JP2005054941A - Cooling oil circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling oil circuit in which a sufficient cooling oil amount can be supplied even at the low driving of a cooling oil pump, and a rise in hydraulic pressure owing to pressure loss can be suppressed at the high driving of the cooling oil pump. <P>SOLUTION: The cooling oil circuit 1 is provided with a multi-plate wet brake 9 having a cooling path passing cooling oil and a sealing means preventing cooling oil from leaking, a cooling pump 3 feeding cooling oil under pressure into the multi-plate wet brake, a feeding passage 11 communicating with the pump and the brake, and a flow dividing valve 5 limiting cooling oil fed into the brake so that the hydraulic pressure provided in the feeding passage and acting on the sealing means is not greater than a predetermined value. The flow dividing valve can be also replaced with a throttle means 327 limiting cooling oil fed into the brake, and a relief valve 307 arranged upstream of the throttle means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling oil circuit that circulates oil for cooling.

  Conventionally, there is a cooling oil circuit that circulates oil for cooling. As an example, a cooling oil circuit is provided for a wet brake device of a vehicle such as an industrial vehicle or an automobile to cool frictional heat generated during braking. There is a technology (for example, see Patent Document 1). In such a cooling oil circuit, a cooling oil pump directly connected to the engine is provided, and the cooling oil pumped by this pump is supplied to a high temperature portion in the brake device to exchange heat, and then collected in an oil pan. To do. An oil seal or the like for preventing cooling oil leakage is disposed in a cooling path through which the cooling oil passes in the brake device.

JP 2001-193774 A

  In general, the pressure applied to the cooling oil greatly affects the life of the seal such as the oil seal or the face seal. Therefore, it is desirable that the pressure applied to the cooling oil is smaller for the life of the seal. On the other hand, the cooling efficiency is better when the flow rate of the cooling oil is larger. However, if the flow rate is increased, the hydraulic pressure increases due to pressure loss, and as described above, the service life of the seal and oil leakage are likely to occur. In addition, because the coolant oil pump directly connected to the engine is used, the maximum oil pressure (maximum flow rate) that is generated because the flow rate of the cooling oil varies depending on the engine speed can be designed according to the engine maximum speed. There arises a problem that a sufficient cooling oil flow rate cannot be obtained in the idling state. Further, when the driving of the cooling oil pump is changed from the engine direct connection type, there arises a problem that a great cost is required.

  The present invention has been made in view of such problems, and can supply a sufficient amount of cooling oil even when the cooling oil pump is driven low, and suppresses an increase in hydraulic pressure due to pressure loss when the cooling oil pump is driven high. It is an object of the present invention to provide a cooling oil circuit that can be used.

  In order to achieve the above-described object, the cooling oil circuit of the present invention is driven by an internal combustion engine having a cooling path that allows the cooling oil to pass through and a sealing means that prevents leakage of the cooling oil from the cooling path. And a pump that pumps cooling oil to the cooled part, a supply path that communicates the pump and the cooled part, and a hydraulic pressure that is provided in the supply path and that acts on the sealing means is less than a predetermined value. And a diverter valve for limiting the cooling oil supplied to the cooled part.

  Further, another cooling oil circuit of the present invention for achieving the same object includes a cooled portion having a cooling passage through which the cooling oil passes and a sealing means for preventing leakage of the cooling oil from the cooling passage, and an internal combustion engine A pump that is driven by an engine to pump cooling oil to the cooled part, a supply path that communicates the pump and the cooled part, and a hydraulic pressure that is provided in the supply path and that acts on the sealing means is a predetermined value or less. As described above, a throttle means for limiting the cooling oil supplied to the cooled part, and a relief valve arranged upstream of the throttle means in the supply path are provided.

  Preferably, a recovery path for recovering the cooling oil to an oil storage means such as an oil tank or an oil pan is connected to the housing of the cooled portion. Further, the cooled portion may be a brake device. Further, a hydraulic pressure of 0.5 MPa or less may act on the sealing means.

  According to the present invention, a sufficient amount of cooling oil can be supplied even when the cooling oil pump is driven low, and an increase in hydraulic pressure due to pressure loss can be suppressed when the cooling oil pump is driven high.

  Hereinafter, a cooling oil circuit according to the present invention will be described with reference to the accompanying drawings as an embodiment in a case where the cooling oil circuit is applied to a wet multi-plate brake device of a forklift. In the drawings, the same reference numerals indicate the same or corresponding parts.

Embodiment 1 FIG.
As shown in FIG. 1, the cooling oil circuit 1 mainly includes a cooling pump 3, a diverter valve 5, a relief valve 7, and a pair of wet multi-plate brake devices 9 that are cooled parts. Yes. The cooling pump 3 is directly connected to an engine (not shown) of the forklift, and operates when the driving force of the engine is transmitted. That is, the discharge flow rate of the cooling pump 3 is low when the engine is idling and high when the engine is rotating at high speed. The outlet of the cooling pump 3 and the inlet of each wet multi-plate brake device 9 are communicated with each other by a supply path 11.

  A diversion valve 5 is disposed downstream of the cooling pump 3 on the supply path 11. The diversion valve 5 may be a well-known one, and has a valve body in which an orifice that communicates the main inflow port 5a and the main outflow port 5b is formed. A flow path to 5c is also secured. A discharge path 13 is provided downstream of the diversion outlet 5c, and an oil tank 15 as oil storage means is disposed at the downstream end thereof. The oil storage means is not limited to the tank type, and other storage types such as an oil pan can be used.

  A filter 17 is disposed downstream of the main flow outlet 5 b of the diversion valve 5 on the supply path 11. Further, an oil cooler 19 is disposed downstream of the filter 17. The supply path 11 is branched into two starting from a branch point a downstream of the oil cooler 19, and a wet multi-plate brake device 9 is provided for each.

  A relief valve 7 is arranged at a position b between the branch point a and the oil cooler 19 on the supply path 11. The relief valve 7 may be a well-known one, and has a structure in which the flow path is blocked below the relief pressure and opened when the relief pressure is reached, due to the balance between the pilot pressure and the spring elastic force. In addition to such a structure, a structure may be used in which the valve body blocking the flow path is opened and relief is performed when the pressure is simply higher than the relief pressure without using the pilot pressure. A relief path 21 is connected to the outlet of the relief valve 7, and its downstream end reaches the oil tank 15.

  Each wet multi-plate brake device 9 has a well-known configuration, and prevents the cooling oil from leaking outside the device from other than the cooling path that houses the multi-plate and allows the cooling oil to pass therethrough. Sealing means. A collection path 23 is connected to the housing of each wet multi-plate brake device 9 at the outlet of the cooling path. The downstream end of the recovery path 23 reaches the oil tank 15. In addition, the oil tank 15 is connected to the other end of the suction path 25 whose one end is connected to the suction port of the cooling pump 3.

  Next, the operation of the cooling oil circuit having the above configuration will be described. First, generally, as shown in the graph of FIG. 2, when the maximum cooling flow rate of the brake device is set to 20 liters / minute at a pump rotational speed of 2500 rpm which is the maximum engine speed, it is indicated by a symbol L in the figure. In this way, the cooling flow rate is 4.8 liters / minute at a pump rotational speed of 600 rpm during engine idling, and the brake device cannot be sufficiently cooled. Conversely, if the minimum cooling flow rate of the brake device is set to 12 liters / minute at a pump rotational speed of 600 rpm at the time of engine idling, as indicated by symbol H in the figure, at a pump rotational speed of 2500 rpm at the maximum engine speed. The cooling flow rate becomes 50 liters / minute, and this time, the internal pressure of the brake device becomes too high, and there is a problem that the cooling oil leaks from the sealing means or the life of the sealing means is shortened.

  Therefore, in the present embodiment, the above problem is prevented as follows. When the cooling pump 3 is driven, the cooling oil is supplied to each wet multi-plate brake device 9 through the supply path 11 while passing through the flow dividing valve 5, the filter 17 and the oil cooler 19. At this time, when the rotational speed of the cooling pump 3 is in a low drive range of 1000 rpm or less, the pump flow rate is less than the control flow rate of the diverter valve 5 (20 liters / min in the present embodiment). As indicated by the solid line, the pump flow rate becomes the cooling flow rate of the brake device as it is. Further, in a high drive range where the number of rotations of the cooling pump 3 exceeds 1000 rpm, the pump flow rate exceeds the control flow rate of the flow dividing valve 5, so that the cooling oil of the control flow rate flows out from the main flow outlet 5 b of the flow dividing valve 5. The remaining cooling oil obtained by subtracting the control flow rate from the pump flow rate flows out into the discharge path 13 from the diversion outlet 5c of the valve 5. That is, in the high drive range of the cooling pump 3, the cooling flow rate supplied to the brake device is kept constant at the control flow rate of the diversion valve 5 even if the pump speed increases. As described above, in the present embodiment, the cooling pump 3 can be set so as to provide a sufficient amount of cooling oil to the wet multi-plate brake device 9 when the cooling pump 3 is driven low, and the wet pump It can be avoided that a large amount of cooling oil is pumped too much into the plate brake device 9 and that the cooling oil leaks or the life of the sealing means is shortened.

  Further, in this embodiment, the pressure acting on the sealing means of the brake device is limited to 0.2 MPa to prevent leakage of cooling oil and shortening of the life of the sealing means. Here, for example, when an attempt is made to limit the downstream hydraulic pressure to 0.2 MPa by a relief valve, a general relief valve is difficult because the limiting hydraulic pressure is 0.5 MPa or less and the valve opening / closing operation is not stable. However, in the present embodiment, the flow rate of the cooling oil is limited by the diverter valve 5, and therefore the valve for stably limiting the flow rate is a mode in which the pressure acting on the sealing means is limited to 0.2 MPa. It is possible to ensure opening and closing operations.

  In general, the flow rate of the diverter valve may not be stable due to the change in the viscosity of the cooling oil due to temperature due to the structure. However, in this embodiment, since the relief valve 7 is also arranged downstream of the diverter valve 5, in the unlikely event that the diverter valve 5 flows cooling oil at a flow rate exceeding the control flow rate downstream thereof. In addition, the pressure applied to the sealing means in the wet multi-plate brake device 9 by the operation of the relief valve 7 can be reduced.

Embodiment 2. FIG.
FIG. 3 shows an outline of the cooling oil circuit 201 according to the second embodiment. Cooling oil circuit 201 has the same structure as cooling oil circuit 1 according to Embodiment 1 except for the parts described below. A branch point c is provided downstream of the diversion valve 5, a filter 17 is disposed on one side thereof, and a relief valve 207 is disposed on the other side. A relief path 221 is connected to the outlet of the relief valve 207, and its downstream end reaches the oil tank 15. Also in such a cooling oil circuit 201, it can be set to provide a sufficient amount of cooling oil to the wet multi-plate brake device 9 when the cooling pump 3 is driven low, and wet when the cooling pump 3 is driven high. It can be avoided that a large amount of cooling oil is pumped to the multi-plate brake device 9 to leak the cooling oil or shorten the life of the sealing means.

Embodiment 3 FIG.
FIG. 4 shows an outline of the cooling oil circuit 301 according to the third embodiment. Cooling oil circuit 301 has the same structure as cooling oil circuit 1 according to Embodiment 1 except for the parts described below. A branch point d is provided downstream of the cooling pump 3, a throttle means 327 is disposed on one side thereof, and a relief valve 307 is disposed on the other side. The throttling means 327 is configured to allow a constant control flow rate (20 liters / min in this embodiment) to flow from the throttling inlet 327a to the throttling outlet 327b. A relief path 321 is connected to the outlet of the relief valve 307, and its downstream end reaches the oil tank 15. In the cooling oil circuit 301 having such a configuration, when the rotational speed of the cooling pump 3 is in a low driving range of 1000 rpm or less, the pump flow rate is less than the control flow rate of the throttle means 327, so that the pump flow rate remains as it is in the brake device. The cooling flow rate is as follows. On the other hand, in the high drive range where the number of rotations of the cooling pump 3 exceeds 1000 rpm, the pump flow rate exceeds the control flow rate of the throttle means 327, so that the control flow of cooling oil flows out from the throttle outlet 327b of the throttle means 327. The remaining cooling oil obtained by subtracting the control flow rate from the flow rate, that is, the remaining cooling oil that cannot flow through the throttle means 327 reaches the relief valve 307 from the branch point d and flows to the oil tank 15 through the relief path 321. For this reason, in the high drive range of the cooling pump 3, the cooling flow rate supplied to the brake device is kept constant at the control flow rate of the throttle means 327 even if the pump speed increases. As described above, the present embodiment can also be set so as to provide a sufficient amount of cooling oil to the wet multi-plate brake device 9 when the cooling pump 3 is driven low, and when the cooling pump 3 is driven high, It can be avoided that a large amount of cooling oil is pumped to the plate brake device 9 to leak the cooling oil or shorten the life of the sealing means.

  The present invention described above is not limited to the above embodiment, and various modifications can be made. The positions of the filter 17 and the oil cooler 19 disposed on the supply path 11 are not limited thereto. Therefore, for example, they can be disposed at positions as indicated by reference numerals 417 and 419 in FIG. In addition, although relief valves 7 and 207 are provided in FIGS. 1 and 3, respectively, these relief valves are not indispensable, and the flow dividing valve can perform more accurate flow rate control with respect to the temperature condition of the cooling oil. If it can be used, the relief valve can be omitted. Furthermore, in the said embodiment, although illustrated as a cooling oil circuit which uses the wet multi-plate brake device of a forklift as a to-be-cooled part, this invention is not limited to this. In other words, the present invention is not intended for the case where the cooled portion is provided with an oil tank that receives oil that drops from the beginning of the cooled portion in preparation for leakage of the cooling oil, but from the housing of the cooled portion. The present invention is implemented for a configuration in which cooling oil is introduced and circulated through an internal cooling path, and the cooling oil is recovered by a predetermined recovery path while preventing leakage by a sealing means. Therefore, if it has such a structure, it can also implement other than a wet multi-plate brake device, for example, the transfer with which the transmission was equipped can also be implemented as a to-be-cooled part.

It is a figure which shows the structure of the cooling oil circuit which concerns on Embodiment 1 of this invention. It is a graph which shows the relationship between the cooling flow volume and pump rotation speed regarding the cooling oil circuit of this invention. It is a figure which shows the structure of the cooling oil circuit which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the cooling oil circuit which concerns on Embodiment 3 of this invention.

Explanation of symbols

1,201,301 Cooling oil circuit 3 Cooling pump 5 Split valve 9 Wet multi-plate brake device (cooled part)
11 Supply path 15 Oil tank 23 Recovery path 307 Relief valve 327 Throttle means

Claims (5)

A cooled part having a cooling path through which the cooling oil passes and a sealing means for preventing leakage of the cooling oil from the cooling path;
A pump driven by an internal combustion engine to pump cooling oil to the cooled part;
A supply path communicating the pump and the cooled part;
A cooling oil circuit, comprising: a diversion valve that restricts cooling oil to be supplied to the cooled portion so that a hydraulic pressure that is provided in the supply path and acts on the sealing means is a predetermined value or less. A cooled part having a cooling path through which the cooling oil passes and a sealing means for preventing leakage of the cooling oil from the cooling path;
A pump driven by an internal combustion engine to pump cooling oil to the cooled part;
A supply path communicating the pump and the cooled part;
Throttle means for limiting the cooling oil supplied to the cooled part so that the hydraulic pressure that is provided in the supply path and acts on the sealing means is a predetermined value or less;
A cooling oil circuit comprising: a relief valve disposed upstream of the throttle means in the supply path.   The cooling oil circuit according to claim 1, wherein a recovery path for recovering the cooling oil to the oil storage means is connected to the housing of the cooled part.   The cooling oil circuit according to claim 1, wherein the cooled part is a brake device.   The cooling oil circuit according to any one of claims 1 to 4, wherein a hydraulic pressure of 0.5 MPa or less acts on the sealing means.

Images