JP2512856Y2 - Vehicle brake control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is for a vehicle that is provided in a hydraulically driven vehicle such as a wheel hydraulic excavator or a wheel loader and is preferably used to control the operation of a parking brake. Brake control device

[Conventional technology]

FIG. 3 and FIG. 4 show, as an example of a conventional vehicle brake control device, a hydraulic motor drive circuit and a brake control circuit of a wheel hydraulic excavator.

In FIG. 1, reference numeral 1 denotes a hydraulic pump that is rotationally driven by a prime mover (not shown) such as an engine. The hydraulic pump 1 sucks hydraulic oil in a tank 2 and discharges high-pressure oil (hereinafter referred to as pressure oil). It is designed to let you. Reference numeral 3 denotes a traveling hydraulic motor connected to the hydraulic pump 1 and the tank 2 via a pair of main pipes 4A and 4B. The output shaft of the hydraulic motor 3 is connected to the front and rear axles via either a speed reducer or the like. (Not shown), and the pressure oil from the hydraulic pump 1 is connected to the main pipes 4A, 4
By being supplied and discharged via B, they are rotated in the forward or reverse direction to drive these axles for traveling.

Reference numeral 5 denotes a control valve which is located between the hydraulic motor 3 and the hydraulic pump 1 and the tank 2, and which is provided in the middle of the main pipelines 4A and 4B. The control valve 5 includes a pair of hydraulic pilot portions 5A and 5B. 8 port 3 position hydraulic pilot type directional control valve which has a neutral position (a)
To the left and right switching positions (b) and (c).
The control valve 5 controls the flow rate of the pressure oil supplied to and discharged from the hydraulic motor 3 in accordance with the stroke amount when the neutral position (a) is switched to the switching positions (b) and (c), and the switching position ( The rotation direction of the hydraulic motor 3 is controlled to be forward or reverse between the (b) side and the switching position (c) side.

6 is a hydraulic pump for supplying pilot pressure, which is driven by a prime mover together with the hydraulic pump 1, and 7 is a control valve 5 from the neutral position (a) to the switching position (b) and (c) side to the operation amount of the traveling pedal 7A. A pressure-reducing valve type pilot valve is shown as an operating means for traveling, which is operated in accordance with the switching operation to control the traveling speed. Is connected to the pilot line 8. The pilot valve 7 is interlocked with a traveling pedal 7A provided in a driver's cab (not shown), and a pilot pressure corresponding to an operation amount (depression amount) of the traveling pedal 7A is supplied from the hydraulic pump 6 to the pilot conduit 8 It is designed to be supplied inside.

Reference numeral 9 denotes a forward / reverse switching valve as forward / reverse switching means for switching and connecting the pilot conduit 8 to the pilot conduits 8A and 8B. The switching valve 9 is constituted by a 4-port 3-position directional switching valve, The lever 9A for switching provided on the switch is operated to switch from the neutral position (N) to the forward drive position (F) or the reverse drive position (R). Where the pilot conduit 8
A and 8B are connected to the hydraulic pilot parts 5A and 5B of the control valve 5,
When the switching valve 9 is switched to the forward position (F), the pilot pressure from the pilot valve 7 is applied to the hydraulic pilot section 5A.
To the reverse position (R),
The pilot pressure is applied to the hydraulic pilot section 5B. Further, reference numeral 10 denotes a slow return valve as a speed regulating valve provided between the pilot valve 7 and the switching valve 9 and provided in the middle of the pilot conduit 8.

11 is located between the hydraulic motor 3 and the control valve 5 and is located in the main pipeline.
Shows the counter balance valve installed in the middle of 4A, 4B,
The counter balance valve 11 is a pair of check valves 12A and 12B.
And a pair of pressure control valves 13A, 13B. When the control valve 5 returns to the neutral position, the pressure control valves 13A, 13B return to the illustrated position in cooperation with the control valve 5, The braking pressure of the motor 3 is generated in the main pipelines 4A and 4B. Reference numerals 14A and 14B denote a pair of overload relief valves provided between the counterbalance valve 11 and the hydraulic motor 3 and provided between the main pipelines 4A and 4B. The overload relief valves 14A and 14B are the hydraulic motor 3 Main line 4 during inertia rotation of
When the braking pressure of the hydraulic motor 3 generated in A, 4B exceeds a predetermined high pressure level (relief setting pressure), the valve is opened to relieve this pressure and prevent excessive pressure from acting on the hydraulic motor 3. At the same time, the hydraulic motor 3 is gradually stopped. 15 is overload relief valve 14A, 14B
The check valve for make-up, which is provided between the main pipelines 4A and 4B and located between the hydraulic motor 3 and the hydraulic motor 3,
Numeral 15 prevents negative pressure in the main pipelines 4A, 4B during braking of the hydraulic motor 3 or the like, and suppresses cavitation.

Reference numeral 16 denotes a center joint provided between the control valve 5 and the counter balance valve 11 and provided in the middle of the main pipelines 4A, 4B. The center joint 16 is a lower traveling body and an upper revolving body of a wheel hydraulic excavator. (Neither is shown), so that pressure oil from the hydraulic pump 1 can be supplied to and discharged from the hydraulic motor 3 even when the upper revolving structure is revolving. That is, the hydraulic motor 3, the counter balance valve 11, etc. are provided in the lower traveling body, and the hydraulic pumps 1, 6, the control valve 5, the pilot valve 7, etc. are provided in the upper revolving body. Further, 17 denotes a main relief valve provided between the hydraulic pump 1 and the tank 2 and the control valve 5 and provided on the discharge side of the hydraulic pump 1. The relief valve 17 is used when the vehicle develops or accelerates. When the driving pressure of the hydraulic motor 3 exceeds a predetermined high pressure level (relief set pressure), this pressure is relieved and the hydraulic motor 3
It is designed to prevent excessive pressure from acting on.

Next, FIG. 4 shows a brake control circuit of the wheel hydraulic excavator.

In the figure, 18 indicates a pressure air source as a pressure source, and the pressure source 18
Is an air pump driven by a prime mover 19 such as an engine
20, an air tank 22 connected to the air pump 20 via a check valve 21 for temporarily storing compressed air discharged from the air pump 20, and the air tank
It is composed of a safety valve 23 that prevents the air pressure inside 22 from becoming an excessive pressure of, for example, 9 kg / cm ² or more.

Reference numeral 24 denotes a positive service brake device that applies a braking force when the vehicle is running.
24 is a master cylinder 25 and piping 26 to the master cylinder 25.
Is generally constituted by service brakes 27, 27, ... Attached to the front and rear wheels, respectively, and each service brake 27 is operated by hydraulic pressure from a master cylinder 25. . Then, the master cylinder 25 of the service brake device 24 is connected to the air tank 22 via a pipe 28, and when the air pressure is supplied from the air tank 22, each service brake 27 is operated to drive the vehicle (wheel type hydraulic excavator). ) Is to apply braking force to each wheel.

Reference numeral 29 denotes a negative-type parking brake device that applies a braking force when the vehicle is parked, and the parking brake device 29 is an air cylinder 31 connected to the air tank 22 via a conduit 30 or the like.
And a parking brake operated by the air cylinder 31
32, and one end side of the pipeline 30 is connected to the pipeline 28 on the upstream side of a service brake valve 36 described later to form a common pipeline for the air tank 22. The parking brake device 29 applies a braking force to the vehicle by the parking brake 32 when the air pressure is discharged from the air cylinder 31, and a braking force by the parking brake 32 when the air pressure is supplied to the air cylinder 31. It is designed to be released.

33 is the air tank 22, master cylinder 25, air cylinder 3
1 shows a brake control valve as a parking brake valve which is located between 1 and 2 and which is provided in the middle of the pipelines 28, 30. The control valve 33 is manually switched by the operating lever 33A to switch the direction of 5 ports 3 positions. The vehicle is provided with a traveling position N configured by a valve and supplying air pressure to the air cylinder 31, a parking position P for discharging the air pressure to the outside from the opening 31B, and a working position W. When the control valve 33 is switched to the traveling position N when the vehicle is traveling, the air pressure from the air tank 22 is supplied to the air cylinder 31 via the pipe 30, the parking brake 32 is released, and the master cylinder 25 is released. The internal air pressure is discharged to the outside via the service brake valve 36. Further, when the control valve 33 is switched between the parking position P and the working position W during parking and working of the vehicle, the parking brake 32 is braked by discharging the air pressure in the air cylinder 31 to the outside from the opening 31B. At the work position W, the air pressure from the conduit 30 side is supplied to the master cylinder 25 so that each service brake 27 is kept in the braking state.

Reference numeral 34 denotes a bypass line that bypasses the brake control valve 33 and is connected to the line 28. A check valve 35 is provided in the middle of the bypass line 34, and the check valve 35 is an air tank.
The air is allowed to be supplied from 22 to the master cylinder 25, and the reverse flow is blocked.

Reference numeral 36 denotes a service brake valve provided between the air tank 22, the control valve 33, and the bypass passage 34 and provided in the middle of the pipeline 28. The brake valve 36 is an air tank when the brake pedal 36A is depressed. The air pressure from 22 is supplied to the master cylinder 25 via the bypass conduit 34 and the like, and the air pressure in the master cylinder 25 and the like is constantly discharged to the outside from the opening 36B.

In the conventional wheel hydraulic excavator configured as described above, first, when the vehicle is parked, the control valve 33 is switched to the parking position P to discharge the air pressure in the air cylinder 31 to the outside through the opening 33B, and the parking brake. Activate 32 to keep the vehicle in braking. Also, when performing excavation work, etc.
The control valve 33 is switched to the work position W to operate the service brakes 27 as well as the parking brake 32 to give a larger braking force to the vehicle, thereby preventing the vehicle from moving due to the excavation reaction force or the like.

On the other hand, when the vehicle is traveling, the control valve 33 is switched to the traveling position N as shown in FIG. 4, the braking of the parking brake 32 and each service brake 27 is released, and the vehicle is set to the traveling state. In this state, the forward / reverse switching valve 9 shown in FIG. 3 is switched from the neutral position (N) to the forward position (F) or the reverse position (R) by manually operating the lever 9A, and the traveling pedal
When 7A is stepped on, the control valve 5 is switched from the neutral position (a) to the switching position (b) or (c) so that the hydraulic motor 3 is rotated, and the vehicle is moved forward or backward to move on the road or the like. Can run. Further, when the brake pedal 36B shown in FIG. 4 is depressed, the service brakes 27 and the like can be actuated during traveling or the like to apply a braking force to the vehicle.

[Problems to be solved by the device]

By the way, in the above-mentioned conventional technology, when the vehicle is going to run, after the brake control valve 33 is manually switched to the travel position N, the forward / reverse switching valve 9 is manually operated to depress the travel pedal 7A. When the control valve 33 is switched to the traveling position N, the parking brake 32
Also, since the braking of each service brake 27 is released, the vehicle may move carelessly before operating the forward / reverse switching valve 9 and the traveling pedal 7A, and there is a problem that safety cannot be improved. is there.

When the vehicle is to be stopped, the parking brake 32 is set unless the control valve 33 is switched from the traveling position N to the parking position P after the forward / reverse switching valve 9 is switched to the neutral position (N). There is a problem that it cannot be operated and the manual operation of the levers 9A, 33A and the like becomes complicated, resulting in extremely poor workability.

The present invention has been made in view of the above-described problems of the prior art. When the forward / reverse switching means is switched to the neutral position, the braking force can be automatically applied to the vehicle by the parking brake device, and the safety can be improved. Another object of the present invention is to provide a vehicle brake control device capable of effectively improving operability and workability.

[Means for solving the problem]

In order to solve the above-mentioned problems, the structure adopted by the present invention is a forward / reverse switching means for switching the traveling direction of a vehicle, and a parking for applying and releasing a braking force to the vehicle by supplying and discharging pressure from a pressure source. Brake control for a vehicle comprising a brake device and a parking brake valve that is operated to be switched by an external operation means provided independently of the forward / reverse switching means to supply and discharge the pressure from the pressure source to the parking brake device. In the apparatus, the parking brake valve is composed of an electromagnetic switching valve which is switched between a pressure supply position and a pressure discharging position by an external operating means, and the forward / reverse switching means is neutralized to stop the vehicle. A neutral position detecting means for detecting whether or not the position has been switched is provided, and when the detecting means detects the neutral position, regardless of the operation position of the external operating means. The is characterized in the fact that the structure for switching the valve position of the solenoid selector valve to apply a braking force to the vehicle.

[Action]

With the above configuration, even if the valve position of the electromagnetic switching valve as the parking brake valve is in the state where the braking by the parking brake device is released, if the forward / reverse switching means is switched to the neutral position,
The valve position of the electromagnetic switching valve can be automatically switched, and the braking force can be applied to the vehicle by the parking brake device. Then, when the forward / reverse switching means is switched from the neutral position to a position other than this, the electromagnetic switching valve (parking brake valve) is set to the pressure supply position by the external operation means provided independently of the forward / reverse switching means. The operation can be switched to the discharge position, and the braking force by the parking brake device can be appropriately applied or released by the external operation means.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the embodiment, the same components as those of the prior art shown in FIGS. 3 and 4 described above are designated by the same reference numerals, and the description thereof will be omitted.

Here, FIG. 1 shows a first embodiment of the present invention.

In the figure, 41 indicates a brake control valve as a parking brake valve provided between the air tank 22, the master cylinder 25, and the air cylinder 31 and provided in the middle of the pipelines 28, 30. Although the control valve 33 has a traveling position N as a pressure supply position, a parking position P as a discharge position, and a work position W, the control valve 41 is 5
It is composed of an electromagnetic switching valve at the port 3 position.
The control valve 41 is provided with left and right solenoids 41A and 41B, and the solenoids 41A and 41B have rotary switches 4 to be described later.
When excited by the energization from 2, the parking position P is switched to the traveling position N and the working position W. Also, the control valve
41 is provided with an opening 41C, and when the parking position P and the working position W are switched, the air pressure in the air cylinder 31 is opened 41C.
It is designed to be discharged from the outside.

Reference numeral 42 denotes a rotary switch as an external operating means for switching the brake control valve 41 from the outside.The rotary switch 42 is connected to a movable contact 42A connected to a battery 43 as a power source and a solenoid 41A via a lead wire 44. Connected running contact 42B and solenoid 41B via lead wire 45
And a parking contact 42D located between the contacts 42B and 42C, which are provided independently of a forward-reverse switching valve 47 and a rotary switch 48 described later.
The rotary switch 42 connects the movable contact 42A to the contacts 42B, 4
By manually switching to 2C and 42D, the brake control valve 41 is switched to the traveling position N, the working position W, and the parking position P.

Reference numeral 46 denotes a relay as a relay disposed in the middle of the lead wire 44. The relay 46 is opened as shown when the coil 46A is energized by a rotary switch 48 described later, and is normally closed to be a rotary switch. 42 contact 42B to solenoid 4
It is designed to allow 1A to be energized. Then, the relay 46 shuts off the power supply to the solenoid 41A when it is opened,
The control valve 41 is prevented from switching to the traveling position N.

Reference numeral 47 denotes a forward / reverse switching valve that constitutes a forward / backward switching means together with the rotary switch 48. The forward / backward switching valve 47 has a neutral position (N) similar to the forward / backward switching valve 9 described in the prior art.
Although it has a forward drive position (F) and a reverse drive position (R), the forward / backward switching valve 47 is composed of a 4-port / 3-position electromagnetic switching valve. The forward / reverse switching valve 47 is provided with solenoids 47A and 47B on both ends thereof, and when the solenoids 47A and 47B are excited by energization from the rotary switch 48, the neutral position (N) to the forward position (F). , To the reverse position (R).

Further, 48 is a rotary switch as a manual operation means for switching the forward / reverse switching valve 47 from the outside, and the rotary switch 48 is a movable contact 48A connected to the battery 43.
And a forward contact 48B connected to the solenoid 47A via a lead wire 49, a reverse contact 48C connected to the solenoid 47B via a lead wire 50, and located between the contacts 48B, 48C,
The neutral contact 48D connected to the coil 46A of the relay 46 via the lead wire 51 is provided, and the movable contact 48A is connected to the contacts 48B, 48C, 48.
By manually switching to D, the forward / reverse switching valve 47 is switched to the forward position (F), the reverse position (R), and the neutral position (N). Here, the contact 48D of the rotary switch 48 constitutes a neutral position detecting means together with the movable contact 48A so that the relay 46 is opened by the coil 46A when the forward / reverse switching valve 47 is switched to the neutral position (N). Has become.

The brake control device for the wheel hydraulic excavator according to the present embodiment has the above-described configuration, and the basic operation thereof is not different from that according to the prior art.

Therefore, in the present embodiment, the brake control valve 41 as the parking brake valve and the forward / reverse switching valve 47 are electromagnetic switching valves, and these are switched from the outside by the rotary switches 42 and 48, and the solenoid of the brake control valve 41 is operated. A normally closed relay 46 is provided in the middle of the lead wire 44 connecting between 41A and the contact 42B of the rotary switch 42, and the coil 46A of the relay 46 is connected to the contact 48D of the rotary switch 48. If the relay 46 is opened when the movable contact 48A is switched to the contact 48D in order to switch the forward / reverse switching valve 47 to the neutral position (N) by the switch 48, for example, to switch the brake control valve 41 to the traveling position N. Even when the movable contact 42A of the rotary switch 42 is switched to the contact 42B as illustrated, the brake control valve 41 is operated while the forward / reverse switching valve 47 is being switched to the neutral position (N). Can be kept in the parking position P shown, the vehicle can be prevented by the parking brake 32 from inadvertently moving, safety is improved.

Then, move the movable contact 48A of the rotary switch 48 to the contact 48.
If the forward / reverse switching valve 47 is switched from the neutral position (N) to the forward position (F) or the reverse position (R) by switching to B and 48C, the solenoid 41A of the brake control valve 41 is excited to park the control valve 41. The position P can be automatically switched to the traveling position N, the parking brake 32 can be released, and the vehicle can be moved forward or backward by operating the traveling pedal 7A, and the operability and workability during traveling and stopping can be greatly improved.

Therefore, in this embodiment, if the rotary switch 42 is switched to the contact 42B when the vehicle is repeatedly run and stopped,
The vehicle can be easily run or stopped only by operating the rotary switch 48, and when the vehicle is stopped, the control valve 41 automatically switches from the running position N to the parking position P. Therefore, the braking force can be applied by the parking brake 32. In addition to the operability and workability, the safety can be surely improved, and various effects can be obtained.

Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The feature of this embodiment resides in that the neutral contact 48D of the rotary switch 48 is connected by the lead wire 61 in the middle of the lead wire 45 connecting the working contact 42C of the rotary switch 42 and the solenoid 41B.

Thus, in the present embodiment configured as described above, even when the rotary switch 42 is switched to the traveling contact 42B as shown in the figure, the brake control valve 41 is parked at the parking position by switching the rotary switch 48 to the neutral contact 48D. It is possible to switch to P, to obtain substantially the same operation and effect as in the first embodiment, and the relay 46 used in the first embodiment can be omitted, which simplifies the circuit configuration and reduces the cost. It can be planned.

In each of the above-mentioned embodiments, the forward / reverse switching valve 47 is described as being constituted by an electromagnetic switching valve. However, instead of this, the forward / backward switching valve 47 is replaced by the forward / backward switching valve 9 described in the related art.
Similarly, a lever-operated switching valve may be used. In this case, a tilt position detector is provided on the operating lever or the like to detect the neutral position of the forward / reverse switching valve, and this detection signal is used to detect the neutral position in FIG. It suffices to open the relay 46 shown in FIG.

Further, in each of the above-mentioned embodiments, the wheel type hydraulic excavator has been described as an example, but the present invention is not limited to this, and is directly driven by a hydraulically driven vehicle such as a hydraulic crane or a prime mover such as an engine, and a shift lever or the like. It can also be applied to various vehicles equipped with the forward / reverse switching means.

Further, in each of the above-described embodiments, the negative type parking brake device 29 that releases the braking force to the vehicle when the pressure from the air tank 22 is supplied and, conversely, applies the braking force when the pressure is discharged. Although described as being used, the present invention is not limited to this, for example, a positive type parking brake device that applies a braking force to the vehicle when pressure is supplied and releases the braking force when pressure is discharged. You may use.

[Effect of device]

As described above in detail, according to the present invention, the electromagnetic switching valve constituting the parking brake valve is switched by the external operation means provided independently of the forward / reverse switching means, and the electromagnetic switching valve is operated under pressure. By switching between the supply position and the discharge position of the vehicle, the braking force is applied to and released from the vehicle by the parking brake device, and the forward / reverse switching means is provided with a neutral position detecting means for detecting whether or not the neutral position is switched. When the detection means detects the neutral position, the valve position of the electromagnetic switching valve is switched so as to apply the braking force to the vehicle regardless of the operating position of the external operating means. When the means is switched to a position other than the neutral position (for example, a forward drive position or a reverse drive position), the electromagnetic switching valve can be switched by the external operating means independently of the forward / reverse switching means, and the parking can be performed. The grant or release of the braking force by the rake device can be performed appropriately by an external operation means.

Then, when the forward / reverse switching means is returned to the neutral position, the parking brake is applied so as to apply the braking force to the vehicle by automatically switching the valve position of the electromagnetic switching valve regardless of the operating position of the external operating means. The device can be operated, the vehicle can be prevented from moving carelessly, the operability and workability can be reliably enhanced, and the safety can be significantly improved.

[Brief description of drawings]

FIG. 1 is a brake control circuit diagram showing a first embodiment of the present invention, FIG. 2 is a brake control circuit diagram showing a second embodiment,
FIGS. 3 and 4 show the prior art, FIG. 3 is a hydraulic circuit diagram, and FIG. 4 is a brake control circuit diagram. 18 …… pressure source (pressure source), 20 …… air pump, 22 …… air tank, 24 …… service brake device, 29 …… parking brake device, 31 …… air cylinder, 32 …… parking brake, 36 …… service Brake valve, 41 …… Brake control valve (parking brake valve), 41A, 41B …… Solenoid, 42 ……
Rotary switch (external operating means), 43 ... battery,
46 …… Relay, 47 …… Forward / backward switching valve (forward / backward switching means), 48 …… Rotary switch (neutral position detection means).

Claims (1)

(57) [Scope of utility model registration request] 1. A forward / reverse switching means for switching the traveling direction of a vehicle, a parking brake device for applying and releasing a braking force to and from the vehicle by supplying / discharging a pressure from a pressure source, and the forward / backward switching means are independent of each other. In a vehicle brake control device including a parking brake valve that is switched by an external operation means provided to supply and discharge the pressure from the pressure source to and from the parking brake device, the parking brake valve is operated by an external operation means. A neutral position which is constituted by an electromagnetic switching valve that switches between a pressure supply position and a pressure discharge position, and the forward / reverse switching means detects whether or not the forward / reverse switching means has been switched to a neutral position in order to stop the vehicle. Detecting means is provided, and when the detecting means detects the neutral position, regardless of the operating position of the external operating means,
A vehicle brake control device, wherein the valve position of the electromagnetic switching valve is switched so as to apply a braking force to the vehicle.