JPS6134197Y2 - - Google Patents

Description

[Detailed description of the invention] This invention connects the discharge port of the oil pump to the lift arm drive cylinder via a high pressure line with a control valve in the middle. The present invention relates to a device for replenishing a reservoir with oil.

Conventionally, to replenish oil into the oil reservoir,
Either a separate pump is provided for oil replenishment, or oil is replenished by gravity from a separate replenishment tank. However, in the case of a separate pump type, a pump and its drive mechanism are required, making it expensive. In addition, in the case of a separate tank type, it is often difficult to find an appropriate space for installing the tank.

The idea is to use the discharged oil from the lift arm drive cylinder and supply this discharged oil to the reservoir, which will be explained below with reference to the drawings.

In the figure, 1 is an oil pump driven by an engine, its suction port 2 is connected to a tank 6 through a low pressure line 5 having filters 3 and 4, and its discharge port 7
is connected to the lift arm driving cylinder 14 via a high pressure line 8, high pressure lines 10 and 11 in the draft position control valve 9, and a high pressure line 13 in the lift arm control section 12.
The lift arm 15 rises when hydraulic pressure is supplied to the cylinder 14, and descends when the hydraulic pressure within the cylinder 14 is discharged.

The safety valve 16 in the control valve 9 is connected to the line 17
is connected to line 8 through line 8, and opens when the oil pressure in line 8 rises above a predetermined value, line 18, throttle 4
0 to tank 6 to prevent abnormal pressure rise in line 8.

The switching valve 20 is connected to the line 8 via a line 21 and to the switching valve 23 via a line 22. In the neutral state shown in the figure, the lines 21 and 22 are connected and the switching valve 23 is connected to the switching valve 23 via a line 22. Hydraulic pressure is applied to hold the switching valve 23 in the illustrated drain position against the elasticity of the spring. As a result, the line 10 is connected to the drain line 18, and the pressure inside the line 8 becomes low. There is a check valve 24 in the line 11 that allows flow only in the direction of the lift arm driving cylinder 14, and the line 11 is closed at the switching valve 23, and a line 2 branched from the line 13
5 passes through the throttle 26 and closes at the switching valve 27, so the oil pressure in the cylinder 14 is maintained and the lift arm 15 is in a stopped state.

When the switching valve 20 is manually shifted to the left in the figure (in the direction of arrow U), the line 21 closes at the switching valve 20 and the line 22 connects to the drain line 18, so the switching valve 23 closes due to the elasticity of the spring. It moves to the left in the figure and switches, lines 10 and 11 are connected and hydraulic pressure is supplied to the lift arm 14.
This causes the lift arm 15 to rise.

When the switching valve 20 is manually switched to the right in the figure (in the direction of arrow D), the lines 21 and 22 are connected in the same way as in the neutral state shown in the figure, the switching valve 23 is switched to the state shown in the figure, and the line 10 is connected to the drain line. Connect to line 18. At the same time, the switching valve 27 that is interlocked with the switching valve 20 is shifted to the right in the figure, so the line 25 is connected to the drain line 18, and the oil pressure in the cylinder 14 is passed through the lines 13, 25, 18, and the throttle 40. It is ejected and the lift arm 15 descends. Note that 41 is a safety valve that opens when the oil pressure in line 13 rises to a predetermined value or more, and connects line 13 and line 18.

In this way, when the lift arm driving cylinder is odorless and the switching valve 20 is in the neutral position shown in the figure or in the lowered position switched to the right (direction of arrow D), the oil discharged by the oil pump 1 flows through the lines 8, 10, 1.
8. Since the oil is drained into the tank 6 through the throttle 40, the oil pump 1 continues to operate in vain. The present invention attempts to supply oil during this period to the oil reservoir 31 of the master cylinder 30, and for this purpose, from the discharge oil line 18 upstream of the throttle 40 to the replenishment line (supply path) 42.
branch and connect this line 42 to the oil reservoir 31
is connected to.

The master cylinder 30 is provided with a plunger 34 operated by a brake pedal 33 therein, and the master cylinder 30 is connected to left and right hydraulic brakes 37, 38 through lines 35, 36. In order to keep the master cylinder 30 filled with oil at all times, it is necessary to constantly replenish the oil reservoir 31 with oil. The oil reservoir 31 has a connection port for a line 39 for releasing excess oil into the tank 6 and an oil replenishment line 42. A line 44 having a throttle 43 branches from the line 42, and this line 44 is connected to the line 39. Connecting. The throttle 40 in the line 18 and the throttle 43 in the line 44 serve to prevent the oil pressure in the replenishment line 42 from dropping too low, and for example, the maximum oil pressure in the replenishment line 42 can be reduced by 0.5.
Even if the pressure is maintained at about Kg/cm ² and the diameter of the connection port of the line 42 provided in the oil reservoir 31 is small, the drained oil can be injected into the oil reservoir 31. If the diameter of the connection port is sufficiently large and oil can be injected by the action of gravity, the throttle 43 can be omitted.

In the neutral state shown in the figure, the high pressure line 8 is line 17,
18. The oil connected to the tank 6 through the throttle 40 and pressurized by the oil pump 1 is discharged to the tank 6, but a part of the oil flowing through the line 18 passes through the replenishment line 42 and enters the oil reservoir 31. Enter,
The oil reservoir 31 is filled, and excess oil flows out into the tank 6 through a line 39. When lowering the switching valve 20 by switching it to the right (direction D) in the figure, the switching valve 27 switches to the right in conjunction with the switching valve 20, so that the lift arm driving cylinder 14
is connected to tank 6 through lines 13, 25, aperture 26, line 18, and aperture 40, and lift arm 1
5 goes down. At this time, a part of the oil discharged from the cylinder 14 is supplied to the oil reservoir 31 through the replenishment line 42 in the same manner as in the neutral state.
When the switching valve 20 is switched to the left in the figure (in the direction of arrow U) and raised, oil is no longer discharged to the line 18 and therefore the oil reservoir 31 is not replenished with oil. However, since the raising stroke is extremely short, there is no fear that the oil in the oil reservoir 31 will be completely consumed during that time. Therefore, there will be no problem until oil replenishment to the oil reservoir 31 is resumed at the next neutralization or lowering.

As explained above, according to this device, the brake master cylinder 31 and the discharge oil passage (line 18) of the lift arm drive cylinder 14 are connected via the supply line 42, so the oil that was wasted when the brake master cylinder 31 was in neutral and the oil that was discharged when the switching valve 20 was switched to the lowering direction (arrow D direction) can be automatically supplied to the oil reservoir 31, eliminating the need for a separate pump for oil supply and its drive mechanism, resulting in a significant reduction in costs. Also, the required volume is extremely small compared to the separate tank type.
Design is also easier.

In addition, when embodying this invention, the discharge oil line 18
It is also possible to connect directly to the supply oil inlet of the oil reservoir 31. In that case, the escape line 39 also serves as a part of the line 18. In the illustrated embodiment, if oil can be replenished into the oil reservoir 31 by the action of gravity, the throttle 40 may be omitted.

[Brief explanation of the drawing]

The figure is a hydraulic circuit diagram of an agricultural tractor to which the present invention is applied. 1...Oil pump, 7...Discharge port,
8... High pressure line, 9... Draft position control valve, 14... Lift arm drive cylinder, 18... Discharge oil line, 31... Oil reservoir, 37, 38... Hydraulic brake.

Claims (1)

[Scope of utility model registration request] In agricultural tractors with hydraulic brakes, the discharge port of the oil pump is connected to a lift arm drive cylinder via a high pressure line with a control valve in the middle, and the oil reservoir of the brake master cylinder and the lift arm drive cylinder are discharged. A hydraulic brake oil replenishment device characterized by a connected oil passage.