JP2007085187A - Structure of compression pressure open type brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compression pressure open type brake capable of securing a stable braking force at all times by absorbing the malfunction of a valve clearance and the wear and displacement of parts and hard to be affected by thermal expansion and a method of controlling the compression pressure open type brake. <P>SOLUTION: A piston stop member formed of a cam driven by a DC motor is installed at the piston stop position of an hydraulic actuator so that a piston lift amount determined by the contact of the piston on the piston stop member can be varied by changing the rotating angle of the piston stop member. An exhaust valve lift amount measuring means measuring the valve lift amount of an exhaust valve and a control means controlling the rotating angle of the DC motor are installed so that the control means can control the rotating angle of the piston stop member by the DC motor on the basis of the measured results of the exhaust valve lift amount measuring means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a compression pressure releasing brake that obtains a braking force by opening a predetermined amount of an exhaust valve or a third valve that replaces the exhaust valve, with the compression pressure increased by a piston in the first half of the compression process.

  In addition to the exhaust brake as a means to increase the engine brake, a compression pressure release type brake (or decompression) that obtains a braking force by opening the exhaust valve by a predetermined amount of the compression pressure increased by the piston in the first half of the compression process Brake) is known (see, for example, Patent Documents 1 to 3).

  2 and 3 are operation diagrams partially showing the operation of the embodiment of the present invention. However, since only a part of the hydraulic actuator is different and the other is the same, FIG. 2 and FIG. The outline of the operation of the compression pressure release type brake will be described with reference to FIG.

FIG. 2 shows a state where the brake is not operated, and FIG. 3 shows a state where the brake is operated.
In FIG. 2, the exhaust valve 1 has an upper end fixed to a valve spring seat 2, and a valve spring 4 is interposed between the valve spring seat 2 and the upper surface of the cylinder head 3, and is illustrated by the bias of the valve spring 4. The exhaust port is not closed.

The rocker arm 5 rotates on the outer periphery of the bush portion 6a of the eccentric bush 6, and the eccentric bush 6 has a swing arm 61 extending leftward in the illustrated example.
A rotating shaft 62 of the swing arm 61 is pivotally attached to the cylinder head 3 by a rocker bracket (not shown) with an axis 62c as a center of rotation.

On the other hand, the shaft core 6ac of the bush portion 6a of the eccentric bush 6 is offset (provided eccentrically) to the right of the shaft 62c of the rotating shaft 62 of the swing arm 61 in the illustrated example. ing.
That is, the shaft core 62 c of the rotating shaft 62 of the swing arm 61 is fixed to the cylinder head 3, but the shaft core 6 ac of the bush portion 6 a of the eccentric bush 6 is pivoted by the swing of the swing arm 61. It is formed to rotate around the core 62c.

  A contact ball 51 that contacts the stem top portion 1t of the exhaust valve 1 is attached to the left end side of the rocker arm 5 shown in the figure, and a roller 52 that rotates and contacts the cam 7 is attached to the right end side of the rocker arm 5 shown in the figure.

  The compression pressure release type brake is provided with a hydraulically operated actuator 10. The actuator 10 is configured such that a cylinder 12 is formed above a body 11 and a piston 14 provided with a pressing rod 13 is slid in the cylinder 12. In the state shown in FIG. 3, no hydraulic pressure is applied.

  Although the upper end 13t of the pressing rod 13 is drawn away in the drawing, the actuator 10 is disposed so as to come into contact with the bottom 61b of the tip of the swing arm 61.

Therefore, as shown in FIG. 4, when the engine brake is operated in the compression process and hydraulic oil flows into the cylinder 12 of the actuator 10, the piston 14 and the pressing rod 13 of the actuator 10 rise and the upper end of the pressing rod 13 is reached. At 13 t, the bottom surface 61 b at the tip of the swing arm 61 is pushed up.
Then, the shaft portion 62 of the swing arm 61 rotates, and as a result, the shaft core 6ac of the bush portion 6a of the eccentric bush 6 rotates clockwise around the shaft core 62c of the shaft portion 62.

  The rotation of the shaft core 6ac of the bush portion 6a of the eccentric bush 6 around the shaft core 62c is accompanied by the vertical movement of the shaft core 6ac. That is, the shaft core 6ac moves downward as the shaft portion 62 of the swing arm 61 rotates clockwise.

Here, when the shaft portion 62 rotates clockwise, the lower end of the roller 52 attached to the right end of the rocker arm 5 is in contact with the cam 7 by the contact point Pc.
On the other hand, since the shaft core 6ac of the bush portion 6a moves downward, the rocker arm 5 that is rotatably engaged with the bush portion 6a is rotated counterclockwise with the contact point Pc as a fulcrum. The contact ball 51 at the left end of the rocker arm 5 moves downward.
As a result, the exhaust valve 1 is pushed down with respect to the non-actuated state of the actuator 10 (FIG. 3), acts to reduce the compression in the compression process, and the engine brake is activated.

FIGS. 3 and 4 are a part of the configuration of the embodiment of the present invention. In the prior art, the piston stopper 15 having a substantially elliptical cross section provided above the actuator 10 of FIGS. The DC motor 16 that is a driving means for the piston stopper 15 is not used.
The piston stopper 15 and the DC motor 16 will be described in detail when the embodiment is described.

In the compression pressure release type brake having the above-described configuration and structure, the valve clearance is not adjusted properly, the exhaust valve upper end 1t and the contact ball 51 are worn during the use process, the tip bottom 61b of the swing arm 61 and the actuator 10 are pressed. The braking force varies depending on the wear of the rod upper end 13t and the displacement of each part.
Alternatively, there is a problem that the braking force changes due to the difference in thermal expansion of the exhaust valve 1 due to the load.

However, Patent Document 1 aims to prevent the C-ring that engages the actuator guide with the cylinder from receiving a bending moment during use or bending stress to the actuator cylinder. Patent Document 2 reduces the number of parts. This is the purpose, and Patent Document 3 aims to improve the operation responsiveness, and does not improve the above-described problems.
JP-A-8-156767 JP-A-8-158836 JP-A-8-246827

  The present invention has been proposed in view of the above-described problems of the prior art, and absorbs the wear and misalignment even if valve clearance is poorly adjusted or wear or misalignment occurs in each part during use. Therefore, it is an object of the present invention to provide a compression pressure releasing brake that can always secure a stable braking force and is hardly affected by thermal expansion, and a control method thereof.

  The compression pressure release type brake of the present invention includes an eccentric bush (6) having a swing arm (61) and a rocker arm of a valve operating mechanism of an exhaust valve (1) by rotating the outer periphery of the eccentric bush (6). 5), a hydraulic actuator (10) for swinging the swing arm (61), and a direction switching solenoid valve (22) interposed in a circuit (20) communicating with the hydraulic actuator (10). In the open brake, a piston stop member (15) comprising a cam (15c) driven by a DC motor (16) is provided at the piston stop position of the hydraulic actuator (10), and the rotation angle of the piston stop member (15) is changed. Thus, the piston lift amount determined by the piston (14) coming into contact with the piston stop member (15) is changed, and the valve lift amount of the exhaust valve (1) is changed. An exhaust valve lift amount measuring means (magnetic sensor 20) for measuring and a control means (30) for controlling the rotation angle of the DC motor (16) are provided, and the control means (30) is configured to measure the exhaust valve lift amount measuring means ( The rotation angle of the piston stop member (15) is controlled by the DC motor (16) based on the measurement result of the magnetic sensor (20) (Claim 1).

  The shape of the cam (15c) of the piston stop member (15) is configured such that the piston lift amount decreases when the measurement result of the valve lift amount measuring means (20) increases the valve lift amount. (Claim 2).

  The exhaust valve lift amount measuring means (magnetic sensor 20, magnetic body 22) includes a magnetic sensor (20) fixed to the cylinder head (3) side and a magnetic body (22) embedded in the upper surface of the valve seat. Preferred (claim 3).

  According to the control method of the compression pressure release type brake of the present invention, the lift amount of the exhaust valve (1) is controlled by the exhaust valve lift amount measuring means (magnetic sensor 20, magnetic body 22) when controlling the compression release type brake of claim 1. Measuring step (S1), determining whether or not the exhaust valve lift amount is within a predetermined range, and piston lift corresponding to an appropriate valve lift amount when the exhaust valve lift amount is within the predetermined range And a step of determining the amount (S3).

The compression pressure release brake of the above-described configuration and control method is provided with the piston stop member (15) driven by the DC motor (16) at the piston stop position of the hydraulic actuator (10), and the rotation of the piston stop member (15). The piston lift is changed by changing the angle.
An exhaust valve lift amount measuring means (magnetic sensor 20) for measuring the valve lift amount of the exhaust valve (1) and a control means (control unit 30) for controlling the rotation angle of the DC motor (16) are provided, The control means (30) controls the rotation angle of the piston stop member (15) by the DC motor (16) based on the measurement result of the exhaust valve lift amount measurement means (magnetic sensor 20).
Therefore, even if the valve clearance is poorly adjusted, the wear of each part in the process of use, or the deviation of each part occurs, the opening degree of the exhaust valve (1) during operation of the engine brake is kept constant, and a stable braking force can always be secured. .
Further, since the valve lift amount is finally maintained constant even under the influence of thermal expansion, a stable braking force can be obtained.

Hereinafter, with reference to the accompanying drawings, a configuration of a compression pressure release brake according to an embodiment of the present invention will be described.
It should be noted that the embodiment of the present invention has many configurations similar to those of the conventional compression pressure release brake, and the valve mechanism mechanism and the main parts of the actuator have already been described in the description of the prior art. In the following description, portions not described in the prior art and configurations unique to the embodiment of the present invention will be described.

  1 and 2, a DC motor 16 is attached to the upper outer peripheral portion of the cylinder 12 of the hydraulic actuator 10, and penetrates the drive shaft 16s into the cylinder 12 so as to be rotatable. As shown in FIGS. 4 and 5, for example, a piston stopper 15 formed of a cam 15 c having an elliptical cross section is fixed to the drive shaft 16 s.

As shown in FIG. 4, when the major axis of the ellipse in the cross section of the piston stopper 15 is directed in the vertical direction, the piston lift amount H1 is minimized. For example, it is set to this state at the time of a trial operation of the engine, and is aligned with a valve lift amount at the time of a trial operation which is a measurement result of an exhaust valve clearance described later.
On the other hand, as shown in FIG. 5, when the major axis of the ellipse in the cross section of the piston stopper 15 faces the horizontal direction, the lift amount H2 of the piston 14 becomes maximum. The valve lift amount in that case may be made to coincide with the valve lift amount at the time of periodic inspection, for example.
That is, since the valve clearance is always checked in the periodic inspection, the amount of change in the valve lift due to wear or the like generated so far can be absorbed by the adjustment amount (H2-H1) of the piston lift.

In the actuator 10 configured as described above, the cam 15c having an elliptical cross section of the piston stopper 15 is rotated by the rotation of the DC motor 16, and the lift amount of the piston 14 changes along the elliptic profile of the cam.
Accordingly, the lift amount of the pressing rod 13 standing on the piston 14 also changes, and the swing angle of the swing arm 61 pressed upward by the press rod 13 changes. As a result, the lift amount of the exhaust valve 1 is reduced. Can be adjusted.

    In other words, the amount of wear of the valve mechanism that wears during the period of the periodic inspection is grasped in advance, and ½ of the difference between the major axis and the minor axis of the piston stopper 15 matches the amount of wear. By doing so, at least within the period of the periodic inspection, the braking force of the compression pressure release type engine brake when the engine brake is operated can be kept close to a constant state.

  Returning to FIG. 1, the cylinder 12 of the hydraulic actuator 10 communicates with the direction switching electromagnetic valve 40 via the hydraulic circuit Lp. The direction switching solenoid valve 40 communicates the cylinder 12 with the hydraulic pump 8 when energized, and communicates the cylinder 12 with the return tank 9 when de-energized.

Referring to FIG. 6, a magnetic sensor 20 is fixed to the cylinder head 3 by a bracket B at a position that is a predetermined distance from the valve spring seat 2 immediately above the exhaust valve 1 of the cylinder head 3. On the other hand, a knock pin hole is drilled at a position facing the magnetic sensor 20 on the upper surface of the valve spring seat 2, and a steel pin 22, which is a magnetic body, is fitted (embedded) in the knock pin hole.
In FIG. 6, symbol δ indicates a gap corresponding to the valve lift amount to be measured. That is, in this embodiment, the magnetic sensor 20 plays the role of a gap sensor.

Here, the configuration of the controller 30 as the control means will be described with reference to FIG.
The controller 30 includes an exhaust valve lift amount determination block 31, a comparison block 32, a piston lift amount determination block 33, a cam rotation angle determination block 34, an output signal generation block 35 for a DC motor, and a storage block (database). 36.

The exhaust valve lift amount determination block 31 receives lift amount information from the magnetic sensor 20 and transmits the received information to the comparison block 32.
The comparison block 32 compares the received information with the data stored in the storage block 36 (the appropriate range of the exhaust valve lift) and transmits the comparison result and deviation to the piston lift amount determination block 33.
The piston lift amount determination block 33 determines the piston lift amount based on the received comparison result and deviation, and the relational characteristics between the piston lift amount and the exhaust valve lift amount.
The cam rotation angle determination block 34 determines the cam rotation angle from the determined piston lift amount and the relational characteristics between the rotation angle of the piston stopper (elliptical cam) stored in the storage block 36 and the piston lift amount.
The DC motor output signal generation block 35 transmits a control signal to the DC motor so as to obtain the determined rotation angle.

  The control unit 30 is connected to the magnetic sensor 20 by an input signal line Li, and is connected to the direction switching electromagnetic valve 40 and the control signal line Lo2 by the DC motor 16 and the control signal line Lo1 (FIG. 1). reference).

Next, based on FIG. 8, the brake control method of the compression pressure release type | mold brake which is embodiment of this invention is demonstrated.
First, in step S <b> 1, the lift amount of the exhaust valve 1 is measured by the magnetic sensor 20. Proceeding to step S2, the control unit 30 determines whether or not the valve lift is within a predetermined range, and if it is within the predetermined range (YES in step S2), the control unit 30 proceeds to step S3.

  On the other hand, if it is not within the predetermined range (NO in step S2), it is determined whether the control is finished (step S6). If it is finished (YES in step S6), the process is finished as it is, and if not finished (step S6). NO) Return to step S1, and start again from step S1.

In step S3, a piston lift amount corresponding to an appropriate valve lift amount is determined. In the next step S4, the elliptical cam 15c of the piston stopper 15 is rotated to an appropriate angle.
In step S5, the control unit 30 determines whether or not the determined piston lift amount is reached, and if it is the determined piston lift amount (YES in step S5), the process returns to step S1, and the step S1 and subsequent steps are repeated.
On the other hand, if it is not the determined piston lift amount (NO in step S5), the process returns to step S4, and step S4 and subsequent steps are repeated.

  1 to 6 show an embodiment relating to an engine having one exhaust valve per cylinder. On the other hand, the modification shown in FIG. 9 shows an embodiment in which there are two exhaust valves per cylinder, as represented by, for example, four valves.

In the modification of FIG. 9, two exhaust valves are connected by a bridge 100, and are configured to contact the contact ball 51 of the rocker arm 5 by a socket 100 s provided at the top of the bridge 100. Other than that, it is substantially the same as the embodiment of FIGS.
In FIG. 9, the valve spring is omitted.

According to the present embodiment having the above-described configuration and control method, the piston stopper 15 that is driven by the DC motor 16 and has an elliptical cross section is provided at the piston stop position of the hydraulic actuator 10. The piston lift amount of the actuator 10 is changed by changing the rotation angle.
The control unit 30 for controlling the rotation angle of the DC motor 16 is configured so that the rotation angle of the piston stopper 15 is controlled by the DC motor 16 based on the measurement result of the magnetic sensor 20 which is the exhaust valve lift amount measurement means. ing.
Therefore, even if the valve clearance is poorly adjusted, the wear of each part in the process of use, or the deviation of each part occurs, the opening degree of the exhaust valve 1 during operation of the engine brake is kept constant, and a stable braking force can always be secured.

  Further, since the valve lift amount is finally maintained constant even under the influence of thermal expansion, a stable braking force can be obtained.

  The illustrated embodiment is merely an example, and is not a description of the purpose of limiting the technical scope of the present invention. For example, in the illustrated example, a sliding body including a piston 14 and a pressing rod 13 in the cylinder 12 of the hydraulic actuator 10. The amount of movement is adjusted by an elliptical cam. However, the slide body is changed to a plunger, a guide groove having a stop position is formed on a part of the outer periphery of the plunger, and the cam is formed in the guide groove. Can be configured to rotate and adjust the amount of movement.

  In the illustrated embodiment, the valve for releasing the compression pressure is an exhaust valve. However, the valve for releasing the compression pressure may be a third valve different from the exhaust valve and the intake valve. .

The block diagram which showed the whole structure of the compression pressure release brake of embodiment of this invention. The operation diagram of the compression pressure release brake concerning the embodiment of the present invention, the state figure showing the engine brake non-operation state. The operation diagram of the compression pressure release brake concerning the embodiment of the present invention, the state figure showing the engine brake operation state. The mode figure in case the amount of lifts is the minimum at the time of the action | operation of the actuator for brake actuation which concerns on embodiment of this invention. The mode figure in case the amount of lifts is the maximum at the time of the action | operation of the actuator for brake actuation which concerns on embodiment of this invention. Sectional drawing which shows the principal part which showed the attachment method of the gap sensor which concerns on embodiment of this invention. The block diagram explaining the structure of the control unit which concerns on embodiment of this invention. The flowchart explaining the control which concerns on embodiment of this invention and adjusts the braking force of an engine brake. The figure which showed the modification of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exhaust valve 2 ... Valve spring seat 3 ... Cylinder head 4 ... Valve spring 5 ... Rocker arm 6 ... Eccentric bush 6ac ... Shaft core 7 ... Cam 8 ..Hydraulic pump 9 ... Return tank 10 ... Hydraulic actuator 12 ... Cylinder 13 ... Pressing rod 14 ... Piston 15 ... Piston stopper 16 ... DC motor 30 ... Control unit 40 ... Direction switching solenoid valve 51 ... Contact ball 52 ... Roller cam 61 ... Swing arm 62 ... Rotating shaft 62c ... Shaft core

Claims (4)

  An eccentric bush having a swing arm, a rocker arm of a valve operating mechanism of an exhaust valve by rotating the outer periphery of the eccentric bush, a hydraulic actuator for swinging the swing arm, and a circuit communicating with the hydraulic actuator In the compression pressure release type brake having the direction switching solenoid valve, a piston stop member comprising a cam driven by a DC motor is provided at the piston stop position of the hydraulic actuator, and the piston is moved to the piston by changing the rotation angle of the piston stop member. The piston lift amount determined by contacting the stop member is changed, and an exhaust valve lift amount measuring means for measuring the valve lift amount of the exhaust valve and a control means for controlling the rotation angle of the DC motor are provided. The control means controls the DC motor based on the measurement result of the exhaust valve lift amount measuring means. Compression pressure open type brake which is characterized in that allowed to control the rotation angle of the piston stop member.   2. The compression according to claim 1, wherein the cam shape of the piston stop member is configured such that the piston lift amount decreases when the measurement result of the valve lift amount measuring means increases the valve lift amount. Pressure release type brake.   3. The compression pressure release type brake according to claim 1, wherein the exhaust valve lift amount measuring means includes a magnetic sensor fixed to the cylinder head side and a magnetic body embedded in the upper surface of the valve seat.   The control of the compression release type brake according to claim 1, wherein a step of measuring the lift amount of the exhaust valve by the exhaust valve lift amount measuring means, a step of determining whether or not the exhaust valve lift amount is within a predetermined range, and an exhaust valve lift And a step of determining a piston lift amount corresponding to an appropriate valve lift amount when the amount is within a predetermined range.

Images