JPS58156448A - Pressure difference sensing device for a two-system brake - Google Patents

Abstract

PURPOSE:To prevent occurrence of a serious accident by emitting an alarm when a pressure difference in output brake pressure is generated between those two doubler devices furnished in the two systems, which constitute this braking arrangement, only in case the ratio of pressure difference to the input pressure to doubler device has exceeded a certain specified critical value. CONSTITUTION:When wear of the brake lining in one of the two systems, which constitute this braking arrangement, progresses to exceed a certain set tolerance value, the pressure difference DELTAp between the input pressures to the pressure inlets 30, 31 of a pressure difference sensing device 10, which shall receive the liquid pressures from the two doubler devices, will become large comparatively to the input pressure Pa to be applied to a pressure inlet 28. When this pressure ratio DELTAP/Pa exceeds a certain preset critical value, the piston 13 will move getting over a ball 24 as a braking member to receive the input pressure Pa and, at the same time, an actuator pin 19a will move upward to put on the alarm switch 19. Thus the alarm lamp 21 will light up to inform the driver that an inspection and eventual repair are needed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a differential pressure detection device that is applied to a dual-system brake system used in large vehicles, etc., and that can detect the differential pressure between each system and always issue an appropriate alarm depending on the brake pressure. Regarding 0 Air-over-hydraulic systems used as braking devices for large trucks, etc. have the advantage of being able to divide the brake system into two or more systems. The braking force is boosted by an independent booster. However, in such a two-system brake system, if a differential pressure occurs between the output brake pressures between the two systems for some reason, the high pressure t ] There is a problem in that the brake system is overused more than the low brake system, causing the brake lining to wear out sooner ◇ In addition, the brake unilateral phenomenon occurs, making the vehicle posture unstable during braking. , there was a risk that the cargo could shift or lead to an accident.

In order to solve the above problem, a differential pressure detection device has been proposed that detects the differential pressure of each output brake pressure of the booster between the two systems and issues an alarm when the differential pressure exceeds an allowable value. There is.

However, such conventional differential pressure detection devices are intended to detect only large differential pressures between systems, such as when one system's (B) path is damaged.
Differential pressure that affects braking stability (2 to 10 &/d
) was not intended to detect

Furthermore, there is a considerable difference in the magnitude of the brake pressure, that is, the input pressure to the booster or the operating pressure of the power piston, between 11 braking and sudden braking, and this variation in brake pressure can be tolerated. Although the differential pressure changes,
The device did not take this point into consideration.

That is, the brake pressure mentioned above is relatively small during gentle braking, and in this case, the allowable value of the differential pressure of each brake ball amount boosted and output from the booster also naturally becomes small!
! l! K, the brake pressure is relatively large during sudden braking, and the allowable value of the differential pressure between the respective brakes may also be larger than during gentle braking.

In other words, the difference in braking capacity, such as the difference in the amount of brake lining wear between the two systems, is constant at a certain point in time, but the differential pressure in the output brake ball amount fluctuates and remains constant depending on the slow and fast brake operation conditions. Must not be.

Now, if the input pressure to the booster is equal to P, and the output pressures of both boosters are P, P, then the difference in brake pressure between both systems is ΔP = lPb - Pol And...
ΔP/P& is constant unless the difference in the amount of lining wear changes, but even in this case, if the input pressure (P, ) is small, the absolute value of the differential pressure (ΔP) will naturally become large.

The problem here is the ratio of differential pressure to manual pressure (ΔP/P
&), and for example, if the brake lining of one system becomes simpler, the differential pressure (ΔP) between both systems will increase even if the human pressure (Pl) is the same, and the above ΔPZP&
also changes. Therefore, this ratio! 1v: The alarm means should be set to 5 only when the set value exceeds the answerable value, but conventional differential pressure detectors use this ratio (ΔP/P, )
It is not designed to detect changes in the pressure, but if the differential pressure (ΔP) changes and exceeds the set value, the brake operation condition (μ
It was designed to operate uniformly regardless of the I.

For this reason, when the input brake pressure is small, the above-mentioned ΔP/P exceeds the allowable value, which is a state in which an alarm should be issued, but the differential pressure between the two systems itself is small, so the alarm is activated. .Conversely, when the brake pressure is large, the differential pressure also increases proportionally, so
There has been a problem in that the alarm device is activated even though the value of ΔP/P is within an allowable range.

In addition, for the above reasons, the critical value of the differential pressure that activates the alarm device is set to a very high value, so in many cases it can only be detected when a large differential pressure between systems occurs due to circuit damage. Ta.

In view of this problem in the prior art, the present invention always operates properly based on a constant standard even when the differential pressure generated between the output pressures of both systems fluctuates due to fluctuations in the input brake pressure, and one system The purpose is to provide a differential pressure detection device that can issue a threat warning to the driver only in the event that inspection, repair, etc. are required. In addition to the configuration of the device to be detected, by providing a braking mechanism that applies a predetermined load proportional to the input pressure to the booster on the piston surface of the device, the differential pressure between the output pressures of both boosters can be detected. and the above input pressure exceeds an allowable critical ratio, the -F period piston is moved and the alarm switch is activated. Hereinafter, preferred embodiments of the present invention An example will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a dual-system brake system equipped with a differential pressure detection device according to the present invention, and this embodiment shows a case where the brake system is applied to a so-called air over hydraulic system.

In the figure, 1 is a compressor, and compressed air generated by the compressor is stored in an air reservoir 2. The air reservoir 2 is connected to a dual brake valve 4 through a pair of passages 3. The pulp 4 is communicated with the input ports 61 of the pair of inertia devices 16 through a pair of passages 5, 5 corresponding to the passages 3, 3, and the output ports 62 of the pair of boosters 16, 513
7 and 7 are connected to the front wheel 8 and the rear wheel 9, respectively, and when the driver depresses the pedal 4a of the dual brake valve 4, the compressed air in the near reservoir 2 is released into the passage according to the depressing pressure. 3.4, it is supplied to the booster 6 from the power port 61.

Accordingly, the booster 16 converts the depression pressure of the pedal 4m into hydraulic pressure via compressed air pressure and boosts the pressure in this embodiment. Brake pressure is sent to 9 to perform predetermined braking.

Reference numeral 10 denotes a differential pressure detecting device, and as shown in FIG. 1 and FIG. 2, which is a conceptual diagram of the device,
A piston 13 is in a cylinder 12 formed inside the cylinder 1.
Axial direction of the cylinder 12 (horizontal direction in FIG. 2)
K is slidably arranged.

A first chamber 14 formed on both sides of the piston 130
and a compression spring 16 in the second chamber 15, respectively.
and 17 are equipped, and the piston 13 is equally biased from the inner surface with predetermined spring forces f and ft.

A guide groove 18 having a seven-shaped cross-section is formed approximately in the center 1% of the piston 13, and the actuating pin 19a of the alarm switch 19 comes into elastic contact with the guide 118 with a predetermined biasing force f8.
engaged.

Warning ll Sui 7 f19 No terminal 19b, 19b is 1! Connected to E*20 and alarm lamp 21,
When the alarm switch 19 is closed by moving the operating bottle 19a upward in FIG. 2, the alarm lamp 21 is turned on.

The differential pressure detection device klO is also provided with a braking mechanism 22 that applies a predetermined load to the piston 13 from the side, and the mechanism n is configured as follows.

That is, a protrusion 11a is provided approximately at the center of the body 110, and a sub-cylinder n formed within the protrusion 11a.
The above cylinders 12 and 1! A brake member serving as a braking member is engaged with the guide lever 18 of the piston 13, and the lever 24 is connected to the guide lever 5 of the piston 13.
A predetermined biasing force ftK is applied by the compression spring 26 via
and comes into elastic contact with the guide groove 18.

The other end of the spring guide is attached to a sub-piston l which is slidable vertically in the sub-cylinder 23 in FIG. It is formed in communication with the cylinder 23.

The pressure introduction hole 4 of the braking mechanism 22 of the piston 13 is connected to the first booster 1 as shown in FIG.
16a is in communication with the passage 5 near the human power 061, and when the dual brake pulp 4 is operated, a predetermined pressure M+atmospheric pressure from the near reservoir 2 acts on the sub-piston 27 (・ru0). As shown in FIG. 2, pressure introduction holes 30 and 31 are also formed at both ends of the chamber 11 so as to communicate with the first and second chambers 14 and 15, respectively.
As shown in the figure, the first pressure introduction hole (9) is connected to the first branch passage 32.
The second pressure introduction hole 31 is connected to the passage 7 of the second booster 6B by a second branch passage 33, and both boosters are connected to each other. W
The output pressures 6a and 6b are respectively introduced and are configured to act on both end surfaces of the piston 13 in the sliding direction.

In this embodiment, as shown in FIG. 3, the pressure-receiving area of the piston 131IIIl end is equal to B, and the pressure-receiving area of the sub-piston 27 is equal to A and the compression spring 2.
The biasing force of 6 is applied to the compressed air pressure introduced from the pressure introduction holes 28, 30° 31, and the hydraulic pressure to P&, Pb, Po, respectively.
, Joki V-shaped guide If the angle in 8 above is θ, then the output pressure and P. When r & IlK differential pressure occurs, the differential pressure ΔP=
lPb-Pol, B, and Pb>P.

In this case, the piston 13 is moved to the third
On the other hand, as a force for braking the movement of the piston 13 when it tries to move rightward in the figure, the sub-piston is The angle (θ) of the guide groove 18 of the pressure (PaA) that presses the ball U
The total sum of component forces determined by T = (P, A + ft + f,
)・α [α is a constant] acts in the left direction in FIG. Here, since it is sufficiently small compared to the above f, jiP&, Pb, Po, the piston 13 starts to move because the above differential pressure (JP) is equal to the braking force L (T=P, A・α
) is thought to be the case. In this embodiment, the permissible amount of wear on the brake lining is determined based on the performance of the booster 1116 and the correlation between the amount of wear on the brake lining and the magnitude of the differential pressure (JP) generated thereby. A critical ratio of the ratio (ΔP/P,) between the differential pressure (JP) and the input pressure (Pl) corresponding to the eye limit value of is set in advance, and the sub-piston n is set so that this condition is satisfied. The pressure receiving pressure (Ill right (5)), the pressure receiving area @ of the piston 13 and the angle (@) of the guide groove 18 are set.

In other words, the piston 13 has no relation to the fluctuation of the differential pressure (JP) due to the fluctuation of the input pressure (P&), and the piston 13 maintains the difference between the differential pressure (rp) and the input pressure (
The braking force (T=P
This is when the differential pressure (JP) becomes larger than &A·α).

In addition, in this embodiment, the above-mentioned booster WM6 has a diaphragm type power chamber 34 as shown in FIG.
and a hydraulic cylinder 35 in combination.

The power chamber is formed by an upper cover 36 and a lower chamber 37, and is airtightly defined by a diaphragm 38 into a first chamber 39 and a second chamber 40. The first chamber 39 is connected to the pressure inlet 61 and I! !
Throughout, the second chamber probe is communicated with the atmosphere by a boat 401. In addition, hydraulic cylinder 41
Oil, etc. is supplied from the reservoir 42 (see # in Figure 1) and 42a.When compressed air at a predetermined pressure is introduced into the 1,000th yam bar 39 from the inlet 61, the diaphragm The wing moves to the right in FIG. 4, and in conjunction with this, the piston plate 43 and the bushing rod I move to the right against the biasing force of the spring 45. Due to the propulsive force of the bushing rod 44, the rod I The tip of the hydraulic cylinder 35 presses the piston inside the hydraulic cylinder 35 to generate boosted hydraulic pressure.The hydraulic pressure is transmitted from the output port 62 to the front wheel 8 and rear wheel 9 via the passage 7. ◎ Next, the operation of this embodiment will be explained. First, when both the output pressures (Pb) and (Po) are equal, that is, both the boosters 116a When the boosting performance of 6b and 6b is the same and both systems are operating normally, the piston 13 does not move and the alarm switch 19 does not operate. Next, only the brake lining of one system is worn out. Let us assume a case where a differential pressure (jP) occurs in the output pressure between the two systems, such as when the

Even in this case, for example, if the wear amount of the brake lining has not reached the permissible limit, the ratio of the differential pressure (Δequal) to the input pressure (Pl) will exceed the preset critical ratio as described above. Therefore, under these conditions, the differential pressure when Pb>Po in Fig. 3 is
P-(Pb-P, ), B is the braking force due to the above input pressure (P&); it never becomes larger than T=P&A・α, the piston 13 does not move to the right, and the alarm switch is activated. 1
9 does not work.

However, when the wear of the brake lining in one system progresses and exceeds the allowable value, the relative magnitude of the differential pressure (jP) to the input pressure (Pl) increases and exceeds the critical ratio. So, in Figure 3, the differential pressure (jP)
is larger than the braking force, the piston 13 moves, and the actuation pin 19 of the alarm switch 19 is activated by the action of the guide groove 18.
O moves upward to close the switch 19, and lights up the warning lamp 21 to notify the driver that inspection and repair is required. It is not only based on the magnitude of the differential pressure (jP) between the output pressures of the power device [6], but also detects the differential pressure (jP) and at the same time detects the input pressure (P) K corresponding to the differential pressure.
Since the braking force is applied to the piston 13, for example, only the lining of the - system brake is worn out.
An alarm can be issued only when the wear amount k exceeds the allowable value, and if the wear amount is a certain value within the allowable value, the input pressure (
Pl) changes, and correspondingly the differential pressure between the output pressures (ΔP
Even if the vehicle changes, the above-mentioned warning switch will not operate, and there is no risk of issuing a false warning to the driver.

In addition, in a normal dual-system brake, for example, the above 70
The front F wheel 8 and the rear wheel 9 have different wheel cylinder diameters, and the shoe gap of each brake shoe (not shown) is different.
When a diaphragm-type power chamber is used as the input point of 6, the effective pressure receiving area of the diaphragm 38 changes depending on the position of the diaphragm 38.The output pressure also changes accordingly.Therefore, as mentioned above. If the shoe gaps of the brakes are different, the stroke position of the diaphragm of both systems becomes the original KJ4, which causes a problem that a pressure difference is created from the beginning between the output pressures of the two systems.

For this reason, the power chicken bar 34 of the diamond slam type was not compatible with the two-system brake multiplier mechanism, but by being equipped with the differential pressure detection device according to this embodiment,
For brake boosting mechanisms that inherently generate differential pressure.
・If this differential pressure is incorporated into the differential pressure/input pressure critical ratio setting condition in advance, the above-mentioned alarm will be activated only when a situation requiring inspection or repair occurs, regardless of the existence of the differential pressure. Therefore, the above-mentioned diaphragm type booster 6 can be used, compared to the power piston type booster commonly used in air-over-hydro link type brake devices. lightweight·
Miniaturization is possible.

In this embodiment, the input pressure introduced into the differential pressure detection device 10 is pneumatic pressure, and both output pressures are hydraulic pressure. However, the type of introduced pressure may be arbitrary. For example, all The same effect can be achieved even if the introduction pressure is pneumatic pressure or hydraulic pressure.Furthermore, in this embodiment, the braking member in the piston braking mechanism 22 is located in the guide groove 18 common to the drive bottle 19a. Although an example in which they are engaged is shown, this locking position is arbitrary as long as the piston 13 can be braked from its side. Furthermore, the Wk#jJ shape of the guide groove 18 is not limited to the above-mentioned V-shape, but may have a shape that generates a component force in the direction opposite to the direction of the differential pressure (jP) due to the braking force from the piston surface. Bye(・.

Furthermore, regarding the manner in which the brake system is divided into two systems, in addition to this embodiment in which the brake system is divided into the front wheel and the rear wheel, an arbitrary manner can be used, for example, the left side front wheel and the right side rear wheel are of the same system. Various modifications can be made without changing the gist of the present invention, such as the possibility of adopting various embodiments.

As detailed above, in the present invention, a braking mechanism that applies a predetermined load proportional to the input pressure to the booster is provided on the side surface of the piston of the differential pressure detection device, and the output brake balls of both boosters are provided. When a pressure difference occurs in the quantity, the system is configured so that an alarm can be issued only when the ratio between the pressure difference and the input pressure to the inertial force device exceeds a predetermined critical ratio. Even if the input brake pressure fluctuates and the differential pressure between the output pressures of both systems fluctuates, the difference in pressure does not change and one system becomes in a state that requires inspection or repair. It is possible to notify the driver of the occurrence of the condition only in the main event, which eliminates unnecessary inspections as in the conventional case. There is no risk that it will lead to

In addition, even in the case of a mechanism in which a pressure difference occurs from the beginning in the meat booster, by installing the pressure difference detection device according to the present invention, the difference in pressure can be avoided and the same as above can be achieved. It has various useful effects, such as being able to properly detect malfunctions, etc.

[Brief explanation of the drawing]

Figures 1 to 4 show one embodiment of the present invention, Figure 1 is a circuit diagram of a brake boosting mechanism equipped with a differential pressure detection device, Figure 2 is a conceptual diagram of the differential pressure detection device, and Figure 3 is a circuit diagram of a brake boosting mechanism equipped with a differential pressure detection device. The figure is an explanatory diagram showing the force relationship when differential pressure occurs, No. 41i1! ! I is a vertical side view of the inertial force device OlO...Differential pressure detection device,
11...Pod, 12...Cylinder, 13...Piston, 18...Guide groove, 19...Alarm switch, n.
-...braking mechanism, U...braking member, %--spring, 27...C flavor to sub-piston 0Q Ajiwa
: : Status-■ Ogo

Claims (3)

[Claims] (1) A piston is slidably disposed in the cylinder of the body, and the first and second brakes are configured to apply output pressures generated from both inertia devices of a dual-system brake to both end surfaces of the piston in the sliding direction. A pressure introduction hole is provided, an actuating part of an alarm switch is brought into elastic contact with the piston, and the differential pressure between the output earth surfaces acting on the piston is detected through the first and second pressure introduction holes to activate the piston. In the differential pressure detection device that moves the piston and activates the alarm switch, a braking mechanism is provided on the side surface of the piston to apply a load proportional to the input pressure to the booster, and the ratio between the differential pressure and the input pressure is determined. K so that the piston moves only when K exceeds an allowable critical ratio.
A dual-brake differential pressure detection device featuring the following features◎ (2) The braking mechanism includes a braking member that engages with a guide groove formed on the front surface of the piston, and a predetermined pressure introduction hole that receives the input pressure from the braking member through a spring in proportion to the input pressure. A differential pressure detection device for a two-system brake according to claim 1, which supports a sub-piston to which a load is applied. (3) The guide groove of the piston is formed in a cross-sectional shape of cedar, and is configured to generate a component force of the load in a direction opposite to the acting direction of the differential pressure. Two-system brake differential pressure detection device 0