JPS5912883B2 - Flow divider negative pressure prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative pressure prevention device for a flow divider having a flow dividing function and a flow collecting function.

Flow dividers of this type are used, for example, to synchronize two actuators, such as the boom telescoping cylinder of a front truck crane.

However, with conventional flow dividers, cavitation occurs during flow collection, and not only does the tuning function disappear, but also
There was a risk of noise generation and even damage to the flow divider.

The reasons for this are as follows.

This type of flow divider A has two pump motors A1 with a pump function and a motor function, as shown in Fig. 2.
, A2 are coaxially connected. Conventionally, this flow divider A is used as is, and when dividing the flow, the pressure oil in the collecting side flow path B is divided by the flow divider A and the flow is connected to the divided side flow. At the time of flow collection, the pressure oil in the branch side flow path C2D was directly introduced into the flow divider A, and the flow was collected and led out to the collection side flow path B.

In this case, at the time of convergence, the inflow amounts Qc and Qd from flow paths C and D to flow divider A are
If the dividing or collecting ratio of is 1:1, then Q c =Q d.

If it is 1:2, Qc = 2Qd, but if there is a difference between the inflow amounts Qc and Qd, that is, the flow rate ratio of Qc and Qd is the dividing or concentrating ratio of flow divider A. If they are different, the rotation of the pump motors A1 and A2 of the flow divider A is determined by the amount of oil flowing into the flow path, so the flow path with the smaller flow becomes negative pressure due to the pumping action of the pump motor A1 or A2, causing cavitation. .

For example, if the inflow amount Qc from the flow path C is too large, the flow path becomes negative pressure and cavitation occurs.

The present invention provides a device that can prevent the flow divider from becoming negative pressure, particularly in the flow divider side flow path during flow collection, and can prevent the occurrence of cavitation.

A feature of the present invention is that a flow divider, which is formed by coaxially connecting two pump motors with a flow dividing function and a flow collecting function, has one flow passage on the primary side and one flow passage on the secondary side. The two branch flow channels are connected to the flow divider, and a check valve is installed in the middle of each branch flow channel to allow the flow of branch oil from the flow divider toward the end of each branch flow channel. A bypass flow path that bypasses each check valve from the end of the flow path and guides the collection oil toward the flow divider is connected in parallel, and both bypass flow paths are provided with both branch flow sides between the flow divider and the check valve. A switching valve is provided which operates depending on the difference between the lower flow paths, and the switching valve is configured to throttle or block the amount of oil flowing into the flow divider from the higher flow flow path on the lower side. Located in the negative pressure prevention device of the flow divider.

The present invention will be explained below with reference to an embodiment shown in FIG.

Reference numeral 1 denotes a flow divider, which is configured so that two pump motors 1a and 1b having a pump function and a motor function are coaxially connected to exhibit a flow dividing function and a flow collecting function, and the flow is collected on the primary side. The side flow path 2 is connected to the flow paths 3a and 3b on the secondary side.
The branch flow channels 3 and 4, which are composed of flow channels 4a and 4b, are connected to each other.

Reference numerals 5 and 6 designate check valves that allow flow from the flow divider 1 in the middle of both the flow paths 3 and 4, that is, between the flow paths 3a and 3b and between the flow paths 4a and 4b, toward the end of the flow paths on the divided flow path. It is set in the direction of

Reference numerals 7 and 8 designate bypass channels, which are connected to each of the branch flow channels 3 and 4 so as to bypass the check valves 5 and 6 and guide the collecting oil from the end of each branch flow channel toward the flow divider. The check valves 5 and 6 are connected in parallel.

9 is a switching valve, which is provided in the middle of the bypass channels 7 and 8;
The flow path 3a is connected to the pilot ports at both ends during flow convergence.
4a to the pilot flow path 10°11 and the throttle valve 12,
A pilot king is guided through 13 and is actuated by the pressure difference to throttle or block the amount of oil flowing into the lower higher channel 3a or 4a.

Check valves 14 and 15 are provided between the switching valves 9 of the bypass flow paths 7 and 8 and the flow paths 3a and 4a in a direction that allows the flow of the collecting oil toward the flow divider.

Next, the effect will be explained.

At the time of separation, the oil guided in the direction of arrow A from the flow path 2 on the collecting side flows into the flow divider 1, and is divided into a predetermined separation ratio by the two pump motors 1a and 1b, and the oil that has passed through the pump motor 1a flows into the flow divider 1. The oil is led to the branch flow path 3 and flows in the direction of the arrow, through the flow path 3a, the check valve 5, and the flow path 3b to an actuator (not shown), and the oil that has passed through the pump motor 1b is led to the flow path 3 on the diversion side. It is guided into the flow path 4 and guided in the convex direction of the arrow,
It flows into other actuators (not shown) through the flow path 4a, the check valve 6, and the flow path 4b.

At this time, check valves 14 and 15 are installed in the bypass channels 7 and 8.
Since this is provided, the diverted oil does not flow into the switching valve 9 and flows smoothly in the convex direction of the arrow.

Thereby, oil can be supplied to both actuators at a predetermined division ratio, and both actuators can be operated in synchronism at a speed commensurate with the division ratio.

At the time of flow collection, the flow collecting oil that flows into the branch flow path 3 from an actuator (not shown) is guided from the flow path 3b in the two directions of the arrows, and passes through the bypass flow path 7, the switching valve 9, the check valve 14, and the flow path 3a. The flow collecting oil flowing into the pump motor 1a of the flow divider 1 and flowing into the branch flow path 4 from another actuator is guided from the flow path 4b in the direction of the arrow H, and flows into the bypass flow path 8.
, the switching valve 9, the check valve 15, and the flow path 4b before flowing into the pump motor 1b of the flow divider 1.

Then, the oil for the art collection is merged or collected in the flow divider 1, led out to the collection side flow path 2, and flowed out in the direction of the arrow.

At this time, check valves 5 and 6 are installed in the middle of the branch flow paths 3 and 4.
are provided, so that the collecting oil flows through the flow paths 3b and 4b.
The flow does not directly flow into the flow divider 1 , but always flows into the bypass channels 7 and 8 , and flows into the flow divider 1 via the switching valve 9 .

At the time of the above flow convergence, if the amount of oil that has flowed into the flow path 3b is greater than the amount of oil that has flowed into the flow path 4b (based on the flow divider or flow concentration ratio of the flow divider 1), then the arrow The oil guided in the direction flows into the pump motor 1a and drives the pump motor 1a, and accordingly, the pump motor 1b, which is coaxially connected, is driven and exerts a pumping action. The flow path 4a between the check valve 6 and the flow path 3a becomes under negative pressure.

4a is guided to pilot ports at both ends of the switching valve 9 via pilot flow paths 10, 11 and throttle valves 12, 13, and the pressure difference between the flow paths 3a and 4a causes the switching valve 9 to open as shown in FIG. is switched downward, from the flow path 3b to the flow path 7.
The oil that is about to flow into the flow path 3a via the switching valve 9 is throttled, and the amount of oil that drives the pump motor 1a is controlled to be reduced.

Note that when the flow rate flowing into the flow path 4b, that is, the flow in the direction of the arrow H, is zero, the switching valve 9 is completely switched downward in FIG. 1, and the flow in the two directions of the arrows is blocked.

In this way, the switching valve 9 is switched by the pressure difference in the flow paths 3a, 4a, so that the flow rate flowing into the flow paths 3a, 4a always has a predetermined dividing or collecting ratio. It is automatically controlled to rotate at a predetermined splitting or collecting ratio.

Thereby, even if there is a difference in the amount of oil flowing into the flow paths 3b and 4b, it is possible to prevent cavitation from occurring in the flow divider 1 as in the conventional case.

In addition, two pump motors 1a of the flow divider 1,
Since the driving pressure of ib can always be the same,
It is possible to maintain synchronization during flow collection.

That is, if the pressures in the flow paths 3a and 4a are different, a leakage difference occurs inside the flow divider 1, and the precision of flow collection deteriorates, but according to the present invention, such a fear is eliminated.

As explained above, according to the present invention, in a flow divider equipped with a flow dividing function and a flow collecting function, it is possible to prevent negative pressure in the flow path on the dividing side especially during flow collecting, and to prevent cavitation from occurring. It is possible to improve the accuracy of flow collection, suppress the generation of noise, and improve the mechanical life of the flow divider.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram showing an example of use of a conventional flow divider. DESCRIPTION OF SYMBOLS 1...Flow divider, 1a, 1b...Pump motor, 2...Collection side flow path, 3, 3a, 3b,
4. 4a, 4b...Diversion side flow path, 5, 6...Check valve, 7.8...Bypass flow path, 9...Switching valve.

Claims (1)

[Claims] 1. A flow divider consisting of two pump motors with a flow dividing function and a flow collecting function connected coaxially. One flow path on the primary side of the flow divider and two flow paths on the secondary side of the flow divider. A check valve is installed in the middle of each diversion side flow path to allow the flow of the diversion oil from the flow divider toward the end of each diversion side flow path, and a check valve is installed to bypass each check valve from the end of each diversion side flow path. A switching valve is connected in parallel to a bypass flow path that guides oil for collection toward the flow divider, and is operated by a pressure difference between the flow divider and the check valve on both the diversion side flow paths. , and the switching valve is configured to throttle or block the amount of oil flowing into the flow divider from the branch flow path with higher pressure. Pressure prevention device.