JPS5814241Y2 - hydraulic circuit - Google Patents

Description

[Detailed description of the invention] The present invention relates to a hydraulic circuit equipped with a bladder type accumulator, and provides a hydraulic circuit that exhibits good durability and pressure accumulation performance for pressure accumulation fluid (oil) over a wide temperature range. It is something.

Bladder type accumulators generally store pressurized oil in a bladder (bag) made of rubber, and the elasticity of the bladder allows the oil to accumulate pressure. Due to their characteristics, there are no materials that consistently exhibit good temperature resistance over a wide range of temperatures, and only exhibit temperature resistance within a narrow temperature range.

In particular, nitrile rubber bladders used in mineral oil accumulators have contradictory properties: improving low temperature resistance will result in poor high temperature resistance, and improving high temperature resistance will result in poor low temperature resistance. Because of this, the temperature at which the accumulator can be used has been limited by the bladder.

In order to improve cold and heat resistance, some bladders are made of expensive epichlorohydrin rubber, but this rubber has the property of corroding metals it comes into contact with. Not only that, but also the rubber itself tends to be poorly fused, making it unsuitable from the viewpoint of manufacturing difficulties and reliability.

In view of these points, the present invention aims to provide a hydraulic circuit that is less constrained by oil temperature.In addition to providing a plurality of accumulators, the bladders of these accumulators are controlled at different temperatures. The accumulator is constructed from an elastic body exhibiting the best temperature resistance characteristics, and is characterized in that these accumulators are selected and used according to the oil temperature.

The present invention will be described below with reference to an illustrated embodiment. This embodiment exemplifies a braking and steering hydraulic system for a vehicle as a hydraulic circuit equipped with a bladder type accumulator.

In the figure, 1 is a pump, 2 is a power steering device (hereinafter p,
3 is a flake booster, and the oil discharged from the pump 1 reaches the booster 3 via a discharge pipe 4, and further passes through a pipe 5 to P, 8.2. .

6 and 7 are boosters 3, P, S, and 2 to pump 1, respectively.
8 is a brake pipe that guides the brake fluid pressure of the booster 3 to the wheel cylinder 9.

The pump 1 has a built-in hydraulic pressure regulating valve and a flow regulating valve.

Reference numerals 10 and 11 are two bladder-type accumulators that are a feature of the present invention, and although their internal structure is the same as that of conventional products, the rubber that constitutes the built-in bladder (not shown) However, one side (tentatively referred to as 10 side) is manufactured so as to have relatively excellent low temperature resistance, and the other side (represented as 11 side) is manufactured so as to have excellent high temperature resistance.

The pressure accumulation pipes 12 and 13 of these two accumulators 10 and 11 are connected to the discharge pipe 4 of the pump 1 via a switching valve 14 and a pipe 15, and the pressure relief pipes 16 and 17 are connected via a pipe 18. and is connected to the booster 3.

20゜21 are pressure accumulation pipes 12, 13, pressure relief pipes 16, 17
A check valve is installed on each of the valves to allow oil flow only on the pressure accumulation side and the pressure release side, respectively.

The switching valve 14 has two ports 14a and 14b, and connects either one of the pressure accumulation lines 12 and 13 to the line 15, and its operation signal is provided in the line 15 to determine the oil temperature there. This is given by a thermostat 22 that detects.

That is, the thermostat 22 excites the solenoid 14c of the switching valve 14 when the oil temperature exceeds a certain value.

Note that 23 is a pressure switch that closes when the hydraulic pressure in the accumulators 10 and 11 exceeds a predetermined value, and when the pressure switch is closed, the alarm device 25 is activated by the power source 24.

In this device having the above configuration, assuming that the oil temperature in the pipe line 15 detected by the thermostat 22 is low and the thermostat 22 does not emit an excitation signal for the solenoid 14c of the switching valve 14, the switching valve 14 is 14a connects the pipe line 15 and the pressure accumulation pipe line 12.

The discharge fluid from the pump 1 is transferred from the discharge pipe line 4 to the booster 3.
It is further supplied to P, 8.2 via conduit 5.

As is well known, the booster 3 obtains an auxiliary force from this supplied hydraulic pressure when the brake is applied, and generates brake hydraulic pressure from the brake pipe 8 to the wheel cylinder 9, and P, S, and 2 similarly apply hydraulic pressure to the steered wheels. The booster 3
Oh p, s.

2 increases the liquid pressure in the discharge pipe 4 (and pipe 5), and a part of the increased pressure fluid is transferred to the pipe 15 and the switching valve 14.
The pressure is accumulated in the accumulator 10, which has relatively excellent low-temperature characteristics, through the port 14a1 and the pressure accumulation pipe 12.

In the event of an accident such as a failure of the pump 1 or damage to the pipe line, the pressure fluid accumulated in the accumulator 10 will be transferred to the pipe line.
8 to the booster 3, which is further connected to the brake pipe 8.
is supplied to the foil cylinder 9 to ensure braking action in an emergency.

Note that various specific structures of the booster 3 and connection structures between the booster 3 and the conduit 18 are known, and this is not critical; however, in general, the connection between the booster 3 and the conduit 18 is A ball valve is provided in this section, and when the control valve in the booster 3 opens this ball valve under pressure, the conduit 18 and the brake pipe 8 are brought into communication.

However, in the present invention, when the temperature of the pressure fluid flowing in the pipe line 15 reaches a predetermined constant value, the thermostat 22
detects this, energizes the solenoid 14c of the switching valve 140, and connects the port 14b to the conduit 15.

Therefore, the pipe 15 will be connected to the other pressure accumulation pipe 13, and from then on, the pressure will be stored in the accumulator 11, which has relatively excellent high temperature characteristics, and the accumulator 10 will not be used.

This switching operation is performed at any time depending on whether the oil temperature in the pipe line 15 is below (low temperature) or above (high temperature) a certain value. Only the accumulator in use is used and the other is not, which increases the durability of the entire hydraulic circuit,
Expands the usable temperature range.

According to experiments, for example, an accumulator that uses a bladder, which has excellent durability at high temperatures, will not bend if it is not used at low temperatures and is simply left at low temperatures. Durability is rarely adversely affected.

Therefore, the effectiveness of the present invention is confirmed. In addition, in order to release the accumulated pressure fluid of the accumulator that is not used, the switching valve 14
A tank side passage 26 may be connected to the tank side passage 26 as shown by the chain line in the figure.

In the above embodiment, the temperature range is divided into high temperature and low temperature, but the temperature range is further subdivided and multiple accumulators are used that exhibit the best temperature resistance performance in each temperature range. You can also.

Note that the switching valve 14 may be of a type in which the accumulator to be used is manually switched.

The present invention is applicable not only to the hydraulic circuit shown in the embodiment, but also to the bladder.
Although the present invention can be applied to other hydraulic circuits that use a type accumulator and are used in a wide temperature range, it can be specifically applied to, for example, hydraulic equipment used inside and outside of a freezer.

As described above, according to the present invention, it is possible to reduce the restrictions on the operating temperature of the accumulator, enable the use of a hydraulic circuit in a wide temperature range, and prevent accumulator accidents such as bladder damage, thereby increasing durability. It is possible to provide a hydraulic circuit with improved performance and reliability.

[Brief explanation of drawings]

1 is a connection diagram showing an embodiment of a hydraulic circuit according to the present invention; FIG. 1... Pump, 10, 11... Accumulator, 12, 13... Pressure accumulation pipe, 14.
......Switching valve, 16.17...Pressure relief pipe,
22...Thermostat.

Claims (1)

[Claims for Utility Model Registration] 1. In a hydraulic circuit equipped with bladder-type accumulators, a plurality of the above accumulators are installed, and the bladders of the accumulators on the complementary side each exhibit the best temperature resistance performance at different temperatures. What is claimed is: 1. A hydraulic circuit comprising an elastic body and comprising a switching valve that selectively connects the plurality of accumulators to the hydraulic circuit. 2. The hydraulic circuit according to claim 1, wherein the switching valve is operated by a thermostat that senses the temperature of oil flowing through the hydraulic circuit, and an accumulator with temperature resistance suitable for the oil temperature is connected to the hydraulic circuit.