JP2002188718A - Fluid pressure transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a stopping/holding function of a vehicle when an occupant leaves the vehicle without activating a parking brake in an HST for traveling and driving the vehicle. SOLUTION: This device is provided with closed circuits 4a and 4b for transmitting a fluid pressure from a pump 1 to a motor 2, a charge circuit 5 provided with a charge pump 5a for supplying an insufficient flow rate to the closed circuits 4a and 4b and a charge relief valve 5c for returning an excessive supply flow rate, a parking brake circuit 12 for connecting the charge circuit 5 with a spring brake device 11 for parking, a solenoid valve 13 for opening the parking brake circuit 12 to a tank side at in energization time and communicating the parking brake circuit 12 with the charge circuit 5 when the energization is interrupted, and a parking release switch 14 for turning on a power source circuit of the solenoid valve 13 at only the brake release position according to a parking brake operation. When the occupant leaves a fixed position to perform a traveling operation of the vehicle, a driver detection switch 20 turned off for the time is interposed in series with the parking release switch 14 in the power source circuit of the solenoid valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic transmission (HST) for sending hydraulic pressure from a pump driven by power to a motor to perform work, and particularly to a vehicle. The present invention relates to a fluid pressure transmission device suitable for use in a drive device.

[0002]

2. Description of the Related Art FIG. 2 shows a very common hydraulic circuit of a two-pump / two-motor system in an HST for driving a vehicle. Reference numeral 1 denotes a variable displacement pump whose volume changes between forward discharge, neutral, and reverse discharge in accordance with a control lever (not shown). Reference numeral 2 denotes a constant displacement motor connected to a drive shaft of a drive wheel via a speed reducer 3. There is passage 4 between these
A loop (closed circuit) is formed by a and 4b. 5 is a charge circuit for replenishing the insufficient flow to the closed circuits 4a and 4b, 6
Is a prime mover (engine) that drives the variable displacement pump 1 and the charge pump 5a, 7 is an unload valve (manually operated valve), 8a and 8b release excessive pressure from the high pressure side to the low pressure side of the closed circuits 4a and 4b. High pressure relief valve. The charge circuit 5 includes a charge pump 5a and a filter 5
b, check valves 5d and 5e, and a charge relief valve 5c for returning an extra supply flow rate (charge flow rate) to the tank.
And are provided.

In the operating state of the prime mover 6, the discharge flow rate of the charge pump 5a is charged into the charge circuit 5, and the excess flow rate is supplied to the closed circuits 4a and 4b while the excess flow rate is supplied via the charge relief valve 5c. It is returned to the tank side and the charge circuit 5 is set at a predetermined pressure (charge relief pressure).
To hold. The variable displacement pump 1 supplies a constant flow displacement motor 2 with a discharge flow according to the operation amount of the control lever.

When the control lever is operated to the forward (positive discharge) side, a discharge flow in the positive direction corresponding to the operation amount of the control lever is sent from the variable displacement pump 1 to the constant displacement motor 2. The constant displacement motor 2 is driven by receiving this flow rate, and its output is transmitted to the drive wheels via the speed reducer 3 to cause the vehicle to travel in the forward direction. When the control lever is operated to the neutral position, when the variable displacement pump 1 is in a neutral position, the discharge flow rate thereof becomes 0, and the transmission of power (fluid pressure) to the constant displacement motor 2 is stopped. When the control lever is operated to the reverse (reverse discharge) side, the discharge flow in the reverse direction according to the operation amount of the control lever is sent from the variable displacement pump 1 to the constant displacement motor 2. The constant displacement motor 2 is driven by receiving this flow rate, and its output is transmitted to the drive wheels via the reduction gear 3,
The vehicle is driven in the reverse direction.

Reference numeral 10 denotes a brake disk formed on a drive shaft for driving force, and a parking spring brake device 11 having a brake pad 11a opposed to the disk surface is arranged. A parking brake circuit 12 for connecting the pressure chamber 11b of the spring brake device 11 to the charge circuit 5 is provided, and a solenoid valve 13 for turning on and off the spring brake is interposed in the brake circuit 12.

When the energization is on, the solenoid valve 13 switches to the position (a), and the hydraulic pressure of the charge circuit 5 (charge relief pressure) is changed to the spring brake device 11.
When the power is off, the position is switched to the position (b), and the pressure chamber 11b of the spring brake device 11 is opened to the tank side. The spring brake device 11 is provided between the solenoid valve 13 and the pressure chamber 11.
b is supplied with the charge relief pressure, the pressure chamber 11
b expands in the compression direction of the brake spring 11c to separate the brake pad 11a from the brake disk 10 of the driving wheel, and when the pressure chamber 11b is opened to the tank side via the solenoid valve 13, the brake spring 1
1c expands in the compression direction of the pressure chamber 11b and presses the brake pad 11a against the brake disk 10.

[0007] The solenoid valve 13 is connected to a power supply via a parking release switch 14. Reference numeral 15 denotes a parking lever, and the parking release switch 14 is turned on (energizes the solenoid valve 13) when the parking lever 15 is at the brake release position, and turned off when the parking lever 15 is separated from the brake release position.

When the parking lever 15 is operated to the brake operating position when the vehicle is stopped, the solenoid release valve 13 is switched to the position (b) by turning off the parking release switch 14, and the spring brake device 11 is turned on.
Is released to the tank side, so that the spring brake operates on the brake disc 10 via the brake pad 11a. When the parking lever 15 is operated to the brake release position, the solenoid release valve 13 is switched to the position (a) by turning on the parking release switch 14, and when the prime mover 6 is in operation, the charge circuit 5 switches the spring brake device 11 from the charge circuit 5. Since the charge relief pressure is supplied to the pressure chamber 11b to separate the brake pad 11a from the brake disk 10,
Spring brake is released.

[0009]

On a slope, the own weight of the vehicle acts on the constant displacement motor 2 as a rotational input (load). Therefore, when the variable displacement pump 1 is returned to the neutral position, the occupant will not be able to use the vehicle. Away from
The vehicle starts moving downhill. If there is no oil leakage (leakage of pressurized oil) from the variable displacement pump 1 or the constant displacement motor 2, the closed circuits 4a and 4b are oil-locked, and the risk of the vehicle running on its own can be prevented. However,
Actually, the variable displacement pump 1 and the constant displacement motor 2,
In particular, since oil leaks from the variable displacement pump 1, the closed circuit 4
Since the oils a and 4b flow to the variable displacement pump 1, rotation of the constant displacement motor 2 due to the weight of the vehicle cannot be suppressed.

In order to prevent this, it is conceivable to add a counterbalance valve 16 between the passages 4a and 4b as shown in FIG. The pilot pressure is introduced into the counter balance valve 16 from both sides of the variable displacement pump 1 in the passages 4a and 4b, and the counter balance valve 16 is switched to the high pressure side position (a) or (b), and the discharge flow rate of the variable displacement pump 1 is fixed. While allowing the closed circuits 4a and 4b to circulate through the displacement motor 2 while the pilot pressures at both ends are the same, the position is switched to the neutral position (c), and the discharge oil of the displacement motor 2 is switched to the neutral position (c). From flowing to the variable displacement pump 1 side. Incidentally, in the counter balance valve 16, 16
Reference symbol a denotes a check valve that allows only the flow of oil from the variable displacement pump 1 to the constant displacement motor 2.

Thus, when the control lever 15 is in the neutral position when the parking brake is released, the oil flowing from the constant displacement motor 2 to the variable displacement pump 1 through the closed circuits 4a and 4b by the counter balance valve 16 is provided. Since the vehicle is shut off, self-propelled operation of the vehicle based on oil leakage from the pump 1 can be prevented. However, even in the constant displacement motor 2,
Since a slight oil leak occurs, it is conceivable that the vehicle may run on its own slowly.

Since the counter balance valve 16 is switched based on the balance between the spring force at both ends and the pilot pressure, the initial setting of the spring force and the initial setting of the throttle (interposed in the pilot oil passage) are performed. It is difficult to tune the setting, and depending on the setting of both, if the control lever is suddenly returned to the neutral position during traveling, the discharge flow rate of the variable displacement pump 1 is greatly reduced, so that the pressure relationship between the passages 4a and 4b is reduced. Is reversed, and the counterbalance valve 16 causes hunting, which may cause a strange behavior (repetition of stop and running) of the vehicle. 3, the same components as those in FIG. 1 are denoted by the same reference numerals.

[0013] The present invention has been made in view of such a problem.
A vehicle stop / hold function can be ensured when the occupant leaves the vehicle without applying the parking brake.

[0014]

According to a first aspect of the present invention, there is provided a closed circuit for transmitting fluid pressure from a pump to a motor, a charge pump for supplying an insufficient flow rate to the closed circuit, and a charge relief valve for returning an excess supply flow rate to a tank. A parking brake circuit that connects the parking brake device to the charging circuit, and a solenoid valve that opens the parking brake circuit to the tank side when energized and connects the parking brake circuit to the charging circuit when energization is interrupted. And a switch circuit for turning on and off the energization of the solenoid valve in response to the parking brake operation, when the occupant leaves the home position for performing the traveling operation of the vehicle, the parking brake operation is performed during that time. Means for automatically activating the parking brake without relying on Characterized in that was.

According to a second aspect of the present invention, there is provided a closed circuit for transmitting fluid pressure from a pump to a motor, a charge circuit including a charge pump for supplying an insufficient flow rate to the closed circuit and a charge relief valve for returning an excess flow rate to a tank. A parking brake circuit for connecting a parking spring brake device to the charging circuit, a solenoid valve for opening the parking brake circuit to the tank side when the power is supplied, and connecting the parking brake circuit to the charging circuit when the power is cut off; A parking release switch that turns on the power supply circuit of the solenoid valve only at the brake release position in response to a driver detection that turns on when the occupant leaves the home position for performing the driving operation of the vehicle. Switch to the solenoid valve power supply circuit. It is characterized in that interposed King release switch and the series.

According to a third aspect of the present invention, a plurality of the driver detection switches according to the second aspect of the invention are wired in parallel to a power supply circuit of the solenoid valve, and are arranged in a fixed position range for performing a traveling operation of the vehicle. It is characterized by the following.

[0017]

According to the first aspect of the present invention, when the occupant leaves the home position for performing the driving operation of the vehicle, the parking brake is automatically operated during the period without depending on the parking brake operation. When the vehicle stops, it is possible to reliably prevent the unmanned vehicle from moving under its own weight.

According to the second aspect of the present invention, when the occupant leaves the home position for performing the driving operation of the vehicle, the driver detection switch is turned off during that time, so the parking release switch is turned on (the parking brake operation is at the brake release position).
Also in the case of (1), the power supply circuit of the solenoid valve is shut off, the parking brake circuit is opened to the tank (low pressure side) via the solenoid valve, and the spring brake device is operated (the parking brake is activated). Therefore, when the vehicle is stopped on a slope or the like, it is possible to reliably prevent the unmanned vehicle from moving under its own weight.

In the third aspect of the present invention, a plurality of driver detection switches are wired in parallel, and are arranged in a fixed position range for performing a traveling operation of the vehicle, so that the occupant moves in the fixed position range. However, the solenoid valve does not turn on and off (hunting), and the occupant can accurately detect this when the occupant moves away from the home position.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 denotes a brake disk formed on a drive shaft for driving force, 11 denotes a parking spring brake device having a brake pad 11a opposed to the disk surface, and 12 denotes a pressure chamber thereof. 11b is a parking brake circuit that connects the charging circuit 11b to the charging circuit 5. The parking brake circuit 12 is provided with a solenoid valve 13 for turning on and off a spring brake. In FIG. 1, the same components as those in FIG. 2 are denoted by the same reference numerals.

The solenoid valve 13 switches to the position (a) when energization is on, and changes the fluid pressure (charge relief pressure) of the charge circuit 5 to the spring brake device 1.
While the power is supplied to the first pressure chamber 11b, when the power is turned off, the position is switched to the position (b), and the pressure chamber 11b of the spring brake device 11 is opened to the tank side. The spring brake device 11 is connected to the pressure chamber 1 from the solenoid valve 13.
When the charge relief pressure is supplied to the pressure chamber 1b, the pressure chamber 1
1b expands in the compression direction of the brake spring 11c, and moves the brake pad 11a to the brake disk 10 of the drive wheel.
While the pressure chamber 11b is separated from the solenoid valve 13
, The brake spring 11c expands in the compression direction of the pressure chamber 11b and presses the brake pad 11a against the brake disk 10.

The solenoid valve 13 is connected to a power supply via a parking release switch 14. The parking release switch 14 is turned on (energizes the solenoid valve 13) when the parking lever 15 is at the brake release position.
It is set so that it will be turned off when it comes away from the brake release position. A driver detection switch 2 that is turned on only when an occupant is present at a fixed position for performing a traveling operation of the vehicle.
0 is interposed in the power supply circuit of the solenoid valve 13 in series with the parking release switch 14.

When the vehicle has a driver's seat (fixed position), the driver detection switch 20 is arranged at the driver's seat, and is set to turn on when an occupant is seated in the driver's seat and to turn off when the driver stands. When the vehicle does not have a driver's seat and performs a traveling operation while the occupant is standing, the driver detection switch 20 is disposed on the floor at the traveling operation position (fixed position), and the occupant is placed on the floor. It is set to turn on when standing and to turn off when the occupant leaves the floor. The driver detection switch 20 has a plurality of power supply circuits 20a and 20b connected in parallel to the power supply circuit of the solenoid valve 13 (in series with the parking release switch 14) so that the presence of the occupant can be accurately detected even when the occupant moves to the home position. These are wired and arranged in a range of a fixed position for performing a traveling operation of the vehicle.

When the parking lever 15 is operated to the brake operating position when the vehicle is stopped, the solenoid release valve 13 is switched to the position (b) by turning off the parking release switch 14, and the spring brake device 11 is turned on.
Is released to the tank side, so that the spring brake operates on the brake disc 10 via the brake pad 11a. When the parking lever 15 is operated to the brake release position, the solenoid release valve 13 is switched to the position (a) by turning on the parking release switch 14, and when the prime mover 6 is in operation, the charge circuit 5 switches the spring brake device 11 from the charge circuit 5. Since the charge relief pressure is supplied to the pressure chamber 11b to separate the brake pad 11a from the brake disc 10,
Spring brake is released.

When the occupant leaves the home position, the driver detection switch 20 is turned off during that time. Therefore, even when the parking release switch 14 is turned on, the solenoid valve 13 is turned off.
, The parking brake circuit 12 is opened to the tank (low pressure side) via the solenoid valve 13, and the spring brake device 11 presses the brake pad 11a against the brake disk 10. That is, since the parking brake is operated, it is possible to reliably prevent the unmanned vehicle from moving under its own weight when stopping on a slope or the like.

In this example, since the driver detection switch 20 is simply added to the power supply circuit of the solenoid valve 13, the cost advantage is greater than when the counter balance valve 16 is interposed as shown in FIG. Further, since the counterbalance valve 16 (see FIG. 3), which is difficult to tune at the initial setting, is unnecessary, if a sudden brake is applied as in the prior art, the counterbalance valve 16 hunts and causes strange behavior in the vehicle. There is no such thing. The driver detection switch 20 includes a plurality of driver detection switches 20a, 20b.
And the solenoid valves 13 are turned on and off (hunting) even when the occupant moves in the fixed position range by arranging these in parallel and arranging them in a fixed position range for performing the traveling operation of the vehicle. When the occupant moves away from the home position, this can be accurately detected.

If there is no need to provide a plurality of driver detection switches 20, only one driver detection switch 20 may be provided. The point is that it only has to be provided in series with the parking release switch. Further, the parking brake device 11 is not limited to the spring brake, but may be a device that operates by receiving a supply of fluid pressure (actuates the parking brake). In this case, the power supply circuit of the solenoid valve 13 is provided with a parking operation switch that is turned on only when the parking lever is operated to the brake operation position, instead of the parking release switch 14, while the driver detection switch 20 is controlled by the occupant. It is also conceivable to change the switch to a switch that turns on only during that time, and to wire the switch in parallel with the parking operation switch to the power supply.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional technique.

FIG. 3 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable displacement pump 2 Constant displacement motor 4a, 4b Passage (closed circuit) 5 Charge circuit 5a Charge pump 5c Charge relief valve 5d, 5e Check valve 10 Brake disk 11 Parking spring brake device 11a Brake pad 11b Pressure chamber 11c Brake Spring 12 Parking brake circuit 13 Solenoid valve 14 Parking release switch 15 Parking lever 20 (20a, 20b) Driver detection switch

Claims (3)

[Claims] 1. A closed circuit for transmitting a fluid pressure from a pump to a motor, a charge circuit for replenishing an insufficient flow rate to the closed circuit, and a charge relief valve for returning a surplus replenished flow rate to a tank. A parking brake circuit for connecting the brake device, a solenoid valve that opens the parking brake circuit to the tank side when energized and a solenoid valve that connects the parking brake circuit to the charge circuit when energization is cut off, and a solenoid valve that responds to the parking brake operation And a switch circuit for turning on and off the power supply of the vehicle, when the occupant moves away from a fixed position for performing the traveling operation of the vehicle, the parking brake is automatically operated during the period without depending on the parking brake operation Means for providing a fluid pressure transmission device . 2. A closed circuit for transmitting a fluid pressure from a pump to a motor, a charge circuit having a charge pump for supplying an insufficient flow rate to the closed circuit and a charge relief valve for returning an excess flow rate to a tank, and parking in the charge circuit. Brake circuit for connecting a spring brake device for use, a solenoid valve that opens the parking brake circuit to the tank side when energized, and a solenoid valve that connects the parking brake circuit to the charge circuit when energization is cut off, and a brake in accordance with the parking brake operation And a parking release switch that turns on the power supply circuit of the solenoid valve only in the release position.In the hydraulic pressure transmission device, when the occupant leaves the home position for performing the traveling operation of the vehicle, the driver detection switch that is turned off during that time is provided by the solenoid valve. Parking release switch Fluid pressure transmission operated device being characterized in that interposed Ji series. 3. The driver detecting switch according to claim 2, wherein a plurality of driver detecting switches are wired in parallel to a power supply circuit of the solenoid valve, and are arranged in a fixed position range for running the vehicle. The fluid pressure transmission according to any of the preceding claims.