the second blade orifice.

12. The variable cam timing phaser of claim 10, wherein the housing defines a housing bore adjacent to the advance chamber, wherein the housing defines a second housing bore adjacent to the retard chamber, wherein the chamber piston, the chamber biasing member, and the chamber check valve are disposed in the housing bore, wherein the second chamber piston, the second chamber biasing member, and the second chamber check valve are disposed in the second housing bore, wherein the chamber piston and the chamber check valve form a pressure chamber in the housing bore, and wherein the second chamber piston and the second chamber check valve form a second pressure chamber in the second housing bore.

13. The variable cam timing phaser of claim 10, wherein the chamber biasing assembly provides a first force to the rotor to bias the rotor to rotate about the axis, wherein the second chamber biasing assembly provides a second force opposite to the first force to bias the rotor to rotate about the axis, and wherein the first force and the second force are equal to each other.

14. The variable cam timing phaser of claim 10, wherein the chamber biasing assembly provides a first force to the rotor to bias the rotor to rotate about the axis, wherein the second chamber biasing assembly provides a second force opposite to the first force to bias the rotor to rotate about the axis, and wherein the first force and the second force are different from each other.

15. The variable cam timing phaser of claim 10, wherein the chamber piston defines a chamber annulus, wherein the chamber annulus is configured to selectively fluid couple to a first stop line, wherein the second chamber piston defines a second chamber annulus, wherein the second chamber annulus is configured to selectively fluid couple to a second stop line.

16. A variable cam timing system, comprising a variable cam timing phaser according to any one of claims 1-15, and further comprising the camshaft.

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