JP7515315B2 - Valve unit - Google Patents

Description

The present invention relates to a valve unit that controls oil.

Taking the hydraulic circuit of a tractor as an example, Patent Document 1 shows a pair of pilot flow paths (called pilot passages in the document) that guide the load pressure of a rolling cylinder, and of the pilot pressures of the pair of pilot flow paths, the higher pilot pressure is applied to a flow dividing valve.

In this hydraulic circuit, for example, when the rolling cylinder reaches the end of its stroke and the load pressure rises, the high-pressure pilot pressure operates the diverter valve, and the hydraulic oil supplied to the rolling cylinder is discharged from the diverter valve, making it possible to reduce the load.

JP 2011-2073 A (paragraph number [0045], etc.)

For example, in a vehicle such as a tractor that can be fitted with multiple hydraulic cylinders externally, a diversion valve that allows the supply and discharge of hydraulic oil to these multiple hydraulic cylinders is provided on the vehicle body side, and, as in Patent Document 1, an oil passage configuration may be adopted in which the highest pilot pressure among the load pressures acting on the multiple hydraulic cylinders is selected by a high-pressure selection valve, and the diversion valve is controlled by the selected load pressure.

In such vehicles, it is possible that fewer hydraulic cylinders than the number that can be installed may be installed, in which case the pilot flow passage that applies pilot pressure to the high-pressure selection valve will be blocked by a plug.

However, when the pilot flow path was blocked by a plug, pilot oil leaking from the high pressure selection valve, etc., could flow into the blocked pilot flow path, causing the pressure in the pilot flow path to rise. This type of pressure is called "trapped pressure." When trapped pressure occurs, it can act on the high pressure selection valve, impairing the proper operation of the high pressure selection valve.

For these reasons, there is a demand for a valve unit that can prevent the phenomenon of pressure increasing in a blocked flow path.

A characteristic configuration of a valve unit according to the present invention is that it comprises a valve housing having a flow passage connected to a port and a drain flow passage communicating with the flow passage, and a flow passage pressure control body inserted into the flow passage, the flow passage pressure control body being arranged at a position where the port is closed to connect the flow passage to the drain flow passage , the flow passage pressure control body being housed so as to be freely movable relative to the flow passage, being cylindrical with a bypass flow passage drilled in a direction in which the flow passage is formed, and having a communication path whose inner end communicates with the bypass flow passage and whose outer end communicates with an outer peripheral surface, and the flow passage pressure control body being configured to be freely switchable between a communication position where the communication path is connected to the drain flow passage and a non-communication position where the communication path is separated from the drain flow passage .

According to this characteristic configuration, for example, when a port is blocked by a blocking plug, the flow path pressure control body is positioned in a position that connects the blocked flow path to the drain flow path. Even if pilot oil leaks from a valve inside the housing, for example, the oil can be discharged into the drain flow path to suppress a pressure increase in the flow path.
Therefore, a valve unit capable of preventing the phenomenon of pressure rise in a blocked flow passage is configured.
Furthermore, a cylindrical flow path pressure control body is inserted into the flow path so as to be movable in a direction along the axis of the flow path, and when the port of the flow path is blocked, the flow path is connected to the drain flow path via the bypass flow path and the communication path by setting the flow path pressure control body to the communication position, thereby preventing a pressure rise in the flow path. On the other hand, when the opening of the flow path is not blocked, it is possible to set the flow path pressure control body to the non-communication position to prevent communication between the flow path and the drain flow path, so that oil is not wasted in the drain flow path and the oil can flow through the bypass flow path of the flow path pressure control body.

As an additional configuration to the above configuration, the valve housing may be capable of mounting either a blocking plug that blocks the port or a hose plug that communicates with the flow path by connecting to the port, and when the blocking plug is mounted on the port, the flow path pressure control body may be held in the communicating position by abutting against the blocking plug, and when the hose plug is mounted on the port, the flow path pressure control body may be held in the non-communicating position by abutting against the hose plug.

According to this, when a blocking plug is attached to the port, the flow path pressure control body is held in a communicating position by abutting against this blocking plug, and pressure rise in the flow path can be suppressed. Also, when a hose plug is attached to the port, the flow path pressure control body is held in a non-communicating position by abutting against this hose plug, making it possible to communicate between the flow path and the hose without incurring the inconvenience of hydraulic oil flowing into the drain flow path.

In addition to the above configuration, a biasing member may be provided to bias the flow path pressure control body toward the port.

As a result, the flow path pressure control body can be maintained in contact with the blocking plug or hose plug by the biasing force of the biasing member, and the flow path pressure control body can be maintained in either the communicating position or the non-communicating position.

A characteristic configuration of another valve unit according to the present invention is that it comprises a valve housing having a flow passage connected to a port and a drain flow passage communicating with the flow passage, and a flow passage pressure control body inserted into the flow passage, the flow passage pressure control body is arranged at a position where the port is closed to connect the flow passage to the drain flow passage, the valve housing can be fitted with either a blocking plug that blocks the port or a hose plug that communicates with the flow passage by being connected to the port, the blocking plug is provided with the flow passage pressure control body, when the blocking plug is attached to the port, the flow passage pressure control body connects the flow passage to the drain flow passage, and the hose plug is provided with a cylindrical body, when the hose plug is attached to the port, the cylindrical body connects the flow passage to the hose plug without connecting the flow passage to the drain flow passage.

According to this characteristic configuration, for example, when a port is blocked by a blocking plug, the flow path pressure control body is positioned in a position that connects the blocked flow path to the drain flow path. Even if pilot oil leaks from a valve inside the housing, for example, the oil can be discharged into the drain flow path to suppress a pressure increase in the flow path.
Therefore, a valve unit capable of preventing the phenomenon of pressure rise in a blocked flow passage is configured.
When the port of the flow passage is blocked with a blocking plug, the flow passage pressure control body connects the flow passage to the drain passage, thereby suppressing a pressure rise in the supply flow passage. When a hose plug is attached to the port of the flow passage, the flow passage and the hose are connected, and the cylindrical body does not connect the flow passage and the drain passage.

FIG. FIG. FIG. FIG. 3 is a rear view of the valve unit; FIG. 2 is a hydraulic circuit diagram of the valve unit. FIG. 4 is a cross-sectional view of a sensing port portion of the valve unit. FIG. 2 is a cross-sectional view of a high pressure selection valve. 4A and 4B are cross-sectional views showing the pressure control cylinder in a communication position and a non-communication position. FIG. 13 is a cross-sectional view showing a blocking plug of another embodiment (a).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
〔Valve unit〕
As shown in FIGS. 1 to 5, a valve unit A is configured by incorporating a flow dividing valve V, a relief valve R, a first high pressure selection valve S1, and a second high pressure selection valve S2 in a valve housing H.

This valve unit A forms a pump port P in the valve housing H to which hydraulic oil is supplied from the hydraulic pump 1, and also forms three supply ports Q (a superordinate concept of the first, second, and third supply ports) in the valve housing H, a first supply port Q1, a second supply port Q2, and a third supply port Q3, in order to send out hydraulic oil controlled by the diversion valve V. In addition, the valve unit A forms in the valve housing H a first tank port T1 that discharges hydraulic oil from the diversion valve V, and a second tank port T2 that discharges hydraulic oil from the relief valve R.

The valve unit A has three sensing ports SP (a superordinate concept of the first, second, and third sensing ports) formed in the valve housing H: a first sensing port SP1, a second sensing port SP2, and a third sensing port SP3, in order to acquire the load pressure acting on the hydraulic actuator of the work device (not shown).

As shown in Figures 1 to 4, the valve housing H is generally block-shaped, and if the upper side in Figures 1 and 4 is described as the upper side of the valve housing H, a pump port P is formed in a protrusion that protrudes downward from the main body of the valve housing H, and a second tank port T2 is formed at the upper end of the main body of the valve housing H. In addition, a diversion valve V is housed in a space that penetrates the main body of the valve housing H in the horizontal direction, and a relief valve R is housed in the space above this diversion valve V.

As shown in FIG. 1, if the direction in which the flow diverter valve V extends is the left-right direction, the first supply port Q1, the first sensing port SP1, and the first tank port T1 are formed on one surface in the front-rear direction, which is a direction perpendicular to the left-right direction. Also, as shown in FIG. 1 and FIG. 3, the second supply port Q2 is formed on the side of the portion where the first supply port Q1 is formed.

Furthermore, as shown in FIG. 2, a third supply port Q3, a second sensing port SP2, and a third sensing port SP3 are formed on the lower end surface Ha of the main body portion of the valve housing H.

This valve unit A is provided on a vehicle such as a tractor, and has multiple (three in this embodiment) supply ports Q formed therein to supply hydraulic oil to multiple hydraulic actuators provided on the vehicle. This valve unit A also has multiple (three in this embodiment) sensing ports SP formed therein to acquire the load pressure of multiple hydraulic actuators provided on the vehicle.

When controlling multiple hydraulic actuators with this valve unit A, the supply port Q is connected to the hydraulic actuators via a supply hose, and the sensing port SP is connected to the hydraulic actuators via a sensing hose 21b so that the load pressure of these hydraulic actuators is acquired by the valve unit A.

To facilitate such connections, in the valve housing H shown in Figures 1 to 4, the first supply port Q1 and the first sensing port SP1 are located close to each other, the second supply port Q2 and the second sensing port SP2 are located close to each other, and the third supply port Q3 and the third sensing port SP3 are located close to each other.

[Oil passage configuration]
As shown in FIG. 5, this valve unit A comprises a main flow path 2 to which hydraulic oil from a hydraulic pump 1 is supplied via a pump port P, a branch valve V that switches the flow of hydraulic oil supplied to this main flow path 2, a branch flow path 5 that branches off from the main flow path 2, and a relief valve R that opens when the pressure in this branch flow path 5 exceeds a set value, and these are housed in a valve housing H.

The flow dividing valve V is configured to selectively send hydraulic oil to either the supply flow path 3 or the discharge flow path 4. The supply flow path 3 is connected to the first supply port Q1, the second supply port Q2, and the third supply port Q3, and the discharge flow path 4 is connected to the first tank port T1. When the relief valve R is opened, the hydraulic oil in the branch flow path 5 is discharged to the second tank port T2.

The flow dividing valve V has a spool that controls the hydraulic oil, and this spool is biased by a spool spring Vs to a position where the hydraulic oil in the main flow path 2 is sent to the discharge flow path 4. The spool also receives pressure from the hydraulic oil so that it can be maintained in a position where the hydraulic oil is supplied to the supply flow path 3, and this pressure keeps the spool in a position where the hydraulic oil in the main flow path 2 is sent to the supply flow path 3 against the biasing force of the spool spring Vs.

This flow-diverting valve V is configured so that the pilot pressure selected by the second high-pressure selection valve S2 (described later) is applied to the end of the spool on which the biasing force of the spool spring Vs acts, via the operating pilot flow path 6, and the spool can be operated to a position that sends hydraulic oil from the main flow path 2 to the discharge flow path 4.

As a result, when the pilot pressure acting from the operating pilot flow path 6 exceeds a preset pressure, the spool is operated to send a portion of the hydraulic oil in the main flow path 2 to the discharge flow path 4, eliminating the effect of excessive load acting on the hydraulic actuator.

[Oil passage configuration: pilot oil passage]
The valve unit A houses the first high pressure selection valve S1 and the second high pressure selection valve S2 as shown in Figures 5 and 6. The valve housing H forms a third pilot flow path 13 between the third sensing port SP3 and one input side of the first high pressure selection valve S1, and forms a second pilot flow path 12 between the second sensing port SP2 and the other input side of the first high pressure selection valve S1.

The valve housing H also forms a pilot flow path (not numbered) between the output side of the first high pressure selection valve S1 and one input side of the second sensing port SP2, and forms a first pilot flow path 11 between the first sensing port SP1 and the other input side of the second high pressure selection valve S2.

Furthermore, the valve housing H is formed with the aforementioned operating pilot flow path 6 so that the pilot pressure from the output side of the second high pressure selection valve S2 acts on the spool of the flow dividing valve V. The first pilot flow path 11, the second pilot flow path 12, and the third pilot flow path 13 are referred to as the pilot flow path PC. This pilot flow path PC is an example of a flow path connected to a port (sensing port SP).

[Oil passage configuration: high pressure selection valve]
The high pressure selection valve is a generic concept of the first high pressure selection valve S1 and the second high pressure selection valve S2, and as shown in Fig. 7, this high pressure selection valve comprises a main body portion 15a, a plug-shaped case 15 arranged in contact with a bush portion 15b, and a ball 16 housed inside the plug-shaped case 15. The plug-shaped case 15 has a flow passage hole 15c formed in a region extending from the main body portion 15a to the bush portion 15b in a direction along the case axis (the central axis of the plug-shaped case 15), and the ball 16 is housed in the large diameter portion of this flow passage hole 15c at the boundary between the main body portion 15a and the bush portion 15b.

The main body 15a has an input side communication hole 17 that communicates from the flow passage hole 15c to the outer periphery of the main body 15a. The main body 15a also has an output side communication hole 18 that communicates from the large diameter portion of the flow passage hole 15c to the outer periphery of the main body 15a. In particular, the high pressure selection valve has the flow passage hole 15c formed in the bush portion 15b, the outer end position of the plug-shaped case 15, and the aforementioned input side communication hole 17 function as the input side, and the output side communication hole 18 functions as the output side.

With this configuration, the high pressure selection valve operates the ball 16 to the low pressure side using the high pressure of the pilot pressures acting on the two input sides (the input side communication hole 17 and the end of the flow passage hole 15c), making it possible to extract the high pressure from the output side (the output side communication hole 18).

As shown in FIG. 5, this valve unit A is configured to combine a first high-pressure selection valve S1 and a second high-pressure selection valve S2 to select and extract the highest pressure from the pilot pressure acting on the first sensing port SP1, the pilot pressure acting on the second sensing port SP2, and the pilot pressure acting on the third sensing port SP3, and apply it to the flow divider valve V.

[Sensing port]
In this valve unit A, when the load pressure acting on the working device is acquired, a hose plug 21 is connected to the sensing port SP as shown in Fig. 8. In contrast, when the sensing port is not used, the sensing port SP is blocked by a blocking plug 22. To enable such a connection, the male threads of the hose plug 21 and the blocking plug 22 have a common standard, and the female threads of these plugs have a common standard so that they can be screwed into the female threads of multiple sensing ports SP. As shown in Fig. 8, the hose plug 21 is provided at the end of the sensing hose 21b.

Now, let us consider a situation in which the sensing port SP is blocked by the blocking plug 22. When pilot oil leaks from the high pressure selection valve or the like and flows into the pilot flow path PC of the sensing port SP due to the sensing port SP being blocked by the blocking plug 22, a so-called "trapped pressure" is generated that increases the pressure in the pilot flow path PC. This "trapped pressure" can sometimes hinder the proper operation of the high pressure selection valve.

To prevent such inconveniences, as shown in Figures 5, 6, and 8, a drain passage 23 that connects the pilot passage PC and the second tank port T2 is formed in the valve housing H, and a pressure control cylinder 24 (an example of a passage pressure limiter) that controls the flow of pilot oil between the pilot passage PC and the drain passage 23 is provided in a state where it is inserted into the pilot passage PC.

As shown in FIG. 8, when the hose plug 21 is connected to the second sensing port SP2 (sensing port SP), the pressure control cylinder 24 is held in a non-communicating position that blocks the flow of pilot oil between the drain passage 23 and the second pilot passage 12 (pilot passage PC), and the pilot pressure acting from the sensing hose 21b is transmitted to the pilot passage PC.

In contrast, when the blocking plug 22 is connected to the third sensing port SP3 (sensing port SP) as shown in FIG. 8, the pressure control cylinder 24 is held in a communication position that connects the third pilot flow path 13 (pilot flow path PC) to the drain flow path 23, and is configured to discharge pilot oil into the drain flow path 23 and prevent the generation of "trapped pressure."

In other words, the first pilot flow passage 11, the second pilot flow passage 12, and the third pilot flow passage 13 are formed in the valve housing H with the same inner diameter as the pilot flow passage PC, and the drain flow passage 23 is formed in the valve housing H so as to communicate with these pilot flow passages PC.

The pressure control cylinder 24 is molded with an outer diameter that fits tightly around the inner circumference of the pilot flow path PC, and is inserted into each of the three pilot flow paths PC so that it can move freely in a direction along the axis of the pilot flow path PC. In addition, the valve unit A accommodates a spring 25 (an example of a biasing member) inside the pilot flow path PC, which biases the pressure control cylinder 24 in a direction approaching the sensing port SP.

The pressure control tube 24 is formed in a cylindrical shape with a bypass flow passage 24a coaxial with the axis of the pressure control tube 24, and a flow passage groove 24b is formed around the entire circumference of the outer periphery. This pressure control tube 24 is formed with a communication flow passage 24c that connects the flow passage groove 24b and the bypass flow passage 24a, and a small diameter section 24d is formed at one outer end (the side close to the sensing port SP).

At the boundary between the small diameter portion 24d and the main body of the pressure control cylinder 24, a stepped portion 24e is formed perpendicular to the axis of the pressure control cylinder 24. The flow groove 24b and the communication flow path 24c form a communication path. The bypass flow path 24a is drilled in the same direction as the pilot flow path PC when the pressure control cylinder 24 is inserted into the pilot flow path PC.

As shown in FIG. 8, the hose plug 21 is generally cylindrical, with a fitting protrusion 21a formed on the inner end side of the male thread. The inner diameter of the cylindrical part of this fitting protrusion 21a is set to be larger than the outer periphery of the small diameter part 24d of the pressure control tube 24. In contrast, the blocking plug 22 is formed with an abutment protrusion 22a on the inner end side of the male thread, the abutment protrusion having an end face perpendicular to the axis of the blocking plug 22.

As a result, as shown in FIG. 8, when the hose plug 21 is attached to the second sensing port SP2, the small diameter portion 24d of the pressure control tube 24 enters the inside of the cylindrical portion of the fitting protrusion 21a. This causes the stepped portion 24e of the pressure control tube 24 to come into contact with the protruding end of the fitting protrusion 21a of the hose plug 21, causing the pressure control tube 24 to reach a non-communicating position, and the biasing force of the spring 25 holds the pressure control tube 24 in the non-communicating position. As a result, while maintaining a state in which pilot pressure acts in the bypass flow path 24a, leakage of pilot oil between the bypass flow path 24a and the drain flow path 23 is prevented.

In contrast, as shown in FIG. 8, when the blocking plug 22 is attached to the third sensing port SP3, the protruding end of the small diameter portion 24d of the pressure control tube 24 abuts against the abutment protrusion 22a of the blocking plug 22, causing the pressure control tube 24 to reach the communication position, and the biasing force of the spring 25 holds the pressure control tube 24 in the communication position. As a result, the hydraulic oil in the bypass flow path 24a is discharged to the drain flow path 23 via the communication flow path 24c and the flow path groove 24b, eliminating the "trapped pressure" in the pilot flow path PC.

[Effects of the embodiment]
As shown in Figure 8, the position at which the drain passage 23 communicates with the pilot passage PC is set at a distance based on the lower end surface Ha of the valve housing H, and the position of the passage groove 24b formed in the pressure control cylinder 24 is set at a distance based on the end of the protruding side of the small diameter portion 24d.

This makes it possible to hold the pressure control tube 24 in a non-communicating position regardless of which sensing port SP the hose plug 21 is attached to. Also, it makes it possible to set the pressure control tube 24 in a communicating position regardless of which sensing port SP the blocking plug 22 is attached to.

By forming a drain passage 23 inside the valve housing H and configuring the valve unit A so that the pressure control tube 24 and spring 25 are inserted into the pilot passage PC, when either the hose plug 21 or the blocking plug 22 is attached, the pressure control tube 24 can be appropriately set to either the communicating position or the non-communicating position without any other manual operation, making it possible to obtain the appropriate pilot pressure in the pilot passage PC, or to eliminate the "trapped pressure" in the pilot passage PC.

[Another embodiment]
The present invention may be configured as follows other than the above-described embodiment (common numbers and symbols as in the embodiment are used to designate components having the same functions as in the embodiment).

(a) As shown in FIG. 9, a pressure control tube 24 (an example of a flow path pressure limiter) is formed integrally with the blocking plug 22, and a cylindrical body 30 is formed integrally with the hose plug 21. In this alternative embodiment (a), a drain flow path 23 is formed in the valve housing H in the same manner as in the embodiment, and the pressure control tube 24 formed integrally with the blocking plug 22 has a bypass flow path 24a, a flow path groove 24b, and a communication flow path 24c formed therein in the same manner as in the embodiment.

When the hose plug 21 is attached, there is no need to connect the pilot flow path PC to the drain flow path 23, so the cylindrical body 30 has a structure in which a through hole 30a is formed along the axis. This through hole 30a functions to transmit pilot pressure in the same way as the bypass flow path 24a of the pressure control tube 24. Note that this alternative embodiment (a) may adopt a configuration in which the pressure control tube 24 is integrally formed with the hose plug 21 instead of the cylindrical body 30.

With this configuration, when the blocking plug 22 is attached to the sensing port SP, the pressure control tube 24 is held in the communication position, so the bypass flow path 24a and the drain flow path 23 are connected to each other, eliminating the "pressure buildup" in the pilot flow path PC. Furthermore, when the hose plug 21 is attached to the sensing port SP, the cylindrical body 30 can maintain the pilot flow path PC in a connected state.

(b) The communication path formed in the pressure control cylinder 24 is not limited to the configuration of the combination of the flow groove 24b and the communication flow path 24c described in the embodiment. In other words, for example, by forming an annular groove that communicates with the drain flow path 23 on the inner circumference of the pilot flow path PC, it is possible to configure the communication path with a communication hole drilled in the radial direction to communicate the area from the bypass flow path 24a of the pressure control cylinder 24 to the outer circumference of the pressure control cylinder 24.

(c) It is also possible to configure the valve unit A without the spring 25 (an example of a biasing member) that applies a biasing force to the pressure control cylinder 24. As an alternative configuration, it is also possible to use multiple O-rings as biasing members instead of the spring 25.

(d) The valve unit A can be configured to control a diversion valve or the like so that the hydraulic oil supplied from the hydraulic pump 1 is supplied to another hydraulic actuator when the load pressure acting on the vehicle's hydraulic actuator increases. In addition to this configuration, the hydraulic pump 1 may be configured as a variable displacement type, and the flow rate of the hydraulic oil supplied from the hydraulic pump 1 may be controlled when an increase in the load pressure is detected.

The present invention can be used in a valve unit that controls oil.

21 Hose plug 21b Sensing hose (hose)
22 Blocking plug 23 Drain passage 24 Pressure control cylinder (passage pressure control body)
25 Spring (biasing member)
24a: bypass flow passage 24b: flow passage groove (communication path)
24c Communication flow path (communication path)
30 Cylindrical body H Valve housing Q Sensing port (port)
PC Pilot flow passage (flow passage connected to the port)

Claims (4)

a valve housing including a passage communicating with the port and a drain passage communicating with the passage;
a flow path pressure control body inserted into the flow path,
the flow passage pressure control body is disposed at a position where the flow passage is connected to the drain flow passage by closing the port,
the flow passage pressure control body is accommodated in the flow passage so as to be freely movable relative to the flow passage, has a cylindrical shape having a bypass flow passage drilled in a direction in which the flow passage is formed, and has a communication path whose inner end communicates with the bypass flow passage and whose outer end communicates with an outer circumferential surface,
The flow passage pressure control body is a valve unit configured to be freely switched between a communication position where the communication passage communicates with the drain flow passage and a non-communication position where the communication passage is separated from the drain flow passage. the valve housing is capable of mounting either a blocking plug that blocks the port or a hose plug that is connected to the port to communicate with the flow path,
2. The valve unit according to claim 1, wherein when the blocking plug is attached to the port, the flow path pressure control body is held in the communicating position by abutting against the blocking plug, and when the hose plug is attached to the port, the flow path pressure control body is held in the non-communicating position by abutting against the hose plug . The valve unit according to claim 2 , further comprising a biasing member that biases the flow path pressure control body toward the port. a valve housing including a passage communicating with the port and a drain passage communicating with the passage;
a flow path pressure control body inserted into the flow path,
the flow passage pressure control body is disposed at a position where the flow passage is connected to the drain flow passage by closing the port,
the valve housing is capable of mounting either a blocking plug that blocks the port or a hose plug that is connected to the port to communicate with the flow path,
the blocking plug is provided with the flow path pressure control body, and when the blocking plug is attached to the port, the flow path pressure control body connects the flow path to the drain flow path,
The valve unit includes a cylindrical body provided on the hose plug, and when the hose plug is attached to the port, the cylindrical body connects the flow path to the hose plug without connecting the flow path to the drain flow path.

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