JP4674563B2 - Valve gear - Google Patents

Description

The present invention utilizes the fluid pressure relates valve operating equipment for opening and closing the valve.

  2. Description of the Related Art In recent years, a valve operating device of a type that opens and closes a valve using fluid pressure is known as a variable valve operating mechanism that operates an intake / exhaust valve of an internal combustion engine variably at an opening / closing timing.

  For example, the applicants of the present application have proposed a valve operating device in Patent Document 1 and Patent Document 2 in which drive energy is reduced.

  The valve drive device of Patent Document 1 is applied to, for example, a common rail engine, and uses fuel (hereinafter referred to as hydraulic oil) as a working fluid.

  As shown in FIG. 3, the valve drive apparatus 300 of Patent Document 1 includes a spring 302 and a magnet 303 that bias a valve (engine valve) 301 in a valve closing direction, and hydraulic oil for opening the valve 301. A control chamber 304 to be introduced, a high-pressure supply source 305 that supplies high-pressure hydraulic oil to the control chamber 304, and a low-pressure chamber 306 that stores hydraulic oil having a pressure lower than that of the high-pressure supply source 305 are provided. . Specifically, the high-pressure supply source 305 is a supply pump that provides a common rail pressure, and supplies high-pressure (for example, several tens to several hundreds of MPa) hydraulic oil. On the other hand, in the low pressure chamber 306, hydraulic oil of about 0.5 MPa that is pumped from the fuel tank 307 by the feed pump 308 is stored.

  A high-pressure control valve 310 is provided in the high-pressure passage 309 that communicates the control chamber 304 with the high-pressure supply source 305, and the low-pressure passage 311 that communicates the control chamber 304 with the low-pressure chamber 306 travels from the low-pressure chamber 306 to the control chamber 304. A check valve 312 is provided that allows only flow. The control chamber 304 is connected to a discharge path 313 for discharging the working fluid to the fuel tank 307.

  In order to open the valve 301, basically, the high-pressure control valve 310 is opened and the working fluid is introduced into the control chamber 304. However, the valve drive apparatus 300 of FIG. Therefore, the valve opening period of the high-pressure control valve 310 is shortened to reduce the amount of high-pressure working fluid used.

  That is, the high-pressure control valve 310 is opened for a short time, the initial valve opening energy (operation pressure × operation flow rate) required for opening (lifting) is applied to the valve 301, and the valve 301 is lowered. When the pressure in the control chamber 304 decreases, a working fluid that satisfies the capacity for holding the lift amount is supplied from the low pressure chamber 306.

  As shown in FIG. 4, in the valve drive device 320 of Patent Document 2, the discharge passage 313 (see FIG. 3) is omitted, and the control chamber 304 is placed in the low pressure chamber 306 or the fuel tank 307 in the low pressure passage 311. A second operating valve 314 that communicates with any one of the above is provided. In addition, a supply oil passage 315 for supplying a working fluid from the downstream of the feed pump 308 to the low pressure chamber 306 is connected to the low pressure chamber 306 of the valve drive device 320.

International Publication No. WO2002 / 079614 JP 2003-328713 A

  However, in the valve drive apparatuses 300 and 320 described above, when the valve 301 is opened, the inside of the control chamber 304 is excessively decompressed, and reduced-pressure boiling or dissolved air deposition occurs in the hydraulic oil in the control chamber 304. There was a problem that.

  In the valve drive apparatus 300 of FIG. 3, when the valve 301 starts to open, the pressure in the control chamber 304 is suddenly reduced with the volume change, and the pressure in the control chamber 304 is lower than that in the low pressure chamber 306. When the pressure is reached, the check valve 312 is opened, and the low pressure hydraulic oil flows from the low pressure chamber 306 into the control chamber 304.

  At this time, in addition to the operation delay of the check valve 312, it is difficult to ensure a sufficient opening area, and the pressure of the hydraulic oil in the low pressure chamber 306 is relatively low (feed pump discharge pressure, 0.5 MPa). Therefore, the pressure in the control chamber 304 decreases excessively.

  Due to this excessive pressure drop, air dissolved in the hydraulic oil is deposited, or when the pressure is further reduced, a reduced-pressure boiling state occurs and hydraulic oil vapor is generated. As a result, the controllability and stability of the lift amount of the valve 301 are impaired.

  In the valve drive device 320 of FIG. 4, when the valve 301 moves up and down by the operation of the high pressure control valve 310, the working fluid is discharged to the low pressure chamber 306 side. Each time the valve is closed, it gradually rises. However, when the engine is started, only a relatively low pressure working fluid from the feed pump 308 is stored in the low pressure chamber 306, and bubbles due to negative pressure are generated in the control chamber 304 until the pressure rises. There is a problem of doing.

An object of the present invention is to solve the above problems, it is to provide a valve operating equipment which can prevent flash boiling and dissolution and precipitation of the air of the working fluid.

In order to achieve the above object, the present invention provides a control chamber in which hydraulic oil is supplied and discharged to open and close a valve, a low-pressure chamber communicated with the control chamber, and a high-pressure supply source that stores hydraulic oil having a common rail pressure. And a high-pressure control valve that controls the supply of hydraulic oil from the high-pressure supply source to the control chamber, and operates the high-pressure control valve to supply hydraulic oil from the high-pressure supply source to the control chamber. When the pressure in the control chamber falls below a predetermined value due to the operation of the high pressure control valve, hydraulic oil having a pressure lower than the common rail pressure is supplied from the low pressure chamber to the control chamber to keep the valve open. In the valve operating apparatus, a first passage for communicating the control chamber and the low pressure chamber, and the first passage is provided in the first passage, and when the control chamber is depressurized more than the low pressure chamber, Open the hydraulic oil in the low-pressure chamber A check valve for supplying the control chamber, a second passage for communicating the first passage on the upstream side and the downstream side of the check valve, and a second passage provided in the second passage for boosting the low pressure chamber and opening the second passage and a introduction valve for controlling hydraulic oil supply to the low-pressure chamber from the control chamber, the control from the high pressure source to operate the high-pressure control valve and the inlet valve when the engine is started The hydraulic oil is supplied to the low-pressure chamber through the chamber.

Preferably, in order to adjust the pressure of the low pressure chamber, a regulator that releases the hydraulic oil in the low pressure chamber is provided, and a set pressure of the regulator is set to be equal to or higher than a saturated vapor pressure of the hydraulic oil .

  According to the present invention, it is possible to exhibit an excellent effect that the working fluid can be prevented from boiling under reduced pressure and dissolved air.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The valve gear of the present embodiment is applied to, for example, a diesel engine (hereinafter referred to as an engine) of a vehicle, and opens and closes an engine valve (hereinafter referred to as a valve) that forms an intake valve or an exhaust valve of the engine. is there. Furthermore, the engine of this embodiment is a common rail type engine, and the valve gear opens and closes the valve using the common rail pressure.

  Based on FIG. 1, the valve gear of this embodiment is demonstrated.

  As shown in FIG. 1, the valve operating apparatus 1 includes a control chamber 3 to which a working fluid (for example, light oil, hereinafter referred to as working oil) is supplied and discharged to open and close a valve 2 that forms an intake valve or an exhaust valve. The low-pressure chamber 4 that supplies hydraulic oil when the control chamber 3 is depressurized is communicated.

  Specifically, the valve operating apparatus 1 includes an actuator body 11 fixed to the cylinder head 100 of the engine. In the actuator body 11, the upper portion of the valve 2 is accommodated and the control chamber 3 is partitioned.

  Further, the valve operating apparatus 1 has a valve by a supply means 5 for supplying pressurized hydraulic oil to the control chamber 3, a discharge means 6 for discharging the hydraulic oil from the control chamber 3, a supply means 5 and the like. And a control means 7 for controlling the valve actuation of 2.

  The supply means 5 includes a high-pressure supply source 51 for storing high-pressure hydraulic oil, a high-pressure passage 52 for communicating the high-pressure supply source 51 and the control chamber 3, and a high-pressure control valve for opening and closing the high-pressure passage 52. 53.

  The high-pressure supply source 51 of this embodiment is composed of an engine common rail, and the common rail 51 has a high-pressure fuel boosted to a common rail pressure (for example, several 10 to several 100 MPa) by a supply pump (not shown). (Hydraulic oil) is stored.

  In the illustrated example, the high-pressure control valve 53 is a pressure balance valve and is provided in the actuator body 11. The high-pressure control valve 53 communicates with the balance chamber 532 in which the balance valve main body 531 can be moved up and down, and the balance chamber 532 through an orifice 533, and an amateur chamber 535 in which an amateur 534 for opening and closing the orifice 533 is accommodated. With.

  The balance chamber 532 is connected to a first high-pressure path 521 that communicates with the control chamber 3, and the connection port is opened and closed by the balance valve body 531. In addition, a balance valve spring 536 is provided in the balance chamber 532 to urge the balance valve body 531 downward so as to close the first high-pressure path 521 (connection port).

  In addition, a second high pressure path 522 and a third high pressure path 523 communicating with the common rail 51 are connected to the upper portion and the middle portion of the balance chamber 532, respectively. The first high pressure path 521 to the third high pressure path 523 are formed in the actuator body 11 and constitute a part of the high pressure path 52.

  The amateur chamber 535 includes an armature spring 537 that biases the armature 534 downward to close the orifice 533, and an electromagnetic solenoid 538 that lifts the armature 534 against the armature spring 537 to open the orifice 533. Is provided.

  When the high pressure control valve 53 is closed, the hydraulic oil supplied from the second high pressure passage 522 urges the upper surface of the balance valve body 531 downward, and the high pressure passage 52 (first high pressure passage 521) is closed. .

  On the other hand, when the high-pressure control valve 53 is opened, the armature 534 is pulled up by the electromagnetic solenoid 538, and the hydraulic oil above the balance valve body 531 flows into the armature chamber 535, and the operation applied to the upper surface of the balance valve body 531. Hydraulic pressure decreases. As a result, the balance valve main body 531 is raised, and the high pressure path 52 (the first high pressure path 521 and the third high pressure path 523) is opened.

  The discharge means 6 includes a fuel tank 61 that collects the hydraulic oil discharged from the control chamber 3, a discharge passage 62 that communicates the fuel tank 61 and the control chamber 3, and a discharge valve that opens and closes the discharge passage 62. 63.

  The control chamber 3 is defined by the valve 2 and the actuator body 11.

  Specifically, the valve 2 includes a valve body portion 21 and a stem portion 22 extending upward from the valve body portion 21, and an upper portion (piston portion) of the stem portion 22 is placed in the actuator body 11. The stem hole 111 is accommodated.

  The control chamber 3 is defined by an upper surface of the valve 2 and an inner surface and a ceiling surface of the stem hole 111 that accommodates the valve 2.

  The upper surface of the valve 2 that defines the control chamber 3 forms a pressure receiving surface that receives the hydraulic pressure of the control chamber 3. That is, when hydraulic oil is supplied to the control chamber 3, the pressure receiving surface is pressed by the hydraulic oil, and the valve 2 is urged in the valve opening direction (downward in FIG. 1).

  On the other hand, a flange portion 221 is formed on the stem portion 22 of the valve 2, and a valve that presses the flange portion 221 below the flange portion 221 to urge the valve 2 in the valve closing direction (upward in FIG. 1). A spring 8 is provided, and a magnet 9 (permanent magnet in the illustrated example) 9 that attracts the flange 221 and biases the valve 2 in the valve closing direction is provided above the flange 221.

  The low pressure chamber 4 stores hydraulic oil having a pressure lower than the hydraulic pressure of the supply means 5 (common rail 51), and the pressure in the control chamber 3 is reduced from that of the low pressure chamber 4 when the valve 2 is opened. When it does, it supplies to the control room 3.

  Specifically, the valve gear 1 of the present embodiment is provided in the first passage 12 for communicating the control chamber 3 and the low pressure chamber 4, and the first passage 12, and the control chamber 3 is the low pressure chamber 4. When the pressure is further reduced, the check valve 13 for opening the first passage 12 and supplying the working fluid in the low pressure chamber 4 to the control chamber 3, the upstream side of the check valve 13 (left side in FIG. 1), and A second passage 14 for communicating with the first passage 12 on the downstream side (the right side in FIG. 1), and the second passage 14 provided in the second passage 14 and opening the second passage 14 to increase the pressure of the low pressure chamber 4 are controlled. An introduction valve (relief valve) 15 for introducing the working fluid in the chamber 3 into the low pressure chamber 4 is provided.

  The introduction valve 15 is connected to the control means 7 so that a control signal can be communicated. In the illustrated example, the introduction valve 15 is an electromagnetic valve, and the energization of the electromagnetic solenoid 151 is switched by the control means 7.

  Furthermore, the valve gear 1 of the present embodiment includes a regulator 18 that releases the working fluid in the low-pressure chamber 4 in order to regulate the low-pressure chamber 4, and the set pressure of the regulator 18 is set to be equal to or higher than the saturated vapor pressure of the working fluid. The In the illustrated example, the set pressure is set to about 2.0 MPa.

  Specifically, a relief passage 41 communicating with the fuel tank 61 (hydraulic oil tank) is connected to the low pressure chamber 4, and the regulator 18 is provided in the relief passage 41.

  The fuel tank 61 is set to a pressure lower than that of the low pressure chamber 4, and the regulator 18 passes through the relief passage 41 from the low pressure chamber 4 when the operating oil pressure of the low pressure chamber 4 (relief passage 41) exceeds the set pressure. The hydraulic oil is discharged into the fuel tank 61. Thereby, the pressure in the low pressure chamber 4 does not exceed the set pressure.

  The low pressure chamber 4 is attached with a pressure sensor (pressure switch) 19 for detecting the hydraulic pressure in the low pressure chamber 4. The pressure sensor 19 is connected to the control means 7 so that the detected hydraulic pressure can be transmitted.

  For example, the control means 7 may be an engine control device. The control means 7 receives detection signals from sensors such as a pressure sensor 19 and a crank angle sensor (not shown). Further, the control means 7 outputs a control signal to actuators such as the high pressure control valve 53 and the introduction valve 15.

  Next, the control method of the valve gear 1 of this embodiment is demonstrated.

  First, an outline of valve operation control during normal operation will be described.

  In the present embodiment, in normal valve operation control, the high pressure control valve 53 (balance valve main body 531) is opened only for a short time in order to reduce valve opening drive energy (operating pressure × hydraulic oil flow rate). Then, when the valve 2 is provided with initial energy for lowering and then the volume of the control chamber 3 is increased by the lowering of the valve 2 and the control chamber 3 is depressurized, the low pressure chamber 4 is relatively low pressure. The hydraulic fluid (hereinafter referred to as the low-pressure side hydraulic fluid) is supplemented to maintain the lift amount.

  Here, when the hydraulic oil pressure in the low-pressure chamber 306 (low-pressure side hydraulic oil pressure) is low as in the valve drive device of FIG. 3, the pressure of the hydraulic oil supplied from the low-pressure chamber 306 is changed in the control chamber 304. It will decrease too much, and boiling under reduced pressure and precipitation of dissolved air will occur.

  Therefore, in the present embodiment, the pressure in the low-pressure chamber 4 (low-pressure side hydraulic oil pressure) is set to a relatively high value (specifically, the hydraulic oil pressure is reduced before the normal valve operation control is performed, such as when the engine is started. (Saturated vapor pressure or higher) was set.

  That is, the control method of this embodiment is to drive the intake valve or exhaust valve 2 of the engine by the valve operating device 1 to control the valve operating device 1, and crank the engine to start the engine. In this case, the control means 7 opens the high-pressure control valve 53 to supply pressurized hydraulic oil into the control chamber 3 and opens the high-pressure control valve 53 (balance valve body 531) for control. The hydraulic oil supplied into the chamber 3 is further introduced into the low-pressure chamber 4, and the inside of the low-pressure chamber 4 is increased to a predetermined pressure (in the illustrated example, the saturated vapor pressure of the hydraulic oil) or more.

  Furthermore, the control means 7 of this embodiment detects that the low-pressure chamber 4 has been raised to the saturated vapor pressure or higher of the hydraulic oil by the pressure sensor 19, and then controls the valve operating device 1 to perform normal valve operating. Transition to control.

  As described above, in the present embodiment, the pressure in the low-pressure chamber 4 is set to be equal to or higher than the saturated vapor pressure of the working fluid in advance before normal valve operation control (specifically, the lift of the valve 2) is executed. By increasing the pressure, the pressure of the working fluid supplied from the low pressure chamber 4 does not excessively decrease even when the control chamber 3 is depressurized as the valve 2 is opened. Thereby, it is possible to prevent vacuum boiling in the control chamber 3 and precipitation of dissolved air.

  Next, the control method of the valve gear 1 of this embodiment is demonstrated in detail.

  First, when starting the engine, when cranking is started by a starter or the like and the crankshaft of the engine rotates, the supply pump operates simultaneously with the rotation. Since the pressure from the supply pump increases the pressure on the common rail 51, at this time, the high-pressure control valve 53 and the introduction valve 15 are opened simultaneously. By opening both the valves 15 and 53, the hydraulic oil from the common rail 51 is guided to the low pressure chamber 4, and the low pressure side hydraulic oil pressure rises to a predetermined pressure. In this way, the hydraulic pressure in the low-pressure chamber 4 is first raised before the engine completes explosion.

  At this time, the pressure in the low pressure chamber 4 does not rise above the set pressure (specified value) by the regulator 18. The set pressure is not a pressure until the engine valve 2 is opened by overcoming the seating holding force applied to the valve 2 by the valve spring 8, the magnet 9, or the hydraulic pressure while the valve 2 is seated. The valve operating mechanism is not adversely affected (the valve 2 is not lowered (opened)).

  That is, the set pressure is set to be equal to or higher than the saturated vapor pressure of the hydraulic oil, and the force received by the pressure receiving surface of the valve 2 by the set pressure is smaller than the valve closing force by the valve spring 8 or the magnet 9. .

  Further, the pressure sensor 19 (which may be a pressure switch) detects the pressure in the low pressure chamber 4 and determines whether or not the pressure in the low pressure chamber 4 is equal to or higher than the set pressure of the regulator 18.

  After the pressure sensor 19 senses that the pressure in the low pressure chamber 4 (low pressure side hydraulic oil pressure) has risen to a predetermined pressure (set pressure) (specifically, when the pressure becomes higher than the set pressure), The high pressure control valve 53 and the introduction valve 15 are closed substantially simultaneously.

  Thereafter, normal valve actuation control (operation mode) is started.

  During normal operation, the high-pressure hydraulic oil for opening the hydraulically driven valve system of the valve gear 1 is released to the low-pressure chamber 4 side after the valve-opening operation. The internal pressure does not decrease, and the regulator 18 maintains the predetermined pressure without excessively increasing the pressure.

  That is, in normal valve operation control, the control means 7 opens the discharge valve 63 to discharge the hydraulic oil in the control chamber 3 from the discharge passage 62 and closes the introduction valve 15 when the valve 2 is closed. The valve is opened so that the hydraulic oil in the control chamber 3 is introduced into the low pressure chamber 4. At this time, the introduction valve 15 functions as a relief valve for discharging the hydraulic oil in the control chamber 3.

  Thereby, the low pressure chamber 4 is maintained at the set pressure even during normal valve operation control.

  Next, an example of the control method of this embodiment is demonstrated based on the flowchart of FIG.

  The flowchart of FIG. 2 is executed by the control means 7 when the engine is started, for example.

  First, in step S1, the control means 7 determines whether or not the key is ON.

  If the key is ON in step S1, it is determined that cranking is to be performed to start the engine. Therefore, in step S2, the control means 7 determines that the low pressure chamber 4 is less than the set pressure based on the pressure detected by the pressure sensor 19 in step S2. It is determined whether or not.

  If the detected pressure of the pressure sensor 19 is less than the set pressure in step S2, the control means 7 supplies the hydraulic oil of the common rail 51 into the low pressure chamber 4 through the control chamber 3 in step S3. Specifically, the control means 7 energizes the electromagnetic solenoid 538 of the high pressure control valve 53 to open the high pressure passage 52 and energizes the electromagnetic solenoid 151 of the introduction valve 15 to open the second passage 14. In the present embodiment, the high pressure passage 52 is opened (the high pressure control valve 53 is opened) and the second passage 14 is opened (the introduction valve 15 is opened) simultaneously.

  The control means 7 returns to step S2 after step S3.

  The control means 7 performs the above process until it is determined in step S2 that the low pressure chamber 4 is at the set pressure, and after the set pressure is reached, shifts to normal valve operation control.

  As described above, in this embodiment, when the engine is started (before the complete explosion), the pressure of the low-pressure side hydraulic oil is increased to the set pressure (2.0 MPa in the illustrated example) in advance, thereby opening the valve 2. Sometimes, the pressure in the control chamber 3 can be prevented from being excessively reduced, and generation of bubbles, that is, reduced-pressure boiling and dissolution air can be prevented.

  Here, for example, in the valve drive apparatus 300 of FIG. 3, in order to increase the pressure of the low-pressure side hydraulic oil (for example, from about the discharge pressure (0.5 MPa) of the feed pump 308 to about 2.0 MPa) Normally, a hydraulic pump is required, which causes a problem in mounting on the engine. In this embodiment, the high-pressure pump (supply) is opened by opening both the high-pressure control valve 53 and the introduction valve 15 at the start. The pressure in the low pressure chamber 4 can be increased using a pump).

  As a result, no additional hydraulic pump or the like is required, and reduced pressure boiling or dissolved air deposition that adversely affects valve motion can be avoided without deteriorating the mountability.

  Further, in this embodiment, the pressure in the low pressure chamber 4 quickly rises to the set pressure, so that there is a sufficient time margin until the engine completes explosion (that is, until the valve 2 is opened). There is no hindrance to the operation of the valve mechanism.

  In addition, since the control chamber 3 is used as a part of the passage from the high-pressure side (common rail 51) to the low-pressure chamber 4, no new piping for connecting the common rail 51 to the low-pressure chamber 4 is required, and the layout is simple. And manufacturing cost can be reduced.

  Further, the valve operating apparatus 1 of the present embodiment can be configured only by adding the second passage 14 and the introduction valve 15 to the valve operating drive apparatus 300 of FIG. It can be used as it is, and the design cost and manufacturing cost can be reduced.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

FIG. 1 shows a valve gear according to an embodiment of the present invention. FIG. 2 is an example of a flowchart for explaining the control method of the valve gear of the present embodiment. FIG. 3 shows a conventional valve gear. FIG. 4 shows a conventional valve gear.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve apparatus 2 Valve 3 Control chamber 4 Low pressure chamber 12 First passage 13 Check valve 14 Second passage 15 Introduction valve (relief valve)

Claims (2)

A control chamber in which hydraulic oil is supplied and discharged to open and close the valve, a low-pressure chamber communicating with the control chamber, a high-pressure supply source storing hydraulic oil having a common rail pressure, and the high-pressure supply source to the control chamber A high pressure control valve for controlling the hydraulic oil supply of
Actuating the high pressure control valve to supply hydraulic oil from the high pressure supply source to the control chamber to open the valve;
In the valve operating apparatus for supplying hydraulic oil having a pressure lower than a common rail pressure from the low-pressure chamber to the control chamber when the pressure in the control chamber becomes a predetermined value or less by the operation of the high-pressure control valve, and holding the valve open. ,
A first passage for communicating the control chamber and the low pressure chamber, and the first passage is provided in the first passage, and when the control chamber is depressurized more than the low pressure chamber, the first passage is opened and the low pressure chamber is opened. A check valve for supplying the hydraulic oil of the chamber to the control chamber, a second passage for communicating the first passage on the upstream side and the downstream side of the check valve, and the low pressure passage provided in the second passage, in order to boost the chamber by opening the second passage and a introduction valve for controlling hydraulic oil supply to the low-pressure chamber from the control chamber,
A valve operating apparatus that operates the high-pressure control valve and the introduction valve when starting an engine to supply hydraulic oil from the high-pressure supply source to the low-pressure chamber through the control chamber.   The valve operating apparatus according to claim 1, further comprising a regulator that releases hydraulic oil in the low-pressure chamber to regulate the low-pressure chamber, and a set pressure of the regulator is set to be equal to or higher than a saturated vapor pressure of the hydraulic oil.

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