JP2003512252A - Brake equipment for construction machinery - Google Patents

Abstract

(57) The present invention is a brake device (1) for a construction machine, which is connected to a first brake member (4) provided on a first axle (6) of the machine. A first brake circuit (2), a second brake circuit (8) coupled to a second brake member (10) provided on a second axle (12) of the machine; And a second brake circuit (2, 8) independent of each other and connected to the first and second brake circuits (2, 8), a pressure source (14) for hydraulic fluid, A brake valve (16, 16 ') coupled to the second brake circuit (2, 8), said brake valve (16, 16') being connected to the axle (6, 12) from a pressure source (14); ), The brake device (4) being designed to control hydraulic fluid up to the brake members (4, 10). ) On. The first or second brake circuit (2, 8) has a limiting element (18, 42 '), which brake valve (16, 16') moves from the pressure source (14) to the axle ( When controlling the hydraulic fluid up to the brake members (4, 10) provided in 6, 12), the pressure and / or flow rate of the hydraulic fluid is limited.

Description

Detailed Description of the Invention

The present invention relates to a brake device for a construction machine, the first brake circuit being connected to a first brake member provided on a first axle of the machine, and a second brake circuit of the machine. A second brake circuit connected to a second brake member provided on the axle of, and the first and second brake circuits are independent of each other, and connected to the first and second brake circuits. A pressure source for the hydraulic fluid, and a brake valve connected to the first and second brake circuits, the brake valve from the pressure source to the brake member provided on the axle. It relates to a braking device designed to control hydraulic oil.

Construction machines, for example wheeled loaders or dump trucks, must be equipped with brakes suitable for the various characteristics of the machine. In one extreme case, the fully loaded machine must be strongly decelerated, and in the other extreme, the same machine with no load must be gently braked. In order for the machine operator to be able to control the machine, under all operating conditions the deceleration of the machine must be felt to be controllable and manageable. From an ergonomic point of view, the force exerted by the driver on the brake pedal should be as low as possible. The control stroke of the brake pedal must also be as small as possible.

Brake systems installed in conventional construction machines have two or more independent brake circuits controlled by one brake valve. The brake valve is connected to a brake pedal, which when acted on by a driver,
The valve is opened to allow the hydraulic fluid under pressure to flow to the braking elements on the axles or wheels of the machine. The braking element has a piston, which moves under the pressure of hydraulic fluid and pushes the brake lining 7 to exert a force on the brake disc. When the driver releases the brake pedal, the pressure applied to the brake piston 5 disappears and the brake lining 7 moves to the initial position by the action of the return spring.

When the driver depresses the brake pedal to open the brake valve, it takes a certain time for the brake piston 5 to move from the initial position to the position of the brake piston 5 where the brake lining is pressed against the brake disc. Requires. This time is called the brake application time. When the brake piston moves to the latter position, pressurization to the brake piston by the hydraulic fluid is started,
This causes a strong overpressure surge in the form of pressure pulses in the hydraulic fluid. Due to this excessive pressure surge, brake impact, that is, sudden deceleration of the machine within a short time,
Occurs and the driver feels it as a jerk. This overpressure surge also occurs in elements of the braking member that are exposed to large forces, which is especially noisy. Jerk and noise are perceived as a source of irritation by machine drivers.

For gentle braking, the force exerted on the brake pedal should be small. If the machine is moving on an uneven surface and the machine jumps and rocks,
It makes it difficult for the driver to control the braking system by means of the brake pedal in order to achieve a gentle braking. In this case, the deceleration of the machine changes and the driver therefore finds it difficult to control the braking system. In order to achieve good controllability of the braking system, the braking application time should be as short as possible and the overpressure surge should be as small as possible. A short braking application time is realized by a large flow rate of hydraulic fluid through the brake valve, but the larger the flow rate of hydraulic fluid, the greater the overpressure surge.

It is an object of the present invention to provide a braking device which is suitable for different operating conditions of construction machines and thus avoids machine jerk and noise during braking of the machine.

Another object of the invention is to provide a braking device that exhibits little sensitivity to mild braking.

[0008] The above-mentioned object is that when the limiting element arranged in the first or the second brake circuit controls the hydraulic fluid from the pressure source to the brake member provided on the axle, the hydraulic fluid controls the hydraulic fluid. Is achieved by a braking device of the type mentioned at the outset, which limits the pressure and / or the flow rate of the.

The limiting element serves to reduce the braking action exerted on one axle at the beginning of the braking sequence, thus reducing the sensitivity of the braking device. When the driver gently depresses the brake pedal for gentle braking, a small flow of hydraulic fluid, if any, occurs in the brake circuit with the restrictive element installed, while the restrictive element is installed. A large flow of hydraulic fluid occurs in the unbrake circuit. After a certain period of time elapses or when the pressure of the hydraulic fluid reaches a predetermined limit, the pressure applied to the brake member of the axle that has been subjected to a small braking action from the start causes the braking action on that axle. Increase. For example, in emergency stop braking, all axles of the vehicle are braked as soon as the driver depresses the brake pedal.

[0010]   Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 is a graph showing how the hydraulic pressure changes when a known braking device is activated. The horizontal axis represents time T and the vertical axis represents pressure P. As mentioned at the beginning, it takes a certain time t1 for the brake piston to move from the initial position to the position of the brake piston where the brake lining (where the brake piston is pressed) is pressed against the brake disc. When the brake piston moves to this latter position, pressurization of the brake piston by the hydraulic fluid is started,
This causes a strong overpressure surge in the form of pressure pulses in the hydraulic fluid. This pressurization is performed for the time of t2. This excessive pressure surge causes a brake shock, that is, a rapid deceleration of the machine within a short period of time, which the driver feels as jerk. It also happens that the brake system is noisy as a result of this overpressure surge.

FIG. 2 shows a first embodiment of the braking device 1 according to the present invention. The braking device 1 has a first braking circuit 2, which is connected to a first braking member 4 provided on a first axle 6 of a construction machine. The brake member 4 has a brake piston 5 mounted on each wheel, which piston interacts with a brake disc (not shown) connected to the axle 6 by one or more brake linings 7. The braking device 1 also has a second braking circuit 8, which is connected to a second braking member 10 provided on a second axle 12 of the construction machine. When this brake device is installed, the first and second brake circuits 2, 8 are independent of each other. That is, the pressure in one of the circuits 2 and 8 does not affect the pressure oil pressure in the other one of the circuits 2 and 8. If one of the circuits 2, 8 fails, the construction machine can be braked by the other one of the circuits 2, 8. A pressure source 14 for hydraulic fluid is connected to the first and second brake circuits 2, 8. The pressure source 14 can be, for example, in the form of a hydraulic pump and / or one or more pressure accumulators (not shown). The brake valve 16 includes the first and second brake circuits 2
, 8 and is designed to control the hydraulic fluid from the pressure source 14 to the brake members 4, 10 provided on the axles 6, 12. A limiting element in the form of a sequence valve 18 is arranged in the second brake circuit 8.

When the brake valve 16 controls the pressure medium oil from the pressure source 14 to the brake members 4, 10 provided on the axles 6, 12, the sequence valve 18 controls the pressure medium oil to have a predetermined pressure. When it becomes lower than the pressure, the flow rate of the hydraulic fluid to the second brake member 10 is limited. This limitation may mean that very little, if any, hydraulic fluid flows through the sequence valve 18. The sequence valve 18 is opened when the pressure of the hydraulic fluid reaches a predetermined pressure, so that a large flow rate of hydraulic fluid flows through the sequence valve 18. Therefore, the function of the sequence valve 18 can be compared to the function of the pressure relief valve.

When the brake device 1 operates, the pressure medium oil in the brake members 4 and 10 is discharged. That is, the hydraulic fluid exits the brake members 4, 10 and flows toward the brake valve 16 and the tank 20. In order to realize this, the first bypass line 22 bypasses the sequence valve 18 and is connected, and the pressure oil is connected to the sequence valve 18.
It is possible to bypass. A check valve 24 is arranged in the first bypass line 22 so that the hydraulic fluid passes through the first bypass line 22 and the second brake member 10.
It is designed to prevent the flow in the direction of.

In the first embodiment, the brake valve 16 has first and second valves 26, 28 which are acted upon by a brake pedal 30. When the brake pedal 30 is depressed, the first and second slip valves 26, 28 are opened, so that the hydraulic fluid flows from the pressure source 14 toward the first and second brake members 4, 10. Preferably, the pressure in the first brake circuit 2 influences the opening of the second slide valve 28, which is indicated by the duct 29 between the first brake circuit 2 and the second slide valve 28. Has been done.

Alternatively, the first and second slide valves 26, 28 and the sequence valve 18
, And the first bypass line 22 with check valve 24 can be replaced by a single brake valve 16 ', as shown in FIG. This brake valve 1
6'is a first slider 3 for controlling the flow rate of the pressure medium oil in the first brake circuit 2.
2 and a second slider 34 for controlling the flow rate of the pressure medium oil in the second brake circuit 8.
Have and. The first slider 32 is configured to control the second slider 34, and when the pressure in the first brake circuit 2 reaches a predetermined pressure, the second slider 34 causes the second brake circuit 8 to move. Is open. The predetermined pressure is determined by the spring force of the first spring 36 of the brake valve 16 '. The first slider 32 is connected to the brake pedal 30, and when the brake pedal 30 is stepped on, the first slider 32 is displaced in the brake valve 16 ', and the first brake circuit 2 is opened. A second spring 38 located between the first slider 32 and the second slider 34 ensures that the second slider 34 is not initially displaced by the first slider 32. . When the first slider 32 is largely displaced to the position where the first circuit 2 is opened, the pressure medium oil in the first branch line 33 provided in the circuit 2 causes the slider 32 and the slider 34 to move.
Pressurize the space between and. The pressure in the first circuit 2 is
When the force of the first spring 36 acting on is exceeded, the second slider 34 opens the second circuit 8. The second branch line 35 provided in the second circuit 8 carries the hydraulic fluid to the end of the second slider 34, which faces the first spring 36. The second slider 34 closes the second circuit 8 when the pressure in the second circuit 8 together with the force from the first spring 36 exceeds the pressure in the first circuit 2. Then, the pressure in the second circuit 8 becomes lower than the pressure in the first circuit 2. The pressure difference between the first circuit 2 and the second circuit 8 depends on the magnitude of the spring force of the first spring 36. At this time, the first spring 36
Acts as a limiting factor.

Due to the gentle braking, only the first axle 6 is braked when the brake pedal 30 is depressed a small distance. For stronger braking, the force of the first spring 36 must be overcome to open both brake circuits 2,8, at which time both axles 6,12 are braked.
When one of the circuits 2 and 8 fails and the hydraulic pressure of one of the circuits 2 and 8 does not work in the use of the brake device 1, the brake pedal 30 is depressed until the second spring 38 is compressed, and the second slider is pressed. 34 can also be displaced so that the second brake circuit 8 is also opened.

FIG. 4 shows a second embodiment of the present invention. In the case of this embodiment, the second bypass line 40 is arranged so as to bypass the sequence valve 18. A restrictor valve 42, which allows a limited flow of hydraulic fluid to bypass the sequence valve 18 at any time, is arranged in the second bypass line 40. Due to this limited flow rate of hydraulic fluid, the second brake member 10 is operated slowly,
If the pressure of the hydraulic fluid does not reach the predetermined pressure at which the sequence valve opens, the second axle 12 is braked by gentle braking. Therefore, delayed braking of the second axle 12 is realized.

In the third embodiment shown in FIG. 5, the restrictor valve 42 ′ can be attached only to the second brake circuit 8 so that the delayed braking of the second axle 12 occurs. In this case, the restrictor valve 42 'constitutes a limiting element. In this way, the gentle braking of the machine prevents brake impacts. Further, as shown in the fourth embodiment of FIG. 6, it is possible to attach the first bypass line 22 having the check valve 24, which bypasses the restrictor valve 42 ′, to the second brake circuit 8. is there. This allows for rapid ejection from the second brake member 10 when the braking device 1 is deactivated.

The brake device 1 having the two brake circuits 2 and 8 has been described above. However, it is also possible to design the braking device 1 with more than two braking circuits. It is also possible to arrange the limiting elements 18, 42 ′ in the first brake circuit 2 instead of the second brake circuit 8. The first axle 6 can be the front wheel axle of the machine and the second axle 12 can be the rear wheel axle, or vice versa.

[Brief description of drawings]

FIG. 1 is a graph showing hydraulic pressure as a function of time required to operate a known braking device.

[Fig. 2]   1 is a diagram showing a first embodiment of a braking device according to the present invention.

[Figure 3]   FIG. 3 shows a brake valve for a braking device according to the invention.

[Figure 4]   It is a figure which shows 2nd embodiment of the brake device by this invention.

[Figure 5]   It is a figure which shows 3rd embodiment of the brake device by this invention.

[Figure 6]   It is a figure which shows 4th embodiment of the brake device by this invention.

[Explanation of symbols]

  1 Brake device   2 First brake circuit   4 First brake member   5 Brake piston   6 first axle   7 Brake lining   8 Second brake circuit   10 Second brake member   12 second axle   14 Pressure source   16 brake valve   16 'brake valve   18 Sequence valve   20 tanks   22 First bypass line   24 Check valve   26 First slip valve   28 Second slide valve   29 ducts   30 brake pedal   32 first slider   33 First branch line   34 Second slider   35 Second branch line   36 first spring   38 Second spring   40 Second bypass line   42 restrictor valve   42 'restrictor valve

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, C A, CH, CN, CR, CU, CZ, DE, DK, DM , DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, K E, KG, KP, KR, KZ, LC, LK, LR, LS , LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, SL, TJ, TM , TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (12)

[Claims] 1. A braking device for a construction machine, the first braking circuit (2) being connected to a first braking member (4) provided on a first axle (6) of the machine. And a second brake circuit (8) connected to a second brake member (10) provided on the second axle (12) of the machine, the first and second brake circuits being provided. A pressure source (14) for the hydraulic fluid, (2, 8) being independent of each other and connected to the first and second brake circuits (2, 8), and first and second brake circuits Brake valve (16, connected to (2, 8)
16 '), and the brake valve (16, 16') is connected to the axle (6, 1) from the pressure source (14).
2) is designed to control the hydraulic fluid up to the brake members (4, 10), and is configured to control the brake valves (16, 16 ').
A braking device having a brake pedal (30) connected to 16, 16 '), a limiting element (18, 36) arranged in the first or second braking circuit (2, 8).
, 42 '), wherein the limiting element is a brake valve (16, 16') from a pressure source (14) to an axle (14).
When controlling the hydraulic fluid up to the brake members (4, 10) provided in 6, 12), the pressure element and / or the flow rate of the hydraulic fluid is restricted, It is suitable for limiting the flow rate of the limiting element (18, 36, 42 ') to the brake member (10) of the brake circuit (8) up to a predetermined hydraulic fluid pressure, and the limiting element (18, 36). , 42 ') are opened to achieve a delayed actuation of the brake member (10) of the brake circuit of the limiting element (18, 36, 42') when the predetermined pressure is reached, and the hydraulic oil is completely removed. A braking device characterized by being suitable for providing a through flow rate. 2. The braking device according to claim 1, wherein the limiting element comprises a sequence valve (18) which opens when the pressure of the hydraulic fluid reaches a predetermined pressure. 3. The brake system according to claim 1, wherein the limiting element is a restrictor valve (42 ′) that limits the flow rate of the hydraulic fluid. 4. The first bypass line (22) comprises a limiting element (18, 42 ').
) To allow the hydraulic fluid to bypass the limiting element (18, 42 ') and a check valve (24) is arranged in the first bypass line (22). , The hydraulic fluid passes through the first bypass line (22) and the brake members (4, 10).
4. The brake device according to claim 2 or 3, characterized in that it is prevented from flowing in the direction (4). 5. The second bypass line (40) is a sequence valve (18).
And the restrictor valve (42) is connected to the second bypass line (
40. The braking device according to claim 2, characterized in that it is arranged at 40) so that a limited flow of hydraulic fluid can bypass the sequence valve (18). 6. Brake device according to claim 1, characterized in that the brake valve (16 ') comprises the limiting element (36). 7. A first slider (32) for controlling the flow rate of hydraulic fluid in the first brake circuit (2) by the brake valve (16 '), and a second brake circuit (32).
8) has a second slider (34) for controlling the flow rate of pressure medium oil, and the first slider (32) controls the pressure in the first brake circuit (2) to reach a predetermined pressure. 7. The second slider (34) is configured to control the second slider (34) so as to open the second brake circuit (8) when the second slider (34) is opened. Brake device. 8. Brake arrangement according to claim 7, characterized in that the limiting element comprises a first spring (36) acting on a second slider (34). 9. A method for braking a construction machine, the machine being connected to a first brake member (4) provided on a first axle (6) of the machine. A brake circuit (2), and a second brake circuit (8) connected to a second brake member (10) provided on the second axle (12) of the machine. In the method, the first brake member (4) is activated when the brake pedal is depressed a small distance, and the second brake member (10) is activated substantially with a retarding effect. How to characterize. 10. The pressure of the hydraulic fluid on the second brake member (10) is limited until a predetermined pressure of the hydraulic fluid on the first brake member (4) is reached, and the first brake member (4). 10. The method according to claim 9, characterized in that the second brake member (10) is actuated substantially when the predetermined hydraulic oil pressure for (1) is reached. 11. A second brake member (10) until the predetermined pressure is reached.
The method according to claim 9 or 10, characterized in that the is operated substantially continuously. 12. A second brake member (10) when the predetermined pressure is reached.
A method according to any one of claims 9 to 11, characterized in that the pressure control valve (18) in the brake circuit is opened.