Variable valve timing control apparatus and method for engines
First Claim
1. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
- a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied; and
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine, wherein the unlocking chamber is communicated with the retarding chamber and is supplied with fluid pressure from the retarding chamber; and
the unlock control means controls the fluid pressure control means so that the fluid pressure is supplied only to the advancing chamber in cranking the engine.
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Accused Products
Abstract
A variable valve timing control apparatus is constructed so as to supply hydraulic pressure to an unlocking chamber for unlocking a lock pin only from a retarding chamber. In cranking an engine, a hydraulic pressure control valve is controlled so as to supply the hydraulic pressure only to an advancing chamber and so as not to apply the hydraulic pressure to the unlocking chamber. Thereby, the lock pin is prevented from being unlocked in cranking the engine in advance. After that, control current of a solenoid of the hydraulic pressure control valve is switched to hold current for holding the position of the camshaft phase at the point of time when a time necessary for enabling to supply the hydraulic pressure sufficient to control the camshaft phase from the completion of cranking to supply the hydraulic pressure equally to the both advancing and retarding chambers. Thereby, the hydraulic pressure is supplied also to the unlocking chamber from the retarding chamber and the lock pin is unlocked.
74 Citations
15 Claims
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1. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
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a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied; and
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine, wherein the unlocking chamber is communicated with the retarding chamber and is supplied with fluid pressure from the retarding chamber; and
the unlock control means controls the fluid pressure control means so that the fluid pressure is supplied only to the advancing chamber in cranking the engine. - View Dependent Claims (2, 3, 4, 5)
the unlock control means continues to positively prevent the pressure in the unlock chamber from increasing a predetermined period elapses from the completion of cranking.
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3. A variable valve timing control apparatus as in claim 1, wherein:
the unlock control means starts to supply fluid pressure to the unlocking chamber when the fluid pressure controlled by the fluid pressure control means becomes greater than a predetermined pressure.
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4. A variable valve timing control apparatus as in claim 1, wherein:
the unlock control means unlocks the lock means by increasing the fluid pressure in the unlocking chamber when the fluid pressure is increased in at least one of the advancing chamber and the retarding chamber.
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5. A variable valve timing control apparatus as in claim 1, wherein:
the unlock control means unlocks the lock means by controlling the fluid pressure control means to increase the fluid pressure in the advancing and retarding chambers.
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6. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
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a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied; and
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine, wherein the unlocking chamber is communicated with the advancing chamber and is supplied with fluid pressure from the advancing chamber; and
the unlock control means controls the fluid pressure control means so that the fluid pressure is supplied only to the retarding chamber in cranking the engine.
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7. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
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a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied; and
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine, wherein the unlock control means continues to positively prevent the pressure in the unlock chamber from increasing a predetermined period elapses from the completion of cranking; and
the predetermined period is determined by the temperature of the fluid.
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8. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
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a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied; and
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine, wherein the unlock control means continues to positively prevent the pressure in the unlock chamber from increasing a predetermined period elapses from the completion of cranking; and
the predetermined period is determined by the temperature of an engine coolant fluid.
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9. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
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a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied;
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine; and
hold current learning means for learning a hold current of the fluid pressure control means for holding the camshaft phase, wherein the unlock control means sets a control current of the fluid pressure control means in unlocking the lock means around the hold current learned by the hold current learning means.
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10. A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:
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a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine;
a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve;
a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber;
fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber;
valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body;
lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine;
an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied;
unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine; and
hold current calculating means for calculating a hold current of the fluid pressure control means for holding the camshaft phase based on temperature information such as the temperature of the fluid, a coolant temperature or the engine temperature, wherein the unlock control means sets the control current of the fluid pressure control means in unlocking the lock means around the hold current calculated by the hold current calculating means. - View Dependent Claims (11)
the unlock control means sets the control current of the fluid pressure control means in unlocking the lock means to a value obtained by offsetting the hold current by a predetermined value.
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12. A variable valve timing control apparatus of an internal combustion engine, said apparatus comprising:
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valve timing control means for variably controlling valve timing by changing a rotational phase of a camshaft with respect to a crankshaft of the internal combustion engine by hydraulic pressure;
lock means urged to lock the camshaft phase at an intermediate lock phase located almost at the intermediate position of its controllable range when the internal combustion engine is stopped or is cranked;
abnormality determination means for determining whether or not the valve timing control means is abnormal; and
abnormality determination standard relaxing means for relaxing a standard for the abnormality determination for a predetermined time period after the lock means is unlocked to prevent the unlocking from causing a false abnormality detection, wherein the abnormality determination standard relaxing means returns the abnormality determination standard to a normal value after the elapse of a predetermined period from when the unlocked state of the lock means is detected;
the abnormality determination standard relaxing means sets the predetermined period based on the temperature of at least one of oil, a coolant and the engine. - View Dependent Claims (13)
the abnormality determination standard relaxing means returns the abnormality determination standard to a normal value when the camshaft phase stays within a predetermined range for more than a predetermined time after unlocking the lock means.
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14. A variable valve timing control apparatus of an internal combustion engine, said apparatus comprising:
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valve timing control means for variably controlling valve timing by changing a rotational phase of a camshaft with respect to a crankshaft of the internal combustion engine by hydraulic pressure;
lock means for locking the camshaft phase at an intermediate lock phase, which is located approximately midway in its controllable range when the internal combustion engine is stopped or is cranked; and
unlock disabling means for preventing the lock means from unlocking until the camshaft phase is determined to be movable after the engine has been started, wherein;
the unlock disabling means determines whether or not the camshaft phase is movable based on the temperature of at least one of engine oil, a coolant and the engine. - View Dependent Claims (15)
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Specification