JP2008280942A - Hydraulic circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an orifice structure for a hydraulic circuit providing average delivery pressure of a piston pump to a power control regulator. <P>SOLUTION: This invented orifice structure for the hydraulic circuit is provided with a first, a second signal compressed flow paths 46, 48 and a third signal compressed flow path 50 communicating with each main flow path respectively in a sub flow path, is provided with orifices 52, 54 in the first and the second signal compressed flow paths is provide with a guide 87 introducing working fluid discharged from each orifice to the third signal compressed flow path, in the hydraulic circuit provided with the sub flow path, a first and a second main flow paths 20, 22 supplying working fluid discharged from a twin piston pump 10 to a spool of a regulator 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement of a hydraulic circuit.

  Conventionally, a swash plate type piston pump including a horsepower control regulator that controls pump discharge pressure and discharge flow rate with equal horsepower characteristics such that horsepower (that is, output) is substantially constant is known (see Patent Document 1). This swash plate type piston pump is used in a hydraulic machine such as a power shovel, and the swash plate type piston pump is driven by an output of an engine of the hydraulic machine.

In the hydraulic circuit of such a conventional hydraulic machine, when the swash plate type piston pump is a so-called dual piston pump in which two pairs of suction ports and discharge ports are formed, each discharge port is connected to the horsepower control regulator. The downstream hydraulic pressure is supplied as the signal pressure.
JP 2002-202063 A

  However, when the discharge pressure is independently supplied from the discharge port to the spool of the horsepower control regulator as the signal pressure, the horsepower control regulator is increased in size. .

  In this case, an orifice is provided in each upstream signal pressure channel branched from the channel communicating with each discharge port, and the upstream signal pressure channel joins downstream of the orifice and is connected to the horsepower control regulator as a downstream signal pressure channel. Configured to do.

  Here, in manufacturing the parts, the pair of orifices are formed on the same central axis so that the discharge ports face each other, and the hydraulic oil that has passed through the orifice is provided between the two orifices in a direction perpendicular to the central axis. When formed so as to flow into the downstream signal pressure flow path, if there is a difference in the discharge pressure acting on each orifice, the hydraulic oil discharged from the high pressure side orifice is not the downstream signal pressure flow path but the low pressure side orifice. The hydraulic oil in the downstream signal pressure flow path is drawn in at the time of this reverse flow, and the pressure in the downstream signal pressure flow path may be lower than the average pressure of the discharge pressure. Thus, when the average pressure as the signal pressure decreases, the discharge flow rate of the pump increases in order to maintain the constant horsepower characteristics, which causes torque over which causes an excessive load on the engine.

  The present invention has been made in view of the above problems, and in a hydraulic circuit of a swash plate type double piston pump, a hydraulic pressure for accurately controlling a signal pressure supplied to a horsepower control regulator to an average pressure of each discharge pressure. An object is to provide a circuit.

  The present invention is a swash plate type double piston pump driven by a driving source and having a variable discharge amount, and the inclination of the swash plate according to the discharge pressure so that the horsepower of the swash plate type double piston pump is constant. A horsepower control regulator that controls the discharge flow rate by changing the angle, the first and second main flow paths through which the hydraulic oil discharged from the swash plate type double piston pump flows, and the first and second main flow paths And a sub-flow path that causes the pressure of the hydraulic oil to act on the spool in opposition to the horsepower control spring of the horsepower control regulator, the sub-flow path includes the first and second main flows. First and second signal pressure channels communicating with the respective paths, and a third signal pressure channel connected to the horsepower control regulator by joining the first and second signal pressure channels, the first and second signals An orifice in the pressure channel Provided Re respectively, a hydraulic circuit, characterized in that a rather the third signal pressure flow path to lead guide to collide with each other the hydraulic oil discharged located between the two orifices from each orifice.

  According to the present invention, the hydraulic oil discharged from each orifice by the guide is guided to the third signal pressure channel without colliding, so that the hydraulic pressure in the third signal pressure channel is changed to the discharge pressure in the first and second main channels. Accurate average pressure can be obtained.

  FIG. 1 is a hydraulic circuit diagram to which an orifice structure of a hydraulic circuit according to the present invention is applied.

  The hydraulic circuit is provided with three pumps arranged coaxially and driven by the engine 1. The first pump 10 is a swash plate type double piston pump capable of varying the discharge flow rate, and the second pump 12 and the third pump 14 are configured by a gear pump, for example, whose discharge flow rate is defined according to the rotational speed of the engine 1. Is done.

  The first pump 10 includes two discharge ports 16 and 18, and a first main channel 20 and a second main channel 22 communicate with the respective discharge ports 16 and 18, and the first and second ports 24 and 26 thereof. Hydraulic fluid is supplied to a bucket cylinder that drives, for example, a shovel bucket through a flow path (not shown). The third main channel 30 communicates with the discharge port 28 of the second pump 12, and hydraulic oil is supplied from the third port 32. Further, the fourth main flow path 36 communicates with the discharge port 34 of the third pump 14, and low pressure (so-called pilot pressure) hydraulic oil is supplied from the fourth port 38.

  The hydraulic circuit includes a horsepower control regulator 40 that tilts the swash plate of the first pump 10 in order to control the discharge flow rate according to the discharge pressure so that the driving horsepower of the first pump 10 is substantially constant.

  The horsepower control regulator 40 is a three-port two-position switching valve, and at one end of the spool, the average pressure of the discharge pressure of the first pump 10 and the discharge pressure of the second pump 12 are switched at positions a and b. Supplied as signal pressure. The urging force of the horsepower control spring 44 against the supplied hydraulic pressure acts on the other end of the spool.

  The sub flow path for supplying the average discharge pressure of the first pump 10 to the spool of the horsepower control regulator 40 is a first signal branched from the main flow paths 20 and 22 communicating with the discharge ports 16 and 18 of the first pump 10, respectively. The pressure channel 46, the second signal pressure channel 48, and the third signal pressure channel 50 where the first and second signal pressure channels 46, 48 are merged, and the third signal pressure channel 50 is a spool of the horsepower control regulator 40. Supply hydraulic pressure to Orifices 52 and 54 are installed in the first and second signal pressure channels 46 and 48 to relieve pressure pulsations in the first and second main channels 20 and 22 for transmission. The configuration of the orifices 52 and 54 will be described later in detail with reference to FIG.

  The horsepower control regulator 40 includes a signal pressure based on the sum of the average discharge pressure of the first pump 10 acting on one end of the spool and the discharge pressure of the second pump 12, and a horsepower control spring 44 acting on the other end. Positions a and b are defined by the magnitude relationship with the power.

  The horsepower control regulator 40 switches to the position b when the signal pressure based on the combined pressure of the average discharge pressure of the first pump 10 and the discharge pressure of the second pump 12 is smaller than the urging force of the horsepower control spring 44, The third source pressure channel 75 connected to the load sensing valve 42 that is a servo valve and the suction side channel 56 connected to the suction side of each pump via the drain channel 59 are in communication.

  On the other hand, when the signal pressure based on the combined pressure of the average discharge pressure of the first pump 10 and the discharge pressure of the second pump 12 is larger than the urging force of the horsepower control spring 44, the position is switched to the position a, and the main flow path 20 and 22, the first source pressure channel 58 and the third source pressure channel 75 through which the high-pressure side hydraulic fluid is guided are in communication with each other.

  The load sensing valve 42 is provided in the middle of the fourth source pressure channel 74 that transmits the pressure of the third source pressure channel 75 switched by the horsepower control regulator 40 to the hydraulic actuator 76 that changes the tilt angle of the swash plate of the first pump 10. It is done. The load sensing valve 42 detects and switches the hydraulic circuit load pressure acting on the first to third ports 24, 26, 32, etc. For this reason, the spool is positioned at both ends of the spool of the load sensing valve 42. Signal pressure for each is added. One is the hydraulic pressure from the fifth port 60, and the fifth port 60 is supplied with pressure based on the pressure on the upstream side of a control valve (not shown) installed downstream of the first and second ports 24 and 26. The Here, the control valve is a valve for controlling a bucket cylinder for operating a bucket of a hydraulic machine, for example, a power shovel.

  Also, the hydraulic pressure from the sixth port 62 acts on the opposite end of the spool as the second signal pressure against the signal pressure based on the hydraulic pressure of the fifth port 60. A flow path downstream of the control valve is connected to the sixth port 62, and therefore the hydraulic pressure supplied from the sixth port 62 to the spool is based on the load pressure supplied to the bucket cylinder, for example.

  Further, as an action force against the signal pressure from the fifth port 60, the action force of the hydraulic actuator 64 is configured to act on the spool.

  The hydraulic actuator 64 is supplied with the pilot hydraulic oil of the third pump 14 through the first and second differential pressure passages 70 and 72 to the left and right oil chambers sandwiching the piston, but is connected to the right oil chamber in the figure. An orifice 68 is provided in the middle of the second differential pressure flow path 72 to generate an acting force that moves the rod of the hydraulic actuator 64 connected to the spool of the load sensing valve 42 to the right side in the drawing, that is, the spool to the right side.

  Therefore, the position of the load sensing valve 42 is such that the hydraulic oil pressure (signal pressure) from the sixth port 62 and the hydraulic actuator 64 are different from the hydraulic pressure (signal pressure) from the fifth port 60 acting on the spool. It is defined by the magnitude relationship of the total acting force with the acting force.

  The load sensing valve 42 has three ports. When the signal pressure from the fifth port 60 is larger than the total signal pressure from the sixth port 62 and the like, the spool moves to the left side in the figure and becomes the position d. The second source pressure channel 73 through which hydraulic fluid flows and the fourth source pressure channel 74 connected to the hydraulic actuator 76 that tilts the swash plate of the first pump 10 communicate with each other.

  On the other hand, when the signal pressure from the fifth port 60 is smaller than the combined signal pressure of the sixth port 62 and the like, the spool moves to the right side in the figure, becomes the position c, and is a third original pressure flow path communicating with the horsepower control regulator 40. 75 and the fourth source pressure channel 74 communicate with each other.

  When the operating hydraulic pressure supplied from the load sensing valve 42 to the hydraulic actuator 76 increases, the hydraulic actuator 76 tilts the swash plate in a direction that decreases the tilt angle of the swash plate, that is, in a direction that decreases the discharge flow rate of the first pump 10. Turn. A return spring 78 that generates an urging force against the acting force is provided, and the stroke amount of the hydraulic actuator 76 is defined by the magnitude relationship between the hydraulic pressure acting on the hydraulic actuator 76 and the urging force of the return spring 78.

  Next, the operation of the horsepower control regulator 40 will be described.

  In the hydraulic circuit configured as described above, when negative pressure is acting on the hydraulic circuit, that is, when the load sensing valve 42 detects a load, the spool of the load sensing valve 42 acts on the signal pressure, etc. In accordance with the difference, the right side of the figure moves to the right, and the position c is switched over at a predetermined load pressure or higher. In this state, when the discharge pressure of the first pump 10 increases, the spool of the horsepower control regulator 40 moves to the right in the figure against the urging force of the horsepower control spring 44 and switches to the position a. Among the ten discharge pressures, the hydraulic oil on the high pressure side is regulated and sent to the load sensing valve 42 through the first and third source pressure channels 58 and 75. Since the load sensing valve 42 is located at the position c, high-pressure hydraulic oil from the third source pressure channel 75 is supplied to the hydraulic actuator 76 through the third source pressure channel 75, and the hydraulic actuator 76 corresponds to the supplied hydraulic pressure. Stroke to reduce the tilt angle of the swash plate of the first pump 10.

  Therefore, when the discharge pressure (average discharge pressure) of the first pump 10 increases, the tilt angle of the swash plate of the first pump 10 is changed to reduce the discharge flow rate.

  On the other hand, when the discharge pressure of the first pump 10 decreases, the spool of the horsepower control regulator 40 moves to the left side in the figure and switches to the position b, via the third source pressure channel 75 and the drain channel 59. The suction side flow path 56 communicates. The third source pressure channel 75 communicates with the fourth source pressure channel 74 via the position c of the load sensing valve 42. Therefore, the hydraulic oil of the hydraulic actuator 76 is discharged to the suction side flow path 56 through the fourth and third pressure flow paths 74 and 75, and the hydraulic pressure acting on the hydraulic actuator 76 that defines the tilt angle of the swash plate of the first pump 10 is obtained. The return spring 78 increases the tilt angle of the swash plate of the first pump 10. Thereby, it changes to the direction where the discharge flow volume of the 1st pump 10 increases.

  Here, the tilt angle of the swash plate of the first pump 10 is fed back to the horsepower control spring 44 of the horsepower control regulator 40, and the swash plate is stopped at a position balanced with the pump discharge pressure. That is, one end of the horsepower control spring 44 is connected to the swash plate of the first pump 10, and when the swash plate tilts and changes in a direction in which the discharge flow rate decreases, the horsepower control spring 44 increases the urging force. When the swash plate tilts to the opposite side, the urging force decreases. For this reason, when the inclination angle of the swash plate corresponding to the average pressure of the discharge pressure of the first pump 10 is reached, the position of the horsepower control regulator 40 is alternately switched by the balance with the horsepower control spring 44 and supplied to the hydraulic actuator 76. The hydraulic pressure is maintained, and eventually the discharge flow rate is determined according to the pump discharge pressure.

  As described above, the discharge flow rate is decreased when the discharge pressure of the first pump 10 is increased, and on the other hand, the discharge flow rate is increased according to the discharge pressure and the discharge flow rate when the discharge pressure is decreased. It is possible to perform equal horsepower control for controlling the horsepower of the first pump 10 to be substantially constant.

  Next, the operation of the load sensing valve 42 will be described.

  The load sensing valve 42 is displaced according to the balance of the signal pressure acting on both ends of the spool. When the load pressure supplied from the sixth port 62 is equal to or higher than a predetermined pressure (high load range), the load sensing valve 42 is positioned at position c. Located in.

  When the load pressure decreases from this state, the differential pressure between the signal pressure from the fifth port 60 and the signal pressure from the sixth port 62 and the like changes, and the spool moves according to the differential pressure. When the position of the spool is set at an intermediate position between the position c and the position d, the second source pressure channel 73 and the third source pressure channel 75 communicate with the fourth source pressure channel 74. Here, the hydraulic pressure supplied from the second source pressure channel 73 and the third source pressure channel 75 is added according to the opening degree of the load sensing valve 42, and is higher than the hydraulic pressure only from the third source pressure channel 75. The pressure is adjusted so as to be supplied from the fourth source pressure flow path 74 to the hydraulic actuator 76. The adjusted hydraulic pressure moves the tilt angle of the swash plate of the first pump 10 in the direction in which the discharge flow rate decreases. Thereby, when the load of the hydraulic circuit decreases, the discharge flow rate with respect to the same pump discharge pressure relatively decreases.

  Furthermore, for example, when the load pressure supplied to the bucket cylinder is low, such as no load, the load sensing valve 42 switches to position d in response to the low load pressure, and the discharge pressure of the first pump 10 is reduced. The hydraulic pressure is supplied to the hydraulic actuator 76 through the second source pressure channel 73 and the fourth source pressure channel 74.

  In this way, when the load pressure is a low pressure such as an unloaded state, the discharge flow rate is reduced to the minimum value even if the discharge pressure of the first pump 10 is low without performing the equal horsepower control.

  Next, the orifice structure used in the hydraulic circuit described so far will be described with reference to FIGS.

  First, the orifice structure of the present invention will be described with reference to FIG. The figure is a sectional view of a hydraulic circuit through which hydraulic oil formed in the block 100 circulates, and communicates with the discharge ports 16 and 18 of the first pump 10, respectively, and is formed substantially parallel to each other in the vertical direction in the figure. 1 and the second main flow paths 20 and 22 are formed orthogonally to the first and second main flow paths 20 and 22 from the left in the figure so as to communicate with the first and second main flow paths 20 and 22. The second main flow path 22, and the horizontal flow path 80 that opens to the first main flow path 20, the plug 82 fitted in the horizontal flow path 80, the first and second main flow paths 20, 22, The third signal pressure channel 50 formed in parallel with these and communicating with the transverse channel 80 is shown.

  The lateral flow path 80 has a stepped shape, and a step portion 89 is formed between the first main flow path 20 and the third signal pressure flow path 50. By this step portion 89, the stepped plug 82 fitted in the horizontal flow path 80 is positioned from the left in the figure.

  The plug 82 is made of a cylindrical member, and a pair of through-holes 86 formed in a direction perpendicular to the central axis are formed in the central portion in the central axial direction. Here, the through hole 86 is, for example, two parallel through holes communicating with the third signal pressure flow path 50, and a partition wall 87 as a guide is formed between the through holes 86. Or you may make it form the partition which pierces one through-hole and separates a center part. Holes 90 and 92 having a predetermined depth from both end faces 88 of the plug 82 are formed on the central axis toward the through hole 86. At this time, the holes 90 and 92 are deep enough not to communicate with the through hole 86. The holes 90 and 92 and the through holes 86 are formed so as to communicate with each other through orifices 52 and 54 having a smaller diameter than the holes 90 and 92.

  With such a configuration, the hydraulic oil in the first main flow path 20 flows into the third signal pressure flow path 50 through the lateral flow path 80, the hole 90 of the plug 82, the orifice 52, and the through hole 86. On the other hand, the hydraulic oil in the second main flow path 22 flows into the third signal pressure flow path 50 through the hole 92 of the plug 82, the orifice 54 and the through hole 86.

  Here, when there is a difference in the discharge pressure between the first main flow path 20 and the second main flow path 22 connected to the discharge port of the first pump 10, a conventional structure as shown in FIG. That is, when two orifices are configured to face each other on the same axis and the partition wall 87 is not provided, a phenomenon in which hydraulic oil on the high pressure side is discharged from one orifice and flows into the other orifice on the low pressure side ( Hereinafter, this is referred to as a blow-through). When this blow-through occurs, the hydraulic oil in the third signal pressure channel 50 is guided by the discharged hydraulic oil and enters the other orifice. As a result, the pressure (average pressure) in the third signal pressure channel 50 is increased. Will be reduced. As described above, the third signal pressure passage 50 communicates with the horsepower control regulator 40, and the hydraulic pressure of the hydraulic oil in the third signal pressure passage 50 acts on the spool of the horsepower control regulator 40. When this hydraulic pressure decreases, the horsepower control regulator 40 is switched, the third source pressure channel 75 and the drain channel 59 communicate with each other, and the operation in the hydraulic actuator 76 that controls the tilt angle of the swash plate of the first pump 10 is performed. Oil is discharged, and the tilt angle of the swash plate changes in the direction in which the discharge flow rate increases. For this reason, there exists a possibility of causing the torque over which an excessive load will be caused to an engine.

  However, in the orifice structure of the present invention, since the partition wall 87 is provided between the two orifices 52 and 54 provided on the same axis so as to face each other in the discharge direction, the hydraulic oil discharged from the orifices 52 and 54 by the partition wall 87 is provided. The flow of the oil flows into the third signal pressure flow path 50 without colliding with each other, and the hydraulic oil discharged from one orifice 52 (54) does not flow into the other orifice 54 (52), and the hydraulic oil is blown through. Can be reliably prevented, and a decrease in the average pressure supplied to the horsepower control regulator can be prevented. In this way, the pressure guided to the third signal pressure channel 50 accurately becomes the average pressure of the first and second main channels 20, 22, and the horsepower control regulator 40 can perform highly accurate equal horsepower control.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The present invention can be applied to a hydraulic circuit used in a hydraulic machine.

It is a hydraulic circuit diagram to which the present invention is applied. It is a figure explaining the orifice structure of this invention. It is a figure explaining the conventional orifice structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 10 1st pump 20 1st main flow path 22 2nd main flow path 40 Horsepower control regulator 42 Load sensing valve 44 Horsepower control spring 46 1st signal pressure flow path 48 2nd signal pressure flow path 50 3rd signal pressure flow path 52 Orifice 54 orifice 56 suction side flow path 58 first original pressure flow path 59 drain flow path 60 fifth port 62 sixth port 73 second original pressure flow path 74 fourth original pressure flow path 75 third original pressure flow path 76 hydraulic actuator 78 return spring 80 Cross flow channel 82 Plug 86 Through hole 87 Bulkhead 88 Both end faces 89 Step portion 90 Hole 92 Hole 100 Block

Claims (3)

A swash plate type double piston pump driven by a drive source and having a variable discharge amount;
A horsepower control regulator that controls the discharge flow rate by changing the tilt angle of the swashplate in accordance with the discharge pressure so that the horsepower of this swashplate type double piston pump is constant,
First and second main flow paths through which hydraulic oil discharged from the swash plate type double piston pump flows;
In a hydraulic circuit including a sub-flow path that branches from the first and second main flow paths and causes the pressure of hydraulic oil to act on the spool in opposition to the horsepower control spring of the horsepower control regulator,
The sub-flow path is connected to the horsepower control regulator by combining the first and second signal pressure flow paths that communicate with the first and second main flow paths, and the first and second signal pressure flow paths, respectively. A signal pressure channel,
An orifice is provided in each of the first and second signal pressure channels,
A hydraulic circuit comprising a guide that is positioned between the two orifices and that guides hydraulic oil discharged from each orifice to the third signal pressure flow path without colliding with each other.   2. The hydraulic circuit according to claim 1, wherein the guide is a partition wall formed between the orifices and in a joining portion of the third signal pressure flow path. Providing a communication channel for communicating the first and second main channels and the third signal pressure channel;
A plug for controlling the flow of hydraulic oil between the first and second main flow paths and the third signal pressure flow path is installed in the communication flow path,
The plug has a hole having a predetermined depth so as to form the partition along the central axis from each end face facing the first main flow path and the second main flow path, and a bottom portion of the plug is formed. Each open to the third signal pressure channel,
3. The hydraulic pressure according to claim 2, wherein the perforated hole portion corresponds to the first and second main flow paths, and a part of the hole portion is reduced in diameter to form the orifice. circuit.

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