JP3853336B2 - Industrial vehicle control valve - Google Patents

Description

  The present invention relates to an industrial vehicle control valve for controlling various actuators in an industrial vehicle such as a garbage truck.

  Conventionally, various industrial vehicles have been provided with electromagnetic control valves for electro-hydraulic control, and actuators of each device are hydraulically controlled.

  For example, as the control valve of this type, the present applicant has previously filed an invention related to an electromagnetic control valve for an industrial vehicle suitable for an industrial vehicle such as an electric-hydraulic control battery forklift (Patent Document 1). FIG. 5 is a hydraulic circuit diagram of the electromagnetic control valve for industrial vehicles.

  As shown in the figure, the present invention is configured to drive and control a lift cylinder 101 that moves a front fork of a forklift up and down with a hydraulic oil supplied from a tank 111 by a hydraulic pump 100 and a tilt cylinder 102 that performs a tilt operation. Has been.

  A main spool 103 that controls the lift cylinder 101 and a main spool 104 that controls the tilt cylinder 102 are disposed on a bypass passage 105 that connects the pump port P and the tank port T, and the main spools 103 and 104 are in a neutral position. Thus, the pump port P and the tank port T are in communication with each other.

  A pilot passage 106 connected to the primary side of the pilot valves 112 to 115 for driving the main spools 103 and 104 from the bypass passage 105 upstream of the main spool 103 located on the upstream side is provided, A pressure reducing valve 107 is provided in the pilot passage 106.

A tank passage 108 is provided for joining the return oil from the cylinders 101 and 102 connected to the control ports of the main spools 103 and 104 to the bypass passage 105 downstream of the main spool 104 on the downstream side. And the bypass passage 105 upstream of the junction 109 and downstream of the main spool 104, the pressure oil flows to generate the primary pressure of the pilot pressure for driving the spools 103, 104 upstream thereof. A primary pressure generating valve 110 is provided.
JP-A-2002-68696 (page 3-9, FIG. 2)

  By the way, in the case of the hydraulic circuit of the electromagnetic control valve, when the oil flows from the pump 100 to the bypass passage 105 when the main spools 103 and 104 are in the neutral position, the primary pressure generating valve 110 is placed on the bypass passage 105. The pressure immediately before the primary pressure generating valve is set to a preset pressure set by the primary pressure generating valve return spring. This set pressure is set to a necessary minimum pressure at which the pilot valves 112 to 115 can switch the main spools 103 and 104. The pressure at the pump port P at this time is a pressure obtained by adding a passage resistance generated in the bypass passage 105 from the pump port P to the primary pressure generating valve 110 to the pressure generated by the primary pressure generating valve 110. .

  Therefore, when the number of valve stations is increased and the bypass passage 105 becomes longer, or when the flow rate flowing through the bypass passage 105 in the neutral state increases, the relationship between the flow rate and the pressure shown in FIG. 6 is schematically shown. As shown in the graph, the pressure loss in the bypass passage 105 increases, and the pressure (unload pressure) of the pump port P is the minimum pressure (primary pressure generating valve) required for the pilot valves 112 to 115 to switch the main spools 103 and 104. 110), the pressure loss generated in the bypass passage 105 is added to the pressure, which becomes very high.

  In the case of the electromagnetic control valve suitable for the battery forklift described above, the hydraulic pump drive motor does not operate unless the lever operation for operating the actuators 101 and 102 is performed, so that no oil flows into the control valve bypass passage 105. When the lever operation for operating the actuators 101 and 102 is performed, the electric motor is operated and the hydraulic pump discharges the oil and the oil flows into the bypass passage. At the same time, the main spools 103 and 104 move to move the actuators 101 and 102. Therefore, there is no problem even if the unload pressure is high when it flows through the primary pressure generating valve section.

  However, in the case of a general industrial vehicle (such as a dust collection vehicle or a detachable body vehicle) in which a pump is driven by an engine, even when the spools 103 and 104 that do not operate the actuators 101 and 102 are in a neutral state, Oil always flows through the bypass passage 105. Moreover, in general industrial vehicles, the number of actuators to be controlled may increase due to an increase in optional equipment. In such a case, the number of spools (the number of valve stations) increases, so that the pressure in the bypass passage 105 is increased as described above. Loss further increases. Some industrial vehicles have a large flow rate set in a valve neutral state, and the pressure loss in the bypass passage 105 also increases in this case.

  For this reason, in the hydraulic circuit of the electromagnetic control valve, the unload pressure is increased and wasteful energy is consumed under the use conditions in which oil always flows through the bypass passage 105, and the temperature of the hydraulic oil also increases. End up.

  Therefore, in order to solve the above problems, the present invention is configured such that the pump port and the tank port are in communication with each other at a neutral position of the plurality of main spools for actuators arranged on the bypass passage. A pilot passage connected to the primary side of a pilot valve that controls each main spool is provided from a bypass passage on the upstream side of the most upstream spool, a pressure reducing valve is provided in the pilot passage, and is connected to a control port of each main spool. In a control valve for an industrial vehicle provided with a tank passage for joining return oil from the actuator to the bypass passage on the downstream side of the most downstream spool, the tank passage and the bypass passage on the bypass passage on the downstream side of the most downstream spool When the pressure oil flows upstream from the merging point with the main spool system, A primary pressure generating valve for generating the primary pressure of the pilot valve for the engine is provided, and a pressure guiding passage for guiding the control pressure to the primary pressure generating valve is connected upstream of the most upstream spool of the bypass passage. . As a result, a pressure upstream of the most upstream spool can always be obtained as the control pressure of the primary pressure generating valve.

  Also, in this industrial vehicle control valve, if the pressure guiding passage is connected upstream of the pilot passage, the pump port pressure is set by the primary pressure generating valve even when the station number or flow rate increases. The constant pressure is obtained.

  The present invention makes it possible to configure a control valve that can prevent wasteful energy consumption by always ensuring the control pressure of the primary pressure generating valve at a constant pressure by means as described above. In addition, it is possible to configure a control valve that can stably obtain a constant pump port pressure (unload pressure) even when the number of valve stations and the flow rate change.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a hydraulic circuit diagram showing an industrial vehicle control valve according to an embodiment of the present invention. In this embodiment, the number of valve stations (in this specification and claims, the term “valve station number” means the number of “valve” stations each having a “main spool for actuator” that drives each actuator. ) Is an example of a quadruple control valve, and the first, second, third and fourth may be attached from the left upstream side illustrated in the description.

  As shown in the figure, in the industrial vehicle control valve 1 of this embodiment, the oil in the tank 2 is supplied from the pump port P to the bypass passage 4 by the hydraulic pump 3, and the tank port T on the most downstream side of the bypass passage 4 is supplied. It is comprised so that it may return to the tank 2 via. The bypass passage 4 is provided with a plurality of actuator main spools 5 to 8 in series. These actuator main spools 5 to 8 are provided independently to the valves 9 to 12 (see FIG. 2), and are configured to drive different actuators.

  Further, the primary side of the pressure reducing valve 13 for making the pilot valve primary pressures of all the spools 5 to 8 constant is connected to the upstream side of the most upstream actuator main spool 5. In this embodiment, the pressure of the pilot line for operating the spools 5 to 8 is always kept constant by providing the pressure reducing valve 13.

  Further, similarly to the primary side of the pressure reducing valve 13, a relief valve 15 is provided on the upstream side of the most upstream actuator main spool 5 to release the pressure oil to the tank passage 14 when the pressure in the bypass passage 4 rises. It has been.

  In this embodiment, pressure oil is independently supplied to the most upstream actuator main spool 5 (first spool) by the branch passage 16 branched from the bypass passage 4. The other three main actuator spools 6, 7 and 8 (second, third and fourth spools) are respectively supplied with pressure oil by a parallel passage 17 branched from the bypass passage 4.

  The branch passage 16 is connected to an inlet port 19 of the first spool 5 via a check valve 18. The parallel passage 17 is connected to the inlet ports 23, 24, 25 of the second to fourth spools 6, 7, 8 via check valves 20, 21, 22 respectively. In this embodiment, the pressure oil is guided from the bypass passage 4 to the first spool 5 and the second to fourth spools 6, 7, 8 in a separate system, but this configuration is an example, and the actuator Other combinations may be used depending on the type of the above.

  Actuators (not shown) driven via these actuator main spools 5 to 8 are hydraulic jacks, hydraulic motors, and the like, and any of ports A1 to A4 and ports B1 to B4 is on the supply side. Is connected to the discharge side.

  Further, these actuator main spools 5 to 8 are configured to unload the pump pressure by returning the pressure oil from the hydraulic pump 3 to the tank 2 when all the neutral spools are in the neutral position and the bypass passage 4 is in the communication state. Yes. The actuator main spools 5 to 8 of this embodiment are configured to block all the ports A1 to A4 and ports B1 to B4 at the neutral position, but may be configured such that one of them is released to the tank at the neutral position. Yes, the configuration of the main spools 5 to 8 may be determined according to the type and conditions of the actuator. Further, in this embodiment, the spools 5 to 8 are all shown in the same configuration, but the main spools 5 to 8 are configured according to the type of actuator, use conditions, and the like.

  These actuator main spools 5 to 8 are stroked by spool driving pilot valves 26 to 33 controlled by a predetermined pilot pressure. These pilot valves 26 to 33 use the pressure from the pilot passage 34 connected to the pressure reducing valve 13 as the primary pressure, and excite the coils of the pilot valves 26 to 33 to thereby apply the secondary pressure to the pilot valves 26 to 33. Occurs, and the actuator main spools 5 to 8 are stroked from the neutral position. Reference numeral 35 denotes a drain passage.

  When the actuator main spools 5 to 8 are in the neutral position, the coils of the pilot valves 26 to 33 of all the actuator main spools 5 to 8 are not excited, and the ports A1 to A1 of the actuator main spools 5 to 8 are not excited. The state where A4 and ports B1 to B4 are blocked is maintained.

  Further, when the upper spool driving pilot valves 26, 28, 30, 32 shown in the drawings of the actuator main spools 5 to 8 are excited, the main spools 5 to 8 are stroked downward in FIG. Switch. When these main spools 5-8 are switched to the upper function, the bypass passage 4 is fully closed, the inlet ports 19, 23, 24, 25 communicate with the ports A1-A4, and the tank passage 14 connects with the ports B1-B4. Communicate. On the contrary, when the lower spool driving pilot valves 27, 29, 31, 33 shown in the figure of the actuator main spools 5-8 are energized, the main spools 5-8 are stroked upward in the drawing. Switch to the side function. When these main spools 5 to 8 are switched to the lower function, the bypass passage 4 is fully closed, the inlet ports 19, 23, 24, and 25 communicate with the ports B1 to B4, and the tank passage 14 is connected to the ports A1 to A4. Communicate with.

  In such a hydraulic circuit, on the downstream side of the most downstream actuator main spool 8 in the bypass passage 4, the merge of the tank passage 14 and the bypass passage 4 that returns the pressure oil from all the actuator main spools 5 to 8 to the tank 2. A primary pressure generating valve 37 that generates a primary pressure for driving the pilot valves 26 to 33 is provided upstream of the point 36.

  The primary pressure generating valve 37 generates a predetermined pressure on the primary side of the pressure reducing valve 13 by controlling the flow of pressure oil in the bypass passage 4, and each oil reduced in pressure by the pressure reducing valve 13 A pilot pressure for operating the actuator main spools 5 to 8 as an electromagnetic control valve (including an electromagnetic operation valve and an electromagnetic proportional valve) is secured.

  A pressure guide passage 38 for operating the primary pressure generating valve 37 is connected to the bypass passage 4 upstream of the connection portion between the pilot passage 34 and the bypass passage 4 that communicates with the pressure reducing valve 13. . In this way, by providing the upstream end of the pressure guiding passage 38 between the pump port P and the connection portion of the pilot passage 34 communicating with the pressure reducing valve 13, the pressure oil immediately after the pump port P is transferred to the primary pressure generating valve 37. It leads directly. A pressure detection path 39 communicating with the pilot passage 34 is connected to the spring side of the primary pressure generating valve 37.

  In this way, by guiding the pressure oil pressure immediately after the pump port P as the control pressure of the primary pressure generating valve 37, the primary pressure generating valve 37 is always in the pump port without being affected by the pressure loss in the bypass passage 4. The pressure of P can be made constant. That is, since the pressure for controlling the primary pressure generating valve 37 is introduced immediately after the pump port P, the pressure of the pump port P is controlled by the primary pressure generating valve 37 regardless of the pressure loss generated in the bypass passage 4. It can be set pressure.

  In this embodiment, the pressure guide passage 38 is connected to the upstream side of the pilot passage 34. However, the pressure guide passage 38 is connected to the upstream side of the most upstream spool 5 and always connected to the most upstream spool 5. Even if the upstream pressure is obtained as the control pressure of the primary pressure generating valve 37, the pressure at the pump port P is not affected by the pressure loss when the number of valve stations is increased and the bypass passage 4 becomes longer. Can always be controlled to be constant.

  2 is a longitudinal sectional view showing the main part of the control valve for an industrial vehicle shown in FIG. 1, and FIG. 3 is a sectional view taken along the line III-III shown in FIG. The left side of FIG. 2 is the pump port side block 40, and the right side of the figure is the bypass passage downstream side block 41. In the figure, only the configuration of the main part is shown. The same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in these drawings, the industrial vehicle control valve 1 includes a pump port side block 40, valves 9 to 12 having the plurality of actuator main spools 5 to 8, and a bypass passage downstream block 41. Are integrally connected.

  The pressure guiding passage 38 is provided so as to penetrate the valves 9 to 12. The pressure guide passage 38 communicates from the upstream side of the bypass passage 4 of the oil chamber 53 formed in the pump port P of the pump port side block 40 to the pressure guide chamber 42 provided in the bypass passage downstream block 41. Is provided.

  The bypass passage downstream block 41 is provided with a slide hole 43 in the vertical direction in the figure. From the top, the slide hole 43 is connected to the pressure guiding chamber 42, the working chamber 44 communicating with the bypass passage 4, the oil discharge chamber 45 communicating with the tank port T, and the secondary side of the pressure reducing valve 13. And a spring chamber 46 through which the pressure is guided through the pressure detection path 39.

  A primary pressure generating valve spool 47 that slides in the vertical direction is provided in the slide hole 43. The lower side of the spool 47 is urged upward by a spring 48 provided in the spring chamber 46. Due to the urging force of the spring 48, the upper end of the spool 47 is in contact with a plug 49 provided at the upper end of the slide hole 43.

  The primary pressure generating valve spool 47 includes a seal portion 50 between the pressure guiding chamber 42 and the working chamber 44, a seal portion 51 between the oil discharge chamber 45 and the spring chamber 46, and the working chamber 44. A closing plate 52 between the oil discharge chamber 45 and the oil discharge chamber 45 is formed. The closing plate 52 closes the space between the working chamber 44 and the oil discharge chamber 45 when the spool 47 is biased upward by the spring 48, and operates when the spool 47 slides downward against the spring 48. The chamber 44 and the oil discharge chamber 45 are communicated with each other.

  Thus, when the pressure guided from the pressure guiding passage 38 to the pressure guiding chamber 42 becomes larger than the resultant force of the force of the spring 48 and the pressure acting on the spring chamber 46 (pressure from the pressure detection path 39), the spool 47 is directed downward. Slide to. When the spool 47 is pushed down, the closing plate 52 is lowered, the working chamber 44 and the oil discharge chamber 45 communicate with each other, and the pressure oil in the working chamber 44 is discharged from the oil discharge chamber 45 to the tank port T.

  That is, the pressure acting on the pressure introducing chamber 42 from the pressure guiding passage 38 is based on the set pressure of the primary pressure generating valve 37 (for example, the pressure equivalent to the spring force of the primary pressure generating valve 37 + the secondary pressure of the pressure reducing valve 13). Since the spool 47 of the primary pressure generating valve 37 slides downward to connect the pump port P side and the tank port T side, the pressure oil flowing in from the pump port P is transferred from the tank port T to the tank 2. (FIG. 1). In this state, the primary pressure of the pressure reducing valve 13 is always equal to or higher than the pressure reducing valve set secondary pressure, so that the secondary pressure of the pressure reducing valve 13 for driving the main spool is always secured.

  Further, when the spool driving pilot valves 26 to 33 are operated at the time of switching the main spools 5 to 8, the main spools 5 to 8 are stroked. In the transient state, the bypass passage 4 is entirely moved by the main spools 5 to 8. Until it is closed, a part of the hydraulic oil flowing in from the pump port P passes through the primary pressure generating valve 37 through the bypass passage 4 and is necessary for driving the main spools 5 to 8 as in the neutral state. A sufficient pilot pressure can be secured. When the bypass passage 4 is completely closed by the main spools 5 to 8, the entire amount of oil flowing from the pump port P flows to the actuator. At this time, a pressure necessary for driving the actuator is generated in the pump port P. Usually, since this pressure is equal to or higher than the set pressure (secondary pressure) of the pressure reducing valve 13, the spool driving pressure is secured.

  Therefore, according to the control valve 1 for industrial vehicles, many actuators are provided like a garbage truck, and even under use conditions in which pressure oil is always supplied to any of those actuators, The pressure oil flowing in from the pump port P flows into the working chamber 44 of the primary pressure generating valve 37 via the bypass passage 4, and the pressure of the pump port P is guided from the pressure guiding passage 38 to the pressure guiding chamber 42. On the other hand, since the secondary pressure of the pressure reducing valve 13 is guided to the spring chamber 46 via the pressure detection path 39, the actuator main spools 5 to 8 can be located at any position between the neutral position and the operating position. The pressure of the pump port P (pressure in the working chamber 44) rises to “primary pressure generating valve spring force equivalent pressure + pressure reducing valve secondary pressure”, and the primary pressure of the pressure reducing valve 13 is ensured. 6-33 it is possible to ensure the pilot pressure required to operate normally.

  As a result, as shown in the graph schematically showing the relationship between the flow rate and the pressure in FIG. 4, a control valve that can always prevent the wasteful energy consumption by ensuring the control pressure of the primary pressure generating valve at a constant pressure is configured. It becomes possible.

  In addition, in this embodiment, the secondary pressure of the pressure reducing valve 13 is guided to the spring chamber 46 of the primary pressure generating valve 37 through the pressure detection path 39, so that the primary pressure generating valve 37 is set to the set pressure of the pressure reducing valve 13. The pressure can be adjusted according to The pressure detection path 39 is not necessarily provided, and a valve that generates a primary pressure equal to or higher than the set pressure of the pressure reducing valve 13 only with a spring may be provided.

  Further, since the primary pressure generating valve 37 in this embodiment obtains a predetermined pressure with the pressure oil guided to the pressure guiding chamber 42 through the pressure guiding passage 38 immediately after the pump port P, the flow rate or the valve station number is high. Even if the pressure loss in the bypass passage 4 changes due to the increase, the primary pressure generating valve 37 can maintain the minimum pressure required as the primary pressure of the pressure reducing valve 13, so the unload pressure becomes high. It is possible to suppress wasteful energy consumption.

  Moreover, according to the industrial vehicle control valve 1, the control pressure of the primary pressure generating valve 37 is maintained at a large flow rate by keeping the pressure of the pump port P constant in the neutral state of each actuator main spool 5-8. Since the (throttle amount) is relatively small, fluid noise (noise) generated when the fluid passes through the primary pressure generating valve 37 is also reduced.

  In the above embodiment, the four-valve station number has been described as an example, but the present invention is not limited to the four-valve valve, and the valve station number is not limited to the above-described embodiment.

  The above-described embodiment shows an example, and various modifications can be made without departing from the gist of the present invention. The present invention is not limited to the above-described embodiment.

  The control valve for an industrial vehicle according to the present invention is useful in an industrial vehicle in which pressure oil is constantly supplied to an actuator, such as a garbage truck.

It is a hydraulic circuit diagram which shows the control valve for industrial vehicles which shows one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the principal part of the control valve for industrial vehicles shown in FIG. It is III-III sectional drawing shown in FIG. It is a graph which shows typically the relation between the flow and pressure in the control valve for industrial vehicles of the present invention. It is a hydraulic circuit diagram which shows the conventional control valve for industrial vehicles. It is a graph which shows typically the relation between the flow and pressure in the conventional industrial vehicle control valve.

Explanation of symbols

1 ... Hydraulic pump
2 ... Tank
3 ... Hydraulic pump
4 ... Bypass passage 5-8 ... Main spool for actuator 9-12 ... Valve 13 ... Pressure reducing valve 14 ... Tank passage 15 ... Relief valve 16 ... Branch passage 17 ... Parallel passage 18 ... Check valve 19 ... Inlet port 20-22 ... Check Valve 23 to 25 ... Inlet port 26 to 33 ... Spool drive pilot valve 34 ... Pilot passage 35 ... Drain passage 36 ... Junction point 37 ... Primary pressure generating valve 38 ... Induction pressure passage 39 ... Pressure detection passage 40 ... Pump port side Block 41 ... Bypass passage downstream block 42 ... Pressure guiding chamber 43 ... Slide hole 44 ... Working chamber 45 ... Oil discharge chamber 46 ... Spring chamber 47 ... Primary pressure generating valve spool 48 ... Spring 49 ... Plug 50, 51 ... Sealing part 52 ... Closure plate 53 ... Oil chamber
P ... Pump port
T ... Tank port

Claims (2)

A pump port and a tank port are in communication with each other at a neutral position of a plurality of actuator main spools arranged on the bypass passage, and each main spool is connected to the main spool from the bypass passage upstream of the most upstream spool of the main spool. A pilot passage connected to the primary side of the pilot valve for controlling the pilot valve, a pressure reducing valve provided in the pilot passage, and return oil from the actuator connected to the control port of each main spool to the downstream side of the most downstream spool In a control valve for an industrial vehicle provided with a tank passage that joins the bypass passage,
On the bypass passage on the downstream side of the most downstream spool, the pressure oil flows upstream from the junction of the tank passage and the bypass passage, so that the primary pressure of the pilot valve for main spool control is upstream of the pressure oil. A control valve for an industrial vehicle, provided with a primary pressure generating valve to be generated, and having a pressure guiding passage for guiding a control pressure to the primary pressure generating valve connected upstream of the most upstream spool of the bypass passage. The control valve for an industrial vehicle according to claim 1,
An industrial vehicle control valve in which the pressure guiding passage is connected upstream of the pilot passage.

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