JP4953250B2 - Intake / exhaust valve drive system - Google Patents

Description

  The present invention relates to an intake / exhaust valve drive device that opens and closes an intake / exhaust valve of an engine with a working fluid.

  Conventionally, there is an intake / exhaust valve driving device as described above, for example, as disclosed in Patent Document 1. According to the technique of Patent Document 1, an inner piston coupled to an exhaust valve is disposed in a cylinder body, and an outer piston slidably fitted to the outer periphery of the inner piston is also disposed in the cylinder body. is there. At the initial stage of valve opening, both the inner and outer pistons are simultaneously slid by the pressure of the hydraulic oil, and after the movement of the outer piston is restricted by the stopper provided in the cylinder body, only the inner piston is slid.

  In general, the exhaust valve needs a load corresponding to the in-cylinder pressure of the engine only at the start of the valve opening, but once the valve is opened, the valve opening can be continued with a small load. In order to correspond to this characteristic, this technology opens the exhaust valve with a large force by a large piston consisting of both inner and outer pistons at the start of valve opening, and opens the exhaust valve with a small force only by the inner piston after opening. It can be opened further.

JP 2000-282823 A

  However, according to this technique, the piston is composed of both inner and outer pistons, the number of parts is increased, and it is necessary to form the inner piston and the outer piston concentrically with the cylinder, which makes machining difficult.

  It is an object of the present invention to provide an intake / exhaust valve drive device having a small number of parts and easy machining.

  The intake / exhaust valve driving device of one embodiment of the present invention has a cylinder body. A piston is provided in the cylinder body so as to be slidable along the length direction. As the piston slides, first and second fluid chambers are formed on both sides of the piston in the longitudinal direction of the cylinder body. That is, a first fluid chamber is formed on one side of the piston, and a second fluid chamber is formed on the other side of the piston. When the volumes of the first and second fluid chambers change as the piston slides and the volume of the first fluid chamber increases, the volume of the second fluid chamber decreases and the volume of the first fluid chamber decreases. When becomes smaller, the volume of the second fluid chamber becomes larger. An intake / exhaust valve body is connected to the piston via a rod in the second fluid chamber. A working fluid supply passage is provided in the cylinder body so as to supply the piston driving working fluid, for example, working oil, to the first fluid chamber. A working fluid discharge passage is provided in the cylinder body so as to discharge the working fluid from the second fluid chamber. The working fluid discharge passage is formed at a position that is closed by the piston when the piston moves a predetermined distance from the first fluid chamber side to the second fluid chamber side. A communication passage is provided in the cylinder body so as to connect the first and second fluid chambers by movement of the piston from the first fluid chamber side to the second fluid chamber side.

  In the intake / exhaust valve drive device configured as described above, when the fluid is supplied to the first fluid chamber, the piston moves from the first fluid chamber side to the second fluid chamber side, and the second fluid Fluid is discharged from the chamber through the working fluid discharge passage. When the piston moves by a predetermined distance, the working fluid discharge passage is closed by the piston, the second fluid chamber and the first fluid chamber communicate with each other through the communication passage, and the fluid in the second fluid chamber passes through the first fluid chamber. Supplied to the fluid chamber. As a result, the flow rate of the fluid supplied to the first fluid chamber can be reduced.

The piston has a large-diameter portion on the first fluid chamber side, a small-diameter portion continuous therewith, and a rod having a smaller diameter than the large-diameter portion provided on the second fluid chamber side . The first fluid chamber includes a fluid chamber for the large diameter portion and a fluid chamber for the small diameter portion, and the communication passage is connected to the fluid chamber for the large diameter portion.

  With this configuration, initially, the piston is moved to the second fluid chamber side by the fluid supplied to the fluid chambers for the large-diameter portion and the small-diameter portion. The valve can be driven with great force. Thereafter, when the working fluid discharge passage is closed by the piston, the fluid passage for the large-diameter portion and the second fluid chamber are connected by the communication passage, and the pressures of both fluid chambers become equal. Therefore, thereafter, the working fluid in the second fluid chamber is supplied to the fluid chamber for the large diameter portion via the communication passage. As a result, the operating flow rate can be reduced by an amount corresponding to the flow rate supplied to the large-diameter portion fluid chamber via the communication passage.

  Furthermore, the large diameter portion may be formed in a shape that gradually connects the communication passage to the fluid chamber for the large diameter portion in accordance with the movement of the piston from the first fluid chamber side to the second fluid chamber side. it can.

  With such a configuration, when the pressure of the large diameter portion becomes equal to the pressure of the second fluid chamber, a sudden pressure change does not occur, the pressure gradually changes, and both become equal. Therefore, it is possible to prevent a rapid change in the piston speed.

  As described above, according to the present invention, the amount of working fluid supplied to the intake / exhaust valve drive device can be reduced, a small fluid source can be used, and the piston can be machined by machining. It becomes easy to make.

  An intake / exhaust valve drive apparatus according to an embodiment of the present invention is an exhaust valve drive apparatus that opens and closes an exhaust valve of an internal combustion engine, for example, a diesel engine, and has a cylinder body 2 as shown in FIG. The main body 2 is formed with a circular cylinder hole, and the piston 4 is accommodated in the cylinder hole. The piston 4 is slidable along the length direction in the cylinder hole. The piston 4 includes a large diameter portion 4a having a diameter that matches the diameter of the cylinder hole. A small-diameter portion 4b having a diameter smaller than that of the large-diameter portion 4a is formed concentrically on one end portion (upper end portion in FIG. 1) of the large-diameter portion 4a. The inside of the cylinder hole is partitioned by the piston 4 into a first working fluid chamber on the upper side in FIG. 1, for example, a working hydraulic chamber 6 and a second working fluid chamber on the lower side in FIG. ing.

  A rod 10 is integrally formed at the lower end of the large diameter portion 4a concentrically with the large diameter portion 4a. The rod 10 has a smaller diameter than the large-diameter portion 4a, and the tip of the rod 10 penetrates the cylinder body 2 and protrudes downward in FIG. 1, and contacts the upper end of the valve rod 12 in FIG. An intake / exhaust valve, for example, a valve body 14 of an exhaust valve is integrally formed at the lower end of the valve rod 12 in FIG. The valve body 14 is seated on a valve seat 16 provided in the diesel engine. The valve body 14 is pressed toward the cylinder body 2 by an elastic means, for example, a coil spring 18, disposed around the valve stem 12, and is firmly seated on the valve seat 16.

  The cylinder hole is opened on the upper side in FIG. A cylinder cover 20 is attached to the opening, and the opening is closed. A sleeve 22 extends from the cylinder cover 20 toward the periphery of the small diameter portion 4b. The outer diameter of the sleeve 22 coincides with the diameter of the cylinder hole, and the inner diameter coincides with the diameter of the small diameter portion 4b. The sleeve 22 forms a small-diameter portion working fluid chamber, for example, a small-diameter portion working hydraulic chamber 6b. In a state where the valve body 14 is seated on the valve seat 16, the piston 4 is closest to the upper side in FIG. 1, and the volume of the small-diameter portion working hydraulic chamber 6b is the smallest. A large-diameter working fluid chamber, for example, a large-diameter working hydraulic chamber 6a, is formed between the tip of the sleeve 22, the inner peripheral surface of the cylinder hole, and the upper end of the large-diameter portion 4a in FIG. Also in the state where the valve body 14 is seated on the valve seat 16, the piston 4 is closest to the upper side in FIG. 1, and the volume of the large-diameter working hydraulic chamber 6 a is the smallest. Conversely, in this state, the volume of the working hydraulic chamber 8 is the largest.

  In this manner, with the piston 4 being on the uppermost side, a working fluid, for example, working oil is supplied to the large-diameter hydraulic oil chamber 6a through the groove 26 formed in the large-diameter hydraulic oil chamber 6a, and the small-diameter hydraulic oil chamber 6a has a small diameter. The working oil is supplied to the small-diameter portion working hydraulic chamber 6b through the groove 28 formed in the portion working hydraulic chamber 6b. These grooves 26 and 28 form a part of the hydraulic oil supply passage.

  In this state, the hydraulic oil is present in the hydraulic oil pressure chamber 8, and the hydraulic oil pressure is discharged by the downward movement of the piston 4 in FIG. 30 is formed. The groove 30 is closed by the large diameter portion 4a when the piston 4 moves a predetermined distance from the position closest to the upper side in FIG. Hydraulic oil discharge is stopped.

  A groove 34 for connecting the communication passage 32 is formed in the working hydraulic chamber 8 at a position closer to the valve body 14 than the groove 30. This communication passage 32 is formed at the position of the inner peripheral surface of the cylinder hole that communicates with the large-diameter hydraulic oil chamber 6a when the piston 4 moves downward by a predetermined distance from the position closest to the upper side in FIG. Connected to the groove 36.

  A flow rate adjusting valve 38 with a check valve 37 is connected to the groove 26, and the flow rate adjusting valve 38 and the groove 28 join together, and a control valve, for example, an output port A of an electromagnetic switching valve 42 is connected via a check valve 40. It is connected to the. The flow rate adjusting valve 38 with the check valve 37 and the check valve 40 constitute the remaining hydraulic oil supply passage.

  The electromagnetic switching valve 42 also has an output port B, which is always closed. In addition, the electromagnetic switching valve 42 has a pump port P and a tank port T, and the pump port P is connected to a pressure accumulator 46 to which hydraulic fluid accumulated by the pump 44 is supplied. The tank port T is connected to the tank 48. In the neutral state, the electromagnetic switching valve 44 connects the ports A and B to the tank port T and closes the pump port P. When switched to the first state, the electromagnetic switching valve 42 connects the port A to the pump port P and connects the port B to the tank port T. Accordingly, hydraulic oil is supplied to the large-diameter portion working pressure oil chamber 6a and the small-diameter portion working pressure oil chamber 6b, respectively. When switched to the second state, the electrical switching valve 42 connects the port A to the tank port T and connects the pump port P to the port B. When the signal processor 52 generates a valve opening signal based on the detection signal from the crank angle sensor 50 of the diesel engine, the electromagnetic switching valve 44 is switched from the second state to the first state through the neutral state.

  The small-diameter portion working hydraulic chamber 6 b is connected to the tank 48 via a flow rate adjustment valve 53 and check valves 54 and 55. The large-diameter working hydraulic chamber 6a is connected to the tank 48 via a flow rate adjusting valve 38 with a check valve 37, a flow rate adjusting valve 53, and check valves 54 and 55. The groove 30 is connected to the tank 48 via a check valve 55. The check valve 55 forms a discharge passage together with the groove 30.

  As shown in FIG. 2, the diameter of the peripheral edge portion of the upper end portion in FIG. 1 of the large diameter portion 4 a of the piston 4 is formed smaller than the diameter of the cylinder hole. An inclined surface 56 whose diameter gradually increases from the peripheral edge toward the lower side in FIG. 1 is formed in the large diameter portion 4a. A straight portion 58 having the same diameter from the tip of the inclined surface 56 toward the hydraulic pressure chamber 8 is formed in the large diameter portion 4a. An inclined surface 60 whose diameter increases with a gentler inclination than the inclined surface 56 is formed in the large-diameter portion 4a from the tip of the straight portion 58 toward the hydraulic pressure chamber 8 side. An inclined surface 62 is formed in the large-diameter portion 4a from the tip of the inclined surface 60 until the diameter matches the diameter of the cylinder hole with a gentler inclination than the inclination of the inclined surface 60. As shown by a broken line in FIG. 2, when the piston 4 moves downward in FIG. 2, that is, toward the hydraulic pressure chamber 8, the large-diameter hydraulic fluid chamber 6 a is first connected to the groove 36 by the inclined surface 62 and then tilted. It connects to the groove | channel 36 by the surface 60, and is connected in order of the linear part 58 and the inclined surface 56 hereafter. Accordingly, the flow rate of the hydraulic oil in the large-diameter hydraulic fluid chamber 6a and the hydraulic fluid chamber 8 changes gradually and does not change abruptly.

  As shown in FIG. 3, the diameter of the coupling surface of the large diameter portion 4a of the piston 4 with the rod 10 (lower end portion in FIG. 1) is formed smaller than the cylinder hole, and from the peripheral surface to the working hydraulic pressure chamber 6 side (see FIG. 3). 3 is formed in the large-diameter portion 4a. From the inclined surface 64 to the inner peripheral surface of the cylinder hole, the inclined surface 66 is formed in the large diameter portion 4a with a gentler inclination than the inclined surface 64. Therefore, when the piston 4 a moves to the hydraulic pressure chamber 8 side and closes the groove 30, the inclined surface 64 first reaches the position of the groove 30, and then the inclined surface 66 reaches the position of the groove 30. Therefore, the change in the flow rate in the groove 30 occurs gradually.

  As shown in FIG. 1, the exhaust valve driving apparatus configured as described above is configured such that the valve body 14 is seated on the valve seat 16 and the piston 4 is located at the uppermost position in FIG. 1. In this state, when the signal processor 52 generates a valve opening signal based on the detection signal from the crank angle sensor 50, the electromagnetic switching valve 42 is switched to the first state, and the hydraulic oil from the pressure accumulator 46 is reversed. It is supplied to the small-diameter hydraulic chamber 6b via the stop valve 40, and is supplied to the large-diameter hydraulic chamber 4a via the check valve 40 and the flow rate adjusting valve 38 with the check valve 37. Thereby, the piston 4 is pressed and moved downward in FIG. 1 by a large load determined by the sum of the area of the upper end portion of the large diameter portion 4a and the area of the upper end portion of the small diameter portion 4b and the pressure of the hydraulic oil. To do. At this time, since the groove 36 is closed by the large diameter portion 4 a of the piston 4, the hydraulic oil in the working hydraulic chamber 8 is discharged from the groove 30 to the tank 48 via the check valve 55. Further, the valve element 14 is moved downward in FIG. 1 so that the valve element 14 is separated from the valve seat 16 against the acting force of the coil spring 18 due to a large load applied to the piston 4.

  Eventually, as shown by the broken line in FIG. 3, the large-diameter portion 4a passes through the groove 30 while the flow rate is moderately suppressed by the inclined surfaces 64 and 66 on the lower side of the large-diameter portion 4a passing through the groove 30. The discharge of hydraulic oil to the tank 48 stops.

  As the piston 4 further moves downward in FIG. 1 and the inclined surfaces 62 and 60, the straight portion 58, and the inclined surface 56 sequentially pass through the groove 36 as shown by broken lines in FIG. The working fluid chamber 8 and the large-diameter portion working hydraulic chamber 6a communicate with each other through the groove 34, the communication passage 32, and the groove 36. As a result, the hydraulic oil in the large-diameter hydraulic hydraulic chamber 6a flows into the hydraulic hydraulic chamber 8 while the flow rate changes slowly, and the pressures in the hydraulic chambers 6a and 8 become equal. Since the load based on the pressure of the hydraulic oil in the hydraulic oil pressure chamber 8 pushes the large diameter portion 4a upward in FIG. 1, the load generated in the large diameter portion 4a by the hydraulic oil in the large diameter hydraulic pressure chamber 6a is Be countered. As a result, the force that pushes the piston 4 downward becomes small, but the valve body 14 is open, so the piston 4 moves downward in FIG. By this movement, the working oil is returned from the working hydraulic chamber 8 to the large-diameter working hydraulic chamber 6a through the communication passage 32. The hydraulic fluid supplied from the electromagnetic switching valve 42 to the large-diameter hydraulic chamber 6a and the small-diameter hydraulic chamber 6b is obtained by subtracting the amount returned from the hydraulic chamber 8 to the large-diameter hydraulic chamber 6a. Only quantity. Therefore, the electromagnetic valve 42, the accumulator 46 and the pump 44 associated therewith have a small capacity. In addition, since the piston can be integrally formed without double, the number of parts is small and the structure is simple. Further, only the piston 14 and the valve seat 16 are required to have a high degree of concentricity, and the ease of manufacturing in machining can be improved.

  When the valve opening signal disappears, the switching valve 44 is switched to the second state, the port A is connected to the tank 48, and the pump port P is connected to the port B. As a result, the supply of new hydraulic fluid to the large-diameter hydraulic chamber 6a and the small-diameter hydraulic chamber 6b is stopped, and the piston 4 is returned to the hydraulic chamber 6 side by the spring force of the coil spring 18 and is activated at this time. The hydraulic oil in the large-diameter hydraulic chamber 6a of the hydraulic chamber 6 is discharged to the tank 48 via the flow rate adjustment valve 38 with the check valve 37, the flow rate adjustment valve 53, and the check valves 54 and 55, and the small-diameter hydraulic pressure is obtained. The hydraulic fluid in the chamber 6 b is discharged to the tank 48 through the flow rate adjustment valve 53 and the check valves 54 and 55.

  In the above embodiment, the working oil is used as the working fluid. However, the present invention is not limited to this, and for example, pressurized air can be used. In the above-described embodiment, the present invention is applied to the exhaust valve drive device. However, the present invention is not limited to this, and the exhaust valve drive device can be used, for example, as an intake valve drive device.

It is a schematic block diagram of the intake / exhaust valve drive device of one Embodiment of this invention. It is a one part enlarged view of the piston of the intake / exhaust valve drive device of FIG. It is an enlarged view of the other part of the piston of the intake / exhaust valve drive device of FIG. It is a schematic block diagram in the operation state of the intake / exhaust valve drive device of FIG.

Explanation of symbols

2 Cylinder body 4 Piston 6 Working hydraulic chamber (first working fluid chamber)
8 Working hydraulic chamber (second working fluid chamber)
14 Valve body 30 Groove (working fluid discharge passage)
32 passage

Claims (2)

A cylinder body,
A piston provided in the cylinder body so as to be slidable along the length direction in the cylinder body;
First and second fluid chambers formed on both sides of the piston in the length direction of the cylinder body and changing in volume according to the sliding of the piston according to the sliding of the piston,
An intake and exhaust valve body connected to the piston via a second fluid chamber;
A working fluid supply passage provided in the cylinder body so as to supply a working fluid for driving the piston to the first fluid chamber;
A working fluid discharge passage provided in the cylinder body so as to discharge the working fluid from the second fluid chamber;
Equipped,
The working fluid discharge passage is formed at a position where the piston is closed by the piston when the piston moves from the first fluid chamber side to the second fluid chamber side by a predetermined distance, and from the first fluid chamber side of the piston. A connecting passage is provided in the cylinder body so as to connect the first and second fluid chambers by movement toward the second fluid chamber ;
The piston has a large diameter portion on the first fluid chamber side, a small diameter portion connected to the large diameter portion, and a rod having a smaller diameter than the large diameter portion on the second fluid chamber side,
The first fluid chamber has a fluid chamber for the large diameter portion and a fluid chamber for the small diameter portion,
The communication passage is an intake / exhaust valve driving device connected to the fluid chamber for the large diameter portion. 2. The intake / exhaust valve driving device according to claim 1 , wherein the large-diameter portion moves the communication passage through the fluid chamber for the large-diameter portion in accordance with the movement of the piston from the first fluid chamber side to the second fluid chamber side. The intake / exhaust valve drive device is formed in a shape that is gradually connected to.

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